An Atlas on Cephalometric Landmarks

An Atlas on Cephalometric Landmarks

An Atlas on

Cephalometric Landmarks

Basavaraj Subhashchandra Phulari BDS MDS (Ortho-TSMA-Russia) FAGE FRSH

Formerly Faculty, Department of Orthodontics and Dentofacial Orthopedics Mauras College of Dentistry, Hospital and Oral Research Institute Republic of Mauritius

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Website: www.jaypeebrothers.com Website: www.jaypeedigital.com © 2013, Jaypee Brothers Medical Publishers All rights reserved. No part of this book may be reproduced in any form or by any means without the prior permission of the publisher. Inquiries for bulk sales may be solicited at: [email protected] This book has been published in good faith that the contents provided by the author contained herein are original, and is intended for educational purposes only. While every effort is made to ensure accuracy of information, the publisher and the author specifically disclaim any damage, liability, or loss incurred, directly or indirectly, from the use or application of any of the contents of this work. If not specifically stated, all figures and tables are courtesy of the author. Where appropriate, the readers should consult with a specialist or contact the manufacturer of the drug or device. An Atlas on Cephalometric Landmarks First Edition: 2013 ISBN: 978-93-5090-324-7 Printed at

To My dear parents Subhashchandra and Shivalingamma Phulari brothers Sangamesh, Jagadish and manjunath my beloved wife Dr Rashmi GS and my dear sons Yashas and Vrishank

Preface Cephalometrics has been used in orthodontics for diagnosis, treatment planning, to evaluate the dentofacial changes during treatment and to assess the dentofacial growth and development. Cephalometrics makes use of certain landmarks on the skull. The first important step in cephalometric analysis is accurate location and tracing of cephalometric landmarks on the cephalogram. Any error in tracing the landmarks may result in incorrect cephalometric analysis. This book focuses on understanding the various cephalometric landmarks. Each cephalometric landmark is explained in detail including its abbreviation, definition by various researchers, origin and radiographic anatomy of the landmarks. There are 20 chapters divided into 11 sections. Chapter two lists the different ways of classifying cephalometric landmarks given in the literature. In addition, a new working classification has been given that lists the numerous cephalometric landmarks logically which makes remembering easier. This working classification is used as a blueprint to systemically explain the cephalometric landmarks from chapter 3 through chapter 19. Chapter 20 explains application of all types of cephalometric landmarks in various cephalometric analyses. In addition to the landmarks on lateral cephalogram, the landmarks on the posteroanterior (P-A) cephalogram and submentovertex (S-V) radiographic projection are also dealt in this book. I regret any deficiencies and shortcomings that might have crept in despite my best efforts. I would also welcome comments and suggestions from both students and teachers for further improvement of the book.

Basavaraj Subhashchandra Phulari [email protected]

Acknowledgments I express my heartfelt gratitude to Dr Rajendrasinh Rathore MDS, Chairman of Manubhai Patel Dental College and Hospital, Vadodara, Gujarat for his inspirational support during this endeavor and throughout my career. I also thank Dr Yashraj Rathore, Trustee, Manubhai Patel Dental College and Hospital, Vadodara, Gujarat, India for encouraging me during this project. I am indebted to my dear parents for all their love and sacrifices that have made me what I am. My special thanks are due to my beloved wife for her valuable comments and suggestions, and my dear sons for being the constant source of inspiration to set and reach new goals in life. I would like to thank Anatomage Inc. for providing images in chapter 17 and for the cover. Most of all I thank the Almighty for all His kindness and blessings showered upon me.

Contents Section 1: Introduction and History 1. Cephalometry in Orthodontics....................................................................................................... 3 Technical Aspects 4 Cephalometric X-ray Tracing Techniques 4

Section 2: Classification of Cephalometric Landmarks 2. Classification of Cephalometric Landmarks................................................................................. 7 Classification of cephalometric landmarks (Points) 7

Section 3: Cephalometric Landmarks Related to Cranial Bones 3. Cephalometric Landmarks Related to Frontal Bone.................................................................. 15 Parts of Frontal Bone 15 Articulation of Frontal Bone 15 Cephalometric Landmarks (Points) on Frontal Bone 15 Radiographic Anatomy of Frontal Bone 15

Nasion 16 Supra-Orbitale 17 Roof of the Orbital Cavity 17 Frontonasal/Frontomaxillary Nasal Suture 18

4. Cephalometric landmarks related to ethmoid bone ............................................................... 21 Parts of Ethmoid Bone 21 Articulation of Ethmoid Bone 21 Cephalometric Landmarks (Points) on Ethmoid Bone 21

Temporale 21

Neck of Crista Galli 23 Medio-orbitale 23 Sphenoethmoidal Point 24 Ethmoidale 24

5. Cephalometric landmarks related to Nasal bone.................................................................... 26 Articulation of frontal bone 26 Radiographic anatomy of nasal bone 26

Nasion 26

Frontonasal/Frontomaxillary Nasal Suture 28 Rhinion 29

6. Cephalometric landmarks related to temporal bone ............................................................. 31 Articulation of Temporal Bone 31 Radiographic Anatomy of Temporal Bone 31 Cephalometric Landmarks (Points) on Temporal Bone 31

Porion 32 Zygomatic Arch 32 Mastiodale 33

7. Cephalometric landmarks related to sphenoid bone ............................................................. 35 Cephalometric Landmarks (Points) on Sphenoid Bone 35

Dorsum of Sella 36 Floor of Sella 37 Clinoidale 38 Spheno-Occipital Synchondrosis 39

Pterygoid point 40 Sella 41 Sella Entrance 41 Sphenoethmoidal point 42 Pterygomaxillary Fissure 44

xii

8. Cephalometric landmarks related to occipital bone .............................................................. 46 Cephalometric landmarks (Points) on occipital bone 46 Radiographic anatomy of Occipital bone 46

Basion 46

Opisthion 48 Bolton’s point 48 Spheno-occipital synchondrosis 50

9. Cephalometric landmarks related to Zygomatic bone ............................................................. 52 Radiographic Anatomy of Zygomatic Bone 52 Cephalometric landmarks (Points) on Zygomatic bone 52

Orbitale 52 Temporale 54

Section 4: Cephalometric Landmarks Related to Facial Bones and Dentition 10. Cephalometric Landmarks Related to Maxilla............................................................................ 59


Cephalometric Landmarks (Points) on Maxilla 59

Anterior Nasal Spine 59 Point A 61 Prosthion 62

Posterior Nasal Spine 64 Pterygomaxillary Fissure 65 Key Ridge 66 Orbitale 67

11. Cephalometric Landmarks Related to Dentition............................................................................ 70 Incision Superius Incisalis 71 Incision Superius Apicalis 73 Incision Inferius Incisalis 74 Incision Inferius Apicalis 75 Anterior Point of Occlusion 76 Posterior Point of Occlusion 77

Maxillary Central Incisor 79 Maxillary First Molar 79 Mandibular Central Incisor 80 Mandibular First Molar 81 mi 82 ms 83

12. Cephalometric Landmarks Related to Mandible............................................................................ 85 Cephalometric landmarks (Points) on Mandible 85 Parts of Mandible 85 Nerve Supply to Mandible 85 Articulations 86

Infradentale 86 Point B 87 Pogonion 88

Gnathion 89 dd 91 Menton 92 Gonion 93 Articulare 93 kk 94 Condylion 95

Section 5: Cephalometric Landmarks Related to Cervical Bones 13. Cephalometric landmarks related to hyoid bone ................................................................. 101 Parts of the Hyoid Bone 101 Radiographic Anatomy of Hyoid Bone 101

Cephalometric Landmarks (Points) on Hyoid Bone 101

Hyoid 101

14. Cephalometric landmarks related to Vertebrae......................................................................... 103 Radiographic anatomy of cervical vertebrae 103 Cephalometric Landmarks on Cervical Vertebra 103 Cephalometric Landmarks (Points) Related to Cervical Vertebra 103

cv2ip 104 cv2ap 104 cv2ia 106 cv3sp 106

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cv5ip 113 cv5sa 113 cv5ia 115 cv6sp 115 cv6ip 116 cv6sa 116 cv6ia 118 Cervical Vertebrae as Indicators of Skeletal Maturity 118

cv3ip 107 cv3sa 107 cv3ia 109 cv4sp 109 cv4ip 110 cv4sa 110 cv4ia 112 cv5sp 112

Section 6: Cephalometric landmarks related to Pharynx 15. Cephalometric landmarks related to Pharynx........................................................................ 123 Nasopharynx 123 Oropharynx 123 Laryngopharynx 123 Cephalometric Landmarks (Points) on Pharynx 123

Posterior Pharyngeal Wall 124 Superior Pharyngeal Wall 124 Tip of the Uvula 124 Point on the Oral Side of the Soft Palate 124

Anterior Nasal Spine, Posterior Nasal Spine and Pterygomaxillary Fissure 123

Point on the Pharyngeal Side of the Soft Palate 124

Anterior Pharyngeal Wall 123

Upper Point of Tongue 124 Significance 124

Section 7: Soft Tissue Cephalometric Landmarks Soft Tissue Cephalometric Landmarks (Points) Related to Forehead 127

Soft Tissue Glabella 127 Soft Tissue Nasion 128 Nasal Crown 129 Pronasale 129 Point “T” 130 Alar Crease Junction 131

Subnasale 131 Soft Tissue Subspinale 133 Labrale Superius 134 Stomion 135 Labrale Inferius 136 Soft Tissue Submentale 136 Soft Tissue Pogonion 138 Soft Tissue Gnathion 139

Contents

16. Soft Tissue Cephalometric Landmarks.......................................................................................... 127

Section 8: 3D Cephalometric Landmarks 17. 3D Cephalometric Landmarks.................................................................................................... 143 Vertex 143 Soft Tissue Nasion 143 Pronasale 144 Subnasale 144 Soft Tissue Subspinale 145 Labrale Superius 146 Stomion 146 Labrale Inferius 146 Soft Tissue Submentale 147 Soft Tissue Pogonion 147 Soft Tissue Gnathion 148 Orbitale 148

Zygomatic Prominence 149 Zygion 149 Condylion 149 Gonion 150 Ch 150 Cheilion 151 Alare 151 Exocanthion 151 Sella 152 Sella entrance 153 Basion 153 Anterior Nasal Spine 154

xiv

Section 9: PA Cephalometric Landmarks 18. PA Cephalometric Landmarks.................................................................................................... 159 Taking Pa Cephalogram 160

Maxillary First Molar 168

Structures Involved in Pa Cephalogram 160

Cuspid 169

Crista galli 160 Top of nasal septum 161 NC 162

Incision Inferius Apicalis 170 Incision inferius frontale 171

Zyg-Zygoma 162

Mandibular First Molar 171

zygion 163

mi 172

Zygomatic arch 163 Zygomatic suture point 164 Jugal process 164

Mandibular molar 173 Menton 173 Articulare 174

Maxillare 165


Incision Inferius Incisalis 169

Incision Superius Incisalis 165 Incision Superius Apicalis 166 Maxillary molar 167

malare 174 Antegonial Tubercles 175 Antegonion 175

Section 10: SV Cephalometric Landmarks

19. SV Cephalometric Landmarks.................................................................................................... 179 Basion 179

Maxillary Apical Base Midline 185

Opisthion 179

Mandibular Dental Midline 185

Foramina spinosa points 180

Mandibular Apical Base Midline 186

Foramina spinosum 180

First Molar Point 187

Odontoid 181

Gonion point 187

Pterygomaxillary fissure 182

Condylion medialis 188

Middle cranial fossa points 182

Condylion lateralis 188

Posterior Vomer point 182

Condylion Anterioris 189

Posterior Cranial vault points 183

Condylion posterioris 190

Angulare point 184

Section 11: Applications of Cephalometric Landmarks 20. Applications of Cephalometric Landmarks.............................................................................. 193 Bjork Cephalometric Analysis 193

Holdaway Cephalometric Analysis 197

Coben Craniofacial and Dentition Cephalometric

Legan and Burstone Soft Tissue Cephalometric

Analysis 194

Analysis 198

Downs Cephalometric Analysis 195

Rickett’s Cephalometric Analysis 198

Farkas and Coworkers Soft Tissue Cephalometric

Sassouni Cephalometric Analysis 199

Analysis 196

Di Paolo’s Quadrilateral Analysis 200

Harvold Cephalometric Analysis 196

Hasund (Bergen) Cephalometric Analysis 200

xv

Jarabak Cephalometric Analysis 201

Wit’s Cephalometric Analysis 206

Riedel Cephalometric Analysis 202

Basis Cephalometric Analysis 207

Schwartz Cephalometric Analysis 203

Cagliari Cephalometric Analysis 207

Wylie Cephalometric Analysis 203

Chieti Cephalometric Analysis 208

Steiner’s Cephalometric Analysis 204

McGann Cephalometric Analysis 209

Tweed’s Cephalometric Analysis 205

Index...................................................................................................................................................... 211

Contents

Section

1

Introduction and History

 Cephalometry in Orthodontics

Chapter

1

Cephalometry in Orthodontics

Cephalometric radiographs are used in orthodontic diagnosis to evaluate the pre-treatment dental and facial relationship of a patient, to evaluate changes during treatment and to assess tooth movement and facial growth at the end of treatment. On the cephalometric film, teeth can be related to one another, to the jaw in which they reside, and to cranial structures. The maxilla and mandible can be related to one another and other structures into the cranium and the soft tissue profile can be evaluated. Cephalometric analysis is one among various diagnostic aids. An orthodontic diagnosis is not possible only on the basis of cephalometry. Cephalometric analysis is an important aid in orthodontic diagnosis only if its findings are correctly and wisely interpreted with the help of other diagnostic aids. In the cephalometric assessment, certain carefully defined points are located on the radiographs, and linear and angular measurements are made from these points. The expressions of these measurements in various ways produce analysis of skeletal size and form.

Figure 1.1: Lateral cephalogram

Types of Cephalogram There are following two types of cephalograms 1. Lateral cephalogram: Lateral cephalogram provides a lateral view of the skull (Fig. 1.1). It is taken with the head in a standardized reproducible position at a specified distance from the source of the x-ray. Lateral cephalogram commonly is used for cephalometric analysis. 2. Frontal cephalogram: This provides an antero-posterior view of the skull (Fig. 1.2).

Uses of Cephalometric Analysis 1. Cephalometric analysis is routinely used for diagnostic purpose to assess whether malocclusion dental or skeletal in origin. 2. It enables clinician to know accurately the extent to which patient deviates from described norms.

Figure 1.2: Frontal cephalogram

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3. It is used to monitor the changes occurring due to growth or treatment or their combination. In other words, precise evaluation of patient’s response to treatment is made possible. 4. Yet another use of cephalometrics is to predict changes that should occur in future for patient after orthodontic treatment. An architectural plan / blueprint of orthodontic treatment.

Technical Aspects

Section 1  Introduction and History

The cephalometric radiographs are taken using an apparatus that consists of an X-ray source and a head holding device called cephalostat. The cephalostat consists of two ear rods that prevent the movement of the head in the horizontal plane. Vertical stabilization of the head is brought about by an orbital pointer that contacts the lower border of the left orbit. The upper part of the face is supported by the forehead clamp positioned above the region of the nasal bridge. The distance between the X-ray source and the mid-sagittal plane of the patient is fixed at 5 feet (152.4 cm). Thus the equipment helps in standardizing the radiographs by use of constant head position and source film distance so that serial radiographs can be compared. There are many systems of cephalometric analysis, which utilize various points and outline on the lateral cephalogram radiograph.

Cephalometric X-ray Tracing Techniques Masking tape is used to attach the cephalometric X-ray to the acrylic acetate tracing paper sheet. Tracing is made on the frosted surface of acetate tracing sheet. The tracing is begun by marking the hard and soft tissue points needed for the analysis on the tracing sheet. Soft tissue profile is traced and then the sella turcica going forward to the planum sphenoidale along the floor of the anterior cranial fossa of the shadows of the greater wings of sphenoid bone are

traced. The anterior surface of the frontal and nasal bones are then traced followed by tracing the outline of the maxilla and from the anterior nasal spine along the floor of the nasal cavity back to posterior nasal spine from posterior nasal spine.

Bibliography 1. Bennett GC, Kronman JH. A cephalometric study of mandibular development and its relationship to the mandibular and occlusal planes. Angle orthodont.1970;40:119-28. 2. Bjork A. Prediction of mandibular growth rotation. Am J Orthodont. 1969;55:585-99. 3. Broadbent BH. A new X-ray technique and its application to orthodontics, Angle Orthod. 1931;1:45-66. 4. Brodie AG, Downs WB, Goldstein A, Myer E. Cephalometric appraisal of orthodontic results: A preliminary report. Angle orthodont. 1938;8:261-5. 5. Downs WB, Variations if facial relationship: Their significance in treatment and prognosis. Am J Orthod. 1948;34:812. 6. Downs WB. Analysis of the dentofacial profile. Angle Orthod. 1956; 26:191. 7. Downs WB. Analysis of the dento-facial profile. Angle orthodont. 1956;26:191-212. 8. Houston WJB. The analysis of error in orthodontics measurements. AM J Orthod. 1983;83:382-90 9. Jacobs. Introduction to Radiographic Cephalometry, Lea and Febiger, Philadelphia. 1985. 10. Jacobson A. Radiographic cephelometry: From basics to video imaging, Chicago 1995, Quintessence Pub Co. 11. Jacobson A. The appraisal of jaw disharmony. Am J Orthod. 1975; 67:125-38. 12. Jakobson S. Cephelometric evaluation of treatment effect on ClassIIDivision I malocclusions. Amer J Orthodont. 1967;53:446-57. 13. Moorrees, CFA, Lebret L. The mesh diagram and cephalometricss. Angle Orthodont. 1962;32:214-31. 14. Rickets RM, Bench RW, Hilgers JJ, Schulhof R. An overview of computerized cephalometrics. Am J Orthodont. 1972;61:1-28. 15. Steiner CC. The use of Cephalometrics as an aid in planning & assessing orthodontic treatment. Am J Orthod. 1960;46:721. 16. Subtelny JD. Cephalometric diagnoss, growth and treatment: something old, something new? Am J Orthodont. 1970;57:262-86. 17. Susomi R. A cephalometric evaluation of dentofacial growth in mandi bular protrusion subjects. J Osaka Univer. Dent. CSch. 1969;9:25-35. 18. Thomas M Graber, Robert L Vanarsdall. Orthodontics current principles and techniques, Mosby year book Inc. 1994. 19. Tweed CH. The diagnosis facial triangle in the control of treatment objectives. Am J Orthodont. 1969;55:667.

Section

2

Classification of Cephalometric Landmarks

 Classification of Cephalometric Landmarks

Chapter

2

Classification of Cephalometric Landmarks

Cephalometry makes use of certain landmarks or points on the skull which are used for quantitative analysis and measurements.

1. Hard tissue cephalometric landmarks. 2. Soft tissue cephalometric landmarks. Flow chart 2.2: Cephalometric landmarks/points

Classification of cephalometric landmarks/points The first two classifications given below are well-known in the literature. In addition to these basic existing classifications, the author has attempted to categorize the cephalometric landmarks in various ways to simplify their understanding and subsequent applications in various cephalometric analysis.

Classification of cephalometric landmarks based on Origin Based on the origin, cephalometric landmarks/points are classified in the following two types (Flow chart 2.1): 1. Anatomic cephalometric landmarks/points. 2. Derived cephalometric landmarks/points. Flow chart 2.1: Cephalometric landmarks/points

Hard tissue cephalometric landmarks These landmarks represent the actual hard tissue structures of the skull, such as nasal bone, ethmoidal bone, frontal bone, maxillary bone, mandible and hyoid, etc. Examples of hard tissue cephalometric landmarks— • Nasion • Neck of crista galli • Temporale • Sella • Menton • Gonion.

Soft tissue cephalometric landmarks Anatomic cephalometric landmarks/points These landmarks represent the actual anatomic structures of the skull, e.g. Nasion, point A, point B, ANS, PNS, etc.

Derived cephalometric landmarks/points These are landmarks that have been obtained secondarily from anatomic structures in a lateral cephalogram, e.g. Gnathion, Anterior Point of Occlusion, etc.

cephalometric landmarks Based on Structures Involved Based on structures involved, cephalometric landmarks/points can be classified as follows (Flow chart 2.2):

Cephalometric landmarks/points located on soft tissues are categorized as soft tissue cephalometric landmarks/points. Soft tissues: • Forehead • Nose • Lips • Chin. Examples of soft tissues cephalometric landmarks— • Soft tissue nasion • Subnasale • Subspinale • Stomion • Soft tissue pogonion • Soft tissue gnathion.

8

Cephalometric landmarks Based on the type or Side Involved

• Point B • Menton, etc.

Based on the side involved cephalometric landmarks/points can be classified as follows (Flow chart 2.3): 1. Unilateral cephalometric landmarks. 2. Bilateral cephalometric landmarks.

Bilateral cephalometric landmarks

Section 2  Classification of Cephalometric Landmarks

Flow chart 2.3: Cephalometric landmarks/points

These are cephalometric landmarks found on both right and left side. Examples • Gonion • Articulare • APOcc • U 6 • L 6, etc.

Hard or Soft Tissue cephalometric landmarks

Unilateral cephalometric landmarks These are cephalometric landmarks or points situated in the midline. Examples • Nasion • Neck of crista galli • Point A

Cephalometric landmarks/points can be hard or soft tissue landmarks. Hard tissue and soft tissue landmarks can be further classified into anatomic and derived and then subclassified into unilateral or bilateral (Flow chart 2.4).

Cephalometric Landmarks/Points can be Found on lateral Cephalogram, PA Cephalogram and SV Cephalogram (Flow Chart 2.5)



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Types of Cephalometric Landmarks/Points Cephalometric landmarks/points can be classified into following three types (Flow chart 2.6) 1. Cephalometric landmarks/points related to cranial bones 2. Cephalometric landmarks/points related to pharynx 3. Cephalometric landmarks/points related to cervical vertebrae

Classification of Cephalometric Landmarks/ Points Based on their Location The detailed description of the cephalometric landmarks/ points in this book follows this working classification (Flow chart 2.7).


A

B

C

Chapter 2  Classification of Cephalometric Landmarks


10

Cephalometric landmarks/points related to cranial bones

Cephalometric landmarks/points related to zygomatic bone

Cephalometric landmarks/points related to frontal bone

• Orbitale • Temporale

• • • • • •

Cephalometric landmarks/points related to Facial Bone and Dentition

Nasion Supra-orbitale Roof of orbit Frontozygomatic suture Frontale Frontomaxillary nasal suture

Section 2  Classification of Cephalometric Landmarks

Cephalometric landmarks/points related to ethmoid bone • • • • •

Temporale Neck of crista galli Medio-orbitale Sphenoethmoidal point Ethmoidale

Cephalometric landmarks/points related to nasal bone • Nasion • Rhinion • Frontonasal/frontomaxillary nasal suture

Cephalometric landmarks/points related to temporal bone • Porion • Zygomatic arch • Mastiodale

Cephalometric landmarks/points related to maxilla • • • • • • • •

Anterior nasal spine Point A Anterior point of occlusion Prosthion Posterior nasal spine Pterygomaxillary fissure Key ridge Orbitale

Cephalometric landmarks/points related to dentition • • • • • • • • • • • •

Incision superius incisalis Incision superius apicalis Incision inferius incisalis Incision inferius apicalis Anterior point of occlusion Posterior point of occlusion Maxillary central incisor Maxillary first molar Mandibular central incisor Mandibular first molar Mi Ms

Cephalometric landmarks/points related to sphenoid bone

Cephalometric landmarks/points related to mandible

• • • • • • • • •

• • • • • • • • • •

Dorsum sella Floor of sella Clenoidale Spheno-occipital synchondrosis Pterygoid point Pterygomaxillary fissure Foramen spinosum point Sella Sphenoethmoidal point

Cephalometric landmarks/points related to occipital bone • • • •

Basion Opisthion Bolton’s point Spheno-occipital synchondrosis

Infradentale Point B Pogonion Gnathion dd Menton Gonion Articulare kk Condylion

Cephalometric landmarks/points related to Cervical bones Cephalometric landmarks/points related to hyoid bone • Hyoid.

11

Cephalometric landmarks/points related to vertebrae • • • • • • • • • •

cv2ap cv2ip cv2ia cv3sp cv3ip cv3sa cv3ia cv4sp cv4ip cv4sa

• • • • • • • • •

cv4ia cv5sp cv5ip cv5sa cv5ia cv6sp cv6ip cv6sa cv6ia

Soft tissue cephalometric landmarks/points

Flow chart 2.8: Soft tissue cephalometric landmarks/points

Chapter 2  Classification of Cephalometric Landmarks

Soft tissue cephalometric landmarks or points can be classified as follows (Flow chart 2.8): 1. Soft tissue cephalometric landmarks or points related to forehead • Trichion • Soft tissue glabella. 2. Soft tissue cephalometric landmarks or points related to nose • Soft tissue nasion

• Nasal crown • Pronasale • Point T 3. Soft tissue cephalometric landmarks or points related to lips Upper lip • Soft tissue subspinale • Labrale superius • Philtrum • Cuspid bow • Vermilion border of upper lips Lower lip • Labrale inferius • Soft tissue point B Upper and lower lips • Stomion - Stomion superius - Stomion inferius 4. Soft tissue cephalometric landmarks/points related to chin • Soft tissue pogonion • Soft tissue menton • Soft tissue gnathion.

Section

3

Cephalometric Landmarks Related to Cranial Bones

      

Cephalometric Landmarks Related to Frontal Bone Cephalometric Landmarks Related to Ethmoid Bone Cephalometric Landmarks Related to Nasal Bone Cephalometric Landmarks Related to Temporal Bone Cephalometric Landmarks Related to Sphenoid Bone Cephalometric Landmarks Related to Occipital Bone Cephalometric Landmarks Related to Zygomatic Bone

ChApTER

3

Cephalometric Landmarks Related to Frontal Bone

The frontal bone (Fig. 3.1) (Os frontale in Latin), is a membranous bone that forms the anterior part of the cranial vault. The frontal is like half a shallow, irregular cap forming the forehead or form on each side a horizontal orbital part roof of most of an orbital cavity. The frontal bone is thick with trabecular tissue between compact laminae, trabecular being absent near the frontal sinuses.

Parts of Frontal Bone Parts of frontal bone are listed below: • Squamous part • Orbital plates • Nasal process • Zygomatic process.

Articulation of Frontal Bone The frontal bone articulates with 12 bones in total and is listed below: • Parital bone • Sphenoid bone • Ethmoid bone • Maxillary bone • Nasal bone • Lacrimal bone • Zygomatic bone • Temporal bone

Table 3.1: Cephalometric landmarks (points) related to frontal bone Cephalometric landmarks

Abbreviation

Type

Origin

Nasion

N or Na

Unilateral

Anatomic

Supra-orbitale

SOr

Bilateral

Anatomic

Roof of orbit

RO

Bilateral

Anatomic

Frontomaxillary nasal suture

FMN

Unilateral

Anatomic

Radiographic Anatomy of Frontal Bone (Fig. 3.2) On lateral cephalogram, the inner and outer cortical plates of frontal bone appear as two parallel radio-opaque lines descending downwards from coronal suture. Anterio-inferiorly, these two radio-opaque lines diverge to encase the frontal sinus, which appears radiolucent area. The outer radio-opaque line representing outer cortical plates meets nasal bone at frontonasal suture, while the inner radio-opaque line representing inner cortical plate meets

Cephalometric Landmarks (Points) on Frontal Bone Cephalometric landmarks seen on the frontal bone are of anatomic origin and are as follows (Table 3.1):

Figure 3.1: Frontal bone

Figure 3.2: Radiographic anatomy of the frontal bone on the lateral cephalogram

16

ethmoid bone at frontoethmoidal suture. Above the horizontal Nasion part of the internal cortical plate, there are two radio-opaque lines. The upper radio-opaque line represents endocranial surface of the frontal bone, which forms the base for anterior Abbreviation cranial fossa, and the other radio-opaque line represents the N–Nasion is abbreviated using English alphabet and is exocranial surface of the frontal bone which forms the roof of expressed as capital letter or upper case N. the orbit.

Definition

Section 3  Cephalometric Landmarks Related to Cranial Bones

Nasion (Figs 3.3A to D) is the most anterior point of the frontonasal suture in the middle.1

A

B

C

D

Figures 3.3A to D: (A) Nasion on lateral cephalogram; (B) Magnified image showing nasion on the lateral cephalogram; (C) Nasion on graphic illustration; and (D) Magnified image of nasion on graphic illustration

17

According to Willam B Downs Nasion is the suture between the frontal and nasal bones.1

• Relationship of anterior and posterior cranial base is assessed using N-S-Ar angle.

Supra-Orbitale

According to TM Graber Nasion is the junction of the nasal and frontal bone as seen on the profile of the cephalometric roentgenogram.2

According to B Holly Broadbent

According to Leslie G Farkas Nasion is the point in the midline of both the nasal root and the frontonasal suture.4

Type Nasion is a unilateral, anatomic, hard tissue cephalometric landmark (Point).

Origin Nasion is a hard tissue cephalometric landmark of anatomic origin.

Tracing of Nasion on the Lateral Cephalogram The outer cortical plate of frontal bone, nasal bone and frontonasal suture appears as radio-opaque line on the lateral cephalogram. The outer cortical plate of frontal bone is denser radio-opaque than compared to other two bony structures. Trace outer cortical plate of frontal bone, nasal bone and frontonasal suture, the point in the midline where all three structures meet is the point of nasion. In other way nasion is the most anterosuperior point on the frontonasal suture in the midline.

Significance (Ref to Chapter 20) Nasion is used as one of the reference points in the construction of angles and planes for the assessment of following: • Relationship of maxilla to cranial base is assessed using SNA angle. • Relationship of mandible to cranial base is assessed using SNB angle. • Maxillo-mandibular relationship with anterior cranial base is assessed using ANB angle. • Inclination upper incisors are assessed using NA-Upper incisor angular and NA-Upper incisor linear. • Inclination lower incisors are assessed using NB-Lower incisor angular and NB-Lower incisor linear.

SOr–Supra-orbitale is abbreviated using English alphabets and is expressed as capital or upper case S, O followed by lower case r and is written continuously without any space between the alphabets.

Definition According to Viken Sassouni

Chapter 3  Cephalometric Landmarks Related to Frontal Bone

Nasion is the craniometric point where the midsagittal plane intersects the most anterior point of the frontonasal suture, the anterior termination of the Bolton’s plane.3

Abbreviation

Supra-orbitale (Figs 3.4A to D) is the most anterior point of the intersection of the shadow of the roof of the orbit and its lateral contour.5

Type

Supra-orbitale is a bilateral, hard tissue lateral cephalometric landmark (point).

Origin

Supra-orbitale is a hard tissue cephalometric landmark of anatomic origin.

Tracing the Supra-Orbitale on the Lateral Cephalogram

Supra-orbitale, the point on the orbital margin where it turns onto the upper roof of the orbital cavity, is comparatively easy to trace.

Significance (Ref to Chapter 20)

• Supra-orbitale is useful reference point for anteroposterior differences and vertical differences between the right and left sides when the orbits are traced. • Supra-orbital landmark is used as a landmark in Sassouni cephalometric analysis.

Roof of the Orbital Cavity Abbreviation RO–Roof of the orbital cavity is abbreviated using English alphabets and is expressed as capital or upper case R, O and is written continuously without any space between the alphabets.


18

A

B

C

D

Figures 3.4A to D: (A) Supra-orbitale on lateral cephalogram; (B) Magnified image showing supraorbitale on the lateral cephalogram; (C) Supra-orbitale on graphic illustration; and (D) Magnified image of supra-orbitale on graphic illustration

Definition The roof of the orbital cavity is formed by the bone between the anterior cranial fossa above and the orbital cavity below.

According to Viken Sassouni The roof of the orbit is the uppermost point of the orbit.5

Type Roof of the orbital cavity (Figs 3.5A to D) is a bilateral, anatomic hard tissue lateral cephalometric landmark.

Frontonasal/Frontomaxillary Nasal Suture Abbreviation FMN–Frontomaxillary suture is abbreviated using English alphabets and is expressed as capital or upper case F, M and N and are written continuously without any space between the alphabets.

Tracing the Roof of Orbit on the Lateral Cephalogram

Definition

On the cephalogram, both right and left roofs of the orbital cavity are superimposed and reveal as a radio-opaque line anteriorly and posteriorly leading to pituitary fossa.

Frontomaxillary nasal suture (Figs 3.6A to D) is the most superior point of the suture, where the maxilla articulates with the frontal and nasal bones.

19

B

C

D

Chapter 3  Cephalometric Landmarks Related to Frontal Bone

A

Figures 3.5A to D: (A) Roof of orbit on lateral cephalogram; (B) Magnified image showing roof of orbit on the lateral cephalogram; (C) Roof of orbit on graphic illustration; and (D) Magnified image of roof of orbit on graphic illustration

A

B

C

D

Figures 3.6A to D: (A) Frontomaxillary suture on lateral cephalogram; (B) Magnified image showing frontomaxillary suture on the lateral cephalogram; (C) Frontomaxillary suture on graphic illustration; and (D) Magnified image of frontomaxillary suture on graphic illustration;

20

Type

References

Frontomaxillary nasal suture is a unilateral, anatomic, hard tissue cephalometric landmark.

1. Downs WB. Variations in facial relationships. Their significance in treatment and prognosis. Am J of Ortho. 1948;34:812-39. 2. Graber TM. New horizons in case analysis-clinical cephalometrics. Am J of Ortho.1952;38:603-24. 3. Broadbent BH Sr. Bolton’s standards of dentofacial developmental growth. The CV Mosby Company. 1975;133-5. 4. Farkas LG. Anthropometry of the head and face in medicine—Elsevier North Holland, Inc. 1981;9-14. 5. Sassouni V. Orthodontics in dental practice. The CV Mosby Company. 1971;330-7.



Frontomaxillary nasal suture is situated/located on anterior cranial base, unlike N and can therefore also be used for measurement or defining the cranial base (Moyers 1988).

Chapter

4

Cephalometric landmarks related to ethmoid bone

The ethmoid bone (Fig. 4.1) (Os ethmoidale in Latin). The Ethmoid bone is cuboidal and fragile, lies anterior in the cranial base and is involved in the structure of the orbital walls and nasal septum, the roof and lateral walls of the nasal cavity. It is described as a heavy horizontal cribriform plate, a median plate and two total labyrinths.

• • • • • •

Parts of Ethmoid Bone

Cephalometric Landmarks (Points) on Ethmoid Bone

Parts of ethmoid bone are listed below: • Cribriform plate • Crista galli • Perpendicular plate.

Articulation of Ethmoid Bone The ethmoid bone articulates with 13 bones in total and is listed below: • Sphenoid bone • Frontal bone

Lacrimal bone – (2) Palatine bone – (2) Vomer Maxillary bone – (2) Inferior nasal concha – (2) Nasal bone – (2).

Cephalometric landmarks seen on the ethmoid bone are of anatomic origin and are as follows (Table 4.1): Table 4.1: Cephalometric landmarks (points) related to ethmoid bone Cephalometric landmarks

Abbreviation

Type

Origin

Temporale

Te

Bilateral

Anatomic

Neck of the crista galli

NC

Unilateral

Anatomic

Medio-orbitale

mo

Bilateral

Anatomic

Sphenoethmoidal point

SE

Unilateral

Anatomic

Ethmoidale

Eth

Unilateral

Anatomic

Radiographic Anatomy of Ethmoid bone (Fig. 4.2) On the lateral cephalogram, the cribriform plate of the ethmoid bone is seen, which appears as a radio-opaque line below the horizontal part of the internal cortical plate of the frontal bone. The intersection of the shadows of the ethmoid and the anterior wall of the infratemporal fossa is identified as temporal and is a bilateral hard tissue cephalometric landmark. The intersection of the shadows of the greater wing of the sphenoid and the cranial floor is identified as Sphenoethmoidal (SE).

Temporale Abbreviation Figure 4.1: Ethmoid bone

Te–Temporale is abbreviated using English alphabets and is expressed as capital or upper case T followed by small letter

22

or lower case e and is written continuously without any space between the alphabets.

Definition Temporale (Figs 4.3A to D) is the intersection of the shadows of the ethmoid and the anterior wall of the infra-temporal fossa.


According to Viken Sassouni Intersection of the shadows of the ethmoid and anterior wall of the infra-temporal fossa.1

Type Temporale (Figs 4.3A to D) is a bilateral, anatomic, hard tissue cephalometric landmark.

Figure 4.2: Radiographic anatomy of ethmoid bone

A

B

C

D

Figures 4.3A to D: (A) Temporale on lateral cephalogram; (B) Magnified image showing temporale on the lateral cephalogram; (C) Temporale on graphic illustration; and (D) Magnified image of temporale on graphic illustration

23

Neck of Crista Galli

• Crista galli lies behind the frontal sinuses on the lateral cephalogram and in the central part of the cranium on the posteroanterior cephalogram.

Abbreviation NC–Neck of Crista Galli is abbreviated using English alpha bets and is expressed as capital or upper case N and C and is written continuously without any space between the alphabets.

Definition

Tracing Neck of Crista Galli on The Lateral Cephalogram It is difficult to identify on the lateral cephalogram whereas it can be easily identified on the PA cephalogram.

Medio-orbitale

According to Viken sassouni

Type Neck of crista galli is an anatomic, unilateral, hard tissue cephalometric landmark.

Abbreviation

Chapter 4  Cephalometric Landmarks Related to Ethmoid Bone

Neck of the crista galli (Figs 4.4A and B) is the most constricted point of the projection of the perpendicular lamina of the ethmoid (almost at the level of planum).1

mo–Medio-orbitale is abbreviated using English alphabets and is expressed as lower case m, o and written continuously without any space between the alphabets.

Definition

Significance (Ref to chapter 20)

According to Athanasios E Athanasiou

• The crista galli is an important landmark of the midline for the analysis of bilateral symmetry in a posteroanterior cephalogram.

Medio-orbitale (Figs 4.5A and B) is the point on the medial orbital margin that is closest to the median plane.2

A

Figures 4.4A and B: (A) Neck of crista galli on frontal cephalogram; (B) Magnified image showing neck of crista galli on the frontal cephalogram

B

Figures 4.5 A and B: Medio-orbitale on the lateral cephalogram; (B) Magnified image showing medio-orbitale on the lateral cephalogram

A

B

24

Type

According to SN Bhatia and BC Leighton

Medio-orbitale is an anatomic, bilateral, hard tissue cephalo metric landmark.

The point of intersection between the greater wings of the sphenoid and the anterior cranial base.4

Type

Sphenoethmoidal Point

Sphenoethmoidal point is an anatomic, unilateral, hard tissue cephalometric landmark.

Abbreviation


SE–Sphenoethmoidal point is abbreviated using English alphabets and is expressed as upper case S, E and written continuously without any space between the alphabets.

Ethmoidale Abbreviation

Definition According to Robert E Moyers

The intersection of the shadows of the grater wing of the sphenoid and the cranial floor as seen in the lateral cephalogram3 (Figs 4.6A to D).

A

B

C

D

Eth–Ethmoidale is abbreviated using English alphabets and is expressed as capital or upper case E and small alphabets or lower case th and written continuously without any space between the alphabets.

Figures 4.6A to D: Sphenoethmoidale: (A) Sphenoethmoidale on the lateral cephalogram; (B) Magnified image showing sphenoethmoidale on the lateral cephalogram; (C) Sphenoethmoidale on graphic illustration; and (D) Magnified image of sphenoethmoidale on graphic illustration

25

B

C

D

Figures 4.7A to D: Ethmoidale: (A) Ethmoidale on the lateral cephalogram; (B) Magnified image showing ethmoidale on the lateral cephalogram; (C) Ethmoidale on graphic illustration; and (D Magnified image of ethmoidale on graphic illustration

Chapter 4  Cephalometric Landmarks Related to Ethmoid Bone

A

Definition

References

According to Arne Bjork

1. Viken Sassouni—Orthodontics in dental practice. The CV Mosby Company. 1971:330-7. 2. Athanasios E Athanasiou, Helmut Drioschk, Charles Bosch. Data and patterns of transverses dentofacial structure of 6 to 15 years–old children; A posteroanterio cephalometric study. 3. Robert M Moyers. Handbook of Orthodontics. Year Book medical Publishers, inc. 1988:251-9. 4. Bhatia SN, Leighton BC. A manual of facial growth–Oxford University press. 1993:10-5. 5. A Bjork. The face in profiles-Sven. Tandlak Tidskr. 1947;40:32-3.

The deepest median point of the anterior cranial fossa, corres ponding to the cribriform plate of the ethmoid bone.5

According to SN Bhatia and BC Leighton Ethmoidale (Figs 4.7A to D) is the lowest point on the anterior cranial fossa or the outline of the cribriform plate.4

Type Ethmoidale is an anatomic, unilateral, hard tissue cephalo metric landmark.

CHAPTER

5

Cephalometric Landmarks Related to Nasal Bone

The nasal bone (Fig. 5.1) (Os nasale in Latin), are paired bones that lie in the midline above the nasal fossae between the frontal processes of the maxilla. They articulate superiorly with the frontal bone at the fronto-nasal suture.

Articulation of Frontal Bone The nasal bone articulates with four bones in total and is listed below: • Maxilla • Frontal bone • Ethmoid bone • Nasal bone of opposite side.

Radiographic Anatomy of Nasal Bone (Fig. 5.2) On lateral cephalogram, the nasal bone appears as a triangular radio-opaque area. Its apex points to the tip of the nose and its base faces the frontonasal suture which appears as an oblique radiolucent line between frontal and nasal bones. The posterior part of the inner surface of the nasal bone merges with the radio-opaque line of the cribriform plate of the ethmoid bone. The anteromedial point of the frontonasal suture is identified as nasion and posteroinferior point is identified as FMN.

Nasion

Cephalometric Landmarks (Points) on Nasal Bone

Abbreviation

Cephalometric landmarks seen on the nasal bone are of anatomic origin and are as follows (Table 5.1):

N–Nasion is abbreviated using English alphabet and is expressed as capital letter or upper case N.

Table 5.1: Cephalometric landmarks related to nasal bone Cephalometric landmarks Nasion

Abbreviation Type N OR Na Unilateral

Orgin Anatomic

Frontonasal/frontomaxillary nasal suture Rhinion

FMN

Unilateral

Anatomic

Rh

Unilateral

Anatomic

Figure 5.1: Nasal bones

Figure 5.2: Radiographic anatomy of nasal bone

27

Definition

According to William B Downs

Nasion (Figs 5.3A to D) is the most anterior point of the frontonasal suture in the middle.

Nasion is the suture between the frontal and nasal bone.3

According to TM Graber

Type

Nasion is the junction of the nasal bone and frontal bones as seen on the profile of the cephalometric roentgenogram.1

Nasion is a unilateral, anatomic, hard tissue cephalometric landmark.

According to B Holly Broadbent Nasion is the craniometric point where the midsagittal plane intersects the most anterior point of the frontonasal suture; the anterior termination of the Bolton plane.2

Origin Nasion is a hard tissue cephalometric landmark of anatomic origin.

B

C

D

Chapter 5  Cephalometric Landmarks Related to Nasal Bone

A

Figures 5.3A to D: (A) Nasion on lateral cephalogram; (B) Magnified image showing nasion on the lateral cephalogram; (C) Nasion on graphic illustration; and (D) Magnified image of nasion on graphic illustration

28

A is a positive value and a posterior position of point A is a negative value. • In Rickett’s cephalometric analysis, the positioning of the chin is determined by the angle formed between the Ba-N plane and plane from foramen rotundum (PT) to Gn. The normal value of this angle is 90 degree. A larger angle suggests a protrusive or forward growing chin whereas a lesser angle suggests a retropositioning of the chin.



Nasion is used as one of the reference point in the construction of angles and planes for the assessment of the following: • Relationship of maxilla to cranial base is assessed using SNA angle. • Relationship of mandible to cranial base is assessed using SNB angle. • Maxillo-mandibular relationship with anterior cranial base is assessed using ANB angle. • Inclination upper incisors are assessed using NA-Upper incisor angular and NA-Upper incisor linear. • Inclination lower incisors are assessed using NB-Lower incisor angular and NB-Lower incisor linear. • Relationship of anterior and posterior cranial base assessed using N-S-Ar angle. • In McNamara cephalometric analysis, the cant of the upper lips is evaluated by constructiong an angle using a line tangent to the upper lip and the nasion. The nasion perpendicular is a vertical line drawn perpendicular to Frankfort horizontal plane. • Anteroposterior orientation of the maxilla to the cranial base is assessed by the linear distance between nasion perpendicular and point A. An anterior position of point

A

C

Frontonasal/Frontomaxillary Nasal Suture Abbreviation FMN–Frontomaxillary suture is abbreviated using English alphabets and is expressed as capital F, M and N and is written continuously without any space between the alphabets.

Definition Frontomaxillary nasal suture (Figs 5.4A to D) is the most superior point of the suture, where the maxilla articulates with the frontal and nasal bones.

B

D

Figures 5.4A to D: (A) Frontomaxillary nasal suture on lateral cephalogram; (B) Magnified image showing frontomaxillary nasal suture on the lateral cephalogram; (C) Frontomaxillary nasal suture on graphic illustration; and (D) Magnified image of frontomaxillary nasal suture on graphic illustration

29

Rhinion

According to Robert M Moyers According to Robert M Moyers, frontomaxillary nasal suture is the most superior point of the suture, where the maxilla articulates with the frontal and nasal bones.4

Type Frontomaxillary nasal suture is a unilateral, hard tissue cephalo metric landmark.

Abbreviation Rh–Rhinion is abbreviated using English alphabets and is expressed as capital or upper case R followed by lower case h, and is written continuously without any space between the alphabets.

Definition According to Spiro J Chaconas

Frontomaxillary nasal suture is a hard tissue cephalometric landmark of anatomic origin.

According to Spiro J Chaconas, Rhinion (Figs 5.5A to D) is the most anterior-inferior point on the tips of the nasal bones as seen from norma lateralis.5

Significance (Ref to Chapter 20) Frontomaxillary nasal suture is situated/located on anterior cranial base, unlike N and can therefore also be used for measure ment or defining the cranial base (Moyers 1988).

Type

Chapter 5  Cephalometric Landmarks Related to Nasal Bone

Origin

Rhinion is an anatomic, unilateral, hard tissue cephalometric landmark.

A

B

C

D

Figures 5.5A to D: (A) Rhinion on lateral cephalogram; (B) Magnified image showing Rhinion on the lateral cephalogram; (C) Rhinion on graphic illustration; and (D) Magnified image of Rhinion on graphic illustration

30

Tracing Rhinion on the Lateral Cephalogram Tracing the rhinion is difficult in few cases, where there is faded image of nasal bone in the tip region, in such cases the margin of the piriform aperture will be helpful in identifying the point rhinion. In most of the cases it is easy to identify on the lateral cephalogram. Trace the nasal bone from the frontonasal suture till the tip, the tip of the nasal bone is the point of rhinion.



Position of rhinion differs from individual to individual. As we learnt in anatomy, there are several types of nasal

bone, especially its inclination that affects the soft tissue profile.

References 1. Graber TM. New horizons in case analysis-clinical cephalometrics. Am J of Ortho. 1952;38:603-24. 2. Broadbent BH Sr. Bolton’s standards of dentofacial developmental growth. The C V Mosby Company. 1975;133-5. 3. Downs WB. Variations in facial relationships. Their significance in treatment and prognosis. Am J of Ortho. 1948;34:812-39. 4. Moyers RM. Handbook of Orthodontics–Year Book Medical Publishers, Inc. 1988;251-9. 5. Spiro J Chaconas. Orthodontics-PSG Publishing Company. 1980;37-45.

Chapter

6

Cephalometric landmarks related to temporal bone

Each temporal bone consists of following two portions (Fig. 6.1): • Squamous portion • Petrous portion. Squamous portion of the temporal bone is large and flat that forms the lateral wall of the cranium. Petrous portion of temporal bone is an irregular bone which forms the inferior part of the temporal bone.

Articulation of Temporal Bone Superiorly temporal bone articulates with parietal bone at squamoparietal suture. Inferiorly, it articulates with mandibular condyle at genoid fossa. Zygomatic process of temporal bone articulates wih zygomatic bone at zygomaticotemporal suture. The major part of the temporal bone that can usually be identified from the lateral cephalogram is the endocranial surface of the petrous portion. It appears as a triangular radioopaque area with its apex pointing upwards and backwards. The side of the triangle that appears as the anterosuperior radio-opaque line represents the posteroinferior limit of the middle cranial fossa. This radio-opaque line continues anteriorly to the endocranial surface of the squamous portion of the temporal bone and the greater wing of the sphenoid

Figure 6.1: Temporal bone

bone. The other side of the triangle, which appears as a vertical line, represents the anterior limit of the posterior cranial fossa.

Radiographic Anatomy of Temporal Bone (Fig. 6.2) The major part of the temporal bone that can usually be identified from the lateral cephalogram is the endocranial surface of the petrous portion. It appears as a triangular radio-opaque area with its apex pointing upwards and backwards.The side of the triangle that appears as the anterosuperior radio-opaque line represents the posteroinferior limit of the middle cranial fossa. This radioopaque line continues anteriorly to the endocranial surface of the squamous portion of the temporal bone. The other side of the triangle, which appears as a vertical line, represents the anterior limit of the posterior cranial fossa.

Cephalometric Landmarks (Points) on Temporal Bone Cephalometric landmarks seen on the temporal bone are of anatomic origin and are as follows (Table 6.1):

Figure 6.2: Radiographic anatomy of temporal bone

32

Table 6.1: Cephalometric landmarks related to temporal bone Cephalometric landmarks Porion Zygomatic arch Mastoidale

Abbreviation

Type

Origin

Po Zyg Ma

Bilateral Bilateral Bilateral

Anatomic Anatomic Anatomic

Porion

Type Porion (Figs 6.3A to D) is a bilateral, hard tissue cephalometric landmark.

Origin Porion is a hard tissue cephalometric point of anatomic origin.


Po–Porion is abbreviated using English alphabets and is expressed as capital letter or upper case P followed by lower case o, and is written continuously without any space between the alphabets.

1. Porion is used as one of the reference points in the construction of Frankfort horizontal plane and is used for the assessment of horizontal growth pattern using following angles: • FH-Mandibular plane angle (Go-Me) • FH-Palatal plane angle (ANS-PNS) • FH-Occlusal plane (APOcc – PPOcc) 2. Porion is also used as one of the reference points in the construction of angle and is used for the assessment of upper incisors torque using FH—long axis of upper incisors.


Abbreviation

Definition Porion is the most superior point of the external auditory meatus (the superior margin of the TMJ fossa, which lies at the same level may be substitute in the construction of the FH).

According to Arne Bjork The midpoint of the upper edge of the porous acoustics externus located by wings of the metal rods on the cephalometer. This is the cephalometric reference point.1

According to Willam B Downs The highest point on the superior surface of the soft tissue of the external auditory meatus.2

According to LB Higley

Zygomatic Arch Abbreviation Zyg–Zygomatic arch is abbreviated using English alphabets and is expressed as capital or upper case Z followed by lower case y and g, and is written continuously without any space between the alphabets.

The highest point on the roof of the left external auditory meatus.3

Definition

According to Robert E Moyers

According to Robert M Ricketts

The top of the ear rods Shadows the external auditory meatus.4

According to B Holly Broadbent Point on the upper margin of the porus acusticus externus the two poria and left orbitale defined the Frankfort horizontal plane.5

According to Robert M Ricketts, the Zygomatic arch is the center of zygomatic arch by inspection for frontal.7

Type Zygomatic arch is bilateral, hard tissue landmark.

According to Leslie G Farkas

Origin

Porion (soft) is the highest point on the upper margin of the cutaneous auditory meatus.6

Zygomatic arch is a hard tissue cephalometric landmark of anatomic origin.

33

B

C

D

Figures 6.3A and D: (A) Porion on lateral cephalogram; (B) Magnified image showing porion on the lateral cephalogram; (C) Porion on graphic illustration; and (D) Magnified image of porion on graphic illustration

Mastiodale Abbreviation Ms–Mastiodale is abbreviated using English alphabets and is expressed as capital or upper case M followed by lower case s, and is written continuously without any space between the alphabets.

Chapter 6  Cephalometric landmarks related to temporal bone

A

Definition According to Viken sassouni According to Viken Sassouni, the mastiodale is the lowest point on the contour of the mastoid process.8

Type Mastiodale (Figs 6.4A and B) is bilateral, cephalometric landmark.


34

A

B

Figures 6.4A and B: (A) Mastiodale on lateral cephalogram; (B) Magnified image showing mastiodale on the lateral cephalogram

Origin

References

Mastiodale is a hard tissue landmark of anatomic origin.

1. Arne Bjork. The face in profiles-Sven. Tandlak Tidskr. 1947;40:32-3. 2. Downs WB. Variations in facial relationships; Their significance in treatment and prognosis. Am J of Orthod. 1948;34:812-39. 3. Higley LB. Cephalometric standards for children 4-8 years of age-Am J of orthod. 1954;40:51-9. 4. Moyers RM. Handbook of Orthodontics. Year Book Medical Publishers, Inc. 1988;251-9. 5. Broadbent BH Sr. Bolton’s standards of dentofacial developmental growth. The CV Mosby Company. 1975;133-5. 6. Farkas LG. Anthropometry of the head and face in medicine—Elsevier north Holland Inc. 1981;9-14. 7. Ricketts RR. Provocations and perceptions in cranio-facial orthopedics –dental science and facial art. Rocky Mountain inc. 1989;797-803. 8. Viken Sassouni. Orthodontics in Dental Practice. The CV Mosby Company. 1971;330-7.

Tracing of Mastiodale on the Lateral Cephalogram Trace the mastoid process, which is located between the temporal bone and cranial base region. The lowest point of the mastoid process in the P-A cephalogram is the point of mastiodale. As we learnt in anatomy, the mastoid process is not so visible in the childhood, but it increases in size with the age and readily visible in both P-A cephalogram and lateral cephalogram.

Chapter

Cephalometric landmarks related to sphenoid bone

7

The sphenoid bone (Fig. 7.1) is in the base of the skull, wedged (as its name implies) between the frontal, temporal and occipital bones. It has a central body paired greater and lesser wings of separating laterally from it and two pterygoid processes descending from the junction of the body of the greater wing.

Cephalometric Landmarks (Points) on Sphenoid Bone Cephalometric landmarks seen on the sphenoid bone are as follows (Table 7.1): Table 7.1: Cephalometric landmarks related to sphenoid bone Cephalometric landmarks

Abbreviation

Type

Origin

Dorsum of sella

Sp

Unilateral

anatomic

Floor of sella

Si

Unilateral

anatomic

Clinoidale

Cl

Bilateral

anatomic

Spheno-occipital synchondrosis

SOS

Unilateral

anatomic

pterygoid point

pt

Bilateral

anatomic

Sella

S

Unilateral

anatomic

Sella entrance

Se

Unilateral

anatomic

Sphenoethmoidal point

Se

Unilateral

anatomic

Foramen spinosum point

Fsp

Bilateral

anatomic

pterygomaxillary fissure

ptm

Bilateral

anatomic

Radiographic anatomy of Sphenoid Bone (Fig. 7.2) The frontal bone, ethmoidal bone and sphenoid bone meet at frontosphenoethmoidal suture, which radiographically appears as a radiolucent line. At the frontosphenoethmoidal suture, these are two radio-opaque lines, one vertical and the other horizontal. The vertical radio-opaque line represents the anterior border of the sphenoid body whereas horizontal line represents the planum sphenoidale, or the superior surface of the sphenoid body.

Figure 7.1: sphenoid bone

Figure 7.2: radiographic anatomy of sphenoid bone

The vertical line terminates at the center of the pterygomaxillary fissure, which on lateral cephalogram appears as inverted teardrop radiolucent area bounded anteriorly by radioopaque line of the maxillary tuberosity and posteriorly by the radio-opaque line of the anterior surface of the pterygoid process of the sphenoid bone. The sella turcica appears as elliptical shape radiolucent area surrounded medially radio-opaque line of medial surface of the sella and most inferiorly radio-opaque line of floor of sella anterosuperiorly curved radio-opaque line of anterior clenoid process and posterosuperiorly radio-opaque line of posterior border of the clenoid process.

36

The center of sella turcica is identified as sella abbreviated using English alphabet as upper case S and the mid-entrance point of the sella turcica is the sella-entrance (Se). Most inferior point of the curved radio-opaque line of floor of sella is identified as Si (Floor of sella ), and the most posterior point on the internal continuation of the sella turcica is identified as dorsum sellae. The most superior point on the contour of the anterior clenoid is identified as clenoidale (Cl).

by small letter or lower case p and is written continuously without any space between the alphabets.

Dorsum of Sella

Most posterior point on the internal contour of the sella turcica.1

Definition Dorsum of sella is the most posterior point on the internal contour of the sella turcica or hypophyseal fossa or pituitary fossa.

according to Viken Sassouni

Type

Sp–Dorsum of sella is abbreviated using English alphabets and is expressed as capital letter or upper case S followed

Dorsum of sella (Figs 7.3A to D) is a unilateral, hard tissue cephalometric landmark.


abbreviation

A

B

C

D

Figures 7.3A to D: (A) Dorsum of sella on lateral cephalogram; (b) Magnified image showing dorsum of sella on the lateral cephalogram; (C) Dorsum of sella on graphic illustration; (D) Magnified image of dorsum of sella on graphic illustration

37

Origin Dorsum of sella is an anatomic hard tissue cephalometric landmark.

Floor of Sella

letter or lower case i and is written continuously without any space between the alphabets.

Definition Floor of sella is the lower most point on the inner contour of the sella turcica or hypophyseal fossa or pituitary fossa.

abbreviation

Type

Si–Floor of sella is abbreviated using English alphabets and is expressed as capital letter or upper case S followed by small

Floor of sella (Figs 7.4A to D) is a unilateral, hard tissue cephalometric landmark.

B

C

D

Figures 7.4A to D: (A) Floor of sella on lateral cephalogram; (b) Magnified image showing floor of sella on the lateral cephalogram; (C) Floor of sella on graphic illustration; (D) Magnified image of floor of sella on graphic illustration

Chapter 7  Cephalometric Landmarks Related to Sphenoid Bone

A

38

Origin

Definition

Floor of sella is an anatomic hard tissue cephalometric landmark.

Clinoidale is the most superior point on the contour of the anterior clinoid.

Clinoidale

according to Viken Sassouni The most superior point on the contour of the anterior clenoid.1

Type

Cl–Clinoidale is abbreviated using English alphabets and is expressed as capital C followed by lower case l.l

Clinoidale (Figs 7.5A to D) is a unilateral, hard tissue cephalometric landmark.


abbreviation

A

B

C

D

Figures 7.5A to D: (A) Clinoidale on lateral cephalogram; (b) Magnified image showing clinoidale on the lateral cephalogram; (C) Clinoidale on graphic illustration; (D) Magnified image of clinoidale on graphic illustration

39

Origin

according to arne Bjork

Clinoidale is a unilateral, anatomic, hard tissue cephalometric landmark.

According to Arne Bjork, the opisthion is the posterior margin of the occipital foramen.2

according to TM Graber

Spheno-Occipital Synchondrosis

According to TM Graber, the opisthion is the most posterior point on the posterior margin of the foramen magnum.3

abbreviation

Type

SOS–Spheno-occipital synchondrosis abbreviated using English alphabets and is expressed as capital letter or upper case S, O and S and is written continuously without any space between the alphabets.

Spheno-occipital synchondrosis (Figs 7.6A to D) is a unilateral, hard tissue cephalometric landmark.

Spheno-occipital synchondrosis is a unilateral, anatomic, hard tissue cephalometric landmark.

Opisthion is the posterior edge of the foramen magnum.

A

C


Origin

Definition

B

D

Figures 7.6A to D: (A) spheno-occipital synchondrosis on lateral cephalogram; (b) Magnified image showing spheno-occipital synchondrosis on the lateral cephalogram; (C) spheno-occipital synchondrosis on graphic illustration; (D) Magnified image of sphenooccipital synchondrosis on graphic illustration

40


lower case t, and is written continuously without any space between the alphabets.

The spheno-occipital synchondrosis is very important structure in growth and development of the cranial base in the growing child.

Definition According to Robert M Ricketts, the pterygoid point is the lower lip of the foramen rotundum (represents the position of the sphenoid bone). Most posterior point on the outline of the pterygopalatine fossa.4

Tracing Spheno-Occipital Synchondrosis on the Lateral Cephalogram


Tracing of SOS is very easy, if it is before the ossification and very difficult if it is after the ossification.

Type Pterygoid point (Figs 7.7A to D) is a bilateral, hard tissue cephalometric landmark.

Pterygoid Point

abbreviation

Origin

Pt–Pterygoid point abbreviated using English alphabets and is expressed as capital or upper case P followed by small or

Pterygoid point is a bilateral, hard tissue cephalometric landmark.

A

B

C

D

Figures 7.7A to D: (A) Pterygoid point on lateral cephalogram; (b) Magnified image showing pterygoid point on the lateral cephalogram; (C) Pterygoid point on graphic illustration; (D) Magnified image of pterygoid point on graphic illustration

41

Tracing Pterygoid Point on the Lateral Cephalogram Trace the pterygopalatine fossa point usually located immediately behind the posterior part of the fossa.

according to arne Bjork The center of sella turcica (the midpoint of the horizontal diameter).2

Type Significance (Ref to Chapter 20) • •

Sella abbreviation S–Sella is abbreviated using English alphabets and is expressed as capital or upper case S.

Definition Sella is the midpoint of sella turcica or hypophyseal fossa or pituitary fossa.

according to Robert E Moyers The center of the hypophyseal fossa (sella turcica). It is selected by the eye since that producer as been shown to be as reliable as a constructed center.4

according to TM Graber The center of pituitary fossa.3

Origin Sella is a unilateral anatomic hard tissue cephalometric landmark point.

Tracing of Sella on the Lateral Cephalogram

The pituitary fossa is round and bottle shaped hollow space, situated in the upper body of the sphenoid bone. This fossa contains pituitary gland. This fossa is bounded anterioly and posteriorly by anterior and posterior clinoid processes. Both anterior and posterior clinoid process appears as radio-opaque line on the lateral cephalogram. First trace the anterior and posterior cliniod process followed by inferior border of the pituitary fossa. Center point of the fossa is the point of sella.


Sella is used as one of the reference points in the construction of angles and planes for the assessment of following: • Relationship of maxilla to cranial base is assessed using SNA angle, S-N-Pr angle and saddle angle (N-S-Ar). • Relationship of mandible to cranial base is assessed using SNB angle and S-N-Id angle. • Relationship of anterior and posterior cranial base assessed using N-S-Ar.

according to B Holly Broadbent Sella turcica (Turkish saddle): The landmark is the center of the sella as seen in the lateral radiograph and located by inspection.5


Pterygoid point is a useful point for Rickett’s cephalometric analysis. Pterygoid point is the intersection border of the foramen rotundum and the posterior wall of pterygopalatine fossa in the lateral cephalogram.

Sella (Figs 7.8A to D) is a unilateral, hard tissue cephalometric landmark.

Sella Entrance abbreviation

The center of sella turcica: The midpoint of the sella turcica orbitrarily determined.6

Se–Sella entrance is abbreviated using English alphabets and is expressed as capital letter or upper case S followed by small letter or lower case e and is written continuously without any space between the alphabets.

according to Willam B Downs

Definition

The center of sella turcica: Located by inspection of the profile image of the fossa.7,8

Sella entrance is the mid entrance point of sella turcica or hypophyseal fossa or pituitary fossa.

according to LB Higley


42

A

B

C

D

Figures 7.8A and B: (A) sella on lateral cephalogram; (b) Magnified image showing sella on the lateral cephalogram; (C) sella on graphic illustration; (D) Magnified image of sella on graphic illustration

Type Sella entrance (Figs 7.9A to D) is a unilateral, hard tissue cephalometric landmark.

Origin

E and written continuously without any space between the alphabets.

Definition according to Robert E Moyers

Sella entrance is a constructed, hard tissue cephalometric landmark.

Sphenoethmoidal Point

The intersection of the shadows of the greater wing of the sphenoid and the cranial floor as seen in the lateral cephalogram.4

abbreviation

according to SN Bhatia and BC Leighton

SE–Sphenoethmoidal point (Figs 7.10A to D) is abbreviated using English alphabets and is expressed as upper case S,

The point of intersection between the greater wings of the sphenoid and the anterior cranial base.9

43

B

C

D

Figures 7.9A to D: (A) sella entrance on lateral cephalogram; (b) Magnified image showing sella entrance on the lateral cephalogram; (C) sella entrance on graphic illustration; (D) Magnified image of sella entrance on graphic illustration

A

B

Figures 7.10A and B: (A) sphenoethmoidal point on lateral cephalogram; (b) Magnified image showing sphenoethmoidal point on the lateral cephalogram


A


44

C

D

Figures 7.10C and D: (C) sphenoethmoidal point on graphic illustration; (D) Magnified image of sphenoethmoidal point on graphic illustration

Type Sphenoethmoidal point is a unilateral, hard tissue cephalometric landmark.

Pterygomaxillary Fissure

abbreviation Ptm–Pterygomaxillary fissure is abbreviated using English alphabets and is expressed as capital or upper case P followed by small or lower case t and m, written continuously without any space between the alphabets. PTM–According to Robert M Moyers, Pterygomaxillary fissure is abbreviated using English alphabets and is expressed as capital or upper case P followed by capital or upper case T and M, written continuously without any space between the alphabets. PTMS–According to Michael L Riolo, Pterygomaxillary fissure is abbreviated using English alphabets and is expressed as capital or upper case P,T,M,S, written continuously without any space between the alphabets.

Definition Pterygomaxillary fissure (Figs 7.11A to D) is a bilateral tear drop shaped area of radiolucency, the anterior shadow of which represents the posterior surface of the tuberosity of the maxilla; the landmark is taken where the two edges, front and back, appear to merge inferiorly.

the anterior margin of the pterygoid process of the sphenoid bone and the profile outline of the posterior surface of the maxilla.

according to Robert M Moyers According to Robert M Moyers, the pterygomaxillary fissure is tear drop shaped radiolucency, the anterior shadow of which represents the posterior surface of the tuberosity of the maxilla; the landmark itself is at the most inferior confluences of the curvatures.

according to Clifton T Forceberg According to Clifton T Forceberg, Pterygomaxillary fissure is the most medial and posterior point of each pterygomaxillary fissure. The ptm line connects right and left ptm points. The ptm access is the perpendicular bisector of the ptm line.

according to Holly Broadbent Inverted, elongated, tear drop-shaped area formed by the divergence of the maxilla from the pterygoid process of the sphenoid. The posterior nasal spine and staphylion are generally located beneath the lower pointed end of this area.

according to LB Higley Junction of the Frankfort plane and a line perpendicular to it from the pterygomaxillary fissure.

according to TM Graber

Type

According to TM Graber, the pterygomaxillary fissure is an oval-looped radiolucency resulting from the fissure between

Pterygomaxillary fissure is an anatomic, bilateral, hard tissue cephalometric landmark.

45

B

C

D

Figures 7.11A to D: (A) Pterygomaxillary fissure on lateral cephalogram; (b) Magnified image showing pterygomaxillary fissure; (C) Pterygomaxillary fissure on graphic illustration; (D) Magnified image of pterygomaxillary fissure on graphic illustration

Significance (Ref to Chapter 20) Pterygomaxillary fissure is used as one of the reference point in Cox cephalometric analysis and is used to assess the posterior limit of the maxilla.

References 1. Viken Sassouni. Orthodontics in dental practice. The CV Mosby Company. 1971;330-7. 2. Arne Bjork. The face in profiles-Sven. Tandlak Tidskr. 1947;40:32-3. 3. Graber TM. New horizons in case analysis-clinical cephalometrics. Am J of Ortho.1952;38:603-24.


A

4. Robert R. Ricketts–Provocations and perceptions in cranio-facial orthopedics–dental science and facial art. Rocky Mountain Inc. 1989; 797-803. 5. Moyers RM. Handbook of Orthodontics–Year Book Medical Publishers, Inc. 1988;251-9. 6. Holley Broadbent B, Sr. Bolton’s standards of dentofacial developmental growth. The CV Mosby Company. 1975;133-5. 7. Higley LB. Cephalometric standards for children 4-8 years of age.Am J of Ortho. 1954;40:51-9. 8. Downs WB. Variations in facial relationships. Their significance in treatment and prognosis. Am J of Ortho.1948;34:812-39. 9. Bhatia SN, Leighton BC. A manual of facial growth–Oxford University. 1993;10-5.

CHAPTER

8

Cephalometric Landmarks Related to Occipital Bone

The occipital bone (Fig. 8.1) forming much of the back and base of the cranium and is trapezoidal and concave internally.

Cephalometric Landmarks (Points) on Occipital Bone Cephalometric landmarks seen on the occipital bone are of anatomic origin and are as follows (Table 8.1):

The inner and outer cortical plates of the occipital bone appear as two radio-opaque lines, which descend parallely and meet together at formen magnum, where the hard tissue cephalometric point opisthion is identified. The exocranial and endocranial surfaces of the occipital bone appear as two radio-opaque lines, the point where these two surfaces meet is the point of basion, which is an important hard tissue cephalometric landmark.

Table 8.1: Cephalometric landmarks related to occipital bone

Basion

Cephalometric landmarks

Abbreviation

Type

Origin

Basion

Ba

Unilateral

Anatomic

Opisthion

Op

Unilateral

Anatomic

Abbreviation

Bolton’s point

Bo

Unilateral

Anatomic

Spheno-occipital synchondrosis

SOS

Unilateral

Anatomic

Ba–Basion is abbreviated using English alphabets and is denoted as capital letter or upper case B followed by small letter or lower case a and is written continuously without any space between the alphabets.

Radiographic Anatomy of Occipital Bone (Fig. 8.2) The occipital bone joins the parietal bone at lambdoid suture, which on lateral cephalogram appears as a radiolucent line.

Figure 8.1: Occipital bone

Definition Basion is the median point of the anterior margin of the foramen magnum can be located by following the images of the slope the inferior border of the basilar part of the occipital bone to its posterior limit.

Figure 8.2: Radiographic anatomy of occipital bone

47


According to Clifton T Forsberg

Point at the center of the anterior border of the foramen magnum at the base of the occipital bone.1

The most anterior point relative to the interspinosum line, on the border of the foramen magnum.5


Type

The most inferior point on the anterior margin of the foramen magnum in the midsagittal plane.2

Basion (Figs 8.3A to D) is a unilateral, hard tissue cephalometric landmark.

Origin


According to Arne Bjork Normal projection of the anterior border of the occipital foramen (endobasion) on the occipital foramen line.4

A

B

C

D

Basion is a anatomic hard tissue cephalometric landmark.

Tracing Basion on the Lateral Cephalogram

Chapter 8  Cephalometric Landmarks Related to Occipital Bone

The most inferior posterior point in the sagittal plane on the anterior rim of the foramen magnum.3

• To identify basion on the lateral cephalogram, following structures need to be traced. • Trace from the posterior clinoid process, down the upper part of the clivus, and past the region of the spheno-occipital synchondrosis to the anterior margin of the foramen magnum.

Figures 8.3A to D: (A) Basion on lateral cephalogram; (B) Magnified image showing basion on the lateral cephalogram; (C) Basion on graphic illustration; (D) Magnified image of basion on graphic illustration

48

• Trace the cranial aspect of the greater wing of the sphenoid one, the inferior, ectocranial aspect of the base of the occipital bone, and the anterior margin of the foramen magnum. These are separate lines and should not be drawn a one continuous line. • Trace carefully from the base of the occipital bone to the compact bone of the occipital condyles. The anterior margins of the occipital condyle and basion are radio-opaque on the lateral cephalogram and should be differentiated. Basion is usually behind the anterior part of the occipital condyle.


Opisthion

Abbreviation Op–Opisthion is abbreviated using English alphabets and is expressed as capital letter or upper case O followed by small letter or lower case p and is written continuously without any space between the alphabets.

Definition Opisthion is the posterior edge of the foramen magnum.

According to Clifton T Forsberg The most posterior point, relative to the inter-spinosum line on the border of the foramen magnum.5

Type Opisthion (Figs 8.4A to D) is a unilateral, hard tissue cephalometric landmark.

Origin Opisthion is an anatomic, hard tissue cephalometric landmark.

Tracing Opisthion on Lateral Cephalogram Trace both the outer, ectocranial surface of the external occipital protuberance and the inner, endocranial surface of the occipital bone. Follow the surfaces anteroinferiorly until the two lines merge as the radio-opaque point, which is opisthion.

Bolton’s Point Abbreviation

Posterior margin of the occipital foramen.4

Bo–Bolton’s point is abbreviated using English alphabets and is expressed as capital letter or upper case B followed by small letter or lower case o and is written continuously without any space between the alphabets.


Definition

The most posterior point on the posterior margin of the foramen magnum.2

Bolton’s point is the highest point in the upward curvature of the retrocondylar fossa.


A

B

Figures 8.4A and B: (A) Opisthion on lateral cephalogram; (B) Magnified image showing opisthion on the lateral cephalogram

49

D

Figures 8.4C and D: (C) Opisthion on graphic illustration; (D) Magnified image of opisthion on graphic illustration


C


According to Viken Sassouni

Point in space, about the center of foramen magnum, that is located on the lateral cephalometric radiograph by the highest point in the profile image of the postcondylar notches of the occipital bone.5

Highest point in the upward curvature of the retrocondylar fossa. In uncertain cases it may be located as the midpoint between opisthion (Op), and basion (Ba); in other words, at the center of foramen magnum.7



The deepest point of the notch in the shadow behind condylus occipitalis.3

The most superior point in the uppet curvature of the retrocondylar fossa. It is just posterior to the occipital condyle.2


Type

The highest point on the concavity behind the occipital condyles.6

Bolton’s point (Figs 8.5A to D) is a unilateral, hard tissue cephalometric landmark.

A

B

Figures 8.5A and B: (A) Bolton’s point on lateral cephalogram; (B) Magnified image showing Bolton’s point on the lateral cephalogram


50

C

D

Figures 8.5C and D: (C) Bolton’s point on graphic illustration: (D) Magnified image of Bolton’s point on graphic illustration

Origin Bolton’s point is an anatomic hard tissue cephalometric landmark/point.

Tracing Bolton’s Point on the Lateral Cephalogram Bolton’s point is the midway between the point basion and opisthion. Trace the basion and opisthion and bisect the distance between these two points to establish the Bolton’s point.

Spheno-Occipital Synchondrosis

and is written continuously without any space between the alphabets.

Type Spheno-occpital synchondrosis (Figs 8.6A to D) is a unilateral, hard tissue cephalometric landmark.

Origin Spheno-occipital synchondrosis is an anatomic hard tissue cephalometric landmarks.

Abbreviation

Tracing Spheno-Occipital Synchondrosis on the Lateral Cephalogram

SOS–Spheno-occipital synchondrosis abbreviated using English alphabets and is expressed as capital S, O and S

Tracing of SOS is very easy, if it is before the ossification and very difficult, if it is after the ossification.

A

B

Figures 8.6A and B: Spheno-occipital synchondrosis on lateral cephalogram; (B) Magnified image showing spheno-occipital synchondrosis on the lateral cephalogram

51

D

Figures 8.6C and D: (C) Spheno-occipital synchondrosis on graphic illustration; (D) Magnified image of spheno-occipital synchondrosis on graphic illustration

Significance (Ref to Chapter 20) The spheno-occipital synchondrosis is very important structure in growth and development of the cranial base in the growing child.

References 1. Ricketts RR. Provocations and perceptions in cranio-facial orthopedics –dental science and facial art. Rocky Mountain Inc. 1989;797-803. 2. Graber TM. New horizons in case analysis-clinical cephalometrics. Am J of Ortho. 1952;38:603-24.


C

3. Moyers RM. Handbook of Orthodontics. Year Book Medical Publishers, Inc. 1988;251-9. 4. Arne Bjork. The face in profiles-Sven. Tandlak Tidskr. 1947;40:32-3. 5. Clifton T Forsberg. Diagnosis and treatment planning of skeletal asymmetry with the sub-mental vertical radiograph. Am J of Ortho. 1984;85:224-37. 6. Downs WB. Variations in facial relationships; Their significance in treatment and prognosis. Am J of Ortho.1948;34:812-39. 7. Viken Sassouni. Orthodontics in dental practice. The CV Mosby Company. 1971;330-7.

Chapter

9

Cephalometric landmarks related to Zygomatic bone

Each zygomatic bone (Figs 9.1A and B) consists of a diamond-shaped body and following four processes: • Frontal process articulates with the frontal bone at zygomaticofrontal suture forming the lateral wall of the orbit. • Temporal process articulates with the zygomatic process of the temporal bone, forming the zygomatic arch. • Maxillary process articulates with the zygomatic process of the maxilla at the zygomaticomaxillary suture, forming the infraorbital rim and the orbital floor. • Jugular process articulates the maxilla at the lateral wall of the maxillary sinus.

Radiographic Anatomy of Zygomatic Bone The frontal process of the zygomatic bone appears as two radio-opaque lines on the lateral cephalogram, one anterior and the other posterior. The anterior line is curved line representing the anterior border of the lateral wall of the orbit. The posterior line is a vertical line that extends downward from the junction with the cribriform plate and merges with the posterior border of the zygomatic process of the maxilla. Between the inferior parts of the two lines, there is another horizontal radio-opaque line, which represents the maxillary

A

process of the zygomatic bone. This line extends posteriorly and merges with the horizontal part of the zygomatic process of the maxilla.

Cephalometric landmarks (Points) on Zygomatic bone Cephalometric landmarks seen on the zygomatic bone are of anatomic origin and are as follows (Table 9.1): Table 9.1: Cephalometric landmarks related to zygomatic bone Cephalometric landmarks

Abbreviation

Type

Origin

Orbitale

Or

Bilateral

Anatomic

Temporale

Te

Bilateral

Anatomic

Orbitale Abbreviation Or–Orbitale is abbreviated using English alphabets and is denoted as capital letter or upper case O followed by small letter or lower case r and is written continuously without any space between the alphabets.

B

Figures 9.1A and B: Zygomatic bone

53

Definition

According to Leslie G Farkas

Orbitale is the lowest point in the inferior margin of the orbit, midpoint between right and left images.

Orbitale is the lowest point on the lower margin of each orbit.It is identified by palpation and is identical to the bony orbitale.4

According to William B Downs Orbitale is the lowest point on the left infraorbital margin.1

According to TM Graber Orbitale is the most inferior point on the lower border of the left orbit.2

Orbitale is the left orbital point used in conjunction with the poria to orient the skull on the Frankfort horizontal plane.3

In the lateral cephalogram, the outlines of the orbital rims overlap. Usually, the lowest point on the averaged outline is used for the construction of Frankfort plane.5

Type

Chapter 9  Cephalometric landmarks related to Zygomatic bone



Orbitale (Figs 9.2A to D) is a bilateral, hard tissue cephalometric.l

Origin

Orbitale is an anatomic hard tissue cephalometric landmarks.

A

B

C

D

Figures 9.2A to D: (A) Orbitale on lateral cephalogram; (B) Magnified image showing orbitale on the lateral cephalogram; (C) Orbitale on graphic illustration; (D) Magnified image of orbitale on graphic illustration

54

Tracing of Orbitale on Lateral Cephalogram Normally, right and left infra-orbital margins are superimposed on the lateral cephalogram, then they reveal radio-opaque line on the lateral cephalogram, when patient is positioned accurately on the cephalostat during the radiographic taking procedure. If the patient is inaccurately positioned then in such cases, the infra-orbital margins appear as two different radio-opaque lines on the lateral cephalogram making difficult to identify the point. In such cases, the orbitale is identified as the mid point of right and left infra-orbital margins.


Significance (Ref to Chapter 20) Orbitale is used as one of the reference points in the construction of Frankfort horizontal plane and is used for the assessment of horizontal growth pattern using following angles:

A

B

C

D

• FH-Mandibular plane angle (Go- Me) • FH- Palatal plane angle ( ANS-PNS) • FH-Occlusal plane ( APOcc – PPOcc).

Temporale Abbreviation Te–Temporale is abbreviated using English alphabets and is expressed as capital or upper case T followed by small letters or lower case e and is written continuously without any space between the alphabets.

Definition Temporale (Figs 9.3A to D) is the intersection of the shadows of the ethmoid and the anterior wall of the infratemporal fossa.

Figures 9.3A to D: (A) Temporale on lateral cephalogram; (B) Magnified image showing temporale on the lateral cephalogram; (C) Temporale on graphic illustration; (D) Magnified image of temporale on graphic illustration

55

According to Viken Sassouni

References

Intersection of the shadows of the ethmoid and anterior wall of the infra-temporal fossa.6

1. Downs WB. Variations in facial relationships; Their significance in treatment and prognosis. Am J of Ortho. 1948;34:812-39. 2. Graber TM. New horizons in case analysis-clinical cephalometrics. Am J of Ortho. 1952;38:603-24. 3. Broadbent BH, Sr. Bolton’s standards of dentofacial developmental growth. The CV Mosby Company. 1975; 133-5. 4. Farkas LG. Anthropometry of the head and face in medicine. Elsevier north Holland inc. 1981;9-14. 5. Moyers RM. Handbook of Orthodontics—Yearbook medical publishers inc. 1988;251-9. 6. Viken Sassouni. Orthodontics in dental practice. The CV Mosby company. 1971;330-7.

Type Temporale is a bilateral, hard tissue cephalometric landmark.

Origin Temporale is an anatomic hard tissue cephalometric landmark.

Chapter 9  Cephalometric landmarks related to Zygomatic bone

Section

4

Cephalometric Landmarks Related to Facial Bones and Dentition

 Cephalometric Landmarks Related to Maxilla  Cephalometric Landmarks Related to Dentition  Cephalometric Landmarks Related to Mandible

ChapteR

10

Cephalometric Landmarks Related to Maxilla

The maxilla (Fig. 10.1) consists of a large hollow body that houses the maxillary sinus and the four prominent processes. • The frontal process • The zygomatic process • The palatine process • The alveolar process.

Cephalometric Landmarks (Points) on Maxilla Cephalometric landmarks seen on the maxilla are as follows (Table 10.1): Table 10.1: Cephalometric landmarks related to maxilla Cephalometric landmarks

Abbreviation

Type

Origin

anterior nasal spine point a

aNS

Unilateral

anatomic

a

Unilateral

anatomic

anterior point of maxilla

apMax

Unilateral

anatomic

prosthion

pr

Unilateral

anatomic

posterior nasal spine

pNS

Unilateral

anatomic

Pterygomaxillary fissure

• Ptm • PTM • PTMS

Bilateral

anatomic

Key ridge

KR

Unilateral

anatomic

Orbitale

Or

Bilateral

anatomic

Anterior Nasal Spine Abbreviation ANS–Anterior nasal spine is abbreviated using English alphabets and is expressed as capital or upper case A, N and S, written continuously without any space between the alphabets.

Figure 10.1: Maxillary bone

According to Viken Sassouni The most anterior point of the nasal floor tip of pre-maxilla on mid-sagittal plane.1

According to B Holly Broadbent Sharp median process formed by the forward prolongation of the anterior aperture of the nose.2

According to TM Graber The tip of the anterior nasal spine as seen on the X-ray film in norma lateralis.3

Definition


Anterior nasal spine (Figs 10.2A to D) is the tip of bony anterior nasal spine in the midline or median plane.

The most anterior point on the maxilla at the level of the palate. The ANS is of limited use for analysis in the posterior-

Section 4  Cephalometric Landmarks related to Facial Bones and Dentition

60

A

B

C

D

Figures 10.2A to D: (A) Anterior nasal spine on lateral cephalogram; (B) Magnified image showing anterior nasal spine on the lateral cephalogram; (C) Anterior nasal spine on graphic illustration; and (D) Magnified image of Anterior nasal spine on graphic illustration

anterior projection as the actual spine often cannot be seen and its location varies considerably according to radiographic exposure.4

Tracing of Anterior Nasal Spine on Lateral Cephalogram

Type

There is an individual variation exists in length and width of ANS. In some individuals ANS are long and thin; while in other are short and thick.

Anterior nasal spine is a unilateral, hard tissue cephalometric landmark.

Radiographic Appearance

Origin Anterior nasal spine is an anatomic hard tissue cephalometric landmark.

• ANS appears slightly posterior to the anatomic spine. • In cases with thin ANS: In such cases, on the cephalogram, ANS will be unclear because it can superimpose by nasal cartilage. • In cases with thick ANS: In such cases, on the cephalogram, ANS is clear and will be ease in tracing.

61


Definition

Anterior nasal spine is used as one of the reference points Point A (Figs 10.3A to D) is the deepest point on the curved in the construction of occlusal plane and is used for the bony outline between the anterior nasal spine (ANS) and assessment of horizontal growth pattern using FH-palatal prosthion (Pr). plane angle (ANS-PNS).

According to Willian B Downs

Point A Abbreviation

The deepest midline point on the premaxilla between the anterior nasal spine and prosthion.5


A

B

Chapter 10  Cephalometric Landmarks related to Maxilla

Point A: Point A is abbreviated using English alphabets and is Deepest point on the curve of the bone between the anterior nasal spine and dental alveolus. Also termed SS or subspinale expressed as A itself. (below the spine).6

C D

Figures 10.3A to D: (A) Point A on lateral cephalogram; (B) Magnified image showing point A on the lateral cephalogram; (C) Point A on graphic illustration; and (D) Magnified image of point A on graphic illustration

62

According to Viken Sassouni Deepest point on midsagittal plane between ANS and prosthion, mesially around the level of and anterior to the apex of the upper central incisors.1


• To establish A point, draw a line between ANS and prosthion. Then draw a line parallel to the ANS–Pr line, tangent to the deepest point between ANS and Pr. This is point A.



Point A is used as one of the reference points in the construction The most posterior point on the pre-maxilla above prosthion of angles and planes for the assessment of the following: and immediately lateral to the contour of projection of the • Relationship of maxilla to cranial base is assessed using anterior nasal spine. It is the junction of the alveolar and basal SNA angle. of the maxilla.3 • Maxillo-mandibular relationship with anterior cranial base is assessed using ANB angle. According to Alex Jacobson and W Caufield • Inclination upper incisors are assessed using NA-Upper incisor angular and NA-Upper incisor linear. Using a line perpendicular to FH locate the most posterior point in the concavity between ANS and maxillary alveolar • Point A is useful indicator of the anteroposterior relationship between the basal bone of the maxilla and the process.7 malocclusion. • In Mc Namara cephalometric analysis, anteroposterior Or orientation of the maxilla to the cranial base is assessed The most posterior midline point in the concavity between the by the linear distance between nasion perpendicular and ANS and prosthion (The most inferior point on the alveolar point A. An anterior position of point A is a positive value bone overlying the maxillary central incisor). and a posterior position of point A is a negative value. • Mid facial length is measured from condylion to Point A According to Robert E Moyers in McNamara analysis. • In Mc Namara cephalometric analysis, method of The most posterior point on the curve between ANS and PR determining of position of maxillary incisor relative to “A” point usually is found approximately 2 mm anterior to point A. Draw vertical line through the nasion called NP the apices of the maxillary central incisor roots. A is not an (Nasion perpendicular) and A vertical line constructed 4 anatomic point, of course. through the point A parallel to the Nasion perpendicular line called the parallel to nasion perpendicular through According to JR Jarabak point A (PNP). The anteroposterior distance from maxiMaxillary denture base, point A is 2 mm labial to the apices of llary incisor to point A. the central incisors.8 • In Mc Namara cephalometric analysis, to determine the anteroposterior position of the mandibular incisors, the distance is measured between the edge of the incisor and Type a line drawn from point A to Pog. In a well-balanced face, Point A is a unilateral, hard tissue cephalometric landmark. this distance should be 13 mm.

Origin

Prosthion

Point A is an anatomic hard tissue cephalometric landmark.

Tracing Procedure for Point A • First trace the palatal bone, the anterior nasal spine, the marginal bone of the alveolar process and the anterior facial surface of the alveolar process. • Thereafter, trace the outline of maxillary central incisor which includes tracing of incisal edge, apex of the root outer surface of the crown and root of maxillary central incisor. • Note:The most important factor which helps in location of point A is that it is at almost the same height as the apex of the incisor.

Abbreviation Pr: Prosthion is abbreviated using English alphabets and is expressed as capital letter or upper case P followed by small letter or lower case r and is written continuously without any space between the alphabets.

Definition Prosthion (Figs 10.4A to D) is the lowermost anterior point of alveolar process of pre-maxilla in the midline between two maxillary central incisors.

63

B

C

D

Figures 10.4A to D: (A) Prosthion on lateral cephalogram; (B) Magnified image showing prosthion on the lateral cephalogram; (C) Prosthion on graphic illustration; and (D) Magnified image of prosthion on graphic illustration


A


Type

The transition point between the crown of the most prominent medial maxillary incisor and the alveolar projection.9

Prosthion is a unilateral, hard tissue cephalometric landmark.


Origin

The point of the maxillary alveolar process in the midline that projects most anteriorly.3

Prosthion is an anatomic hard tissue cephalometric landmark.



The most anterior inferior point on the maxillary alveolar process usually found near the cementoenamel junction of the maxillary central incisor.4

Prosthion is used as one of the reference points in the construction of angles for the assessment of relationship of maxilla skeletal base to cranial base using S-N-Pr angle.

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Posterior Nasal Spine

The bony posterior projection of the horizontal portion of the palatine bone at the midline.3

Abbreviation

PNS: Posterior Nasal Spine is abbreviated using English According to B Holly Broadbent alphabets and is expressed as capital letter or upper case P, N and S and is written continuously without any space between Process formed by the united projecting medial ends of the the alphabets. posterior borders of the two palatine bones.2


Definition Posterior Nasal Spine (Figs 10.5A to D ) is the intersection of a continuation of the anterior wall of the pterygopalatine fossa and the floor of the nose.

According to Michael L Riolo The most posterior point at the sagittal plane on the bony hard palate.10

A

C

According to Viken Sassouni Most posterior point on the contour of the bony palate.1

According to Alex Jacobson and W Caufield Using a line perpendicular to FH, locate PNS at the most posterior aspect of the palatine bone.7

B

D

Figures 10.5A to D: (A) Posterior nasal spine on lateral cephalogram; (B) Magnified image showing posterior nasal spine on the lateral cephalogram; (C) Posterior nasal spine on graphic illustration; and (D) Magnified image of posterior nasal spine on graphic illustration

65

According to Robert M Ricketts Midpoint of the base of the palatine bone at the posterior margin of the hard palate.6

Type

which represents the posterior surface of the tuberosity of the maxilla; the landmark is taken where the two edges, front and back appear to merge inferiorly.


According to TM Graber, the pterygomaxillary fissure is an Posterior nasal spine is a unilateral, hard tissue cephalometric oval-looped radiolucency resulting from the fissure between landmark. the anterior margin of the pterygoid process of the sphenoid bone and the profile outline of the posterior surface of the Origin maxilla.3 Posterior nasal spine is an anatomic hard tissue cephalometric According to Robert M Moyers landmark.



According to Robert M Moyers, the pterygomaxillary fissure is tear drop shaped radiolucency, the anterior shadow of which represents the posterior surface of the tuberosity of the maxilla; the landmark itself is at the most inferior confluences • Like ANS, PNS also has variation in length and width. 4 • PNS is difficult to trace on the cephalogram when there of the curvatures. is unerupted teeth, in these cases the PNS can be located between the floor of nasal cavity and the inferior surface According to Clifton T Forsberg of the palatine bone. According to Clifton T Forsberg, pterygomaxillary fissure is • Usually, it is found that PNS is located below the Ptm. the most medial and posterior point of each pterygomaxillary

Tracing of Posterior Nasal Spine on the Lateral Cephalogram

fissure. The Ptm line connects right and left Ptm points. The Ptm access is the perpendicular bisector of the Ptm line.11

Posterior nasal spine is used as one of the reference points in the construction of occlusal plane and is used for the According to Holly Broadbent assessment of horizontal growth pattern using FH-Palatal Inverted, elongated, tear drop-shaped area formed by the plane angle (ANS-PNS). divergence of the maxilla from the pterygoid process of the sphenoid. The posterior nasal spine and staphylion are Pterygomaxillary Fissure generally located beneath the lower pointed end of this area.2

Abbreviation Ptm: Pterygomaxillary fissure is abbreviated using English alphabets and is expressed as capital or upper case P followed by small or lower case t and m, written continuously without any space between the alphabets. PTM: According to Robert. M. Moyers, Pterygomaxillary fissure is abbreviated using English alphabets and is expressed as capital or upper case P followed by capital or upper case T and M, written continuously without any space between the alphabets.4 PTMS: According to Michael L Riolo, Pterygomaxillary fissure is abbreviated using English alphabets and is expressed as capital or upper case P, T, M, S, written continuously without any space between the alphabets.9

Definition Pterygomaxillary fissure (Figs 10.6A to D) is a bilateral tear drop shaped area of radiolucency, the anterior shadow of

According to LB Higley

Junction of the Frankfort plane and a line perpendicular to it from the pterygomaxillary fissure.12

Type

Pterygomaxillary fissure is bilateral, hard tissue cephalometric landmark.

Origin Pterygomaxillary fissure is an anatomic hard tissue cephalometric landmark.

Significance (Ref to Chapter 20) Pterygomaxillary fissure is used as one of the reference points in Cox cephalometric analysis and is used to assess the posterior limit of the maxilla.


66

A

B

C

D

Figures 10.6A to D: (A) Pterygomaxillary fissure on lateral cephalogram; (B) Magnified image showing pterygomaxillary fissure on the lateral cephalogram; (C) Pterygomaxillary fissure on graphic illustration; and (D) Magnified image of pterygomaxillary fissure on graphic illustration

Key Ridge

Abbreviation KR: Key ridge is abbreviated using English alphabets and is expressed as capital or upper case K, and R, and is written continuously without any space between the alphabets.

According to Viken Sassouni Lowermost point on the contour of the shadow of the anterior wall of the infratemporal fossa.1

According to Robert E Moyers The lowest point on the outline of the zygoma.4

According to TM Graber Definition The key ridge (Figs 10.7A to D) is the lowermost point on the contour shadow of the anterior wall of the infratemporal fossa.

The most inferior point on the zygomatic ridge.3

Type Key ridge is a bilateral, hard tissue cephalometric landmark.

67

B

C

D


A

Figures 10.7A to D: (A) key ridge on lateral cephalogram; (B) Magnified image showing key ridge on the lateral cephalogram; (C) key ridge on graphic illustration; and (D) Magnified image of key ridge on graphic illustration

Origin

Definition

Key ridge is an anatomic hard tissue cephalometric landmark.


Orbitale Abbreviation Or: Orbitale is abbreviated using English alphabets and is expressed as capital or upper case O, followed by small or lower case r and both alphabets are written continuously without any space between them.

The deepest point on the infraorbital margin.The midpoint, or is used where double projection gives rise to two points, or 1 and or 2.9

According to William B Downs The lowest point on the left infra-orbital margin.5

According to TM Graber The most inferior point on the lower border of the left orbit.3

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Type

The left orbital point is used in conjunction with poria to orient the skull on the Frankfort horizontal plane.2

Orbitale is a bilateral (Figs 10.8A to D), anatomic, hard tissue cephalometric landmark.

Leslie G Farkas

Origin

Orbitale is the lowest point on the lower margin of the each orbit. It is identified by palpation and is identical to the bony orbitale.13

Orbitale is an anatomic hard tissue cephalometric landmark.


Orbitale is used as one of the reference points in the construction of angles and planes for the assessment of following: • Growth pattern is assessed using FH plane-Mandibular plane.



In the lateral cephalogram, the outlines of the orbital rims overlap. Usually, the lowest point on the averaged outline is used for the construction of Frankfort plane.4


A

B

C

D

Figures 10.8A to D: (A) Orbitale on lateral cephalogram; (B) Magnified image showing orbitale on the lateral cephalogram; (C) Orbitale on graphic illustration; and (D) Magnified image of orbitale on graphic illustration

69

• Upper incisor torque is assessed using FH-long axis of upper incisor.

Tracing of Orbitale on the Lateral Cephalogram

References 1. Viken Sassuoni. Orthodontics in dental practice. The CV Mosby company. 1971;330-7.


Normally, right and left infra-orbital margins are superimposed on the lateral cephalogram, and then they reveal radio-opaque line on the lateral cephalogram, when patient is positioned accurately on the cephalostat during the radiographic taking procedure. If the patient is inaccurately positioned then in such cases, the infra-orbital margins appear as two different radio-opaque lines on the lateral cephalogram making difficult to identify the point. In such cases, the orbitale is identified as the midpoint of right and left infra-orbital margins.

2. Broadbent BH Sr. Bolton’s standards of dentofacial developmental growth. The CV Mosby Company. 1975;133-5. 3. Graber TM. New horizons in case analysis. Clinical cephalometrics. Am J of Ortho. 1952;38:603-24. 4. Moyers RM. Handbook of Orthodontics.Year book medical publishers, Inc. 1988;251-9. 5. Downs WB. Variations in facial relationships. Their significance in treatment and prognosis. Am J of Ortho. 1948;34:812-39. 6. Ricketts RM. Provocations and perceptions in cranio-facial orthopedics. Dental science and facial art. Rocky Mountains, Inc. 1989;797-803. 7. Alex Jacobson, Caufield W. Introduction to radiographic cephalometry. Lea and Febiger. 1985;37-40. 8. Jarabak JR. Technique and treatment with light wire appliance. The CV Mosby company. 1963;132-3. 9. Arne Bjork. The face in profiles. Sven. Tandlak Tidskr. 1947;40:32-3. 10. Riolo ML. An atlas of craniofacial growth. Cephalometric standards from the university school growth study, the university of Michigan.Center for human growth and development. The University of Michigan. 1974;12-21. 11. Forsberg CT. Diagnosis and treatment planning of skeletal asymmetry with submental. Vertical radiograph. Am J of Ortho. 1984;85:224-37. 12. Higley LB. Cephalometric standards for children 4-8 years of age.Am J of Ortho. 1954;40:51-9. 13. Farkas LG. Anthropometry of the head and face in medicine. Elsevier north Holland, Inc. 1981;9-14.

Chapter

11

Cephalometric Landmarks Related to Dentition

Dental occlusion undergoes significant changes from birth until adulthood and beyond. This continuation of changes in the dental relationship during various stages of the dentition can be divided into four stages: 1. Gum pad stage—0–6 months 2. Deciduous dentition—6 months–6 years 3. Mixed dentition—6–12 years 4. Permanent dentition—12 years and beyond.

Gum Pad Stage (0–6 Months) Usually jaws are devoid of teeth at birth. Gum pad stage extends from birth up to the eruption of first primary tooth usually the lower central incisors at around 6 months of age. The gum pads are pink in color and firm in consistency. The maxillary gum pad is U/square shaped, and the mandibular gum pad is horse-shoe shaped. The gum pads develop in two portions—buccal and lingual portions which are separated by the dental groove. The gum pads in both the arches show certain elevations and grooves that outline the portion of the various primary teeth that are still developing in the alveolar ridges. These grooves are called as transverse grooves. The prominent transverse groove separating canine and first deciduous molar segments in both the arches is called the lateral sulcus. The lateral sulcii are often used to judge the inter-arch relationship at a very early stage. The gingival groove separates the maxillary and mandibular gum pads from the palate and floor of the mouth respectively.

Deciduous Dentition Stage (6 Months to 6 Years) The deciduous dentition stage spans from the time of eruption of primary teeth until the eruption of the first permanent tooth around 6 years of age.

Eruption Chronology of Primary Teeth Eruption of the primary teeth begins by 6 months of age when primary mandibular incisors erupt into oral cavity. Eruption

of all the primary teeth is usually complete by two and half years by which age, the deciduous dentition is in full function. Root formation of primary teeth is usually completed by three years of age. Although considerable variation is seen in the eruption timing of deciduous teeth, there appears to be no significant gender differences. The chronology of primary teeth is presented in the Table 11.1. The sequence of eruption of primary teeth may also show some variation. However, in most of the cases, the lower central incisors are the first teeth to erupt, followed by the upper central incisors. Usually the lateral incisor, first molar and canine tend to erupt earlier in maxilla than in the mandible. Deciduous dentition generally shows the following orders of eruption: AB A • • • • •

D B

C D

E CE

Central incisors Lateral incisors First molars Canines Second molars

By 3 years of age, the occlusion of deciduous dentition is completely established and dental arches remain relatively constant with no significant changes up to 6 years of age.

Mixed Dentition Stage (6–12 Years) Mixed dentition stage is a transition stage when primary teeth are exfoliated in a sequential manner, followed by the eruption of their permanent successors. This stage spans from 6 to 12 years of age, beginning with the eruption of the first permanent tooth, usually a mandibular central incisor or a first molar. It is completed at the time the last primary tooth is shed. Significant changes in occlusion are seen in mixed dentition period due to the loss of 20 primary teeth and eruption of their successor permanent teeth. Most malocclusions are developed at this stage.

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Permanent Dentition Stage

Most Common Eruption Sequence in Maxilla 6-1-2-4-3-5-7-8 or 6-1-2-4-5-3-7-8

Most Common Eruption Sequence for Mandibular Arch (6-1)-2-3-4-5-7-8 or (6-1)-2-4-3-5-7-8 These are also the most favorable sequences for the prevention of malocclusion. It must be noted that, there is a difference in eruption timing of the canines in the two arches. In the mandibular arch, the canine erupts before the premolars, whereas in the maxillary arch the canine generally erupts after the premolars. When second molars erupt before the premolars are fully erupted significant shortening of the arch perimeter occurs, increasing the likelihood of malocclusion.

Cephalometric Landmarks on Dentition Cephalometric landmarks seen on the Dentition are of anatomic origin and are as follows (Table 11.1):

Incision Superius Incisalis Abbreviation Isi–Incision Superius Incisalis is abbreviated using English alphabets and is expressed as Capital or upper case I followed by small letters or lower case s and i and is written continuously without any space between the alphabets.


Abbreviation

Type

Origin

Incision superius incisalis

Isi

Unilateral

Anatomic

Incision superius apicalis

Isa

Unilateral

Anatomic

Incision inferius incisalis

Iii

Unilateral

Anatomic

Incision inferius apicalis

Iia

Unilateral

Anatomic

Anterior point of occlusion

APocc

Unilateral

Anatomic

Posterior point of occlusion

PPocc

Unilateral

Anatomic

Maxillary central incisor

U1

Unilateral

Anatomic

Maxillary first molar

U6

Bilateral

Anatomic

Mandibular central incisor

L1

Unilateral

Anatomic

Mandibular first molar

L6

Bilateral

Anatomic

mi

mi

Bilateral

Anatomic

ms

ms

Bilateral

Anatomic

Chapter 11  Cephalometric Landmarks Related to Dentition

Permanent dentition stage is pretty well established by about 13 years of age, with the eruption of all permanent teeth except the 3rd molars. Permanent successors develop from lingual extension of the dental lamina (successional lamina) and the permanent molar develop from the posterior extension of the dental lamina. The permanent incisors develop lingual to the primary incisors and move labially as they erupt. The premolars develop below the divergent roots of the primary molars. Permanent dentition begins to form at birth, at which time, calcification of the 1st permanent molars becomes evident. Chronology of permanent dentition is depicted in Table 11.1. Sequence of eruption of permanent dentition is more variable than that of the primary dentition. In addition, there are significant differences in the eruption sequences between the maxillary and the mandibular arch.

Table 11.1: Cephalometric landmarks related to dentition

is–Incision Superius is abbreviated using English alphabets and is expressed as small letters or lower case i and s and is written continuously without any space between the alphabets.

Definition

Incision superius Incisalis (Figs 11.1A to D) is the incisal edge of the maxillary central incisor.


Incision superius incisalis is the mid-point of the incisal edge of the most prominent upper central incisor.1


Incision superius incisalis is the incisal tip of the most anterior maxillary central incisor.2

Type Incision superius incisalis is a unilateral, hard tissue cephalo metric landmark.

Origin Incision superius incisalis is a unilateral, anatomic, hard tissue cephalometric landmark.


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A

B

C

D

Figures 11.1A to D: (A) Incision superius incisalis on lateral cephalogram; (B) Magnified image showing incision superius Incisalis on the lateral cephalogram; (C) Incision superius incisalis on graphic illustration; (D) Magnified image of incision superius Incisalis on graphic illustration

Tracing of Incision Superius Incisalis on Lateral Cephalogram The labial and lingual outline of the crown of the maxillary permanent central incisor appears as radio-opaque line on the lateral cephalogram. Trace these two outlines of crown of the maxillary permanent central incisor. The tip of the incisal edge or the intersection of the labial and lingual outline is the point of Incision Superius Incisalis.

Significance (Ref to Chapter 20) Incision superius incisalis is used as one of the reference points in the construction of angles and planes for the assessment of following:

• Inclination of upper incisor is assessed using angle drawn between the long axis of upper incisor plane and the FH plane. • In Arnett’s analysis, the upper incisor torque is assessed using the angle drawn between long axis of upper incisor and occlusal plane. • Inter-incisal relationship of upper and lower incisors are assessed using the angle drawn between the long axis of upper and lower permanent central incisor. • Anteroposterior positioning of maxillary central incisor is assessed using the distance between the incision Superius Incisalis and the NA plane. • Anteroposterior positioning of maxillary central incisor is assessed using the distance between the incision Superius Incisalis and the A-Pog plane.

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According to Michael L Riolo

Incision Superius Apicalis Abbreviation Isa–Incision Superius Apicalis is abbreviated using English alphabets and is expressed as capital or upper case I followed by small letters or lower case s and a and is written continuously without any space between the alphabets. UIA–Upper incisor apex is abbreviated using English alphabets and is expressed as capital or upper case U, I and A and is written continuously without any space between the alphabets.

Incision superius apicalis (Figs 11.2A to D) is the root apex of the most anterior maxillary central incisor; if this point is needed only for defining the long axis of the tooth, the midpoint on the bisection of the apical root width can be used.

A

B

C

D

According to SN Bhatia and BC Leighton The upper incisor apex is the root apex of the most prominent upper incisor.4

Type Incision superius apicalis is a unilateral, anatomic, hard tissue cephalometric landmark.

Origin


Definition

The upper incisor apex is the root tip of the maxillary central incisor. In cases where the root is not yet completed, the midpoint of the growing root tip is marked.3

Incision superius apicalis is an anatomic hard tissue cephalo metric landmark.

Figures 11.2A to D: Incision superius apicalis

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Tracing of Incision Superius Apicalis on Lateral Cephalogram The labial and lingual outline of the root of the maxillary permanent central incisor appears as radio-opaque lines on the lateral cephalogram. Trace these two outlines of root of the maxillary permanent central incisor. The point of intersection of labial and lingual outlines of the root of maxillary permanent central incisor is the point of incision superius apicalis.


Significance (Ref to Chapter 20) Incision superius apicalis is used as one of the reference points in the construction of angles and planes for the assessment of following: • Inclination of upper incisor is assessed using angle drawn between the long axis of upper incisor plane and the FH plane. • In Arnett’s analysis, the upper incisor torque is assessed using the angle drawn between long axis of upper incisor and occlusal plane.

A

B

C

D

• Inter-incisal relationships of upper and lower incisors are assessed using the angle drawn between the long axis of upper and lower permanent central incisor.

Incision Inferius Incisalis Abbreviation Iii–Incision inferius incisalis is abbreviated using English alphabets and is expressed as capital or upper case I followed by small letters or lower case i and i and is written continuously without any space between the alphabets. ii–Incision inferius is abbreviated using English alphabets and is expressed as small letters or lower case i and i and is written continuously without any space between the alphabets.

Definition Incision inferius incisalis (Figs 11.3A to D) is the incisal edge of the most prominent mandibular central incisor.

Figures 11.3A to D: Incision inferius incisalis (A and B) on lateral cephalogram, (C and D) on graphic illustration

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According to Arne Bjork The incision inferius is the incisal point of the most prominent medial mandibular incisor.1

According to Robert E Moyers The incision inferius is the incisal tip of the most labial mandi bular central incisor.2

Type Incision inferius incisalis is a unilateral, anatomic, hard tissue cephalometric landmark.

The labial and lingual outline of the crown of the mandibular permanent central incisor appears as radio-opaque line on the lateral cephalogram. Trace these two outlines of crown of the mandibular permanent central incisor. The tip of the incisal edge or the intersection of the labial and lingual outline is the point of incision inferius incisalis.

Significance (Ref to Chapter 20) Incision inferius incisalis is used as one of the reference point in the construction of angles and planes for the assessment of following: • Inclination of lower incisor is assessed using angle drawn between the long axis of lower incisor plane and the mandibular plane. • In Arnett’s analysis, the lower incisor torque is assessed using the angle drawn between long axis of lower incisor and occlusal plane. • Inter-incisal relationship of upper and lower incisors are assessed using the angle drawn between the long axis of upper and lower permanent central incisor. • Anteroposterior positioning of mandibular central incisor is assessed using the distance between the incision inferius incisalis and the NB plane. • Anteroposterior positioning of maxillary central incisor is assessed using the distance between the incision inferius incisalis and the A-Pog plane.

Incision Inferius Apicalis Abbreviation Iia–Incision inferius apicalis is abbreviated using English alphabets and is expressed as capital or upper case I followed

LIA–lower incisor apex is abbreviated using English alphabets and is expressed as capital or upper case L, I and A and is written continuously without any space between the alphabets.

Definition Incision inferius apicalis (Figs 11.4A to D) is the root apex of the most anterior mandibular central incisor; if this point is needed only for defining the long axis of the tooth, the midpoint on the bisection of the apical root width can be used.

According to SN Bhatia and BC Leighton


Tracing of Incision Inferius Incisalis on Lateral Cephalogram

by small letters or lower case i and a and is written continuously without any space between the alphabets.

The lower incisor apex is the root apex of the most prominent lower incisor.4

Type

Incision inferius apicalis is a unilateral, anatomic, hard tissue cephalometric landmark.

Tracing of Incision Inferius Apicalis on Lateral Cephalogram

The labial and lingual outline of the root of the mandibular permanent central incisor appears as radio-opaque lines on the lateral cephalogram. Trace these two outlines of root of the mandibular permanent central incisor. The point of intersection of labial and lingual outlines of the root of mandibular permanent central incisor is the point of incision inferius apicalis.


Incision inferius apicalis is used as one of the reference points in the construction of angles and planes for the assessment of following: • Inclination of lower incisor is assessed using angle drawn between the long axis of upper incisor plane and the mandibular plane. • In Arnett’s analysis, the lower incisor torque is assessed using the angle drawn between long axis of lower incisor and occlusal plane. • Inter-incisal relationship of upper and lower incisors are assessed using the angle drawn between the long axis of upper and lower permanent central incisors.


76

A

B

C

D

Figures 11.4A to D: Incision inferius apicalis

Anterior Point of Occlusion

Abbreviation APocc–Anterior point of occlusion is abbreviated using English alphabets and is expressed as capital or upper case A and P followed by small letters or lower case o, c and c and written continuously without any space between the alphabets.

Definition Anterior point of occlusion (Figs 11.5A to D) for the occlusal plane–A constructed point, the midpoint of the incisor overbite in occlusion.

Type Anterior point of occlusion is a unilateral, constructed, hard tissue cephalometric landmark.

Tracing of Anterior Point of Occlusion on Lateral Cephalogram • The labial and lingual outline of the crown of the maxillary permanent central incisor appears as radio-opaque line on the lateral cephalogram. Trace these two outlines of crown of the maxillary permanent central incisor. • The labial and lingual outline of the root of the maxillary permanent central incisor appears as radio-opaque lines on the lateral cephalogram. Trace these two outlines of root of the maxillary permanent central incisor. • The labial and lingual outline of the crown of the mandibular permanent central incisor appears as radio-opaque line on the lateral cephalogram. Trace these two outlines of crown of the mandibular permanent central incisor. • The labial and lingual outline of the root of the mandibular permanent central incisor appears as radio-opaque lines on the lateral cephalogram. Trace these two outlines of root of the mandibular permanent central incisor.

77

B

C

D

Figures 11.5A to D: Anterior point of occlusion

• Locate the point where there is maximum intercuspation of maxillary and mandibular permanent central incisors, which is the point of anterior point of occlusion.

Significance (Ref to Chapter 20) Anterior point of occlusion is used as one of the reference points in the construction of angles and planes for the assessment of the following: • Growth pattern is assessed using angle drawn between the occlusal plane and mandibular plane. • Growth pattern is assessed using angle drawn between the occlusal plane and FH plane. • In Arnett’s analysis, the upper incisor torque is assessed using the angle drawn between long axis of upper incisor and occlusal plane. • In Arnett’s analysis, the lower incisor torque is assessed using the angle drawn between long axis of lower incisor and occlusal plane.

Posterior Point of Occlusion Abbreviation


A

PPocc–Anterior point of occlusion is abbreviated using English alphabets and is expressed as capital or upper case P and P followed by small letters or lower case o, c and c and are written continuously without any space between the alphabets.

Definition Posterior point of occlusion (Figs 11.6A to D) for the occlusal plane—the most distal point of contact between the most posterior molars in occlusion (Rakosi).

Type Posterior point of occlusion is a bilateral, anatomic hard tissue cephalometric landmark.


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A

B

C

D

Figures 11.6A to D: Posterior point of occlusion

Tracing of Posterior Point of Occlusion on Lateral Cephalogram • The labial and lingual outline of the crown of the maxillary permanent first molar appears as radio-opaque lines on the lateral cephalogram. Trace these two outlines of crown of the maxillary permanent first molar. • The labial and lingual outline of the root of the maxillary permanent first molar appears as radio-opaque lines on the lateral cephalogram. Trace these two outlines of root of the maxillary permanent first molar. • The labial and lingual outline of the crown of the mandibular permanent first molar appears as radio-opaque lines on the lateral cephalogram. Trace these two outlines of crown of the mandibular permanent first molar. • The labial and lingual outline of the root of the mandibular permanent first molar appears as radio-opaque lines on the lateral cephalogram. Trace these two outlines of root of the mandibular permanent first molar.

• Locate the point where there is maximum intercuspation of maxillary and mandibular permanent first molars, which is the point of anterior point of occlusion.

Significance (Ref to Chapter 20) Posterior point of occlusion is used as one of the reference points in the construction of angles and planes for the assessment of following: • Growth pattern is assessed using angle drawn between the occlusal plane and mandibular plane. • Growth pattern is assessed using angle drawn between the occlusal plane and FH plane. • In Arnett’s analysis, the upper incisor torque is assessed using the angle drawn between long axis of lower incisor and occlusal plane. • In Arnett’s analysis, the lower incisor torque is assessed using the angle drawn between long axis of lower incisor and occlusal plane.

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B

C

D

Figures 11.7A to D: Maxillary central incisor

Maxillary Central Incisor Abbreviation U1–Maxillary central incisor is abbreviated using English alphabets and numeric and is expressed as Capital or upper case U followed by English numeric 1 and is written continuously without any space between them.

Definition Maxillary central incisor (Figs 11.7A to D) is the most labial point on the crown of the maxillary central incisor.

Type Maxillary central incisor is a unilateral, anatomic, hard tissue cephalometric landmark.

Tracing of Maxillary Central Incisor on Lateral Cephalogram


A

The labial and lingual outline of the crown of the maxillary permanent central incisor appears as radio-opaque line on the lateral cephalogram. Trace these two outlines of crown of the maxillary permanent central incisor. The most labial point on the crown of the maxillary central incisor is the point of maxillary central incisor.

Maxillary First Molar Abbreviation U6–Maxillary first molar is abbreviated using English alphabets and numeric and is expressed as capital or upper case U followed by English numeric 6 and is written continuously without any space between the alphabets.


80

A

C

B

D

Figures 11.8A to D: Maxillary first molar

Definition Maxillary first molar (Figs 11.8A to D) is the tip of the mesiobuccal cusp of the maxillary first permanent molar.

Type Maxillary first molar is a bilateral, anatomic, hard tissue cephalometric landmark.

Tracing of Maxillary First Molar on Lateral Cephalogram The labial and lingual and cuspal outlines of the crown of the maxillary permanent first molar appears as radio-opaque lines on the lateral cephalogram. Trace these outlines of crown of the maxillary permanent first molar, the tip of the mesiobuccal cusp of the maxillary permanent molar is the point of maxillary first molar.

Mandibular Central Incisor Abbreviation L1–Mandibular central incisor is abbreviated using English alphabets and numeric and is expressed as capital or upper case L followed by English numeric 1 and is written continuously without any space between the alphabets.

Definition Mandibular central incisor (Figs 11.9A to D) is the most labial point on the crown of the mandibular central incisor.

Type Mandibular central incisor is a unilateral, anatomic, hard tissue cephalometric landmark.

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B

C

D

Figures 11.9A to D: Mandibular central incisor

Tracing of Mandibular Central Incisor on Lateral Cephalogram The labial and lingual outlines of the crown of the mandibular permanent central incisor appear as radio-opaque lines on the lateral cephalogram. Trace these two outlines of crown of the mandibular permanent central incisor. The most labial point on the crown of the mandibular central incisor is the point of mandibular central incisor.

Mandibular First Molar Abbreviation L6–Mandibular first molar is abbreviated using English alphabets and numerical and is expressed as capital or upper case L followed by English numeric 6 and is written continuously without any space between the alphabets.

Definition


A

Mandibular first molar (Figs 11.10A to D) is the tip of the mesiobuccal cusp of the mandibular first permanent molar.

Type

Mandibular first molar is a bilateral, anatomic, hard tissue cephalometric landmark.

Tracing of Mandibular First Molar on Lateral Cephalogram The labial and lingual and cuspal outlines of the crown of the mandibular permanent first molar appears as radio-opaque lines on the lateral cephalogram. Trace these outlines of crown of the mandibular permanent first molar, the tip of the mesiobuccal cusp of the mandibular permanent molar is the point of maxillary first molar.


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A

B

C

D

Figures 11.10A to D: Mandibular first molar

mi

Type mi is a bilateral, hard tissue cephalometric landmark.

Abbreviation mi–mi is abbreviated using English alphabets and is expressed as lower case m and i and written continuously without any space between the alphabets.

Definition mi (Figs 11.11A to D) is the mesial contact of the lower molar projected normal to the plane of occlusion.

Tracing of mi on Lateral Cephalogram The labial and lingual and cuspal outlines of the crown of the mandibular permanent first molar appears as radio-opaque lines on the lateral cephalogram. Trace these outlines of crown of the mandibular permanent first molar, the tip of the mesiobuccal cusp of the mandibular permanent molar is the point of maxillary first molar. mi is the mesial contact of the lower molar projected normal to the plane of occlusion.

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B

C

D

Figures 11.11A to D: mi


A


Definition

mi is used as one of the reference points in the construction of plane and angle in the Bjork cephalometric analysis.

ms (Figs 11.12A to D) is the mesial contact of the upper molar projected normal to the plane of occlusion.

ms

Type ms is a bilateral hard tissue cephalometric landmark.

Abbreviation ms–ms is abbreviated using English alphabets and is expressed as lower case m and s and written continuously without any space between the alphabets.

Tracing of ms on Lateral Cephalogram The labial and lingual and cuspal outlines of the crown of the mandibular permanent first molar appears as radio-opaque lines on the lateral cephalogram. Trace these outlines of


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A

B

C

D

Figures 11.12A to D: ms

crown of the mandibular permanent first molar, the tip of the mesiobuccal cusp of the mandibular permanent molar is the point of maxillary first molar. ms is the mesial contact of the upper molar projected normal to the plane of occlusion.

Significance (Ref to Chapter 20) ms is used as one of the reference point in the construction of plane and angle in the Bjork cephalometric analysis.

References 1. Arne Bjork. The face in profiles-Sven. Tandlak Tidskr. 1947;40:32-3. 2. Robert M Moyers. Handbook of Orthodontics–Year Book Medical Publishers, Inc. 1988;251-9. 3. Michael L Riolo. An atlas of craniofacial growth: Cephalometric standards from the university school growth study, the University of Michigan. Center for human growth and development. The University of Michigan. 1974;12-21. 4. Bhatia SN, Leighton BC. A manual of facial growth. Oxford University Press. 1993;10-5.

Chapter

12

Cephalometric Landmarks Related to Mandible

The mandible (Fig. 12.1 ) (from Latin mandibula—jawbone) or inferior maxillary bone forms the lower jaw and holds the lower teeth in place.

Cephalometric landmarks (Points) on Mandible Cephalometric landmarks on mandible are as follows (Table 12.1): Table 12.1: Cephalometric landmarks related to mandible Cephalometric landmarks

Abbreviation

Type

Origin

Infradentale

Id

Unilateral

anatomic

point B

part B

Unilateral

anatomic

pogonion

pog

Unilateral

anatomic

Gnathion

Gn

Unilateral

anatomic

dd

dd

Unilateral

anatomic

Menton

Me

Unilateral

anatomic

Gonion

Go

Unilateral

anatomic

Articulare

ar

Bilateral

anatomic

kk

kk

Unilateral

anatomic

Condylion

Cd

Bilateral

anatomic

• Mandibular foramen, paired, in the inner (medial) aspect of the mandible, superior to the mandibular angle in the middle of the ramus. • Mental foramen, paired, lateral to the mental protuberance on the body of mandible.

Nerve Supply to Mandible Inferior alveolar nerve, branch of the mandibular division of trigeminal (V) nerve, enters the mandibular foramen and runs forward in the mandibular canal, supplying sensation to the teeth. At the mental foramen the nerve divides into two terminal branches: Incisive and mental nerves. The incisive nerve runs forward in the mandible and supplies the anterior teeth. The mental nerve exits in the mental foramen and supplies sensation to the lower lip.

Parts of Mandible The mandible consists of: • A curved, horizontal portion, the body. • Two perpendicular portions, the rami, which unite with the ends of the body nearly at right angles. • Alveolar process, the tooth bearing area of the mandible. • Condyle, superior (upper) and posterior projection from the ramus, which makes the temporomandibular joint with the temporal bone. • Coronoid process, superior and anterior. • Projection from the ramus. This provides attachment to the temporalis muscle.

Figure 12.1: Mandible

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Articulations

Definition

The mandible articulates with the two temporal bones at the temporomandibular joints.

According to Arne Bjork The infradentale (Figs 12.2A to D) is the point of transition from the crown of the most prominent mandibular medial incisor to the alveolar projection.

Infradentale Abbreviation

According to Robert M Moyers

Section 4  Cephalometric Landmarks Related to Facial Bones and Dentition

Id–Infradentale is abbreviated using English alphabets and is expressed as capital or upper case I followed by lower case or small letters d and written continuously without any space between the alphabets.

A

C

The infradentale is the most anterior superior point on the mandibular alveolar process, usually found near cementenamel junction of the mandibular incisors.

B

D

Figures 12.2A to D: Infradentale

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According to SN Bhatia and BC leighton


The infradentale is the most anterosuperior point on the labial crest of the mandibular alveolar process.

Infradentale is used as one of the reference points in the construction of plane and angle for the assessment of mandibular prognathism in the anterior region using S-N-Id angle.

Type

Point B

Infradentale is a unilateral, anatomic hard tissue landmark.

Tracing of Infradentale on the lateral Cephalogram

Abbreviation

A

B

C

D

Point B–Point B is abbreviated using English alphabets and is expressed as capital or upper case B.


Chapter 12  Cephalometric Landmarks Related to Mandible

The alveolar crest between two mandibular permanent central incisors in the midline appears as radio-opaque lines on the lateral cephalogram. Trace these radio-opaque lines. The intersection of radio-opaque lines of interdental cortical plate in the alveolar crest region between two mandibular permanent central incisors, is the point of infradentale.

The point B (Figs 12.3A to D) is the deepest midline point on the mandible between infradentale and pogonion.

Figures 12.3A to D: Point B

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Definition

The point B is an arbitrary measure point on the anterior profile curvature from the mandibular anthropometric landmark pogonion to the crest of the alveolar process. This most posterior point usually falls just anterior to the apices of the incisor teeth.

According to KKK lew

According to Alex Jacobson and W Caufield


Point B is on a line perpendicular to FH, point B is the most posterior point in the concavity between the chin and mandibular alveolar process.

Most anterior point of mandibular symphysis.

According to William B Downs Pogonion (Figs 12.4A to D) is the most anterior point on the mandible in the midline.



The most anterior point on the symphysis of the mandible.

The point B is the most posterior point of the bony curvature of the mandible below infradentale and above pogonion. B point usually is found near the apical third of the roots of the mandibular incisors and may be obscured during eruption of these teeth, when the profile of the chin is not concave, B point cannot be determined.

According to Robert M Ricketts Most anterior point on the mental protuberance.

According to B Holly Broadbent Most anterior point on the symphysis of the mandible in the median plane when the head is viewed in Frankfort relation.

Type Point B is a unilateral, anatomic, hard tissue cephalometric landmark.

Tracing of Point B on the lateral Cephalogram The labial cortical plate of mandible in the anterior symphysis region appears as vertical shaped radio-opaque line. Trace this line from the infradentale to the point of pogonion. It’s been tough task to establish the precise location of point B on the lateral cephalogram. To make it easy, try to locate infradentale and pogonion and then the mid deepest point is the point B.

According to leslie G Farkas Pogonion is the most anterior midpoint of the chin, located on the skin surface in front of the identical bony landmark of the mandible.

Robert E Moyers The most anterior point on the contour of the chin, pogonion usually is located by drawing a tangent perpendicular to the mandibular plane or by a tangent dropped to the chin from nasion.

Alex Jacobson and W Caufield Move the perpendicular line to FH forward then back to where it first touches the chin. This is pogonion.

Significance Point B is used as one of the reference points in the construction of plane and angle for the assessment of anteroposterior relationship of the mandible in relation to anterior cranial base using S-N-B angle.

Pogonion Abbreviation Pog–Pogonion is abbreviated using English alphabets and is expressed as capital or upper case P followed by lower case or small letters o and g and are written continuously without any space between the alphabets.

Type Pogonion is a unilateral, anatomic, hard tissue cephalometric landmark.

Tracing of Pogonion on the lateral Cephalogram The labial cortical plate of mandible in the anterior symphysis region appears as vertical shaped radio-opaque line. Trace the labial cortical plate from the alveolar crest between two permanent mandibular incisors in the midline to the point anteroinferior point on the mandible. Below the point B follows the convex outline of labial cortical plate of mandible, the most prominent point is the point of pogonion.

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B

C

D

Figures 12.4A to D: Pogonion


A

Significance

Definition

Pogonion is used as one of the reference points in the construction of plane and angle for the assessment of anteroposterior relationship of the mandible in relation to anterior cranial base using S-N-Pog angle (Facial angle).

Gnathion (Figs 12.5A to D) is a point on the chin determined by bisecting the angle formed by the facial and mandibular plane.

Gnathion

According to TM Graber Gnathion is the most outward and everted point on the profile curvature of the symphysis of the mandible.

Abbreviation


Gn–Gnathion is abbreviated using English alphabets and is expressed as capital or upper case G followed by lower case or small letters n and is written continuously without any space between the alphabets.

The most anterior inferior point in the lateral shadow of the chin. Ganthion usually is best determined by selecting the midpoint between pogonion and menton on the contour of the chin.


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A

B

C

D

Figures 12.5A to D: Gnathion

According to Viken Sassouni Midpoint between pogonion and menton can be located at the intersection of the facial; line (Na-Pog) and the mandibular plane (lower border).

Alex Jacobson and W Caufield A point located by taking the point between the anterior (Pogonion) and inferior (Menton) points of the bony chin.

Arne Bjork Lowest point of the mandibular symphysis.

Type Gnathion is a unilateral, constructed or derived, hard tissue cephalometric landmark.

Tracing of Gnathion on the lateral Cephalogram The labial cortical plate of mandible in the anterior symphysis region appears as vertical shaped radio-opaque line. Trace the labial cortical plate from the alveolar crest between two permanent mandibular incisors in the midline to the point anteroinferior point on the mandible. Below the point B follows the convex outline of labial cortical plate of mandible, the most prominent point is the point of pogonion.The anteroinferior point of inferior border of the mandible in the midline is the point of menton. The ganthion is a constructed or derived hard tissue cephalometric point. Draw a line joining the point of pogonion to the menton, the midpoint of this line is the point of gnathion.

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B

C

D

Figures 12.6A to D: dd


A

Significance

Definition

Gnathion is used as one of the reference points in the construction of plane and angle for the assessment of growth pattern using N-S-Gn angle. In Rickett’s cephalometric analysis, the positioning of the chin is determined by the angle formed between the Ba-N plane and plane from foramen rotundum (PT) to Gn. The normal value of this angle is 90 degree. A larger angle suggests a protrusive or forward growing chin whereas a lesser angle suggests a retropositioning of the chin.

dd (Figs 12.6A to D) is the most prominent point of the chin in the direction of measurement.

dd Abbreviation dd–dd is abbreviated using English alphabets and is expressed as lower case or small letters d and d and written continuously without any space between the alphabets.

Type

dd is a unilateral, anatomic, hard tissue cephalometric landmark.

Tracing of dd on the lateral Cephalogram The labial cortical plate of mandible in the anterior symphysis region appears as vertical shaped radio-opaque line. Trace the labial cortical plate from the alveolar crest between two permanent mandibular incisors in the midline to the point anteroinferior point on the mandible. Below the point B follows the convex outline of labial cortical plate of mandible, the most prominent point is the point of pogonion. The anteroinferior point of inferior border of the mandible in the

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midline is the point of menton. The gnathion is a constructed or derived hard tissue cephalometric point. Draw a line joining the point of pogonion to the menton,the midpoint of this line is the point of gnathion. dd is the most prominent point of the chin in the direction of measurement.

According to Viken Sassouni Lower most point of the contour of the chin.

According to Carl F Gugino Menton (Figs 12.7A to D) is the point of the inferior border of the symphysis directly inferior to mental protuberance and inferior to the center of trigoniun mentali.

Significance


dd is used as one of the reference points in the construction of plane and angle in the Bjork cephalometric analysis.

Type

Menton

Menton (Figs 12.7A to D) is a unilateral, anatomic, hard tissue landmark.

Abbreviation Tracing of Menton on the lateral Cephalogram

Me–Menton is abbreviated using English alphabets and is expressed as capital or upper case M followed by lower case or small letter e and is written continuously without any space between the alphabets.

The labial cortical plate of mandible in the anterior symphysis region appears as vertical shaped radio-opaque line. Trace the

A

B

C

D

Figures 12.7A to D: Menton

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labial cortical plate from the alveolar crest between two permanent mandibular incisors in the midline to the point anteroinferior point on the mandible. Below the point B follows the convex outline of labial cortical plate of mandible,the most prominent point is the point of pogonion.The anteroinferior point of inferior border of the mandible in the midline is the point of menton.

Significance

Gonion Abbreviation Go–Gonion is abbreviated using English alphabets and is expressed as capital or upper case G followed by lower case or small letter o and is written continuously without any space between the alphabets.

Significance

Gonion is used as one of the reference points in the construction of plane and angle for the assessment of following: • Constructions of mandibular plane, i.e. the line joining the point menton and gonion. • Growth pattern is assessed using S-N to mandibular plane angle. • Growth pattern is assessed using FH to mandibular plane angle. • Cant of occlusal plane is assessed using occlusal plane (APocc-Ppocc ) to mandibular plane (AvMe-Go) angle. • Growth pattern is assessed using Go1 and Go2 angles. • Rotation of the mandible is also assessed using the S-ArGo angle. • The length of the mandible is measured from condylion to gonion.

Definition

Articulare

According to Clifton T Forsberg The midpoint mediolaterally on the posterior border of each gonial angle.

According to KKK lew The midpoint mediolaterally on the posterior most border of each gonial angle. Gonion is a bilateral structure.

Type Gonion (Figs 12.8A to D) is a unilateral, anatomic, hard tissue cephalometric landmark.

Abbreviation

Ar–Articulare is abbreviated using English alphabets and is expressed as capital or upper case A followed by lower case or small letter r and is written continuously without any space between the alphabets.

Definition Articulare (Figs 12.9A to D) is the point of intersection the dorsal contours of the processus articularis mandibulare and os tempoarle. The midpoint, a is used where double projection gives rise to two points, a1 and a2.

Tracing of Menton on the lateral Cephalogram The inferior and posterior borders of the mandible appear as radio-opaque lines on the lateral cephalogram.Trace these two


Menton is used as one of the reference points in the construction of plane and angle for the assessment of following: • Constructions of mandibular plane, i.e. the line joining the point menton and gonion. • Growth pattern is assessed using S-N to mandibular plane angle. • Growth pattern is assessed using FH to mandibular plane angle. • Cant of occlusal plane is assessed using occlusal plane (APocc-Ppocc) to mandibular plane (Me-Go) angle. • Growth pattern is assessed using Go1 and Go2 angles.

radio-opaque lines and then draw a line tangent to inferior and posterior/ramus borders of the mandible; the point where these two intersects is the point of gonion. Improper positioning of head during cephalometric radiographic projection procedure will result in superimposition of right and left mandibular inferior border. In such cases, there are two radio-opaque lines of right and left mandibular inferior borders. Then trace these two radio-opaque lines and draw an imaginary line exactly middistance between right and left inferior borders of the mandible. To establish the point Gonion tangent line is drawn from the imaginary line and posterior border/ramus border, the instersection of these two lines is the point of Gonion.

Type Articulare is a bilateral, anatomic, hard tissue landmark.


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A

B

C

D

Figures 12.8A to D: Gonion

Tracing of Articulare on the lateral Cephalogram

kk

The posterior or ramus border of the mandible appears as radio-opaque line on the lateral cephalogram. Trace ramus border of the mandible. The point on the ramus border of the mandible at the neck region.

Abbreviation

Significance

Definition

Articulare is used as one of the reference points in the construction of plane and angle for the assessment of the following: • Construction of posterior/ramus border of the mandible, i.e. the line joining the point Articulare and Gonion. • Growth pattern is assessed using Go1 and Go2 angles. • Rotation of the mandible is also assessed using the S-ArGo angle.

kk is the point of intersection between the base and ramus tangents to the mandible. The midpoint is used where double projections gives rise to two points.

kk–kk is abbreviated using English alphabets and is expressed as lower case or small letters k and k and written continuously without any space between the alphabets.

Type kk (Figs 12.10A to D) is a bilateral hard tissue cephalometric landmark.

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B

C

D

Figures 12.9A to D: Articulare

Tracing of Menton on the lateral Cephalogram The inferior and posterior borders of the mandible appear as radio-opaque lines on the lateral cephalogram. Trace these two radio-opaque lines and then draw a line tangent to inferior and posterior/ramus borders of the mandible; the point where these two intersect is the point of gonion. kk is the point of intersection between the base and ramus tangents to the mandible. The midpoint is used where double projections give rise to two points.

Significance kk is used as one of the reference points in the construction of plane and angle in the Bjork cephalometric analysis.

Condylion Abbreviation


A

Cd–Articulare is abbreviated using English alphabets and is expressed as capital or upper case C followed by lower case or small letter d and is written continuously without any space between the alphabets.

Definition According to Clifton T Forsberg Condylion medialis (Figs 12.11A to D)–The tangent point to each medial condylar border of a line drawn parallel to each mandibular body line.


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A

B

C

D

Figures 12.10A to D: kk



Condylion medialis–Most medial aspect of condyle. Bilateral structure.

Condylion anterioris–A point on the anterior of each condylar head which is chosen to represent the mandibular fossa of the temporal bone.



Condylion lateralis–The tangent point in each condylar border of a line drawn parallel to each mandibular body line.

Condylion posterialis–The intersection of the mandibular body line with the posterior border of each condyle.


Type

Condylion lateralis–Most lateral aspect of condyle. Bilateral structure.

Condylion is a bilateral, anatomic, hard tissue cephalometric landmark.

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B

C

D

Figures 12.11A to D: Condylion

Tracing of Condylion on the lateral Cephalogram The posterior or ramus border of the mandible appears as radio-opaque line on the lateral cephalogram. Condyle of the mandible appears as a circular radio-opaque line on the lateral cephalogram. The highest point of superior curvature of the condyle of the mandible is the point of condylion.

Significance Condylion is used as one of the reference points in the construction of plane and angle for the assessment of the following:


A

• Construction of posterior/ramus border of the mandible, i.e. the line joining the point Articulare and Gonion. • Growth pattern is assessed using Go1 and Go2 angles. • Rotation of the mandible is also assessed using the S-ArGo angle. • Midfacial length is measured from condylion to point A in McNamara analysis. • The length of the mandible is measured from condylion to gonion.

Section

5

Cephalometric Landmarks Related to Cervical Bones

 Cephalometric Landmarks Related to Hyoid Bone  Cephalometric Landmarks Related to Vertebrae

Chapter

13

Cephalometric landmarks related to hyoid bone

Like the mandible, the hyoid bone (Figs 13.1A and B) is also a horse-shoe shaped bone suspended in the neck.

Parts of the Hyoid Bone Hyoid bone consists of the following parts: • A body. • Lesser cornu/horn. • Greater cornu/horn. The lesser cornu fuses the body of the hyoid bone superiorly whereas the greater cornu fuses the body of hyoid bone inferiorly.

• In children, greater cornu is seen separately as it is not fused to the body of hyoid but in adults both lesser and greater cornu are fused to the body of hyoid bone.

Cephalometric Landmarks (Points) on Hyoid Bone Cephalometric landmarks seen on the hyoid bone are of anatomic origin and are as follows: Table 13.1: Cephalometric landmark related to hyoid bone Cephalometric landmark

Abbreviation

Type

Origin

Hyoid

Hy or H

Unilateral

Anatomic

Radiographic Anatomy of Hyoid Bone • The hyoid bone is well appreciated on the lateral cephalogram. • On the lateral cephalogram, the hyoid bone appears boomerang-shaped radio-opaque area below the inferior to the middle of the mandibular body. • The greater and lesser cornu of the hyoid bone appear as radio-opaque on the lateral cephalogram. • The body of the hyoid bone on the lateral cephalogram appears as radio-opaque.

A

Hyoid Abbreviation Hy–Hyoid is abbreviated using English alphabet and is expressed as capital or upper case H followed by lower case or small y, and both are written continuously without any space between the alphabets.

B

Figures 13.1A and B: Hyoid bone

Section 5  Cephalometric Landmarks Related to Cervical Bones

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A

B

C

D

Figures 13.2A to D: Hyoid

H–Hyoid is abbreviated using English alphabet and is expressed as capital or upper case H. Note: Most widely and commonly used abbreviation for hyoid is Hy.

Definition Hyoid (Figs 13.2A to D) is the most superoanterior point on the body of the hyoid bone.

According to Robert M Ricketts According to Robert M Ricketts, the hyoid is the point at the anterior-superior margin of the body of the hyoid.1

Type Hyoid is a unilateral, anatomic, hard tissue cephalometric landmark.

Tracing of Hyoid on the Lateral Cephalogram The body, lesser and greater cornu of the hyoid bone appears as boomerang shaped radio-opaque area. The superioanterior point on the body of the hyoid bone is the point of hyoid. It is a unilateral, anatomic hard tissue cephalometric landmark.

Reference 1. Ricketts RR. Provocations and perceptions in cranio-facial orthopedics– dental science and facial art. Rocky Mountain Inc. 1989;797-803.

Chapter

14

Cephalometric landmarks related to Vertebrae

Radiographic anatomy of cervical vertebrae (fig. 14.1) Anteroinferior to the occipital condyle, which appears as a curved radio-opaque line, the anterior arch of the atlas can be identified as a small triangular radio-opaque area. The apex of the triangle faces the posterior border of the mandibular ramus, while its base faces the odontoid process of the axis. The central mass of the atlas, which appears as radioopaque area superimposed on the radio-opaque shadow of the odontoid process. Posterosuperior to the inferior articular facet is the superior articular facet, which can be identified as radioopaque area. Its superior border is concave and corresponds with the contour of the occipital condyle. Next to the superior articular facet is the posterior arch with the posterior tubercle. At the superior border of the posterior arch is a groove for the vertebral artery and the first cervical nerve. The odontoid process and the body of the axis appear as a triangular radio-opaque area. The odontoid process represents the apex of the triangular points toward the occipital condyle. The spinous process of the axis appears as a radio-opaque projection extending superiorly. The radiographic appearance of the third cervical vertebra (C3) to the seventh cervical vertebra (C7) is similar. The body of the each of these cervical vertebrae appears as wedge shaped radio-opaque area situated behind the pharyngeal space. Posterior to the body is the spinous process. The transverse processes, the superior articular process and the inferior articular process appear as radio-opaque area superimposed on the shadow of the body and the spinous process. The body of each cervical vertebra is separated from the adjacent ones by the intervertebral disc, which appears as radiolucent strip. At the midpoint between the third and fourth cervical vertebrae is the hyoid bone, which is separated anteriorly.

Cephalometric Landmarks on Cervical Vertebra Cephalometric landmarks seen on the cervical vertebra are of anatomic origin and are as follows (Table 14.1):

Table 14.1: Cephalometric landmarks related to cervical vertebra Cephalometric landmarks

Abbreviation

Type

Origin

cv2ap

cv2ap

Unilateral

Anatomic

cv2ip

cv2ip

Unilateral

Anatomic

cv2ia

cv2ia

Unilateral

Anatomic

cv3sp

cv3sp

Unilateral

Anatomic

cv3ip

cv3ip

Unilateral

Anatomic

cv3sa

cv3sa

Unilateral

Anatomic

cv3ia

cv3ia

Unilateral

Anatomic

cv4sp

cv4sp

Unilateral

Anatomic

cv4ip

cv4ip

Unilateral

Anatomic

cv4sa

cv4sa

Unilateral

Anatomic

cv4ia

cv4ia

Unilateral

Anatomic

cv5sp

cv5sp

Unilateral

Anatomic

cv5ip

cv5ip

Unilateral

Anatomic

cv5sa

cv5sa

Unilateral

Anatomic

cv5ia

cv5ia

Unilateral

Anatomic

cv6sp

cv6sp

Unilateral

Anatomic

cv6ip

cv6ip

Unilateral

Anatomic

cv6sa

cv6sa

Unilateral

Anatomic

cv6ia

cv6ia

Unilateral

Anatomic

Cephalometric Landmarks (Points) Related to Cervical Vertebra • cv2ap–The apex of the odontoid process of the second cervical vertebra. • cv2ip–The most inferoposterior point on the body of the second cervical vertebra. • cv2ia–The most inferoanterior point on the body of the second cervical vertebra.

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• cv6ip–The most inferoposterior point on the body of the sixth cervical vertebra. • cv6sa–The most superoanterior point on the body of the sixth cervical vertebra. • cv6ia–The most inferoanterior point on the body of the sixth cervical vertebra.

cv2ip


Abbreviation cv2ip–cv2ip is abbreviated using English alphabet and English numeric and is expressed as small letters or lower case c,v followed by English numeric 2 and then it is followed with English alphabets lower case i and p and all of them are written continuously without any space between the alphabets.

Definition The most inferoposterior point on the body of the second cervical vertebra.

Type

Figure 14.1: Radiographic anatomy of cervical vertebra

• cv3sp–The most superoposterior point on the body of the third cervical vertebra. • cv3ip–The most inferoposterior point on the body of the third cervical vertebra. • cv3sa–The most superoanterior point on the body of the third cervical vertebra. • cv3ia–The most inferoanterior point on the body of the third cervical vertebra. • cv4sp–The most superoposterior point on the body of the fourth cervical vertebra. • cv4ip–The most inferoposterior point on the body of the fourth cervical vertebra. • cv4sa–The most superoanterior point on the body of the fourth cervical vertebra. • cv4ia–The most inferoanterior point on the body of the fourth cervical vertebra. • cv5sp–The most superoposterior point on the body of the fifth cervical vertebra. • cv5ip–The most inferoposterior point on the body of the fifth cervical vertebra. • cv5sa–The most superoanterior point on the body of the fifth cervical vertebra. • cv5ia–The most inferoanterior point on the body of the fifth cervical vertebra. • cv6sp–The most superoposterior point on the body of the sixth cervical vertebra.

cv2ip (Figs 14.2A and B) is a unilateral, anatomic, hard tissue cephalometric landmark.

Significance This cephalometric landmark/point is used as a reference point in the cervical vertebrae maturity indicator (CMVI) method.

cv2ap Abbreviation cv2ap–cv2ap is abbreviated using English alphabet and English numeric and is expressed as small letters or lower case c,v followed by English numeric 2 and then it is followed with English alphabets lower case a and p and all of them are written continuously without any space between the alphabets.

Definition The apex of the odontoid process of the second cervical vertebra.

Type cv2ap (Figs 14.3A and B) is a unilateral, anatomic, hard tissue cephalometric landmark.


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B

Figures 14.2A and B: cv2ip-The most inferoposterior point on the body of the second cervical vertebra

A

B

Figures 14.3A and B: cv2ap-The apex of the odontoid process of the second cervical vertebra

Chapter 14  Cephalometric landmarks related to Vertebrae

A

106

cv3sp

Abbreviation

Abbreviation

cv2ia–cv2ia is abbreviated using English alphabet and English numeric and is expressed as small letters or lower case c,v followed by English numeric 2 and then it is followed with English alphabets lower case i and a and all of them are written continuously without any space between the alphabets.

cv3sp–cv3sp is abbreviated using English alphabet and English numeric and is expressed as small letters or lower case c,v followed by English numeric 3 and then it is followed with English alphabets lower case s and p and all of them are written continuously without any space between the alphabets.

Definition

Definition

The most inferoanterior point on the body of the second cervical vertebra.

The most superoposterior point on the body of the third cervical vertebra.

Type

Type

cv2ia (Figs 14.4A and B) is a unilateral, anatomic, hard tissue cephalometric landmark.

cv3sp (Figs 14.5A and B) is a unilateral, anatomic, hard tissue cephalometric landmark.

Significance

Significance

This cephalometric landmark/point is used as a reference point in the cervical vertebrae maturity indicator (CMVI) method.



cv2ia

A

B

Figures 14.4A and B: cv2ia-The most inferioanterior point on the body of the second cervical vertebra

107

B

Figures 14.5A and B: cv3sp-The most superoposterior point on the body of the third cervical vertebra


A

cv3ip

cv3sa

Abbreviation

Abbreviation

cv3ip–cv3ip is abbreviated using English alphabet and English numeric and is expressed as small letters or lower case c,v followed by English numeric 3 and then it is followed with English alphabets lower case i and p and all of them are written continuously without any space between the alphabets.

cv3sa—cv3sa is abbreviated using English alphabet and English numeric and is expressed as small letters or lower case c,v followed by English numeric 3 and then it is followed with English alphabets lower case s and a and all of them are written continuously without any space between the alphabets.

Definition

Definition

The most inferoposterior point on the body of the third cervical vertebra.

The most superoanterior point on the body of the third cervical vertebra.

Type

Type


cv3sa (Figs 14.7A and B) is a unilateral, anatomic, hard tissue cephalometric landmark.

Significance

Significance




108

A

A

B

Figures 14.6A and B: cv3ip-The most inferoposterior point on the body of the third cervical vertebra

B

Figures 14.7A and B: cv3sa-The most superoanterior point on the body of the third cervical vertebra

109

cv4sp

Abbreviation

Abbreviation



Definition

Definition

The most inferoanterior point on the body of the third cervical vertebra.

The most superoposterior point on the body of the fourth cervical vertebra.

Type

Type



Significance

Significance



A

B

Figures 14.8A and B: cv3ia-The most inferioanterior point on the body of the third cervical vertebra


cv3ia


110

A

B

Figures 14.9A and B: cv4sp-The most superoposterior point on the body of the fourth cervical vertebra

cv4ip

cv4sa

Abbreviation

Abbreviation


cv4sa–cv4sa is abbreviated using English alphabet and English numeric and is expressed as small letters or lower case c,v followed by English numeric 4 and then it is followed with English alphabets lower case s and a and all of them are written continuously without any space between the alphabets.

Definition

Definition

The most inferoposterior point on the body of the fourth cervical vertebra.

The most superoanterior point on the body of the fourth cervical vertebra.

Type

Type



Significance

Significance



111

B

Figures 14.10A and B: cv4ip-The most inferoposterior point on the body of the fourth cervical vertebra

A

B

Figures 14.11A and B: cv4sa-The most superoanterior point on the body of the fourth cervical vertebra


A

112

cv5sp

Abbreviation

Abbreviation


cv5sp–cv5sp is abbreviated using English alphabet and English numerical and is expressed as small letters or lower case c,v followed by English numeric 5 and then it is followed with English alphabets lower case i and a and all of them are written continuously without any space between the alphabets.

DEFINITION

Definition

The most inferoanterior point on the body of the fourth cervical vertebra.

The most superoposterior point on the body of the fifth cervical vertebra.

Type

Type



Significance

Significance




cv4ia

A

B

Figures 14.12A and B: cv4ia-The most inferoanterior point on the body of the fourth cervical vertebra

113

B

Figures 14.13A and B: cv5sp-The most superoposterior point on the body of the fifth cervical vertebra


A

cv5ip

cv5sa

Abbreviation

Abbreviation



Definition

Definition

The most inferoposterior point on the body of the fifth cervical vertebra.

The most superoanterior point on the body of the fifth cervical vertebra.

Type

Type



Significance

Significance




114

A

B

Figures 14.14A and B: cv5ip-The most inferoposterior point on the body of the fifth cervical vertebra

A

B

Figures 14.15A and B: cv5sa-The most superoanterior point on the body of the fifth cervical vertebra

115

cv6sp

Abbreviation

Abbreviation



Definition

Definition

The most inferoanterior point on the body of the fifth cervical vertebra.

The most superoposterior point on the body of the sixth cervical vertebra.

Type

Type

Cv5ia (Figs 14.16A and B) is a unilateral, anatomic, hard tissue cephalometric landmark.


Significance

Significance



A

B

Figures 14.16A and B: cv5ia-The most inferoanterior point on the body of the fifth cervical vertebra


cv5ia


116

A

B

Figures 14.17A and B: cv6sp-The most superoposterior point on the body of the sixth cervical vertebra

cv6ip

cv6sa

Abbreviation

Abbreviation



Definition

Definition

The most inferoposterior point on the body of the sixth cervical vertebra.

The most superoanterior point on the body of the sixth cervical vertebra.

Type

Type



Significance

Significance



117

B

Figures 14.18A and B: cv6ip-The most inferoposterior point on the body of the sixth cervical vertebra

A

B

Figures 14.19A and B: cv6sa-The most superoanterior point on the body of the sixth cervical vertebra


A

118

cv6ia

Cervical Vertebrae as Indicators of Skeletal Maturity

Abbreviation cv6ia–cv6ia is abbreviated using English alphabet and English numeric and is expressed as small letters or lower case c,v followed by English numeric 6 and then it is followed with English alphabets lower case i and a and all of them are written continuously without any space between the alphabets.

Definition


The most inferoanterior point on the body of the sixth cervical vertebra.

Type cv6ia (Figs 14.20A and B) is a unilateral, anatomic, hard tissue cephalometric landmark.


A

Hand-wrist radiographs have been used conventionally as the standard method of evaluating skeletal maturity. Although accurate, this method necessitates additional radiation exposure to patients. Furthermore, the hand-wrist site is far removed from the jaw which is the site of orthodontic correction. In recent years, evaluation of cervical vertebrae has been increasingly used to determine skeletal maturation. A new system of skeletal maturation assessment using the cervical vertebrae was first developed by Hassel and Farman. A number of subsequent stu dies have shown significant correlation between developmental or maturational changes occurring in the cervical vertebrae than that of the hand-wrist region. Cervical vertebrae maturity indicator (CMVI) method is increasingly being used in the recent years instead of the conventional hand-wrist radiograph method. One of the main reasons for the rising popularity of the method is that cervical vertebral maturation can be assessed on lateral cephalograms (Fig. 14.21), which is used regularly in orthodontic diagnosis, thus precluding the need for an additional radiograph.

B

Figures 14.20A and B: cv6ia-The most inferoanterior point on the body of the sixth cervical vertebra

119

In 1972, Lamparki stated that the cervical vertebrae were as statistically and clinically reliable in assessing skeletal age as the hand-wrist technique. Several authors (San-Roman et al 2002) have reported a high correlation between cervical vertebrae maturation and skeletal maturation of the handwrist. It has been found that cervical vertebrae could offer an alternative method for assessing maturity without the need of hand-wrist radiographs and thus decreasing patient’s radiation exposure. Most methods of cervical vertebral maturation are based on morphologic changes that occur in cervical vertebral bodies as growth progresses. Hassel and Farman developed a method of skeletal maturation assessment using cervical vertebrae in which there are 6 stages of development (Fig. 14.22). They take into account the morphologic characteristics of the cervical (C2, C3 and C4) vertebrae such as: • Shape of the vertebral bodies • Height of the vertebral bodies • Concavity of the lower border of the cervical bodies. The shapes of the cervical vertebral bodies of C3 and C4 change at each level of skeletal development are assessed (Fig. 14.23). • At first they are wedge-shaped, then changed to rectangular, next to square-shaped. • The vertical dimensions of the cervical vertebral bodies increase with increased skeletal maturity. • It is also observed that the inferior borders of the cervical vertebral bodies which are flat at the beginning become concave as they mature. • The concavity of the inferior vertebral borders is seen to appear sequentially from C2 to C3 and then to C4 as the skeleton matures.


Figure 14.21: Cervical vertebral maturation can be assessed on lateral cephalograms

Figure 14.22: Hassel and Farman developed a method of skeletal maturation assessment using cervical vertebrae in which there are 6 stages of development

Figure 14.23: The shapes of the cervical vertebral bodies of C3 and C4 change at each level of skeletal development are assessed

120

Depending on these changes observed in C2, C3 and C4 cervical vertebrae, Hassel and Farman gave 6 stages of development depicted in Table 14.2.

Contd...

Stage

Name

Changes in vertebrae

Stage 5

Maturation

• Cervical vertebrae attain maturity • Concavities at lower borders of C2, C3 and C4 become more accentuated • C3 and C4 are more square in shape • 5–10% pubertal growth remaining

Stage 6

Completion

• Adolescent growth is nearly complete • More accentuated concavities are seen at lower borders of C2, C3 and C4. • Shape of C3 and C4 is square with greater vertical dimension than width • Pubertal growth is complete with no more growth potential remaining.

Table 14.2: Assessment of skeletal maturity using cervical vertebrae Name

Changes in vertebrae

Stage 1

Initiation

• Marks the beginning of adolescent growth. • The cervical vertebral bodies and C2, C3 and C4 are wedge-shaped with their superior borders tapering posteroanteriorly. • Their inferior borders are flat. • 80–95% of growth in remaining pubertal.

Stage 2

Acceleration

• Acceleration of growth occurs. • Concavities are developing on the lower borders of C2 and C3 • Lower border of C4 vertebral body is flat • C3 and C4 assume rectangular shape • 65–85% of pubertal growth remains


Stage

Stage 3

Transition

• Growth is accelerated to reach peak height velocity • Distinct concavity seen in lower borders of C2 and C3. • Concavity is developing in the lower borders of C4. • C3 and C4 are more rectangular in shape. • 25–65% pubertal growth is remaining

Stage 4

Deceleration

• Deceleration of adolescent growth spurt begins • Distinct concavities seen at the lower borders of all three vertebrae, that is, C2, C3 and C4 • C3 and C4 are nearly square in shape • 10–25% of pubertal growth is remaining Contd...

Bibliography 1. Anderson Dl, Thompson GW, Popovich F. Interrelationship of dental maturity, skeletal maturity, height and weight from age 4 to 14 years, Growth. 1975;39:453-62. 2. Bowden BD. Epiphyseal changes in the hand/wrist area as an indicator of adolescent. Aust Orthod J. 1976;4:87-104. 3. Fishman LS. Radiographic evaluation of skeletal maturity. Angle Orthodont. 1982;88-112. 4. Grave, Brown. Skeletal ossification and adolescent growth spurt. Am J Orthod. 1976;69-80. 5. Houston WJB, Miller JC, Tanner JM. pRediction of the timing of the adolescent growth spurt from ossification events in hand/wrist films, Brit J Ortho. 1979;6:145-52. 6. Moore, Moyer, Dubois. Skeletal maturation and craniofacial growth. Am J Orthod. 1990;33-40. 7. Revelo, Fishman. Evaluation of ossification of midpalatal suture. Am J Orthod. 1994;288-92.

Section

6

Cephalometric landmarks related to Pharynx

 Cephalometric landmarks related to Pharynx

Chapter

15

Cephalometric landmarks related to Pharynx

The pharynx is a median fibromuscular tube that extends from the base of the skull. Pharynx opens into nasal cavity, the oral cavity, and the larynx. Pharynx opens into the nasal cavity, the oral cavity and the larynx are termed as nasopharynx, oropharynx and laryngopharynx respectively.

Table 15.1: Cephalometric landmarks related to pharynx Cephalometric landmarks

Abbreviation

Type

Anterior nasal spine

ANS or ans

Unilateral

Anatomic

Posterior nasal spine

PNS or pns

Unilateral

Anatomic

Nasopharynx

Anterior pharyngeal wall

apw

Unilateral

Anatomic

The Nasopharynx is the upper part of the pharynx. It is situated behind the oral cavity above the soft palate. Its superior border is the base of the skull. In the posterior part of the roof and the upper part of the posterior wall, there is an accumulation of lymphoid tissue—the adenoid or pharyngeal tonsil—which may be prominent in children but which becomes indistinct in adulthood. In the lateral wall, 1.5 cm posterior to the inferior nasal concha, is the opening of the auditory tube.The nasopharynx extends downwards and is continuous with the oropharynx at the level below the soft palate.

Posterior pharyngeal wall

ppw

Unilateral

Anatomic

Pterygomaxillary fissure

Ptm

Unilateral

Anatomic

Superior pharyngeal wall

spw

Unilateral

Anatomic

Tip of uvula

U

Unilateral

Anatomic

Point on the oral side of the soft palate

Uo

Unilateral

Anatomic

Point on the pharyngeal side of the soft palate

Up

Unilateral

Anatomic

Upper point of tongue

ut

Unilateral

Anatomic

Oropharynx The oropharynx is the middle part of the pharynx situated between the soft palate and the superior border of the epiglottis. Anteriorly, it opens to the oral cavity and is bordered by the posterior one-third of the tongue. At the lateral boundaries of the opening of the oral cavity into the oropharynx, the palatine tonsils are lodged in the tonsilar fossae.

Laryngopharynx The laryngopharynx is the lower part of the pharynx. It extends from the superior border of the epiglottis to the inferior border of the sixth cervical vertebrae, where it becomes continuous with the esophagus. The upper part of the laryngopharynx is open anteriorly to the larynx via the patent inlet.

Cephalometric Landmarks (Points) on Pharynx Cephalometric landmarks seen on the pharynx are of anatomic origin and are as follows (Table 15.1):

Origin

Anterior Nasal Spine, Posterior Nasal Spine and Pterygomaxillary Fissure Anterior nasal spine, posterior nasal spine and pterygo maxillary fissure are explained in detail in Chapter 10 [Cephalometric Landmarks (Points) Related to Maxilla].

Anterior Pharyngeal Wall Abbreviation apw–Anterior pharyngeal wall is abbreviated using English alphabet and is expressed as small letters or lower case, a, p and w and written continuously without any space between the alphabets.

124

Posterior Pharyngeal Wall Abbreviation ppw–Posterior pharyngeal wall is abbreviated using English alphabet and is expressed as small letters or lower case, p, p and w and written continuously without any space between the alphabets.

Superior Pharyngeal Wall Abbreviation

Section 6  Cephalometric Landmarks Related to Pharynx

spw–Superior pharyngeal wall is abbreviated using English alphabet and is expressed as small letters or lower case, s, p and w and written continuously without any space between the alphabets.

Tip of the Uvula Abbreviation U–Tip of the uvula is abbreviated using English alphabet and is expressed as capital or upper case U.

Point on the Oral Side of the Soft Palate Abbreviation Uo–Point on the oral side of the soft palate is abbreviated using English alphabet and is expressed as capital or upper case U followed by small letter or lower case o and is written continuously without any space between the alphabets.

Point on the Pharyngeal Side of the Soft Palate Abbreviation Up–Point on the oral side of the soft palate is abbreviated using English alphabet and is expressed as capital or upper

case U followed by small letter or lower case p and is written continuously without any space between the alphabets.

Upper Point of Tongue Abbreviation ut—Upper point of tongue is abbreviated using English alphabet and is expressed as small letters or lower case u and t and is written continuously without any space between the alphabets.

Significance In Mc Namara Analysis Upper pharynx Upper pharyngeal width is measured from a point on the posterior outline of the soft palate to the closet point on the pharyngeal wall. This measurement is taken on the anterior half of the soft palate outline. The average nasopharnyx is approximately 15–20 mm in width. A width of 2 mm or less in this region indicates airway impairment.

Lower Pharynx Lower pharyngeal width is measured from the point of intersection of the posterior border of the tongue and the inferior border of the mandible to the closet point on the posterior pharyngeal wall. The average measurement is 11 to 14 mm independent of age. Greater than average lower pharyngeal walls is of possible anterior positioning of the tongue, either as a result of habitual posture or due to tonsillar enlargements A lower than average lower pharyngeal wall indicates the posterior positioning of the tongue.

Section

7

Soft Tissue Cephalometric Landmarks

 Soft Tissue Cephalometric Landmarks

ChapTer

16

Soft Tissue Cephalometric Landmarks

Soft Tissue Cephalometric Landmarks (Points) Related to Forehead Soft tissue cephalometric landmarks related to forehead are listed below and are explained in detail in this chapter. • Trichion • Soft tissue glabella.

Soft Tissue Glabella

Definition

Abbreviation • G–Soft tissue glabella is abbreviated using English alphabet and is expressed as upper case G.

A

B

• Gs–Some authors abbreviate soft tissue glabella as English alphabet upper case G followed by lower cases. • SGLB–Some authors even abbreviate soft tissue glabella as English alphabets upper case S, G L and B written continuously without any space between each alphabet. • Note–Soft tissue glabella can be abbreviated as upper case G or Gs or SGLB, However, G is the most widely used abbreviation.

C

• Soft tissue glabella (Figs 16.1A to D) is the most prominent or anterior point in the midsagittal plane of the forehead at the level of the superior orbital ridges.

D

Figures 16.1A to D: (A) Soft tissue glabella on lateral cephalogram; (B) Magnified image showing soft tissue glabella on the lateral cephalogram; (C) Soft tissue glabella on graphic illustration; (D) Magnified image of soft tissue glabella on graphic illustration

128

• The most prominent or anterior point in mid-sagittal plane of the forehead at the level of the superior orbital ridges (SN Bhatia, BC Leighton, 1993).

All above mentioned soft tissue cephalometric landmarks/ points related to nose are explained below:

Soft Tissue Nasion

Type Glabella is a unilateral soft tissue cephalometric landmark.

Abbreviation

Significance

n–Soft tissue nasion is abbreviated using English alphabet and is expressed as lower case n.

Glabella is used as one of the reference points in the construction of facial angles.

Soft Tissue Cephalometric Landmarks Related to Nose

Section 7  Soft Tissue Cephalometric Landmarks

Soft tissue cephalometric landmarks (points) related to nose are listed below: • Soft tissue nasion • Nasal crown • Pronasale • Point “T” • Alar crease junction.

A

B

N–Soft tissue nasion can also be abbreviated using English alphabet and is expressed as upper case N.

Definition Soft tissue nasion (Figs 16.2A to D) is the concave or retruded point in the tissue overlying the area of the frontonasal suture.

According to Spiro J Chaconas in 1993 The point of intersection of the soft tissue profile with a line drawn from the center of sella turcica through nasion.

C

D

Figures 16.2A to D: (A) soft tissue nasion on lateral cephalogram; (B) Magnified image showing soft tissue nasion on the lateral cephalogram; (C) Soft tissue nasion on graphic illustration; (D) Magnified image of soft tissue nasion on graphic illustration

129

Type

Type

Soft tissue nasion is a unilateral soft tissue cephalometric landmark.

Nasal crown is a unilateral soft tissue cephalometric landmark.

Significance

Significance

Nasal crown is used for the assessment of nasal contour.

Soft tissue nasion is used as one of the reference points on the construction of nasion and soft tissue pogonion plane which is used along with the dorsum surface of nose to determine the nasal prominence and subsequently helps in evaluation of malocclusion pattern.

Nasal Crown

NC–Nasal crown is abbreviated using English alphabet and is expressed as capital (upper case) NC and written continuously without any space between alphabets.

Abbreviation Pn–Pronasale is abbreviated using English alphabet and is expressed as capital (upper case) P followed by lower case n written continuously without any space between alphabets.

Chapter 16  Soft Tissue Cephalometric Landmarks

Abbreviation

Pronasale

Prn–Pronasale is also abbreviated using English alphabet and is expressed as capital (upper case) P followed by lower case r and n and written continuously without any space between alphabets.

Definition

PRN–Pronasale can also be abbreviated using English alphabet and is expressed as capital (upper case) P, R and N and written continuously without any space between alphabets.

Nasal crown (Figs 16.3A to D) is a point along the bridge of the nose halfway between soft tissue nasion (n) and pronasale (Pn).

prn–Pronasale can also be abbreviated using English alphabet and is expressed as small (lower case) p, r and n and written continuously without any space between alphabets.

A

B

C

D

Figures 16.3A to D: (A) Nasal crown on lateral cephalogram; (B) Magnified image showing nasal crown on the lateral cephalogram; (C) Soft tissue nasal crown on graphic illustration; (D) Magnified image of nasal crown on graphic illustration


130

A

B

C

D

Figures 16.4A to D: (A) Pronasale on lateral cephalogram; (B) Magnified image showing pronasale on the lateral cephalogram; (C) Pronasale on graphic illustration; (D) Magnified image of pronasale on graphic illustration

Definition Pronasale (Figs 16.4A to D) is the most prominent or anterior point of the nose.

According to SN Bhatia and BC Leighton in 1993

• Pronasale is also used as one of the reference points in the construction of following planes for the assessment of following: – Ricketts’ E-line used to assess the relationship of upper and lower teeth to the upper and lower lip.

Point “T”

The most prominent or anterior point of the nose tip.

According to Spiro J Chaconas in 1969

Abbreviation

The most anterior point on the midsagittal profile of the nose. In cases where the tip of the nose was more than a definite Point T is abbreviated using English alphabet and is expressed point, pronasale was determined by drawing a line parallel to as capital T. the line nasion to pogonion tangent to the most anterior point Definition on the midsagittal profile of the nose.

According to Leslie G Farkas in 1981 Pronasale is the most protruded point of the apex nasi.This point is difficult to determine if the nasal tip is flat.

The point “T” is the midline point on the nasal tip taken at the level of the dome projecting points of the lower lateral cartilage.

Type Type Pronasale is a unilateral soft tissue cephalometric landmark.

Point “T” (Figs 16.5A to D) is a unilateral constructed point soft tissue cephalometric landmark.

Significance

Significance

• Pronasale helps in the assessment of nasal tip projection.

Point “T” is used in the assessment of nasal tip projection.

131

B

C

D


A

Figures 16.5A to D: (A) Point ‘T’ on lateral cephalogram; (B) Magnified image showing point ‘T’ on the lateral cephalogram; (C) Point ‘T’ on graphic illustration; (D) Magnified image of point ‘T’ on graphic illustration

Alar Crease Junction Abbreviation ACJ–Alar crease junction is abbreviated using English alphabet and is expressed as capital A,C and J.

Definition Alar crease junction is the most posterior point of the curved line formed by the alar crease.

Type

case) n written continuously without any space between them. SN–Subnasale is abbreviated using English alphabet and is expressed as capital (upper case) S and N written continuously without any space between them. sn–Subnasale is abbreviated using English alphabet and is expressed as lower case (Small alphabets) s and n written continuously without any space between them.

Definition

Alar crease junction (Figs 16.6A to D) is a bilateral constructed point soft tissue cephalometric landmark.

Subnasale (Figs 16.7A to D) is the point at which the nasal septum between the nostrils merges with the upper cutaneous tip in the midsagittal plane.

Significance

According to TM Graber (1975)

Alar crease junction is used as a landmark for measuring nasal tip projection.

Subnasale

According to TM Graber, subnasale is the point where the lower margin of the nasal septum is confluent with the integumental upper lip.

According to Spiro J Chaconas and SN Bhatia Abbreviation Sn–Subnasale is abbreviated using English alphabet and is expressed as capital (upper case) S followed by small (lower

Subnasale is the point at which the nasal septum between the nostrils merges with the upper cutaneous lip in the midsagittal plane.


132

A

B

C

D

Figures 16.6A to D: (A) Alar crease junction on lateral cephalogram; (B) Magnified image showing Alar crease junction on the lateral cephalogram; (C) Alar crease junction on graphic illustration; (D) Magnified image of Alar crease junction on graphic illustration

A

B

C

D

Figures 16.7A to D: (A) Subnasale on lateral cephalogram; (B) Magnified image showing subnasale on the lateral cephalogram; (C) Subnasale on graphic illustration; (D) Magnified image of subnasale on graphic illustration

133

Type

Related to Upper and Lower Lip Together

Subnasale is a unilateral soft tissue cephalometric landmark.

• Stomion • Stomion superius • Stomion inferius

Significance • Subnasale helps in the assessment of nasal tip projection and nasal height. • Subnasale is also used as one of the reference points in the construction of following planes for the assessment of following: – Burstone’s B line used to assess the relationship of upper and lower teeth to the upper and lower lip. – Height of upper lip (Sn–Ls) can be assessed.

Related to Lower Lip • Labrale inferius • Soft tissue point B All above mentioned soft tissue cephalometric landmarks (points) related to lips are explained below.

Soft Tissue Subspinale Abbreviation

Soft tissue cephalometric landmarks (points) related to lips are listed below:

Ss–Soft tissue subspinale is abbreviated using English alphabet and is expressed as capital S followed by small s.

Related to Upper Lip

Definition

• Soft tissue subspinale • Labrale superius • Philtrum • Cuspid bow • Vermillion border of upper lip

Soft tissue subspinale (Figs 16.8A to D) is the point of greatest concavity in the midline of the upper lip between subnasale (Sn) and labrale superius (Ls).

A

B

C


Soft Tissue Cephalometric Landmarks (Points) Related to Lips

D

Figures 16.8A to D: (A) Subspinale on lateral cephalogram; (B) Magnified image showing subspinale on the lateral cephalogram; (C) Subspinale on graphic illustration; (D) Magnified image of subspinale on graphic illustration

134

Type

Type

Soft tissue subspinale is a unilateral soft tissue cephalometric landmark.

Labrale superius is a unilateral soft tissue cephalometric landmark.

Significance

Significance

Soft tissue subspinale is also used as one of the reference points in the construction of following planes for the assessment of following: • Steiner’s S line used to assess the relationship of upper and lower teeth to the upper and lower lip.

Abbreviation

Labrale superius is also used as one of the reference points in the construction of following planes for the assessment of the following: • Holdaway “H” line used to assess the relationship of upper and lower teeth to the upper and lower lip. • Merfield’s “Z” angle used to assess the relationship of upper and lower teeth to the upper and lower lip. • It is even used to measure the length of upper lip (Ls-Sn). • It can also be used to assess the planed incisor position (PIP).

Ls–Labrale superius is abbreviated using English alphabet and is expressed as capital L followed by small s.

Philtrum


Labrale Superius

Definition Labrale superius (Figs 16.9A to D) is the most anterior point on the margin of the upper membranous lip.

A

B

Philtrum (Fig. 16.10) is the central and vertically oriented position of the upper lip situated between the two skin reliefs of the philtrum columns. There is gentle concavity on its lower portion, the philtrum dimple.

C

D

Figures 16.9A to D: (A) Labrale superius on lateral cephalogram; (B) Magnified image showing labrale superius on the lateral cephalogram; (C) Labrale superius on graphic illustration; (D) Magnified image of labrale superius on graphic illustration

135

Figure 16.11: Cuspid bow

Cuspid Bow (Fig. 16.11) The central linear portion of the upper lip while roll skin relief of the upper lip between the philtrum and the vermilion. It connects the inferior ends of the philtrum columns.

Vermilion (Fig. 16.12) The most anterior point on the vermilion of the upper lip showing in Figure 16.12.

Stomion Abbreviation Sto–Stomion is abbreviated using English alphabet and is expressed as capital S followed by small t and o.

Definition Stomion (Figs 16.13A to D) is the median point of the oral embrassure when the lips are closed.

Type Stomion is a unilateral soft tissue cephalometric landmark.

Figures 16.12: Vermillion


Figure 16.10: Philtrum


136

A

B

C

D

Figures 16.13A to D: (A) Stomion on lateral cephalogram; (B) Magnified image showing stomion on the lateral cephalogram; (C) Stomion on graphic illustration; (D) Magnified image of stomion on graphic illustration

Significance Stomion is established only at rest when teeth are in centric occlusion and centric relation. Presence of stomion indicates averagely positioned upper and lower teeth.

• It is even used to measure the length of lower lip (Li-Me). • It can also be used to assess the planed incisor position (PIP).

Soft Tissue Submentale (Soft Tissue Point B)

Labrale Inferius

Abbreviation

Abbreviation

Li–Labrale inferius is abbreviated using English alphabet and is expressed as capital L followed by small i.

B–Soft tissue point B is abbreviated using English alphabet and is expressed as capital “B”.

Definition

Definition

Labrale inferius (Figs 16.14A to D) is the most anterior point on the lower margin of the lower membrane lip.

Soft tissue point B or Soft tissue submentale (Figs 16.15A to D) is the point of greatest concavity in the midline of the lip between labrale inferius (Li) and soft tissue pogonion (Pog’ or Pogs).

Type Labrale inferius is a unilateral soft tissue cephalometric landmark.

Significance Labrale inferius is also used as one of the reference points in the construction of following planes for the assessment of following:

Type Soft tissue point B or soft tissue submentale is a unilateral soft tissue cephalometric landmark.

Significance • Soft tissue point B or soft tissue submentale is used in the assessment of deepness of submental.

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B

C

D

Figures 16.14A to D: (A) Labrale inferius on lateral cephalogram; (B) Magnified image showing labrale inferius on the lateral cephalogram; (C) Labrale inferius on graphic illustration; (D) Magnified image of labrale inferius on graphic illustration

A

B

C

D

Figures 16.15A to D: (A) Soft tissue point B on lateral cephalogram; (B) Magnified image showing soft tissue point B on the lateral cephalogram; (C) Soft tissue point B on graphic illustration; (D) Magnified image of soft tissue point B on graphic illustration


A


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A

B

C

D

Figures 16.16A to D: (A) Soft tissue pogonion on lateral cephalogram; (B) Magnified image showing soft tissue pogonion on the lateral cephalogram; (C) Soft tissue pogonion on graphic illustration; (D) Magnified image of soft tissue pogonion on graphic illustration

• Soft tissue pogonion is also used as one of the reference points in the construction of following planes for the assessment of following: – It is even used to measure the length of lower lip (Li-Me). – It can also be used to assess the planed incisor position (PIP).

denoted as capital P followed by small o and g’ ending with ’ as a superscript.

Soft Tissue Cephalometric Landmarks Related to Chin

Type

Soft tissue cephalometric landmarks/points related to chin are listed below: • Soft tissue pogonion • Soft tissue gnathion All above mentioned soft tissue cephalometric landmarks/ points related to chin are explained below:

Soft Tissue Pogonion Abbreviation Pogs or Pog’–Soft tissue pogonion is abbreviated using English alphabet and is expressed as capital P followed by small o and g with s in subscript position. It can also be

Definition Soft tissue pogonion (Figs 16.16A to D) is the most prominent or anterior point on the soft tissue chin in the midsagittal plane.

Soft tissue pogonion is a unilateral soft tissue cephalometric landmark.

Significance • Soft tissue pogonion is used to the prominence of the chin. • Soft tissue pogonion is also used as one of the reference points in the construction of following planes for the assessment of following: – Steiner’s “S” line used to assess the relationship of upper and lower teeth to the upper and lower lip. – Rickett’s E-line used to assess the relationship of upper and lower teeth to the upper and lower lip. – Burstone’s B line used to assess the relationship of upper and lower teeth to the upper and lower lip. – Holdaway “H” line used to assess the relationship of upper and lower teeth to the upper and lower lip.

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B

C

D


A

Figures 16.17A to D: (A) Soft tissue gnathion on lateral cephalogram; (B) Magnified image showing soft tissue gnathion on the lateral cephalogram; (C) Soft tissue gnathion on graphic illustration; (D) Magnified image of soft tissue gnathion on graphic illustration

Soft Tissue Gnathion

Definition

Abbreviation

Soft tissue gnathion (Figs 16.17A to D) is the midpoint between the most anterior and inferior points of the soft tissue chin in the midsagittal plane.

Gns–Soft tissue gnathion is abbreviated using English alphabet and is expressed as capital G followed by small n with s in subscript position.

Type

Soft tissue gnathion is a unilateral constructed point soft tissue cephalometric landmark.

SECTION

8

3D Cephalometric Landmarks

 3D Cephalometric Landmarks

CHAPTER

17

3D Cephalometric Landmarks

Vertex Abbreviation V–Vertex is abbreviated using English alphabet and is expressed as capital or upper case V.

Definition Vertex (Fig. 17.1) is the most superior point of calvarium in center line.

Type Vertex is an anatomic, unilateral, soft tissue cephalometric landmark.

Significance Vertex is used as one of the reference points in the construction of angles and planes in 3D cephalometric analysis.

Figure 17.1: Vertex (Image created with the Invivo5 software by Anatomage Inc.)

Soft Tissue Nasion Abbreviation n–Soft tissue nasion is abbreviated using English alphabet and is expressed as small letter or lower case n. N’–Soft tissue nasion can also be abbreviated using English alphabet and is expressed as upper case or capital letter N and ending with ’ in superscript position.

Definition Soft tissue nasion (Fig. 17.2) is the concave or retruded point in the tissue overlying the area of the frontonasal suture.

According to Spiro J Chaconas The point of intersection of the soft tissue profile with a line drawn from the center of sella turcica through nasion.

Figure 17.2: Soft tissue nasion (Image created with the Invivo5 software by Anatomage Inc.)

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Type Soft tissue nasion is a unilateral, soft tissue cephalometric landmark.

According to SN Bhatia and BC Leighton in 1993 The most prominent or anterior point of the nose tip..

Significance

According to Spiro J Chaconas

Soft tissue nasion is used as one of the reference points on the construction planes and angles in 3D cephalometric analysis.

The most anterior point on the midsagittal profile of the nose. In cases where the tip of the nose was more than a definite point, pronasale was determined by drawing a line parallel to the line nasion to pogonion tangent to the most anterior point on the midsagittal profile of the nose.

Pronasale Abbreviation Pn–Pronasale is abbreviated using English alphabets and is expressed as capital (upper case) P followed by lower case n written continuously without any space between alphabets.

Section 8  3D Cephalometric Landmarks

Prn–Pronasale is also abbreviated using English alphabet and is expressed as capital (upper case) P followed by lower case r and n written continuously without any space between alphabets. PRN–Pronasale can also be abbreviated using English alphabet and is expressed as capital (upper case) P, R and N written continuously without any space between alphabets. prn–Pronasale can also be abbreviated using English alphabet and is expressed as small (lower case) p, r and n written continuously without any space between alphabets.

Definition Pronasale (Figs 17.3A and B) is the most prominent or anterior point of the nose.

A

According to Leslie G Farkas in 1981 Pronasale is the most protruded point of the apex nasi. This point is difficult to determine if the nasal tip is flat.

Type Pronasale is a unilateral, soft tissue cephalometric landmark.

Significance Pronasale is used as one of the reference points on the construction planes and angles in 3D cephalometric analysis.

Subnasale Abbreviation Sn–Subnasale is abbreviated using English alphabets and is expressed as capital (upper case) S followed by small (lower case) n written continuously without any space between them.

B

Figures 17.3A and B: Pronasale (Image created with the Invivo5 software by Anatomage Inc.)

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SN–Subnasale is abbreviated using English alphabet and is expressed as capital (upper case) S and N written continuously without any space between them. sn–Subnasale is abbreviated using English alphabet and is expressed as lower case (small alphabets) s and n written continuously without any space between them.

Definition Subnasale (Fig. 17.4) is the point at which the nasal septum between the nostrils merges with the upper cutaneous tip in the midsagittal plane.

According to TM Graber (1975)

According to Spiro J Chaconas (1980) and SN Bhatia According to Spiro J Chaconas (1980) subnasale is the point at which the nasal septum between the nostrils merges with the upper cutaneous lip in the midsagittal plane.

Type

Subnasale is used as one of the reference points on the construction planes and angles in 3D cephalometric analysis.

Soft Tissue Subspinale Abbreviation Ss–Soft tissue subspinale is abbreviated using English alphabets and is expressed as capital S followed by small letter or lower case s and is written continuously without any space between the alphabets.

Definition Soft tissue subspinale (Fig. 17.5) is the point of greatest concavity in the midline of the upper lip between subnasale (Sn) and labrale superius (Ls).

Type

Chapter 17  3D Cephalometric Landmarks

According to TM Graber, subnasale is the point where the lower margin of the nasal septum is confluent with the integumental upper lip.

Significance

Soft tissue subspinale is a unilateral soft tissue cephalometric landmark.

Significance

Subnasale is a unilateral, soft tissue cephalometric landmark.

Soft tissue subspinale is also used as one of the reference points in the construction of following planes in 3D cephalometric analysis.

Figure 17.4: Subnasale (Image created with the Invivo5 software by Anatomage Inc.)

Figure 17.5: Soft tissue subspinale (Image created with the Invivo5 software by Anatomage Inc.)

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Labrale Superius

Definition Stomion (Fig. 17.7) is the median point of the oral embrassure when the lips are closed.

Abbreviation Ls–Labrale superius is abbreviated using English alphabets and is expressed as capital L followed by small s and is written continuously without any space between the alphabets.

Type

Definition

Significance

Labrale superius (Fig. 17.6) is the most anterior point on the margin of the upper membranous lip.

Stomion is used as one of the reference points on the construction planes and angles in 3D cephalometric analysis.

Stomion is a unilateral soft tissue cephalometric landmark.

Labrale Inferius

Type


Labrale superius is a unilateral soft tissue cephalometric landmark.

Significance Labrale superius is also used as one of the reference points in the construction of planes and angles in 3D cephalometric analysis.

Stomion

Abbreviation Sto–Stomion is abbreviated using English alphabets and is expressed as capital S followed by small t and o and is written continuously without any space between the alphabets.

Figure 17.6: Labrale superius (Image created with the Invivo5 software by Anatomage Inc.)

Abbreviation Li–Labrale inferius is abbreviated using English alphabets and is expressed as capital L followed by small i and is written continuously without any space between the alphabets.

Definition Labrale inferius (Fig. 17.8) is the most anterior point on the lower margin of the lower membrane lip

Type Labrale inferius is a unilateral soft tissue cephalometric landmark.

Figure 17.7: Stomion (Image created with the Invivo5 software by Anatomage Inc.)

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Figure 17.8: Labrale inferius (Image created with the Invivo5 software by Anatomage Inc.)

Figure 17.9: Soft tissue point B (Image created with the Invivo5 software by Anatomage Inc.)

Significance Labrale inferius is used as one of the reference point on the construction planes and angles in 3D cephalometric analysis.

Soft Tissue Submentale (Soft Tissue Point B) Abbreviation B’–Soft tissue point B is abbreviated using English alphabet and is expressed as capital “B”.

Definition Soft tissue point B or soft tissue submentale (Fig. 17.9) is the point of greatest concavity in the midline of the lip between labrale inferius (Li) and soft tissue pogonion (Pog’ or Pogs).

Type Soft tissue point B or soft tissue submentale is a unilateral soft tissue cephalometric landmark.

Figure 17.10: Soft tissue pogonion (Image created with the Invivo5 software by Anatomage Inc.)

Soft Tissue Pogonion

Significance

Abbreviation

Soft tissue point B is used as one of the reference points on the construction planes and angles in 3D cephalometric analysis.

Pogs or Pog’–Soft tissue pogonion is abbreviated using English alphabets and is expressed as capital P followed

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by small o and g with s in subscript position. It can also be denoted as Capital P followed by small o and g’ ending with ’ as a superscript.

Definition Soft tissue pogonion (Fig. 17.10) is the most prominent or anterior point on the soft tissue chin in the midsagittal plane.

Type

Type Soft tissue gnathion is a unilateral, constructed points, soft tissue cephalometric landmark.

Significance Soft tissue gnathion is used as one of the reference point on the construction planes and angles in 3D cephalometric analysis.

Soft tissue pogonion is a unilateral soft tissue cephalometric landmark.

Orbitale Abbreviation

Soft tissue pogonion is used as one of the reference points on the construction planes and angles in 3D cephalometric analysis.

Ors–Orbitale is abbreviated using English alphabets and is expressed as capital O followed by small r with s in subscript position and is written continuously without any space between the alphabets.


Significance

Soft Tissue Gnathion

Abbreviation Gns–Soft tissue gnathion is abbreviated using English alphabets and is expressed as capital G followed by small n with s in subscript position and is written continuously without any space between the alphabets.

Definition Orbitale (Fig. 17.12)—Most inferior portion of orbital floor below the center of eye.

Type Orbitale is a bilateral soft tissue cephalometric landmark.

Definition

Significance

Soft tissue gnathion (Fig. 17.11) is the midpoint between the most anterior and inferior points of the soft tissue chin in the midsagittal plane.

Orbitale is used as one of the reference points on the construction planes and angles in 3D cephalometric analysis.

Figure 17.11: Soft tissue gnathion (Image created with the Invivo5 software by Anatomage Inc.)

Figure 17.12: Orbitale (Image created with the Invivo5 software by Anatomage Inc.)

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Zygomatic Prominence

Definition Zygion (Fig. 17.14)–Most lateral point of each zygomatic arch eye.

Abbreviation ZpS–Zygomatic prominence is abbreviated using English alphabets and is expressed as capital Z followed by small p with s in subscript position and is written continuously without any space between the alphabets.

Type

Definition

Zygion is used as one of the reference points on the construction planes and angles in 3D cephalometric analysis.

Zygomatic prominence (Fig. 17.13)—Most protrusive anterior point on zygomatic arch.

Type

Significance Zygomatic prominence is used as one of the reference points on the construction planes and angles in 3D cephalometric analysis.

Zygion Abbreviation Zys–Zygion is abbreviated using English alphabets and is expressed as capital Z followed by small y with s in subscript position and is written continuously without any space between the alphabets.

Figure 17.13: Zygomatic prominence (Image created with the Invivo5 software by Anatomage Inc.)

Significance

Condylion Abbreviation Cos–Condylion is abbreviated using English alphabets and is expressed as capital C followed by small o with s in subscript position and is written continuously without any space between the alphabets.

Definition


Zygomatic prominence is a bilateral soft tissue cephalometric landmark.

Zygion is a unilateral soft tissue cephalometric landmark.

Condylion (Figs 17.15A and B)–Most superior midline point on condyle of mandible.

Type

Condylion is a bilateral soft tissue cephalometric landmark.

Significance

Condylion is used as one of the reference points on the construction planes and angles in 3D cephalometric analysis.

Figure 17.14: Zygion (Image created with the Invivo5 software by Anatomage Inc.)

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A

B

Figures 17.15A and B: Condylion (Image created with the Invivo5 software by Anatomage Inc.)

A

B

Figures 17.16A and B: Gonion (Image created with the Invivo5 software by Anatomage Inc.)

Gonion

Type Gonion is a bilateral soft tissue cephalometric landmark.

Abbreviation

Significance

Gos–Gonion is abbreviated using English alphabets and is expressed as capital G followed by small o with s in subscript position and is written continuously without any space between the alphabets.

Gonion is used as one of the reference points on the construction planes and angles in 3D cephalometric analysis.

Definition Gos (Figs 17.16A and B)—Most everted point of angle of mandible.

Ch Abbreviation Ch—Ch is abbreviated using English alphabets and is expressed as capital C followed by small h written continuously without any space between the alphabets.

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Alare

Definition Ch (Fig. 17.17)–Most lateral border point of chin.

Abbreviation

Type

Significance

Al–Alare is abbreviated using English alphabets and is expressed as capital A followed by small or lower case l and is written continuously without any space between the alphabets.

Ch is used as one of the reference points on the construction planes and angles in 3D cephalometric analysis.

Definition

Ch is a unilateral soft tissue cephalometric landmark.

Cheilion

Alare (Fig. 17.19)–The most lateral point on each alar contour.

Type Alare is a bilateral soft tissue cephalometric landmark.

C–Cheilion is abbreviated using English alphabet and is expressed as capital C.

Significance

Definition

Alare is used as one of the reference points on the construction planes and angles in 3D cephalometric analysis.

Cheilion (Fig. 17.18)–Most lateral point located at each labial commissure.

Exocanthion

Type


Abbreviation

Cheilion is a unilateral soft tissue cephalometric landmark.

Abbreviation

Significance Cheilion is used as one of the reference points on the construction planes and angles in 3D cephalometric analysis.

Ex–Exocanthion is abbreviated using English alphabets and is expressed as capital E followed by small or lower case x and is written continuously without any space between the alphabets.

Figure 17.17: Ch (Image created with the Invivo5 software by Anatomage Inc.)

Figure 17.18: Cheilion (Image created with the Invivo5 software by Anatomage Inc.)


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Figure 17.19: Alare (Image created with the Invivo5 software by Anatomage Inc.)

Figure 17.20: Exocanthion (Image created with the Invivo5 software by Anatomage Inc.)

Definition


Exocanthion–The point at the inner commissure of the eye tissue.

Sella turcica (Turkish saddle). The landmark is the center of the sella as seen in the lateral radiograph and located by inspection.

Type Exocathion is a bilateral soft tissue cephalometric landmark.

Significance Exocathion is used as one of the reference points on the construction planes and angles in 3D cephalometric analysis.

Sella

Abbreviation S–Sella is abbreviated using English alphabet and is expressed as capital or upper case S.

Definition Sella (Fig. 17.20) is the midpoint of sella turcica or hypophyseal fossa or pituitary fossa.

According to Robert E Moyers The center of the hypophyseal fossa (sella turcica). It is selected by the eye since that producer as been shown to be as reliable as a constructed center.

According to TM Graber The center of pituitary fossa.

According to LB Higley The center of sella turcica. The midpoint of the sella turcica arbitrarily determined.

According to William B Downs The center of sella turcica. Located by inspection of the profile image of the fossa.

According to Arne Bjork The center of sella turcica (the midpoint of the horizontal diameter).

Type Sella is a unilateral, anatomic, hard tissue cephalometric landmark.

Tracing of Sella on the Lateral Cephalogram The pituitary fossa is round and bottle shaped hollow space, situated in the upper body of the sphenoid bone. This fossa contains pituitary gland. This fossa is bounded anterioly and posteriorly by anterior and posterior clinoid processes. Both anterior and posterior clinoid process appears radio-opaque line on the lateral cephalogram. First trace the anterior and posterior clinoid process followed by inferior border of the pituitary fossa. Center point of the fossa is the point of sella.

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Basion

Significance (Ref to Chapter 20) Sella is used as one of the reference points in the construction of angles and planes for the assessment of following: • Relationship of maxilla to cranial base is assessed using SNA angle, S-N-Pr angle and saddle angle (N-S-Ar). • Relationship of mandible to cranial base is assessed using SNB angle and S-N-Id angle. • Relationship of anterior and posterior cranial base assessed using N-S-Ar.

Sella Entrance Abbreviation

Definition Sella entrance (Fig. 17.21) is the mid entrance point of sella turcica or hypophyseal fossa or pituitary fossa.

Type Sella entrance is a unilateral, constructed, hard tissue cephalo metric landmark.

Ba–Basion is abbreviated using English alphabets and is denoted as capital letter or upper case B followed by small letter or lower case a and is written continuously without any space between the alphabets.

Definition Basion (Figs 17.22A to D) is the median point of the anterior margin of the foramen magnum can be located by following the images of the slope the inferior border of the basilar part of the occipital bone to its posterior limit.



Se–Sella entrance is abbreviated using English alphabets and is expressed as capital letter or upper case S followed by small letter or lower case e and is written continuously without any space between the alphabets.

Abbreviation

Point at the center of the anterior border of the foramen magnum at the base of the occipital bone.


The most inferior point on the anterior margin of the foramen magnum in the midsagittal plane.


The most inferior posterior point in the sagittal plane on the anterior rim of the foramen magnum.


Normal projection of the anterior border of the occipital foramen (endobasion) on the occipital foramen line.


The most anterior point relative to the interspinosum line, on the border of the foramen magnum.

Type Basion is a unilateral, anatomic, hard tissue cephalometric landmark.

Tracing Basion on the Lateral Cephalogram

Figure 17.21: Sella entrance (Image created with the Invivo5 software by Anatomage Inc.)

• To identify basion on the lateral cephalogram, following structures need to be traced. • Trace from the posterior cliniod process, down the upper part of the clivus, and past the region of the spheno-

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A

B

C

D

Figures 17.22A to D: Basion (Image created with the Invivo5 software by Anatomage Inc.)

occipital synchondrosis to the anterior margin of the foramen magnum. • Trace the cranial aspect of the greater wing of the sphenoid one, the inferior, ectocranial aspect of the base of the occipital bone, and the anterior margin of the foramen magnum. These are separate lines and should not be drawn a one continuous line. • Trace carefully from the base of the occipital bone to the compact bone of the occipital condyles. The anterior margins of the occipital condyle and basion are radio-opaque on the lateral cephalogram and should be differentiated. Basion is usually behind the anterior part of the occipital condyle.

Anterior Nasal Spine Abbreviation ANS–Anterior nasal spine is abbreviated using English alphabets and is expressed as capital or upper case A, N and S, written continuously without any space between the alphabets.

Definition Anterior nasal spine (Fig. 17.23) is the tip of bony anterior nasal spine in the midline or median plane.

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According to Robert E Moyers The most anterior point on the maxilla at the level of the palate. The ANS is of limited use for analysis in the posterioranterior projection as the actual spine often cannot be seen and its location varies considerably according to radiographic exposure.

Type Anterior nasal spine is a unilateral, anatomic, hard tissue cephalometric landmark.

Tracing of Anterior Nasal Spine on Lateral Cephalogram

According to Viken Sassouni The most anterior point of the nasal floor tip of pre-maxilla on mid-sagittal plane.

According to B Holly Broadbent Sharp median process formed by the forward prolongation of the anterior aperature of the nose.

According to TM Graber The tip of the anterior nasal spine as seen on the X-ray film in norma lateralis.

Radiographic Appearance


Figure 17.23: Anterior nasal spine (Image created with the Invivo5 software by Anatomage Inc.)

There exists an individual variation in length and width of ANS. In some individuals ANS are long and thin; while in other are short and thick.

• ANS appears slightly posterior to the anatomic spine. • In cases with thin ANS–in such cases, on the cephalogram, ANS will be unclear because it can superimpose by nasal cartilage. • In cases with thick ANS–in such cases, on the cephalogram, ANS is clear and will be ease in tracing.


Anterior nasal spine is used as one of the reference points in the construction of occlusal plane and is used for the assessment of horizontal growth pattern using FH-Palatal plane angle (ANS-PNS).

Section

9

PA Cephalometric Landmarks




ChAPter

18


Comprehensive cephalometric analysis systems have been developed to determine the lateral skeletal and dentoalveolar components of a malocclusion (Steiner, 1959; Ricketts, 1960). Approximately 90 percent of orthodontic practitioners in the USA make routine use of lateral cephalograms for every comprehensive case (Keim et al., 2002), illustrating the accepted value of lateral cephalometric analysis as an aid in orthodontic diagnosis and treatment planning. However, accurate diagnosis of discrepancies in width dimensions as well as of occlusal cants and asymmetries may also require a posteroanterior (PA) cephalometric evaluation. Increases in transverse dental arch dimensions are associated with arch perimeter gain (Adkins et al., 1990). Bimaxillary expansion has therefore been recommended as a suitable alternative to premolar extraction, particularly in patients presenting with narrow dental arches (Cetlin and Ten Hoeve, 1983;Vanarsdall, 1999; McNamara et al., 2003; Ferris et al., 2005). However, that treatment decision should be based not only on dental arch measurements but also on suitable PA cephalometric analysis. The high prevalence of arch length deficiency and transverse malocclusions in different populations (Hill, 1992; Behbehani et al., 2005) may indicate that a considerable proportion of orthodontic patients may benefit from PA cephalometric evaluation. Several PA cephalometric analysis systems have been proposed (Sassouni, 1958;Letzer and Kronman, 1967; Ricketts et al., 1972; Hewitt, 1975; Svanholt and Solow, 1977; Grayson et al., 1983; Grummons and Kappeyne Van De Coppello, 1987). Of the two that are commercially available through the Dolphin® software (Ricketts et al., 1972; Grummons and Kappeyne Van De Coppello, 1987), only Ricketts’ analysis (Ricketts et al., 1972) is accompanied by a comprehensive set of norms, proposing age specific adjustments from adolescence to adulthood (Ricketts, 1981, Ricketts et al., 1982). However, the specific materials and methods used for calculating the norms have not been published. Grummons and Kappeyne Van De Coppello (1987) have presented a comprehensive analysis system for comparison of right and left triangular shapes, linear dimensions, and facial proportions. Since their purpose is to identify individual areas of asymmetry rather

than determining actual discrepancies, the analysis is not accompanied by normative data. The focus of the remaining analyses is to evaluate the skeletal and dental components of asymmetry through comparison of right and left triangular measurements (Letzer and Kronman, 1967; Hewitt, 1975), variables suitable for assessment of midline discrepancies (Svanholt and Solow, 1977; Grayson et al., 1983), or to determine the individual harmony of various proportions (Sassouni, 1958). Only a few of these analyses are supported by a limited set of normative data (Letzer and Kronman, 1967; Hewitt, 1975;Svanholt and Solow, 1977). Several well-known craniofacial growth studies include records suitable for transverse analyses. However, with the exception of select measurements of relatively small samples (Woods, 1950; Snodell et al., 1993; Cortella et al., 1997; Huertas and Ghafari, 2001; Hesby et al., 2006), normative data have been published only for 60 subjects without an ideal occlusion (Basyouni and Nanda, 2000). Athanasiou et al. (1992) provided norms for selected PA cephalometric measurements of 588 Austrian schoolchildren aged 6–15 years. Although the sample of adolescents was large, the inclusion of subjects without an ideal occlusion limits the validity of the findings. In addition, while Uysal and Sari (2005) provided PA cephalometric norms for adult Turks, analyzing a large sample with a Class I occlusion and pleasing facial morphology, no adolescents were included in their sample. Ethnic differences of clinical significance have been established in selected width measurements of Chinese relative to published data for Japanese and American Whites (Wei, 1970). Although the sample of Chinese was relatively large, only adults were included without occlusal selection criteria. In addition, similar differences have been established between Egyptians and other ethnic groups (Aboul-Azm and Korayem, 1987). The Egyptian sample was also limited to adults. Cephalometric norms should represent the means and ranges or clinically useful parameters from large samples of subjects of a similar age and ethnicity with untreated almost ideal occlusions to be valid as standards for comparison. According to these criteria, few of the existing data allow

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valid interpretations of skeletal versus dental components of malocclusions in the frontal plane, particularly for adolescent subjects. The aim of this study was to establish PA cephalometric norms for adolescent Kuwaitis of an age comparable with the normal start of comprehensive orthodontic treatment, and to compare these norms with those suggested in the available analysis systems as well as to other published information.

Taking Pa Cephalogram

Section 9  PA Cephalometric Landmarks

The PA cephalogram is taken with the patient’s head held straight (natural head position) or slightly down. The plane that intersects the ear rods, which help to stabilize the head, is known as the porionic, transporionic, or otic plane or axis because it presumably interacts with the external auditory meati. The film-object, film with ear rod, or porion-film distance determines the amount of magnification of the head structure. In early traditional cephalometry, the film holder was placed to touch the nose, and the percentage of magnification was computed and corrected. Later, the film-poronic axis distance could be set at a fixed distance (13-15 cm) with corresponding magnification factors. In digital machines, technological requirements dictate a greater sensor object distance (around 20 cm), leading to enlargement factors of more than 13 percent that can be corrected in the imaging software.

Structures Involved in Pa Cephalogram Following structures are involved in PA cephalogram and need to be traced; Structures of right and left side need to be traced in PA cephalogram: • External peripheral cranial bone surfaces. • Coronal suture. • Mastoid processes. • Occipital condyles. • Planum sphenoidale and superior surface of the floor of the pituitary fossa. • Floor of the nose. • Orbital outline and inferior surface of the orbital plate of the frontal bone. • Oblique line formed by the external surface of the greater wing of the sphenoid in the area of the temporal fossa. • Arcuate eminence . • Lateral surface of the frontosphenoidal process of the zygoma and the zygomatic arch down to and including the key ridge • Cross-section of the zygomatic arch. • Infratemporal surface of the maxilla in the area of the tuberosity, which is seen lateral to the lower outlines of the key ridge after the eruption of the permanent first molar. • Body of the mandible. • Complete dentition or selected dental units. PA cephalometric landmarks/points related to specific bones are listed below:

1. Cephalometric landmarks (points) related to ethmoid bone. 2. Cephalometric landmarks (points) related to nasal bone. 3. Cephalometric landmarks (points) related to zygomatic bone. 4. Cephalometric landmarks (points) related to maxillary bone. 5. Cephalometric landmarks (points) related to dentition. 6. Cephalometric landmarks (points) related to mandible.

Pa Cephalometric Landmarks Related to Ethmoid Bone Cephalometric landmark related to ethmoid bone are as follows (Table 18.1): Table 18.1: Cephalometric landmark related to ethmoid bone Cephalometric landmark

Abbreviation

Type

Origin

Crista galli

Nc

Unilateral

Anatomic

Crista galli abbreviation Nc–Crista galli is abbreviated using English alphabets and is expressed as capital letter or upper case N and small letter or lower case c and is written continuously without any space between the alphabets.

Definition Neck of crista galli (Figs 18.1A and B) is the neck of perpendicular lamina of the ethmoid.

according to Viken Sassouni Neck of crista galli, most constricted point of the projection of the perpendicular lamina of the ethmoid (almost at the level of planum).

Type Neck of crista galli is a unilateral, anatomic, hard tissue PA cephalometric landmark.

Pa Cephalometric Landmarks Related to Nasal Bone Cephalometric landmarks related to nasal bone are as follows (Table 18.2): Table 18.2: Cephalometric landmarks related to nasal bone Cephalometric landmarks

Abbreviation

Type

Origin

top of nasal septum

tns

Unilateral

Anatomic

NC

NC

Unilateral

Anatomic

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Figures 18.1A and B: Crista galli

A

Chapter 18  PA Cephalometric Landmarks

B

A

B

Figures 18.2A and B: Top of nasal septum

Top of Nasal Septum

Definition according to athanasios E athanasiou

abbreviation tns–Top of nasal septum is abbreviated using English alphabet and is expressed as small letter or lower case t, n, s and is written continuously without any space between the alphabets.

The highest point onto the superior aspect of the nasal septum (Figs 18.2A and B).

Type Top of nasal septum is a unilateral, anatomic, hard tissue PA cephalometric landmark.

162

Pa Cephalometric Landmarks Related to zygomatic Bone

NC abbreviation NC–NC is abbreviated using English alphabets and is expressed as capital letter or upper case N, C and is written continuously without any space between the alphabets.

Cephalometric landmarks related to zygomatic bone are as follows (Table 18.3): Table 18.3: Cephalometric landmarks related to zygomatic bone Cephalometric landmarks

Abbreviation

Type

Origin

Zygoma

Zyg

Bilateral

Anatomic

Zygion

Zy

Bilateral

Anatomic

Zygomatic arch

ZA

Bilateral

Anatomic

Type

Zygomatic suture point

Z

Bilateral

Anatomic

NC is a unilateral, anatomic, hard tissue PA cephalometric landmark.

Jugal process

J

Bilateral

Anatomic

Definition according to Robert M Ricketts


Lateral most point on inside surface of the bony nasal cavity (Fig. 18.3).

zyg-zygoma abbreviation Zyg–Zygoma is abbreviated using English alphabet and is expressed as capital letter or upper case Z followed by lower case or small letter y, g and is written continuously without any space between the alphabets.

Definition according to Viken Sassouni Figure 18.3: NC

A

Most lateral and superior point of the shadow of the zygomatic arch (Figs 18.4A and B).

B

Figures 18.4A and B: Zygoma

163

Type

Type

Zygoma is a bilateral, anatomic, hard tissue PA cephalometric landmark.

Zygion is a bilateral, anatomic, hard tissue PA cephalometric landmark.

zygion

zygomatic arch abbreviation

Zy–Zygion is abbreviated using English alphabets and is expressed as capital letter or upper case Z followed by lower case or small letter y and is written continuously without any space between the alphabets.

ZA–Zygomatic arch is abbreviated using English alphabet and is expressed as capital letter or upper case Z, A and is written continuously without any space between the alphabets.

Definition

Definition

according to Robert M Ricketts


Zygion is the most lateral point of each zygomatic arch (Figs 18.5A and B).

Center of zygomatic arch by inspection for frontal (Figs 18.6A and B).

A

B

Figures 18.5A and B: Zygion

A

B

Figures 18.6A and B: Zygomatic arch


abbreviation

164

Type

Jugal Process

Zygomatic arch is a bilateral, anatomic, hard tissue PA cephalometric landmark.

abbreviation J–Jugal process is abbreviated using English alphabet and is expressed as capital letter or upper case J.

zygomatic Suture Point abbreviation

Definition

Z–Zygomatic suture point is abbreviated using English alphabet and is expressed as capital letter or upper case Z.


Definition

Lowest point on the curve of zygomatic bone used in the lateral film, also the point on the jugal process of the maxilla at a crossing with the tuberosity of the maxilla (in the frontal) (Figs 18.8A and B).

according to Robert M Ricketts Medial and anterior junction of the zygomatic bone with the frontal bone (Figs 18.7A and B).

Type


Type

Jugal process is a bilateral, anatomic, hard tissue PA cephalometric landmark.

Zygomatic suture point is a bilateral, anatomic, hard tissue PA cephalometric landmark.

A

B

Figures 18.7A and B: Zygomatic suture point

A

B

Figures 18.8A and B: Jugal process

165

Pa Cephalometric Landmarks Related to Maxilla

Pa Cephalometric Landmarks Related to Dentition

Cephalometric landmarks related to maxilla is as follows (Table 18.4):

PA cephalogram landmarks/points related to dentition are as follows (Tables 18.5 and 18.6):

Table 18.4: Cephalometric landmark related to maxilla

Table 18.5: Cephalometric landmarks related to maxillary teeth

Cephalometric landmark

Abbreviation

Type

Origin


Abbreviation

Type

Origin

Maxillare

Mx or mx

Bilateral

Anatomic

Incision superius incisalis

Isi or is

Unilateral

Anatomic

Incision superius apicalis

Isa or ULA

Unilateral

Anatomic

Maxillary molar

um

Bilateral

Anatomic

Maxillary first molar

U6 or A6

Bilateral

Anatomic

Maxillare abbreviation

Table 18.6: Cephalometric landmarks related to mandibular teeth

Mx–Maxillare is abbreviated using English alphabets and is expressed as capital letter or upper case M and small letter or lower case x and is written continuously without any space between the alphabets.

Definition • • •

Type

Origin

Iii or ii

Unilateral

Anatomic

Incision inferior apicalis

Iia or LIA

Unilateral

Anatomic

Incision inferius frontale

iif

Unilateral

Anatomic

Mandibular first molar

L6 or A6

Bilateral

Anatomic

mi

mi

Bilateral

Anatomic

Mandibular molar

Im

Bilateral

Anatomic

Incision Superius Incisalis

Maximum concavity on the contour of the maxilla between the first molar and malare (Figs 18.9A and B). Maximum concavity on the contour of the maxilla between malare (Ma) and the maxillary first molar (U6). Closely corresponds to the key ridge. The intersection of the lateral contour of the maxillary alveolar process and the lower contour of the maxillozygomatic process of the maxilla (left and right).

abbreviation

Isi–Incision superius incisalis is abbreviated using English alphabets and is expressed as capital or upper case I followed by small letters or lower case s and i and is written continuously without any space between the alphabets. Or is–Incision superius is abbreviated using English alphabets and is expressed as small letters or lower case s and i and is written continuously without any space between the alphabets.

Type Maxillare is a bilateral, anatomic, hard tissue PA cephalometric landmark.

A

Abbreviation

Incision inferior incisalis


mx–Maxillare is also abbreviated using English alphabet and is expressed as small letter or lower case m, x and is written continuously without any space between the alphabets.


B

Figures 18.9A and B: Maxillare

166

•

Definition Incision superius incisalis (Figs 18.10A and B) is the incisal edge of the maxillary central incisor.

•

according to arne Bjork Incision superius incisalis is the mid-point of the incisal edge of the most prominent upper central incisor.

•

according to Robert E Moyers

•

Incision superius incisalis is the incisal tip of the most anterior maxillary central incisor.

Type


Incision superius incisalis is a unilateral, anatomic, hard tissue cephalometric landmark.

Tracing of Incision Superius Incisalis on Lateral Cephalogram

Incision Superius apicalis abbreviation

The labial and lingual outline of the crown of the maxillary permanent central incisor appears as radio-opaque line on the lateral cephalogram. Trace these two outlines of crown of the maxillary permanent central incisor. The tip of the incisal edge or the intersection of the labial and lingual outline is the point of Incision Superius Incisalis.

Significance (Ref to Chapter 20) Incision superius incisalis is used as one of the reference point in the construction of angles and planes for the assessment of following:

A

•

Inclination of upper incisor is assessed using angle drawn between the long axis of upper incisor plane and the FH plane. In Arnett’s analysis, the upper incisor torque is assessed using the angle drawn between long axis of upper incisor and occlusal plane. Inter-incisal relationship of upper and lower incisors are assessed using the angle drawn between the long axis of upper and lower permanent central incisor. Anteroposterior positioning of maxillary central incisor is assessed using the distance between the incision Superius Incisalis and the NA plane. Anteroposterior positioning of maxillary central incisor is assessed using the distance between the incision Superius Incisalis and the A-Pog plane.

Isa–Incision superius apicalis is abbreviated using English alphabets and is expressed as capital or upper case I followed by small letters or lower case s and a and is written continuously without any space between the alphabets. UIA–Upper incisor apex is abbreviated using English alphabets and is expressed as capital or upper case U, I and A and is written continuously without any space between the alphabets.

Definition Incision superius apicalis (Figs 18.11A and B) is the root apex of the most anterior maxillary central incisor; if this

B

Figures 18.10A and B: Incision superius incisalis

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B

Figures 18.11A and B: Incision superius apicalis

point is needed only for defining the long axis of the tooth, the midpoint on the bisection of the apical root width can be used.

•

according to Michael L Riolo

•

The upper incisor apex is the root tip of the maxillary central incisor. In cases where the root is not yet completed, the midpoint of the growing root tip is marked.

•

SN Bhatia and BC Leighton

Inclination of upper incisor is assessed using angle drawn between the long axis of upper incisor plane and the FH plane. In Arnett’s analysis, the upper incisor torque is assessed using the angle drawn between long axis of upper incisor and occlusal plane. Inter-incisal relationship of upper and lower incisors are assessed using the angle drawn between the long axis of upper and lower permanent central incisor.

The upper incisor apex is the root apex of the most prominent upper incisor.

Maxillary Molar

Type Incision superius apicalis is a unilateral, anatomic, hard tissue cephalometric landmark.

Tracing of Incision Superius apicalis on Lateral Cephalogram The labial and lingual outline of the root of the maxillary permanent central incisor appears as radio-opaque lines on the lateral cephalogram. Trace these two outlines of root of the maxillary permanent central incisor. The point of intersection of labial and lingual outlines of the root of maxillary permanent central incisor is the point of Incision Superius Apicalis.

Significance (Ref to Chapter 20) Incision superius apicalis is used as one of the reference points in the construction of angles and planes for the assessment of following:


A

abbreviation

um–Maxillary molar is abbreviated using English alphabets and is expressed as lower case u and m and is written continuously without any space between the alphabets.

Definition according to athanasios E athanasiou The most prominent lateral point on the buccal surface of the second deciduous or first permanent maxillary molar (Figs 18.12A and B).

Type Maxillary molar is a bilateral, hard tissue cephalometric landmark.

168


A

B

Figures 18.12A and B: Maxillary molar

B

A

Figures 18.13A and B: Maxillary first molar

Maxillary First Molar abbreviation U6–Maxillary first molar is abbreviated using English alphabet and numeric and is expressed as capital or upper case U followed by English numeric 6 and is written continuously without any space between the alphabets. OR A6—Maxillary first molar is abbreviated using English alphabet and numeric and is expressed as capital or upper case A followed by English numeric 6 and is written continuously without any space between the alphabets.

Definition Maxillary first molar (Figs 18.13A and B) is the tip of the mesiobuccal cusp of the maxillary first permanent molar.

Type Maxillary first molar is a bilateral, anatomic, hard tissue cephalometric landmark.

Tracing of Maxillary First Molar on Lateral Cephalogram The labial and lingual and cuspal outlines of the crown of the maxillary permanent first molar appears as radio-opaque lines

169

Definition

on the lateral cephalogram. Trace these outlines of crown of the maxillary permanent first molar, the tip of the mesiobuccal cusp of the maxillary permanent molar is the point of maxillary first molar.

Incision inferius incisalis (Figs 18.15A and B) is the incisal edge of the most prominent mandibular central incisor.

according to arne Bjork

Cuspid

The incision inferius is the incisal point of the most prominent medial mandibular incisor.

abbreviation A3–Cuspid is abbreviated using English alphabet and numeric and is expressed as upper case A and numeric 3 and are written continuously without any space between the alphabets.

according to Robert E Moyers The incision inferius is the incisal tip of the most labial mandibular central incisor.

Definition

Type

according to Carl F gugino

Type

Tracing of Incision Inferius Incisalis on Lateal Cephalogram

Cuspid is a bilateral, hard tissue cephalometric landmark.

The labial and lingual outline of the crown of the mandibular permanent central incisor appears as radio-opaque line on the lateral cephalogram. Trace these two outlines of crown of the mandibular permanent central incisor. The tip of the incisal edge or the intersection of the labial and lingual outline is the point of incision inferius incisalis.

Incision Inferius Incisalis abbreviation Iii–Incision inferius incisalis is abbreviated using English alphabets and is expressed as capital or upper case I followed by small letters or lower case i and i and is written continuously without any space between the alphabets.


ii—Incision inferius is abbreviated using English alphabets and is expressed as small letters or lower case i and i and is written continuously without any space between the alphabets.

A


Incision inferius incisalis is a unilateral, anatomic, hard tissue cephalometric landmark.

Tip of the upper permanent canine (Figs 18.14A and B).

Incision inferius incisalis is used as one of the reference point in the construction of angles and planes for the assessment of following:

B

Figures 18.14A and B: Cuspid

170

B

A


Figures 18.15A and B: Incision inferius incisalis

• • • • •

B

A

Figures 18.16A and B: Incision inferius apicalis

Inclination of lower incisor is assessed using angle drawn between the Long axis of lower incisor plane and the mandibular plane. In Arnett’s analysis, the lower incisor torque is assessed using the angle drawn between long axis of lower incisor and occlusal plane. Inter-incisal relationship of upper and lower incisors are assessed using the angle drawn between the long axis of upper and lower permanent central incisorl. Anteroposterior positioning of mandibular central incisor is assessed using the distance between the incision inferius Incisalis and the NB plane. Anteroposterior positioning of maxillary central incisor is assessed using the distance between the incision inferius incisalis and the A-Pog plane.

Incision Inferius apicalis abbreviation Iia–Incision inferius apicalis is abbreviated using English alphabets and is expressed as capital or upper case I followed by small letters or lower case i and a and is written continuously without any space between the alphabets. LIA–lower incisor apex is abbreviated using English alphabets and is expressed as capital or upper case L, I and A and is written continuously without any space between the alphabets.

Definition Incision inferius apicalis (Figs 18.16A and B) is the root apex of the most anterior mandibular central incisor; if this

171

point is needed only for defining the long axis of the tooth, the midpoint on the bisection of the apical root width can be used.

Incision Inferius Frontale

SN Bhatia and BC Leighton

abbreviation

The lower incisor apex is the root apex of the most prominent lower incisor.

iif–Incision inferius frontale is abbreviated using English alphabets and is expressed as lower case i, i and f and is written continuously without any space between the alphabets.

Type

Definition

Incision inferius apicalis is a unilateral, anatomic, hard tissue cephalometric landmark.

according to athanasios E athanasiou

Tracing of Incision Inferius apicalis on Lateal Cephalogram

The midpoint between the mandibular central incisors at the level of the incisal edges (Figs 18.17A and B).

The labial and lingual outline of the root of the mandibular permanent central incisor appears as radio-opaque lines on the lateral cephalogram. Trace these two outlines of root of the mandibular permanent central incisor. The point of intersection of labial and lingual outlines of the root of mmandibular permanent central incisor is the point of incision inferius apicalis.

Type


Mandibular First Molar

Incision inferius apicalis is used as one of the reference point in the construction of angles and planes for the assessment of following: • Inclination of lower incisor is assessed using angle drawn between the long axis of upper incisor plane and the mandibular plane. • In Arnett’s analysis, the lower incisor torque is assessed using the angle drawn between long axis of lower incisor and occlusal plane. • Inter-incisal relationship of upper and lower incisors are assessed using the angle drawn between the long axis of upper and lower permanent central incisors.

A


Incision inferius frontale is a unilateral, hard tissue cephalometric landmark.

abbreviation

L6–Mandibular first molar is abbreviated using English alphabet and numeric and is expressed as capital or upper case L followed by English numeric 6 and is written continuously without any space between the alphabets.

Definition

Mandibular first molar (Figs 18.18A and B) is the tip of the mesiobuccal cusp of the mandibular first permanent molar.

B

Figures 18.17A and B: Incision inferius frontale

172

A

B


Figures 18.18A and B: Mandibular first molar

A

B

Figures 18.19A and B: mi

Type

Definition

Mandibular first molar is a unilateral, anatomic, hard tissue cephalometric landmark.

mi (Figs 18.19A and B) is the mesial contact of the lower molar projected normal to the plane of occlusion.

Tracing of Mandibular First Molar on Lateral Cephalogram

Type

The labial and lingual and cuspal outlines of the crown of the mandibular permanent first molar appears as radio-opaque lines on the lateral cephalogram. Trace these outlines of crown of the mandibular permanent first molar, the tip of the mesiobuccal cusp of the mandibular permanent molar is the point of maxillary first molar.

mi abbreviation mi–mi is abbreviated using English alphabets and is expressed as lower case m and i and is written continuously without any space between the alphabets.

mi is a bilateral, hard tissue cephalometric landmark.

Tracing of mi on Lateral Cephalogram The labial and lingual and cuspal outlines of the crown of the mandibular permanent first molar appears as radio-opaque lines on the lateral cephalogram. Trace these outlines of crown of the mandibular permanent first molar, the tip of the mesiobuccal cusp of the mandibular permanent molar is the point of maxillary first molar. mi is the mesial contact of the lower molar projected normal to the plane of occlusion.

Significance (Ref to Chapter 20) mi is used as one of the reference points in the construction of plane and angle in the Bjork cephalometric analysis.

173

Table 18.6: Cephalometric landmarks related to mandible

Mandibular Molar abbreviation Im–Mandibular molar is abbreviated using English alphabets and is expressed as upper case I and lower case m and is written continuously without any space between the alphabets.


Abbreviation

Type

Origin

Menton

Me

Unilateral

Anatomic

Articulare

Ar

Bilateral

Anatomic

Malare

ma

Bilateral

Anatomic

Antegonial tubercle

Ag

Bilateral

Anatomic

Antegonion

Ag

Bilateral

Anatomic

Definition

Menton

according to athanasios E athanasiou abbreviation

The most prominent lateral point on the buccal surface of the second deciduous or first permanent mandibular molar (Figs 18.20A and B).

Type Mandibular molar is a bilateral, hard tissue cephalometric landmark.


Pa Cephalometric Landmarks Related to Mandible

according to Carl F gugino

Lower most point of the contour of the chin.

Menton (Figs 18.21A and B) is the point on inferior border of symphysis directly inferior to mental protuberance and below center of trigonium mentali.

Cephalometric landmarks related to mandible are as follows (Table 18.6):

A


Me–Menton is abbreviated using English alphabets and is expressed as capital or upper case M followed by lower case or small letter e and is written continuously without any space between the alphabets.

B

Figures 18.20A and B: Mandibular molar

174

A

B

Figures 18.21A and B: Menton


Type Menton (see Figs 12.7A and B) is a unilateral, anatomic, hard tissue landmark.

Tracing of Menton on the Lateral Cephalogram The labial cortical plate of mandible in the anterior symphysis region appears as vertical shaped radio-opaque line. Trace the labial cortical plate from the alveolar crest between two permanent mandibular incisors in the midline to the point anteroinferior point on the mandible. Below the point B follows the convex outline of labial cortical plate of mandible,the most prominent point is the point of pogonion.The anteroinferior point of inferior border of the mandible in the midline is the point of menton.

Significance

or small letter r and is written continuously without any space between the alphabets.

Definition Articulare (Figs 18.22A and B) is the point of intersection the dorsal contours of the processus articularis mandibulare and os tempoarle.The midpoint, a is used where double projection gives rise to two points a1 and a2.

Type Articulare is a bilateral, anatomic, hard tissue landmark.

Tracing of articulare on the Lateral Cephalogram The posterior or ramus border of the mandible appears as radio-opaque line on the lateral cephalogram. Trace ramus border of the mandible. The point on the ramus border of the mandible at the neck region.

Menton is used as one of the reference points in the construction of plane and angle for the assessment of the following: • Constructions of mandibular plane, i.e. the line joining the point menton and gonion. • Growth pattern is assessed using S-N to mandibular plane angle. • Growth pattern is assessed using FH to mandibular plane angle. • Cant of occlusal plane is assessed using occlusal plane (APocc – PPocc ) to mandibular plane (Me-Go) angle. • Growth pattern is assessed using Go1 and Go2 angles.

Articulare is used as one of the reference points in the construction of plane and angle for the assessment of following: • Constructions of posterior/ramus border of the mandible i.e. the line joining the point articulare and gonion. • Growth pattern is assessed using Go1 and Go2 angles. • Rotation of the mandible is also assessed using the S-ArGo angle.

articulare

Malare

Significance

abbreviation abbreviation Ar–Articulare is abbreviated using English alphabets and is expressed as capital or upper case A followed by lower case

ma–Malare is abbreviated using English alphabets and is expressed as lower case or small letters m, a and is written continuously without any space between the alphabets.

175

A

B

Figures 18.22A and B: Articulare


A

B

Figures 18.23A and B: Malare

Definition

Definition



Midpoint of intersection between the projection of the coronoid process and the lower contour of the malar bone (Figs 18.23A and B).

Intersection of the outline of the dense bone of the trihedral eminence with the lower border of the ramus. (Figs 18.24A and B).

Type

Type

Malare is a bilateral, anatomic, hard tissue PA cephalometric landmark.

Antegonial tubercle is a bilateral, anatomic, hard tissue PA cephalometric landmark.

antegonial Tubercles

antegonion

abbreviation

abbreviation

Ag–Antegonial tubercles are abbreviated using English alphabets and is expressed as upper case or capital letter A and lower case or small letters g and is written continuously without any space between the alphabets.

Ag–Antegonion is abbreviated using English alphabets and is expressed as upper case or capital letter A and lower case or small letter g and is written continuously without any space between the alphabets.


176

A

B

Figures 18.24A and B: Antegonial tubercles

A

B

Figures 18.25A and B: Antegonion

Definition

Type

according to athanasios E athanasiou

Antegonion is a bilateral, anatomic, hard tissue PA cephalometric landmark.

The highest point in the antegonial notch (left and right) (Figs 18.25A and B).

SECTION

10

SV Cephalometric Landmarks

 SV Cephalometric Landmarks

CHAPTER

19

SV Cephalometric Landmarks

Basion

Opisthion Abbreviation

Abbreviation Ba–Basion is abbreviated as capital or upper case B followed by small letter or lower case a and is written continuously without any space between the alphabets.

Op–Opisthion is abbreviated as capital or upper case O followed by small letter or lower case p and is written continuously without any space between the alphabets.

Definition

Definition According to Clifton T Forsberg

According to Clifton T Forsberg Basion is the most anterior point, relative to the interspinosum line, on the border of the foramen magnum (Figs 19.1A and B).

Opisthion is the most posterior point, relative to the interspinosum line, on the border of the foramen magnum (Figs 19.2A and B).

Type

Type

Basion is a unilateral hard tissue SV cephalometric landmark/ point.

Opisthion is a unilateral hard tissue SV cephalometric landmark/point.

Origin

Origin

Basion is an anatomic SV cephalometric landmark/point.

Opisthion is an anatomic SV cephalometric landmark/point.

A

B

Figures 19.1A and B: Basion

180

A

B

Section 10  SV Cephalometric Landmarks

Figures 19.2A and B: Opisthion

A

B

Figures 19.3A and B: Foramina spinosa points

Foramina Spinosa Points Abbreviation FSP–Foramina spinosa point is abbreviated as capital or upper case F, S and P and is written continuously without any space between the alphabets.

Definition

Type Foramina spinosa points are bilateral hard tissue SV cephalo metric landmarks/points.

Origin Foramina spinosa points are an anatomic SV cephalometric landmarks/points.

Foramina Spinosum


Abbreviation

Foramina spinosa points are the geometric center of each foramina spinosa (Figs 19.3A and B).

SP–Foramina spinosum is abbreviated as capital or upper case S and P and is written continuously without any space between the alphabets.

181

Odontoid

Definition According to KKK Lew Abbreviation

The geometric center of each foramen spinosum (Figs 19.4A and B).

Od–Odontoid is abbreviated as capital letter or upper case O and followed by small letter or lower case d and is written continuously without any space between the alphabets.

Type Foramina spinosum points are bilateral hard tissue SV cephalo metric landmarks/points.

Definition

Origin

According to KKK Lew

Foramina spinosum points are an anatomic SV cephalometric landmarks/points.

B

Figures 19.4A and B: Foramina spinosum

A

B

Figures 19.5A and B: Odontoid

Chapter 19  SV Cephalometric Landmarks

A

Center of odontoid process on the SMV (Figs 19.5A and B).

182

Middle Cranial Fossa Points

Type Odontoid is a unilateral hard tissue SV cephalometric landmark/point.

Origin Odontoid is an anatomic SV cephalometric landmark/point.

Pterygomaxillary Fissure

Abbreviation MCF–Middle cranial fossa point is abbreviated as capital letters or upper case MCF and is written continuously without any space between the alphabets.

Definition

Abbreviation


PTM–Pterygomaxillary fissure is abbreviated as capital letter or upper case P, T and M and are written continuously without any space between the alphabets.

The most anterior point relative to the interspinosum line, on each lesser wing of the sphenoid bone (LWS) (Figs 19.7A and B).


Definition

Type Middle cranial fossa points is a bilateral hard tissue SV cephalometric landmark/point.

According to Clifton T Forsberg The most medial and posterior point of each pterygomaxillary fissure. The PTM line connects the right and left PTM points. The PTM axis is the perpendicular bisector of the PTM line (Figs 19.6A and B).

Origin Middle cranial fossa point is an anatomic SV cephalometric landmark/point.

Type Pterygomaxillary fissure is a bilateral hard tissue SV cephalometric landmark/point.

Origin Pterygomaxillary fissure is an anatomic SV cephalometric landmark/point.

A

Posterior Vomer Point Abbreviation PVP–Posterior vomer point is abbreviated as capital letter or upper case PVP and is written continuously without any space between the alphabets.

B

Figures 19.6A and B: Pterygomaxillary fissure

183

B

A

Figures 19.7A and B: Middle cranial fossa points

B

Figures 19.8A and B: Posterior vomer point

Definition According to Clifton T Forsberg The intersection of the vomer with the PTM line (Figs 19.8A and B).

Type Posterior vomer point is a unilateral hard tissue SV cephalo metric landmark/point.

Origin Posterior vomer point is an anatomic SV cephalometric landmark/point.

Posterior Cranial Vault Points


A

Abbreviation PCV–Posterior cranial vault points is abbreviated as capital letter or upper case PVP and is written continuously without any space between the alphabets.

Definition According to Clifton T Forsberg The intersections of the lateral borders of the cranial vault with a line, parallel to the interspinosum line, which is drawn across the cranial vault at its section of greatest width (Figs 19.9A and B).

184

B

A


Figures 19.9A and B: Posterior cranial vault points

B

A

Figures 19.10A and B: Angulare point

Type

Definition

Posterior cranial vault points are bilateral hard tissue SV cephalometric landmark/point.


Origin Posterior cranial vault point is an SV anatomic cephalometric landmark/point.

Angulare Point

The most anterior point, relative to the PTM line, of the triangular opacities present at the external orbital angle where the upper and lower orbital rims meet and the zygomatic arch inserts (Figs 19.10A and B).

Type Angulare point is a bilateral hard tissue SV cephalometric landmark/point.

Abbreviation

Origin

A–Angulare point is abbreviated as capital letter or upper case A.

Angulare point is an anatomic SV cephalometric landmark/ point.

185

Maxillary Apical Base Midline

Mandibular Dental Midline

Abbreviation

Abbreviation

MAB–Maxillary apical base midline is abbreviated as capital letter or upper case MAB.

Mand DM–Mandibular dental midline is abbreviated as Mand DM.

Definition

Definition



A point midway between the roots of the maxillary central incisors at a level which is one third of the distance from the apex of the tooth to the alveolar crest. This point is determined on the PA radiograph and its position is then transferred to the SV radiograph in its proper position relative to the dental midline (Figs 19.11A and B).

The point contact between the mesial surfaces of the crowns of the mandibular central incisors (Figs 19.12A and B).

Maxillary apical base midline is a unilateral hard tissue SV cephalometric landmark/point.

Mandibular dental midline is a unilateral hard tissue SV cephalo metric landmark/point.

Origin

Mandibular dental midline is an anatomic SV cephalometric landmark/point.

Origin Maxillary apical base midline is an anatomic SV cephalometric landmark/point.

A


Type

Type

B

Figures 19.11A and B: Maxillary apical base midline


186

A

B

Figures 19.12A and B: Mandibular dental midline

A

B

Figures 19.13A and B: Mandibular apical base midline

Mandibular Apical Base Midline Abbreviation MAB–Mandibular apical base midline is abbreviated as capital letter or upper case MAB.

Definition According to Clifton T Forsberg A point midway between the roots of the mandibular central

incisors at a level which is one third of the distance from the apex to the alveolar crest (Figs 19.13A and B).

Type Mandibular apical base midline is a unilateral hard tissue SV cephalometric landmark/point.

Origin Mandibular apical base midline is an anatomic SV cephalo metric landmark/point.

187

First Molar Point

Origin First molar point is an anatomic SV cephalometric landmark/ point.

Abbreviation FMP–First molar point is abbreviated as capital letter or upper case FMP and is written continuously without any space between the alphabets.

Gonion Point Abbreviation

Definition

Go–Gonion point is abbreviated as capital letter or upper case G followed by small letter or lower case o and is written continuously without any space between the alphabets.

According to Clifton T Forsberg The most distal point in line with the central groove on each mandibular first molar (Figs 19.14A and B).

Definition According to Clifton T Forsberg

First molar point is a bilateral hard tissue SV cephalometric landmark/point.

The midpoint mediolaterally on the posterior border of each gonial angle (Figs 19.15A and B).

A

B

Figures 19.14A and B: First molar point

A

B

Figures 19.15A and B: Gonion point


Type

188

Type

Origin

Gonion point is a bilateral hard tissue SV cephalometric landmark/point.

Condylion medialis is an anatomic SV cephalometric landmark/point.

Condylion Lateralis

Origin Gonion point is an anatomic SV cephalometric landmark/ point.

Condylion Medialis Abbreviation


CM–Condylion medialis is abbreviated as capital letter or upper case CM and is written continuously without any space between the alphabets. OR CoM–Condylion medialis is abbreviated as capital letter or upper case C, small letter o followed by capital letter M and is written continuously without any space between the alphabets.

Abbreviation CL–Condylion lateralis is abbreviated as capital letter or upper case CL and is written continuously without any space between the alphabets. Or CoL–Condylion lateralis is abbreviated as capital letter or upper case C, small letter o followed by capital letter L and is written continuously without any space between the alphabets.

Definition According to Clifton T Forsberg The tangent point to each lateral condylar border of a line drawn parallel to each mandibular body line (Figs 19.17A and B).

Definition According to Clifton T Forsberg The tangent point to each medial condylar border of a line drawn parallel to each mandibular body line (Figs 19.16A and B).

Type Condylion lateralis is a bilateral hard tissue SV cephalometric landmark/point.

Type

Origin

Condylion medialis is a bilateral hard tissue SV cephalometric landmark/point.

Condylion lateralis is an anatomic SV cephalometric land mark/point.

A

B

Figures 19.16A and B: Condylion medialis

189

B

Figures 19.17A and B: Condylion lateralis

A


A

B

Figures 19.18A and B: Condylion anterioris

Condylion Anterioris Abbreviation CA–Condylion anterioris is abbreviated as capital letter or upper case C and A, and is written continuously without any space between the alphabets.

Definition According to Clifton T Forsberg A point on the anterior of each condylar head which is chosen to represent the mandibular fossa of the temporal bone (Figs 19.18A and B).


190

A

B

Figures 19.19A and B: Condylion posterioris

Type

Definition

Condylion anterioris is a bilateral hard tissue SV cephalometric landmark/point.


Origin Condylion anterioris is an anatomic SV cephalometric land mark/point.

Condylion Posterioris

Abbreviation CP–Condylion posterioris is abbreviated as capital letter or upper case C, P and are written continuously without any space between the alphabets.

A point on the posterior of each condylar head which is chosen to represent the mandibular fossa of the temporal bone (Figs 19.19A and B).

Type Condylion posterioris is a bilateral hard tissue SV cephalo metric landmark/point.

Origin Condylion posterioris is an anatomic SV cephalometric land mark/point.

SECTION

11

Applications of Cephalometric Landmarks

 Applications of Cephalometric Landmarks

CHAPTER

20

Applications of Cephalometric Landmarks

Cephalometric Landmarks (Points) used in various cephalo emtric analyses are listed below: 1. Bjork cephalometric analysis 2. Coben craniofacial and dentition analysis 3. Downs cephalometric analysis 4. Farkas and Coworkers soft tissue cephalometric analysis 5. Harvold cephalometric analysis 6. Holdaway cephalometric analysis 7. Legan and burstone soft tissue cephalometric analysis 8. Rickett’s cephalometric analysis 9. Sassouni cephalometric analysis 10. Di Paolo’s quadrilateral cephalometric analysis 11. Hasund (Bergen) cephalometric analysis 12. Jarabak cephalometric analysis 13. Riedel cephalometric analysis 14. Schwartz cephalometric analysis 15. Wylie cephalometric analysis 16. Steiner’s cephalometric analysis

A

17. Tweed’s cephalometric analysis 18. Wit’s cephalometric analysis 19. Basis cephalometric analysis 20. Cagliari cephalometric analysis 21. Chieti cephalometric analysis 22. McGann cephalometric analysis.

Bjork Cephalometric Analysis (Figs 20.1A and B) Cephalometric landmarks used in Bjork cephalometric analysis are as given below: Ar-articulare–The point of intersection of the dorsal contours of processus articularis mandibulae and os temporale. The midpoint is used where double projection gives rise to two articulare points. dd–The most prominent point of the chin in the direction of measurement. gn-gnathion–The deepest point on the chin.

B

Figures 20.1A and B: Bjork cephalometric analysis

194

id-infradentale–The point of transition from the crown of the most prominent mandibular medial incisor to the alveolar projection. ii-incision inferius–The incisal point of the most prominent medial mandibular incisor.

s–The center of sella turcica (the midpoint of the horizontal diameter). sm-supramentale–The deepest point on the contour of the alveolar projection, between infradentale and pogonion. sp-the spinal point–The apex of spina nasalis anterior.

is-incision superius–The incisal point of the most prominent medial maxillary incisor.

snp-spina nasalis posterior–The point of intersection of palatum posterior durum, palatum molle and fossa pterygopalatina.

kk–The point of intersection between the base and ramus tangents to the mandible. The midpoint is used where double projection gives rise to two points.

ss-subspinale–The deepest point on the contour of the alveolar projection, between the spinal point and prosthion.

mi–The mesial contact point of the lower molar projected normal to the plane of occlusion.

io–The incisal point of the most prominent medial mandibular incisor, projected normal to the plane of occlusion.

Coben Craniofacial and Dentition Cephalometric Analysis (Figs 20.2A and B)

N-nasion–Nasion is the most anterior point of the frontonasal suture in the middle.

Cephalometric landmarks used in Coben craniofacial and dentition analysis are as given below:

or-orbitale–The deepest point on the infraorbital margin. The midpoint is used where double projection gives rise to two points.

A-point A (subspinale)–The point at the deepest midline concavity on the maxilla between the anterior nasal spine and prosthion.

pg-pogonion–The most prominent point on the chin.

Ans-anterior nasal spine–The most anterior point of the anterior nasal spine.

Section 11  Applications of Cephalometric Landmarks

ms–The mesial contact point of the upper molar projected normal to the plane of occlusion.

Po-porion–Porion is the most superior point of the external auditory meatus (the superior margin of the TMJ fossa, which lies at the same level may be substitute in the construction of the FH). pr-prosthion–The transition point between the crown of the most prominent medial maxillary incisor and the alveolar projection.

A

Ar-articulare–The point of intersection of the images of the posterior border of the condylar process of the mandible and the inferior border of the basilar part of the occipital bone. B-point B (supramentale)–The point at the deepest midline concavity on the mandibular symphysis between infradentale and pogonion.

B

Figures 20.2A and B: Coben craniofacial and dentition analysis

195

Ba–Basion is the median point of the anterior margin of the foramen magnum can be located by following the images of the slope of the inferior border of the basilar part of the occipital bone to its posterior limit. F-point F (constructed)–The point approximating foramen cecum representing the anatomic anterior limit of the cranial base, constructed as the point of intersection of a perpendicular to the S-N plane from the point of crossing of the images of the orbital roofs and the internal plate of the frontal bone. Go-gonion (constructed)–The point of intersection of the ramus plane and the mandibular plane.

N-nasion–Nasion is the most anterior point of the frontonasal suture in the middle. Or-orbitale–The lowest point on the inferior margin of the orbit, midpoint between right and left images. Po-porion (anatomic)–The superior point of the externa Lauditory meatus (superior margin of temporomandibular fossa, which lies at the same level, may be substituted in the construction of Frankfort horizontal). Pog-pogonion–The most anterior midline point of the mandibular symphysis. Po’-pogonion’ (constructed)–The point of tangency of a perpendicular from the mandibular plane to the most prominent convexity of the mandibular symphysis.

A

S-sella–The point representing the geometric center of the pituitary fossa (sella turcica). Ul-maxillary central incisor (horizontal)–The most labial point on the crown of the maxillary central incisor. Ul-maxillary central incisor (vertical)–The incisal edge of the maxillary central incisor. L1-mandibular central incisor (horizontal)–The most labial point on the crown of the mandibular central incisor. L1-mandibular central incisor (vertical)–The incisal edge of the mandibular central incisor.

Chapter 20  Applications of Cephalometric Landmarks

M-menton–The most inferior midline point on the mandibular symphysis.

Ptm-pterygomaxillary fissure–The point of intersection of the images of the anterior surface of the pterygoid process of the sphenoid bone and the posterior margin of the maxilla.

U6-maxillary first molar (horizontal)–The most distal point on the crown of the maxillary first permanent molar. U6-maxillary first molar (vertical)–The tip of the mesiobuccal cusp of the maxillary first permanent molar. L6-mandibular first molar (horizontal)–The most distal point on the crown of the mandibular first permanent molar. L6-mandibular first molar (vertical)–The tip of the mesiobu ccal cusp of the mandibular first permanent molar.

Downs Cephalometric Analysis (Figs 20.3A and B) Cephalometric landmarks used in Downs cephalometric analysis are as given below:

B

Figures 20.3A and B: Downs cephalometric analysis


196

B

A

Figures 20.4A and B: Farkas and coworkers soft tissue cephalometric analysis


Glabella (g)–The most prominent midline point between the eyebrows.

Bolton point–The highest point on the concavity behind the occipital condyles.

Subnasion (n’)–Deepest point of the nasofrontal angle.

The centre of sella turcica–Located by inspection of the profile image of the fossa.

Subnasale (sn)–Midpoint of the columella base at the apex of the nasolabial angle.

Pronasale (prn)–The most protruded point of the apex nasi.

Orbitale–The lowest point on the left infraorbital margin.

Labiale superius (ls)–Midpoint of the upper vermilion line.

Porion (cephalometric)–The highest point on the superior surface of the soft tissue of the external auditory meati.

Labiale inferius (li)–Midpoint of the lower vermilion line.

Pogonion–The most anterior point on the mandible in the midline.

Pogonion (pg)–The most anterior midpoint of the chin.

Sublabiale (si)–Midpoint of the horizontal labiomental skin ridge.

Point A-subspinale–The deepest midline point on the premaxilla between the anterior nasal spine and prosthion.

Harvold Cephalometric Analysis (Figs 20.5A and B)

Point B-supramentale–The deepest midline point on the mandible between infradentale and pogonion.

Cephalometric landmarks used in Harvold cephalometric analysis are as given below:

Gnathion–A point on the chin determined by bisecting the angle formed by the facial and mandibular planes.

Temporomandibular joint (TMJ)–A point on the contour of the glenoid fossa, where the line indicating the maximum length of the mandible intercepts the contour of the temporomandibular fossa. The midpoint between the right and left side is marked.

Farkas and Coworkers Soft Tissue Cephalometric Analysis (Figs 20.4A and A) Cephalometric landmarks used in Farkas and Coworkers soft tissue cephalometric analysis are as given below: Trichion (tr)–Point on the hairline in the midline of the forehead.

Anterior nasal spine (ANS)–A point on the lower contour of the anterior nasal spine where the vertical thickness is 3 mm, used for horizontal measurements; a point on the upper contour of the anterior nasal spine, where the vertical thickness is 3 mm, employed for vertical measurements.

197

Figures 20.5A and B: Harvold cephalometric analysis

A


B

A

B

Figures 20.6A and B: Holdaway cephalometric analysis

Prognathion (PGN)–A point on the contour of the chin indicating maximum mandibular length measured from the temporomandibular joint. Gnathion (GN)–The most inferior point on the contour of the chin. Pogonion (PG)–The most anterior point on the chin. Nasion (N)–The point at which the nasofrontal suture reaches the contour line of the bones. The forward position of the maxilla, measured from TM to ANS. Mandibular length measured from TM to PGN.

Lower face height measured from ANS to GN. The angle of convexity–The angle between the lines PG-ANS and ANS-N.

Holdaway Cephalometric Analysis (Figs 20.6A and B) Cephalometric landmarks used in Holdaway cephalometric analysis are as given below: 1. The H line or harmony line drawn tangent to the soft tissue chin and the upper lip.


198

A

B

Figures 20.7A and B: Legan and Burstone soft tissue cephalometric analysis

2. A soft tissue facial line from soft-tissue nasion to the point on the soft tissue chin overlying Rickett’s suprapogonion. 3. The usual hard tissue facial plane. 4. The sella-nasion line. 5. Frankfort horizontal plane (FH). 6. A line running at a right angle to the Frankfort plane down tangent to the vermilion border of the upper lip.

Legan and Burstone Soft Tissue Cephalometric Analysis (Figs 20.7A and B) Cephalometric landmarks used in Legan and Burstone soft tissue cephalometric analysis are as given below: Glabella (G)–The most prominent point in the midsagittal plane of the forehead.

Mentolabial sulcus (Si)–The point of greatest concavity in the midline between the lower lip (Li) and chin (Pg’). Soft tissue pogonion (Pg’)–The most anterior point on soft tissue chin. Soft tissue gnathion (Gn’)–The constructed midpoint between soft tissue pogonion and soft tissue menton; can be located at the intersection of the subnasale to soft tissue pogonion line and the line from C to Me. Soft tissue menton (Me’)–The lowest point on the contour of the soft tissue chin; found by dropping a perpendicular from horizontal plane through menton. Cervical point (C)–The innermost point between the submental area and the neck located at the intersection of lines drawn tangent to the neck and submental areas.

Columella point (Cm)–The most anterior point on the columella of the nose.

Rickett’s Cephalometric Analysis (Figs 20.8A and B)

Subnasale (Sn)–The point at which the nasal septum merges with the upper cutaneous lip in the midsagittal plane.

Cephalometric landmarks used in Rickett’s cephalometric analysis are as given below:

Labrale superius (Ls)–A point indicating the mucocutaneous border of the upper lip.

A–The deepest point on the curve of the maxilla between the anterior nasal spine and the dental alveolus.

Stomion superius (Stms)–The lowermost point on the vermilion of the upper lip.

ANS–Tip of the anterior nasal spine.

Stomion inferius (Stmi)–The uppermost point on the vermilion of the lower lip.

CC–Point where the basion-nasion plane and the facial axis intersect.

Labrale inferius (Li)–A point indicating the mucocutaneous border of the lower lip.

DC–A point selected in the center of the neck of the condyle, where the basion-nasion plane crosses it.

BA–Most inferior posterior point of the occipital bone.

199

B

Figures 20.8A and B: Rickett’s cephalometric analysis


A

NA–A point at the anterior limit of the nasofrontal suture.

Angle I’–Angle formed by i and the palatal plane.

PM–Point selected at the anterior border of the symphysis between point B and pogonion where the curvature changes from concave to convex.

Angle I”–Angle formed by I and che ancerior cranial base plane.

PO–Most anterior point on the midsagittal symphysis tangent to the facial plane. XI–The geometric center of the ramus of the mandible.

Sassouni Cephalometric Analysis (Fig. 20.9) Cephalometric landmarks used in Sassouni cephalometric analysis are as given below: Palatocranial angle–Angle formed by the palatal plane and the anterior cranial base plane. Palatomandibular angle–Angle formed by the palatal plane and the mandibular base plane. Occlusopalatal angle–Angle formed by the occlusal plane and the palatal plane. Occlusomandibular angle–Angle formed by the occlusal plane and the mandibular base plane. Angle M–Angle formed by the 6 axis and the occlusal plane. Angle M’ –Angle formed by the 6 axis and che palatal plane. Angle M”–Angle formed by the 6 axis and the anterior cranial base plane. Angle I–Angle formed by 1 and the occlusal plane.

Figure 20.9: Sassouni cephalometric analysis

200

Angle R–Angle formed by the occlusal plane and the ramal plane. Angle i–Angle formed by the occlusal plane and the axis of 1. Angle rfl’–Angle formed by the occlusal plane and the axis of 6.

Di Paolo’s Quadrilateral Analysis (Fig. 20.10) Cephalometric landmarks used in Di Paolo’s Quadrilateral cephalometric analysis are as given below: A–The deepest point on the curve of the maxilla between the anterior nasal spine and the dental alveolus. ANS–Tip of the anterior nasal spine.


Nasion (N)–The point at which the nasofrontal suture reaches the contour line of the bones. Pogonion (PG)–The most anterior point on the chin. Point B-supramentale–The deepest midline point on the mandible between infradentale and pogonion. Ptm-pterygomaxillary fissure–The point of intersection of the images of the anterior surface of the pterygoid process of the sphenoid bone and the posterior margin of the maxilla.

Ar-articulare–The point of intersection of the dorsal contours of processus articularis mandibulae and os temporale. The midpoint is used where double projection gives rise to two articulare points. snp-spina nasalis posterior–The point of intersection of palatum posterior durum, palatum molle and fossa pterygopalatina.

Hasund (Bergen) Cephalometric Analysis (Fig. 20.11) Cephalometric landmarks used in Hasund cephalometric analysis are as given below:

(Bergen)

A-point A (subspinale)–The point at the deepest midline concavity on the maxilla between the anterior nasal spine and prosthion. Ans-anterior nasal spine–The most anterior point of the anterior nasal spine. Ar-articulate–The point of intersection of the images of the posterior border of the condylar process of the mandible and the inferior border of the basilar part of the occipital bone.

Go-gonion (constructed)–The point of intersection of the ramus plane and the mandibular plane.

B-point B (supramentale)–The point at the deepest midline concavity on the mandibular symphysis between infradentale and pogonion.

Figure 20.10: Di Paolo’s quadrilateral cephalometric analysis

Figure 20.11: Hasund (Bergen) cephalometric analysis

201

Ba-basion–The median point of the anterior margin of the foramen magnum located by following the image of the slope of the inferior border of the basilar part of the occipital bone to its posterior limit. N-nasion–The most anterior (midline) point of the frontonasal suture. S-sella–The point representing the geometric centrer of the pituitary fossa (sella turcica).

Ar-articulare–The point of intersection of the images of the posterior border of the condylar process of the mandible and the inferior border of the basilar part of the occipital bone. B-point B (supramentale)–The point at the deepest midline concavity on the mandibular symphysis between infradentale and pogonion.


N-nasion–The most anterior (midline) point of the frontonasal suture.

ii-incision inferius–The incisal point of the most prominent medial mandibular incisor.

S-sella–The point representing the geometric centrer of the pituitary fossa (sella turcica).



Jarabak Cephalometric Analysis (Figs 20.12A and B)


Cephalometric landmarks used in Jarabak cephalometric analysis are as given below:


A-point A (subspinale)–The point at the deepest midline concavity on the maxilla between the anterior nasal spine and prosthion.



snp-spina nasalis posterior–The point of intersection of palatum posterior durum, palatum molle and fossa pterygo-palatina.

A

B

Figures 20.12A and B: Jarabak cephalometric analysis



Ba-basion–The median point of the anterior margin of the foramen magnum located by following the image of the slope of the inferior border of the basilar part of the occipital bone to its posterior limit.

202

Po-porion (anatomic)–The superior point of the external auditory meatus (superior margin of temporomandibular fossa, which lies at the same level, may be substituted in the construction of Frankfort horizontal).

Riedel Cephalometric Analysis (Figs 20.13A and B) Cephalometric landmarks used in Riedel cephalometric analysis are as given below: A-point A (subspinale)–The point at the deepest midline concavity on the maxilla between the anterior nasal spine and prosthion.

is-incision superius–The incisal point of the most prominent medial maxillary incisor. snp-spina nasalis posterior–The point of intersection of palatum posterior durum, palatum molle and fossa pterygopalatina. Po-porion (anatomic)–The superior point of the external auditory meatus (superior margin of temporomandibular fossa, which lies at the same level, may be substituted in the construction of Frankfort horizontal). Or-orbitale–The lowest point on the inferior margin of the orbit, midpoint between right and left images. Ul-maxillary central incisor (horizontal)–The most labial point on the crown of the maxillary central incisor.

B-point B (supramentale)–The point at the deepest midline concavity on the mandibular symphysis between infradentale and pogonion.

Ul-maxillary central incisor (vertical)–The incisal edge of the maxillary central incisor.



N-nasion–The most anterior (midline) point of the frontonasal suture. S-sella–The point representing the geometric center of the pituitary fossa (sella turcica).

L1-mandibular central incisor (horizontal)–The most labial point on the crown of the mandibular central incisor. L1-mandibular central incisor (vertical)–The incisal edge of the mandibular central incisor.


Gnathion (GN)–The most inferior point on the contour of the chin.



A

B

Figures 20.13A and B: Riedel cephalometric analysis

203

Iip–Incision inferius apicalis is the root apex of the most anterior mandibular central incisor; if this point is needed only for defining the long axis of the tooth, the midpoint on the bisection of the apical root width can be used. APOcc-Anterior point of occlusion for the occlusal plane–A constructed point, the midpoint of the incisor overbite in occlusion PPOcc-Posterior point of occlusion for the occlusal plane– The most distal point of contact between the most posterior molars in occlusion (Rakosi). Maxillary central incisor is the most labial point on the crown of the maxillary central incisor.

N-nasion–The most anterior (midline) point of the frontonasal suture. S-sella–The point representing the geometric center of the pituitary fossa (sella turcica). Pogonion–The most anterior point on the mandible in the midline. ii-incision inferius–The incisal point of the most prominent medial mandibular incisor is-incision superius–The incisal point of the most prominent medial maxillary incisor.

Wylie Cephalometric Analysis (Figs 20.15A and B)

Schwartz Cephalometric Analysis (Figs 20.14A and B)

Cephalometric landmarks used in Wylie cephalometric analysis are as given below:

Cephalometric landmarks used in Schwartz cephalometric analysis are as given below: A-point A (subspinale)–The point at the deepest midline concavity on the maxilla between the anterior nasal spine and prosthion. Ans-anterior nasal spine–The most anterior point of the anterior nasal spine. B-point B (supramentale)–The point at the deepest midline concavity on the mandibular symphysis between infradentale and pogonion.

A


Mandibular central incisor is the most labial point on the crown of the mandibular central incisor.

sp–Dorsum of sella is the most posterior point on the internal contour of the sella turcica or hypophyseal fossa or pituitary fossa.

si–Floor of sella is the lower most point on the inner contour of the sella turcica or hypophyseal fossa or pituitary fossa. Cl–Clinoidale is the most superior point on the contour of the anterior clinoid. S–Sella is the midpoint of sella turcica or hypophyseal fossa or pituitary fossa.

B

Figures 20.14A and B: Schwartz cephalometric analysis


204

A

B

Figures 20.15A and B: Wylie cephalometric analysis

ANS–Anterior nasal spine is the tip of bony anterior nasal spine in the midline or median plane.

Steiner’s Cephalometric Analysis (Figs 20.16A and B)

A–Point A is the deepest point on the curved bony outline between the anterior nasal spine (ANS) and prosthion (Pr).

Cephalometric landmarks used in Steiner’s cephalometric analysis are as given below:

PNS–Posterior nasal spine is the intersection of continuation of the anterior wall of the pterygopalatine fossa and the floor of the nose.


Ptm–Pterygomaxillary fissure is a bilateral tear drop shaped area of radiolucency, the anterior shadow of which represents the posterior surface of the tuberosity of the maxilla; the landmark is taken where the two edges, front and back appears to merge inferiorly.

Orbitale–The lowest point on the left infraorbital margin.

Orbitale–The deepest point on the infraorbital margin.The midpoint, or is used where double projection gives rise to two points, or 1 and/or 2.

The center of sella turcica–Located by inspection of the profile image of the fossa. Porion (cephalometric)–The highest point on the superior surface of the soft tissue of the external auditory meati. Point A-subspinale–The deepest midline point on the premaxilla between the anterior nasal spine and prosthion.

Gnathion (GN)–The most inferior point on the contour of the chin.


Pogonion (PG)–The most anterior point on the chin.


Point B-supramentale–The deepest midline point on the mandible between infradentale and pogonion. Po-porion (anatomic)–The superior point of the external auditory meatus (superior margin of temporomandibular fossa, which lies at the same level, may be substituted in the construction of Frankfort horizontal).

PNS–Posterior nasal spine is the intersection of a continuation of the anterior wall of the pterygopalatine fossa and the floor of the nose. ii-incision inferius–The incisal point of the most prominent medial mandibular incisor.

205

B

Figures 20.16A and B: Steiner’s cephalometric analysis

is - incision superius–The incisal point of the most prominent medial maxillary incisor. Go-gonion (constructed)–The point of intersection of the ramus plane and the mandibular plane. APOcc-Anterior point of occlusion for the occlusal plane–A constructed point, the midpoint of the incisor overbite in occlusion PPOcc-Posterior point of occlusion for the occlusal plane– The most distal point of contact between the most posterior molars in occlusion (Rakosi). isa–Incision superius apicalis is the root apex of the most anterior maxillary central incisor; if this point is needed only for defining the long axis of the tooth, the midpoint on the bisection of the apical root width can be used. iia–Incision inferius apicalis is the root apex of the most anterior mandibular central incisor; if this point is needed only for defining the long axis of the tooth, the midpoint on the bisection of the apical root width can be used. Pogonion (PG)–The most anterior point on the chin. Pn–The most anterior point on the midsagittal profile of the nose. In cases where the tip of the nose was more than a definite point, pronasale was determined by drawing a line parallel to the line nasion to pogonion tangent to the most anterior point on the midsagittal profile of the nose.

Tweed’s Cephalometric Analysis (Figs 20.17A and B)


A

Cephalometric landmarks used in Tweed’s cephalometric analysis are as given below: Orbitale–The lowest point on the left infraorbital margin.

Porion (cephalometric)–The highest point on the superior surface of the soft tissue of the external auditory meati.

ii-incision inferius–The incisal point of the most prominent medial mandibular incisor. is-incision superius–The incisal point of the most prominent medial maxillary incisor.

Go-gonion (constructed)–The point of intersection of the ramus plane and the mandibular plane. isa–Incision superius apicalis is the root apex of the most anterior maxillary central incisor; if this point is needed only for defining the long axis of the tooth, the midpoint on the bisection of the apical root width can be used. iia–Incision inferius apicalis is the root apex of the most anterior mandibular central incisor; if this point is needed only for defining the long axis of the tooth, the midpoint on the bisection of the apical root width can be used.


206

A

B

Figures 20.17A and B: Tweed’s cephalometric analysis

A

B

Figures 20.18A and B: Wit’s appraisal

Wit’s Cephalometric Analysis (Figs 20.18A and B) Wit’s Appraisal The WIT’S (University of Witwatersrand, South Africa) appraisal. WIT’S appraisal–WIT’S appraisal measures the extent to which the jaws are related to each other anteroposteriorly. Cephalometric landmarks used in Wit’s cephalometric analysis are as given below:

Point A-subspinale–The deepest midline point on the premaxilla between the anterior nasal spine and prosthion. Point B-supramentale–The deepest midline point on the mandible between infradentale and pogonion. The method of assessing the extent of jaw disharmony entails drawing perpendicular on a lateral cephalometric head film tracing from point A and B on the maxilla and mandible respectively, into the occlusal plane which is drawn through the region of maximum cuspal interdigitation: The point of contact on the occlusal plane from A and B are labeled AO and BO respectively.

207

Cephalometric landmarks used in Basis cephalometric Analysis are as given below:

Isa–Incision superius apicalis is the root apex of the most anterior maxillary central incisor; if this point is needed only for defining the long axis of the tooth, the midpoint on the bisection of the apical root width can be used.


Iii–Incision inferius incisalis is the incisal edge of the most prominent mandibular central incisor.

s-the center of sella turcica (the midpoint of the horizontal diameter).

Iia–Incision inferius apicalis is the root apex of the most anterior mandibular central incisor; if this point is needed only for defining the long axis of the tooth, the midpoint on the bisection of the apical root width can be used.

Basis Cephalometric Analysis (Fig. 20.19)


Point A-subspinale–The deepest midline point on the premaxilla between the anterior nasal spine and prosthion. Point B-supramentale–The deepest midline point on the mandible between infradentale and pogonion. Gn-gnathion–The deepest point on the chin. id-infradentale–The point of transition from the crown of the most prominent mandibular medial incisor to the alveolar projection.

Cagliari Cephalometric Analysis (Fig. 20.20) Cephalometric landmarks used in basis cephalometric analysis are as given below:


PNS–Posterior nasal spine is the intersection of a continuation of the anterior wall of the pterygopalatine fossa and the floor of the nose.

N-nasion–Nasion is the most anterior point of the frontonasal suture in the middle. s–The center of sella turcica (the midpoint of the horizontal diameter).


Pog-pogonion–The most prominent point on the chin.


sm-supramentale–The deepest point on the contour of the alveolar projection, between infradentale and pogonion.


Isi–Incision superius incisalis is the incisal edge of the maxillary central incisor.


Figure 20.19: Basis cephalometric analysis

Figure 20.20: Cagliari cephalometric analysis

208

Gn-gnathion–The deepest point on the chin. id-infradentale–The point of transition from the crown of the most prominent mandibular medial incisor to the alveolar projection. Pog-pogonion–The most prominent point on the chin. sm-supramentale–The deepest point on the contour of the alveolar projection, between infradentale and pogonion. Isi–Incision superius incisalis is the incisal edge of the maxillary central incisor.


Isa–Incision superius apicalis is the root apex of the most anterior maxillary central incisor; if this point is needed only for defining the long axis of the tooth, the midpoint on the bisection of the apical root width can be used. Iii–Incision inferius incisalis is the incisal edge of the most prominent mandibular central incisor. Iia–Incision inferius apicalis is the root apex of the most anterior mandibular central incisor; if this point is needed only for defining the long axis of the tooth, the midpoint on the bisection of the apical root width can be used. Go-gonion (constructed)–The point of intersection of the ramus plane and the mandibular plane. APOcc-Anterior point of occlusion for the occlusal plane– a constructed point, the midpoint of the incisor overbite in occlusion. PPOcc-Posterior point of occlusion for the occlusal plane– the most distal point of contact between the most posterior molars in occlusion (Rakosi). Pogonion (PG)–The most anterior point on the chin. Po-porion (anatomic)–The superior point of the external auditory meatus (superior margin of temporomandibular fossa, which lies at the same level, may be substituted in the construction of Frankfort horizontal).

ANS–Anterior nasal spine is the tip of bony anterior nasal spine in the midline or median plane. PNS–Posterior nasal spine is the intersection of a continuation of the anterior wall of the pterygopalatine fossa and the floor of the nose. Point A-subspinale–The deepest midline point on the premaxilla between the anterior nasal spine and prosthion. Point B-supramentale–The deepest midline point on the mandible between infradentale and pogonion. Gn-gnathion–The deepest point on the chin. id-infradentale–The point of transition from the crown of the most prominent mandibular medial incisor to the alveolar projection. Pog-pogonion–The most prominent point on the chin. sm-supramentale–The deepest point on the contour of the alveolar projection, between infradentale and pogonion. Isi–Incision superius incisalis is the incisal edge of the maxillary central incisor. Isa–Incision superius apicalis is the root apex of the most anterior maxillary central incisor; if this point is needed only for defining the long axis of the tooth, the midpoint on the bisection of the apical root width can be used. Iii–Incision inferius incisalis is the incisal edge of the most prominent mandibular central incisor. Iia–Incision inferius apicalis is the root apex of the most anterior mandibular central incisor; if this point is needed only for defining the long axis of the tooth, the midpoint on the bisection of the apical root width can be used.

Or-orbitale–The lowest point on the inferior margin of the orbit, midpoint between right and left images. Articulare–Articulare is the point of intersection the dorsal contours of the processus articularis mandibulare and os temporale. The midpoint, a is used where double projection gives rise to two points, a1 and a2.

Chieti Cephalometric Analysis (Fig. 20.21) Cephalometric landmarks used in basis cephalometric analysis are as given below: N-nasion–Nasion is the most anterior point of the frontonasal suture in the middle. s–the center of sella turcica (the midpoint of the horizontal diameter).

Figure 20.21: Chieti cephalometric analysis

209

Go-gonion (constructed)–The point of intersection of the ramus plane and the mandibular plane. APOcc-Anterior point of occlusion for the occlusal plane– a constructed point, the midpoint of the incisor overbite in occlusion. PPOcc-Posterior point of occlusion for the occlusal plane– the most distal point of contact between the most posterior molars in occlusion (Rakosi). Pogonion (PG)–The most anterior point on the chin.

Or-orbitale–The lowest point on the inferior margin of the orbit, midpoint between right and left images. Articulare–Articulare is the point of intersection the dorsal contours of the processus articularis mandibulare and os temporale. The midpoint, a is used where double projection gives rise to two point, a1 and a2.

McGann Cephalometric Analysis (Fig. 20.22) Cephalometric landmarks used in basis cephalometric analysis are as given below: N-nasion–Nasion is the most anterior point of the frontonasal suture in the middle.

Figure 20.22: McGann cephalometric analysis


Po-porion (anatomic)–The superior point of the external auditory meatus (superior margin of temporo mandibular fossa, which lies at the same level, may be substituted in the construction of Frankfort horizontal).

Isa–Incision superius apicalis is the root apex of the most anterior maxillary central incisor; if this point is needed only for defining the long axis of the tooth, the midpoint on the bisection of the apical root width can be used. Iii–Incision inferius incisalis is the incisal edge of the most prominent mandibular central incisor.

s-the center of sella turcica (the midpoint of the horizontal diameter).

Iia—Incision inferius apicalis is the root apex of the most anterior mandibular central incisor; if this point is needed only for defining the long axis of the tooth, the midpoint on the bisection of the apical root width can be used.




APOcc-Anterior point of occlusion for the occlusal plane– a constructed point, the midpoint of the incisor overbite in occlusion


PPOcc-Posterior point of occlusion for the occlusal plane– the most distal point of contact between the most posterior molars in occlusion (Rakosi).

Point B-supramentale–The deepest midline point on the mandible between infradentale and pogonion. Gn-gnathion–The deepest point on the chin. id-infradentale–The point of transition from the crown of the most prominent mandibular medial incisor to the alveolar projection. Pog-pogonion–The most prominent point on the chin. sm-supramentale–The deepest point on the contour of the alveolar projection, between infradentale and pogonion. Isi–Incision superius incisalis is the incisal edge of the maxillary central incisor.

Pogonion (PG)–The most anterior point on the chin. Po-porion (anatomic)–The superior point of the external auditory meatus (superior margin of temporomandi bular fossa, which lies at the same level, may be substituted in the construction of Frankfort horizontal). Or-orbitale–The lowest point on the inferior margin of the orbit, midpoint between right and left images. Articulare–Articulare is the point of intersection the dorsal contours of the processus articularis mandibulare and os temporale.The midpoint, a is used where double projection gives rise to two points, a1 and a2.

Index Page numbers followed by f refer to figure

a Alar crease junction 128, 131 on graphic illustration 132f on lateral cephalogram 132f Angle of convexity 197 Angulare point 184, 184f Antegonial tubercles 175, 176f Antegonion 176f Anterior nasal spine 10, 59, 123, 155f, 174, 194, 196, 200, 202, 204, 208, 209 on graphic illustration 60f on lateral cephalogram 60f pharyngeal wall 123 point of occlusion 10, 76, 77f, 208, 209 for occlusal plane 203, 205 Applications of cephalometric landmarks 191, 193, Articulare 93, 95f, 174, 175f, 193 Articulation of ethmoid bone 21 frontal bone 15, 26 temporal bone 31

b Basion 154f, 179f on graphic illustration 47f on lateral cephalogram 47f Basis cephalometric analysis 207, 207f Bjork cephalometric analysis 193, 193f Bolton’s point 10, 48, 196 on graphic illustration 50f on lateral cephalogram 49f

c Cagliari cephalometric analysis 207, 207f Center of sella turcica 196, 204, 208, 209 Cephalometric analysis 3 X-ray tracing techniques 4 Cephalostat 4 Cervical bones 10, 99 point 198 vertebra 103, 104f, 118 vertebral maturation 119f Cheilion 151 Chieti cephalometric analysis 208, 208f Clinoidale 38 on graphic illustration 38f on lateral cephalogram 38f Coben craniofacial and dentition analysis 194f cephalometric analysis 194 Columella point 198

Condylion 95, 97f, 149, 150f anterioris 189, 189f lateralis 188, 189f medialis 188, 188f posterioris 190, 190f Coronal suture 160 Cranial bones 10, 13 Crista galli 160, 161f Cuspid 169 bow 11, 135, 135f

d Deciduous dentition stage 70 Dentition 71 Di Paolo’s quadrilateral cephalometric analysis 200, 200f Dorsum of sella 10, 36 on graphic illustration 36f on lateral cephalogram 36f Downs cephalometric analysis 195, 195f

e Eruption chronology of primary teeth 70 Ethmoid bone 10, 15, 21, 21f, 22f, 26 Ethmoidale 24, 25f on lateral cephalogram 25f on graphic illustration 25f Exocanthion 151, 152

f Facial bone and dentition 10, 57 Farkas and coworkers soft tissue cephalometric analysis 196, 196f First molar point 187, 187f Fissure 123 Floor of nose 160 sella 10, 37 on graphic illustration 37f on lateral cephalogram 37f Foramina spinosa points 180, 180f spinosum 180, 181f Frontal bone 10, 26, 15, 15f on lateral cephalogram 15f cephalogram 3, 3f Frontomaxillary nasal suture 10 on graphic illustration 28f on lateral cephalogram 28f suture on graphic illustration 19f lateral cephalogram 19f Frontozygomatic suture 10

g Glabella 198 Gnathion 89, 90f, 193, 196, 197, 201, 202, 204 Gonion 93, 94f, 150, 150f, 202 point 187, 187f

h Harvold cephalometric analysis 196, 197f Hassel and Farman developed method of skeletal maturation 119f Hasund cephalometric analysis 200, 200f Holdaway cephalometric analysis 197, 197f Hyoid 101, 102f bone 101, 101f

i Incision inferius 194, 201, 202, 203, 204, 205 apicalis 10, 75, 76f, 170, 170f frontale 171, 171f incisalis 10, 74, 74f, 169, 170f superius 194, 201, 202, 203, 205 apicalis 10, 73, 73f, 166, 167f incisalis 10, 71, 72f, 165, 166f Infradentale 86, 194

j Jarabak cephalometric analysis 201, 201f Jugal process 164, 164f

l Labrale inferius 11, 136, 146, 147f, 198 on graphic illustration 137f on lateral cephalogram 137f superius 11, 134, 146, 146f, 198 on graphic illustration 134f on lateral cephalogram 134f Lacrimal bone 15 Laryngopharynx 123 Lateral cephalogram 3, 3f Legan and Burstone soft tissue cephalometric analysis 198, 198f Lower face height 197 lip 11 pharynx 124

m Magnified image of anterior nasal spine on graphic 60f Malare 175f

212


Mandibular apical base midline 186, 186f central incisor 10, 80, 81f, 195, 202, 203 dental midline 185, 186f first molar 10, 81, 82f, 171, 171f, 195 length 197 molar 173, 173f Mastiodale on lateral cephalogram 34f Mastoid processes 160 Maxilla 26, 59 Maxillary apical base midline 185, 185f bone 15, 59f central incisor 10, 79, 79f, 195, 202, 203 first molar 10, 79, 80f, 168, 168f, 195 molar 167, 168f McGann cephalometric analysis 209, 209f Medio-orbitale on lateral cephalogram 23f Mentolabial sulcus 198 Menton 92, 92f, 173, 174f Middle cranial fossa points 182, 183f Mixed dentition stage 70

n

Nasal bone 10, 15, 26, 26f, 26f crown 128, 129 on graphic illustration 129f on lateral cephalogram 129f, 129f process 15 Nasion 16, 26, 194-196, 197, 200 on graphic illustration 16f, 27f on lateral cephalogram 16f, 27f Nasopharynx 123 Neck of crista galli 10, 23 on frontal cephalogram 23f Nerve supply to mandible 85

o

Occipital bone 10, 46, 46f condyles 160 Occlusomandibular angle 199 Occlusopalatal angle 199 Odontoid 181, 181f Opisthion 48, 179, 180f on graphic illustration 49f on lateral cephalogram 48f Orbital plates 15 Orbitale 52, 67, 148, 148f, 194-196 on graphic illustration 53f, 68f on lateral cephalogram 53f, 68f Oropharynx 123

p Palatocranial angle 199 Palatomandibular angle 199 Parital bone 15 Parts of ethmoid bone 21 frontal bone 15 hyoid bone 101 mandible 85 Permanent dentition stage 71 Pharynx 123

Philtrum 135f Planed incisor position 136 Planum sphenoidale 160 Pogonion 88, 196, 197, 200, 201, 204 Point A on graphic illustration 61f lateral cephalogram 61f on oral side of soft palate 123, 124 on pharyngeal side of soft palate 123, 124 T on graphic illustration 131 lateral cephalogram 131f Porion 32, 194-196 on lateral cephalogram 33f Posterior cranial vault points 183, 184f nasal spine 10, 64, 123, 208, 209 on graphic illustration 64f on lateral cephalogram 64f pharyngeal wall 123, 124 point of occlusion 10, 77, 78f, 208, 209 Vomer point 182, 183f Prognathion 197 Pronasale 129, 144, 144f on graphic illustration 130f on lateral cephalogram 130f Prosthion 62, 194 on graphic illustration 63f on lateral cephalogram 63f Pterygoid point 10, 40 on graphic illustration 40f on lateral cephalogram 40f Pterygomaxillary fissure 10, 44, 65, 123, 182, 182f, 195, 200 on graphic illustration 45, 66f on lateral cephalogram 45f, 66f

r Rhinion 29 on graphic illustration 29f on lateral cephalogram 29f Rickett’s cephalometric analysis 198, 199f Riedel cephalometric analysis 202 Roof of orbit on graphic illustration 19f lateral cephalogram 19f orbital cavity 17

s Sassouni cephalometric analysis 199, 199f Schwartz cephalometric analysis 203, 203f Sella 10, 41, 152, 195 entrance 41, 153, 153f on graphic illustration 43f on lateral cephalogram 43f on graphic illustration 42f on lateral cephalogram 42f Shapes of cervical vertebral bodies 119f Soft tissue cephalometric landmarks 11, 125, 127, 128, 133, 138 glabella 127 on graphic illustration 127f on lateral cephalogram 129f

gnathion 11, 139, 148, 148f, 198 on graphic illustration 139 on lateral cephalogram 139f menton 11, 198 nasal crown on graphic illustration 129f nasion 128, 143, 143f on graphic illustration 128f on lateral cephalogram 128f pogonion 11, 138, 147, 198 on graphic illustration 138f on lateral cephalogram 138f point B 147f on graphic illustration 137f on lateral cephalogram 137f submentale 136, 147 subspinale 11, 133, 145, 145f Sphenoethmoidal point 10, 24, 42 on graphic illustration 44f on lateral cephalogram 43f Sphenoethmoidale 24f on graphic illustration 24f on lateral cephalogram 24f Sphenoid bone 10, 15, 35, 35f Spheno-occipital synchondrosis 10, 39, 50 on graphic illustration 39f, 51f on lateral cephalogram 39f, 50f Spina nasalis posterior 194, 200-202 Spinal point 194 Squamous part 15 Steiner’s cephalometric analysis 204, 205f Stomion inferius 11, 198 on graphic illustration 136f on lateral cephalogram 136f superius 11, 198 Subnasale 131, 144, 198 on graphic illustration 132f on lateral cephalogram 132f Subspinale 194 on graphic illustration 133f on lateral cephalogram 133f Superior pharyngeal wall 123, 124 surface of floor of pituitary fossa 160 Supra-orbitale 17 on graphic illustration 18f on lateral cephalogram 18f

t Temporal bone 10, 15, 31, 31f Temporale on graphic illustration 22f, 54f lateral cephalogram 22, 54f Temporomandibular joint 196 Tip of uvula 123, 124 Top of nasal septum 161, 161f Tracing basion on lateral cephalogram 47 Bolton’s point on lateral cephalogram 50 neck of crista galli on lateral cephalogram 23 of anterior nasal spine on lateral cephalogram 60, 155 point of occlusion on lateral cephalogram 76 of articulare on lateral cephalogram 94, 174

213

of gnathion on lateral cephalogram 90 of hyoid on lateral cephalogram 102 of incision inferius apicalis on lateral cephalogram 75, 171 incisalis on lateral cephalogram 75 of incision superius apicalis on lateral cephalogram 74, 167 incisalis on lateral cephalogram 72, 166 of infradentale on lateral cephalogram 87 of mandibular central incisor on lateral cephalogram 81 first molar on lateral cephalogram 81, 172 of mastiodale on lateral cephalogram 34 of maxillary central incisor on lateral cephalogram 79 first molar on lateral cephalogram 80, 168 of menton on lateral cephalogram 92, 93, 95, 174 of MI on lateral cephalogram 82, 172 of MS on lateral cephalogram 83 of nasion on lateral cephalogram 17 of orbitale on lateral cephalogram 54

of pogonion on lateral cephalogram 88 of point B on lateral cephalogram 88 of posterior nasal spine on lateral cephalogram 65 point of occlusion on lateral cephalogram 78 of sella on lateral cephalogram 41, 152 opisthion on lateral cephalogram 48 pterygoid point on lateral cephalogram 41 rhinion on lateral cephalogram 30 roof of orbit on lateral cephalogram 18 spheno-occipital synchondrosis on lateral cephalogram 40, 51 supra-orbitale on lateral cephalogram 17 Trichion 196 Tweed’s cephalometric analysis 205, 206f Types of cephalogram 3

u Upper and lower lips 11 lip 11

pharynx 124 point of tongue 123, 124 Uses of cephalometric analysis 3

v Vermillion 135, 135f border of upper lips 11 Vertex 143, 143f

w Wit’s cephalometric analysis 206 Wylie cephalometric analysis 203, 204f

z Zygion 149, 149f, 163, 163f Zygoma 162, 162f Zygomatic arch 10, 32, 163, 163f bone 10, 15, 52, 52f process 15 prominence 149, 149f suture point 164, 164f

Index

An Atlas on Cephalometric Landmarks

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