Determination of the occlusal plane using a custom-made occlusal plane analyzer: A clinical report Sumit V. V. Bedia, Bed ia, BDS,a Shankar P. Dange, Dange , MDS, MD S,b and Arun N. Khalikar, MDSc Government Dental College and Hospital, Aurangabad, Maharashtra, Maharashtra, India In fixed prosthodontic procedures, when it has been determined that restoration of all or most of the posterior teeth is necessary, the use of the Broderick Broder ick occlusal plane analyzer analyzer provides an easy and practical method to determine an occlusal plane that will fulfill esthetic and functional func tional occlusion requirements. However, several manufacturers of se miadjustable articulators offer no such occlusal plane analyzers analyzers for use with these instruments. This article demonstrates the use of a custom-made Broderick occlusal plane analyzer with a semiadjustable articulator to determine the cor rect curve of Spee for the occlusal plane. (J Prosthet Dent 2007;98:348-352)
Usually, the term, plane, is related to a flat surface. However, this is not the case with the occlusal plane. Instead of a flat surface, the plane of occlusion represents the average curvature of the occlusal surface. The position of the anterior teeth is determined by esthetics, the demand for anterior guidance, and phonetic considerations. Posterior teeth positions are defined by 2 curves, an anteroposterior curve, referred to as the curve of Spee, and the mediolateral curve, referred to as the curve of Wilson. 1,2 Based on anthropological observations in 1919, Monson proposed that the anteroposterior curve forms part of a 3-dimensional sphere, the center of rotation of which is located in the region of the glabella.3 The radius of this curve is reported to be an estimated 4 inches (10.4 cm), as proposed by Monson. The 3 most com-
monly used methods for establishing tients may have mandibular anterior an acceptable plane of occlusion teeth that are not positioned ideally. are direct analysis on natural teeth With some experience and training, through selective grinding, indirect dentists can use the BOPA as an inteanalysis of facebow-mounted casts gral part of their practice. The BOPA with properly set condylar paths, and has now been adapted to only a few indirect analysis using the Pankey- articulator systems, such as the Denar Mann-Schuyler (PMS) method with Anamark Fossae (Teledyne Waterpik, the Broderick occlusal plane analyzer Ft Collins, Colo) and all models of (BOPA).1 When it has been deter- Hanau articulators (Teledyne Watermined that restoration of all or most pik).4,5 For those manufacturers of of the posterior teeth is necessary, the semiadjustable articulators who do PMS technique using BOPA provides not offer such occlusal plane analyza simple and practical method to as- ers for use with their instruments, a sist in determining the preliminary custom made clear acrylic resin BOPA occlusal plane on diagnostic casts. may be fabricated. This clinical report It assists in locating the cusp tips of describes the effective application of the posterior teeth. In addition, it can a custom-made BOPA in conjuncdemonstrate how much tooth reduc- tion with a semiadjustable articulator tion or porcelain addition is needed without the need for any alteration to to idealize the occlusal plane. the upper member of the articulator. The use of Monson’s Monson’s theory is only a starting point for the analysis. Pa-
Awarded Best Scientific Paper Presentation prize at the 8th National Convention of Prosthodontic Postgraduate Postgraduate Students of the Indian Prosthodontic Prosthodontic Society, Mahatma Gandhi Postgraduate Institute of Dental Sciences, Government of Pondicherry Pondicherr y Institution, Pondicherr Pondicherry, y, India, June 2006. Awarded Best Scientific Paper Presentation pr ize at the 34th Indian Prosthodontic Prosthodontic Society Conference, Kanniyakumari, Kanniyakumari, India, November 2006. a
Postgraduate student, Department of Prosthodontics. Prosthodontics. Professor and Head, Department of Prosthodontics. c Associate Professor, Professor, Department D epartment of Prosthodontics. b
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CLINICAL REPORT A 55-year-old man was referred to the Department of Prosthodontics, Goverment Dental College and Hospital, Aurangabad, Maharashtra, India, with a chief complaint of the inability to masticate food efficiently on the right side for the past 4 to 5 months. On clinical examination, long-span fixed partial dentures were present between the maxillary right first premolar to the maxillary right second molar and between the mandibular right first premolar to the mandibular right third molar (Fig. 1). The fixed partial dentures had marginal discrepancies and were fabricated with flat occlusal surfaces at a reduced occlusal vertical dimension. The occlusal plane on the right side was at a lower level compared to the left side. The fixed partial dentures were removed, and irreversible hydrocolloid (Neocolloid; Zhermack, Badia Polesine, Italy) impressions of maxillary and mandibular teeth were made and poured in type III stone (Kalstone; Kalabhai Karson Pvt Ltd, Mumbai, India). Diagnostic casts were mounted on a semiadjustable articulator (Model 8800; Whip Mix Corp, Louisville, Ky) (Fig. 2). Visual examination confirmed a marked discrepancy in the level of the occlusal plane on the left side. The mandibular left first and second molars were extruded, resulting in inadequate occluso-gingival space for the pontics which would replace the maxillary left first and second molar. On the right side, all posterior teeth were previously prepared and did not provide information regarding the level of the original occlusal plane. The use of a Broderick flag was indicated to assess, and, if necessary, redesign, the level and orientation of the occlusal plane. Since no such flag was supplied by the manufacturer, a custom-made flag was fabricated using a 2-mm-thick clear acrylic resin sheet (Gujrat State Fertilizer Co, Ahmedabad, Gujrat, India) (4 inch x 4 inch), which fit into a slot of the same dimensions in a clear acrylic
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resin base, attached to the upper member of the articulator. A sheet of blank paper was attached to both sides of the flag to receive the markings. The maxillary cast was removed from the articulator, and the flag was attached on top of the upper member
of the articulator (Fig. 3). The anterior survey point (ASP) was chosen on the midpoint of the disto-incisal edge of the mandibular left canine from which a long arc with a 4-inch radius was drawn on the flag with a compass (Fig. 4, A). The posterior survey
1 Preexisting dentition.
2 Mounted diagnostic casts. Marked discrepancy was evident in level of occlusal plane: mandibular left first and second molars were extruded, resulting in inadequate occluso-gingival space.
3 Custom-made BOPA attached to semiadjustable articulator.
350 point (PSP) was located on the distobuccal cusp of the mandibular left second molar and a short arc was drawn on the flag to intersect the long arc at the center of the anteroposterior curve (Fig. 4, B).6 The point of the compass was placed at the center of anteroposterior curve on the flag, and a 4-inch radius was drawn through the buccal surfaces of the mandibular teeth (Fig. 5). The mandibular left first and second molars were found to be markedly extruded. Thorough evaluation of the occlusal plane revealed that the left plane was approximately 1.5 mm higher than the right plane. The solution was to lower the left plane by approximately 1.5 mm, thus creating a more pleasing appearance. Another line, termed the “preparation line”, was scribed by opening the compass by an amount equal to the desired occlusal thickness of the proposed restoration. A softened modelling wax sheet (Modelling wax; Deepti Dental Products of India Pvt Ltd, Ratnagiri, Maharashtra, India) was adapted to the buccal surfaces of the mandibular cast. The wax was cut carefully back to this line and trimmed along the mucobuccal fold so that the wax could be fitted accurately against the teeth intraorally, and this was termed the “occlusal plane cutting guide”. Trial preparations were performed on articulated duplicate stone casts using these markings as a guide, and a diagnostic waxing was completed with even occlusal contacts in maximum intercuspation and avoidance of posterior interferences in protrusive or lateral excursions. The decision was made to restore the entire mandibular arch and maxillary arch with fixed restorations, except for the maxillary left posterior molars, for which a removable partial denture was planned. The occlusal scheme was planned as a group function occlusion. All prerestorative treatment was completed. When preparing the mandibular posterior teeth, the cutting guide was placed snugly against the buccal surfaces of the dried teeth, and the entire
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A
B
4 A, Anterior survey point (ASP) chosen as midpoint of disto-incisal edge of mandibular left canine from which long arc of 4-inch radius is drawn on flag with compass. B, Posterior survey point (PSP) located on disto-buccal cusp of mandibular left second molar and short arc drawn on flag to intersect long arc at center of anteroposterior curve.
5 Point of compass was placed at center of anteroposterior curve on flag and 4-inch radius was drawn through buccal sur faces of mandibular teeth. Mandibular left first and second molars were found to be markedly extruded.
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November 2007 occlusal surface of each tooth was reduced to the preparation line (Fig. 6). Preparations were located sufficiently more apically on the lingual surfaces than on the buccal to accommodate for the mediolateral curve. Following occlusal reduction, the teeth were prepared according to the predetermined treatment plan. Templates of the diagnostic waxing were fabricated using vinyl polysiloxane putty (Flexitime, Easy Putty; Heraeus Kulzer, Hanau, Germany). These templates were used to fabricate provisional restorations in tooth-colored autopolymerizing resin (DPI-Self Cure Tooth Moulding Powder; Dental Products of India, Mumbai, India). This allowed duplication of the occlusal anatomy from the waxing to the provisional restorations. The polished provisional restorations were then cemented intraorally with eugenol-free provisional luting cement (Templute; Prime Dental Products Pvt Ltd, Mumbai, India). Cementation was completed for the entire mandibular arch first and then the maxillary arch. At this time, most minor occlusal adjustments were performed to equilibrate the occlusion. There was a significant esthetic improvement in the preexisting occlusal plane. After a 4-week trial period, the patient reported that the provisional restorations were comfortable. No abnormal wear facets were evident, occlusal contacts were present in maximum intercuspation (MI), no interferences in protrusive and lateral excursions were detected, and gingival health remained optimal. The patient reported comfort and satisfaction with masticatory performance and esthetics of the provisional restorations. It was then decided to fabricate the definitive restorations in porcelain (Ceramco 3; Dentsply India Pvt Ltd, Mumbai, India) and metal (MEAlloy; Dentsply India Pvt Ltd). The same procedure that was used for determining the occlusal plane was used effectively to establish the correct occlusal plane on the wax patterns. By using a special wax cutting blade (Rotex, Mumbai,
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India) in the compass, the overwaxed patterns were cut back to the correct height (Fig. 7). The angle of the blade automatically produced an acceptable mediolateral curve, positioning the lingual cusps more apically than
the buccal cusps. Thus, through use of the custom-made BOPA and a semiadjustable articulator, it was possible to create an esthetic and functionally correct occlusal plane (Fig. 8). The selection of a 4-inch radius
6 Wax occlusal plane cutting guide used to prepare teeth.
7 By using wax-cutting blade in compass, overwaxed patterns were cut back to correct height.
8 Definitive restorations.
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Volume 98 Issue 5 may seem arbitrary. Depending on the skeletal and dental morphology of the individual, the radius may vary slightly. A 3.75-inch radius may be indicated for a class II skeletal relationship, while a 5-inch radius may be indicated for a class III skeletal relationship.7 The center of the curve may also be moved in an anterior or posterior direction from the intersection of the arcs, but should always lie along the arc drawn from the anterior survey point. This alteration will not affect the position of the anterior survey point, an important consideration when the position of the mandibular anterior teeth is esthetically and clinically suitable.
SUMMARY The use of BOPA aids the clinician in the development of an initial mandibular occlusal plane in diagnostic casts, and later, as an integral part of both the contours of the definitive restorations as well as a guide for the actual tooth preparations. This simple custom-made occlusal plane analyzer enables the clinician to use an occlusal plane analyzer with a widely used semiadjustable articulator when no such accessory is available.
REFERENCES 1. Dawson PE. Evaluation, diagnosis and treatment of occlusal problems. 2nd ed. St Louis: Elsevier; 1989. p. 85, 373-81. 2. The glossary of prosthodontic terms. 8th ed. J Prosthet Dent 2005;94:10-92.
3. Monson GS. Occlusion as applied to crown and bridgework. J Nat Dent Assoc 1920;7:399-413. 4. Toothaker RW, Graves AR. Custom adaptation of an occlusal plane analyzer to a semi-adjustable articulator. J Prosthet Dent 1999;81:240-2. 5. Small BW. Occlusal plane analysis using the Broadrick flag. Gen Dent 2005;53:250-2. 6. Bowley JF, Stockstill JW, Attanasio R. A preliminary diagnostic and treatment protocol. Dent Clin North Am 1992;36:551-68. 7. Lynch CD, McConnell RJ. Prosthodontic management of the curve of Spee: Use of the Broadrick flag. J Prosthet Dent 2002;87:593-7. Corresponding author: Dr Sumit V. Bedia C-6/05, Breezy Apartments Jeevan Bima Nagar Borivali (West) Mumbai, Maharashtra INDIA 400103 Fax: +91-22-28935157 E-mail:
[email protected] Copyright © 2007 by the Editorial Council for The Journal of Prosthetic Dentistry.
Noteworthy Abstracts of the Current Literature
The effect of personality type on denture satisfaction Ozdemir AK, Ozdemir HD, Polat NT, Turgut M, Sezer H. Int J Prosthodont 2006;19:364–70. Purpose: The aim of this study was to determine the correlation between personality type and denture satisfaction of totally and partially edentulous patients. Materials and Methods: Two hundred thirty-nine patients (107 women and 132 men) aged 31 to 78 years (mean, 51.87) using removable dentures (165 maxillary and mandibular partial, 51 maxillary and mandibular complete, and 23 maxillary complete and mandibular partial) were asked to fill out a questionnaire on their satisfaction with their dentures with regard to esthetics, speaking ability, and masticatory function. Personality types were evaluated using both the responses to this questionnaire and the Type A Behavior Pattern Test. Chi-square test and logistic regression analysis were used to compare the denture satisfaction scores of the groups (Type A, Type B, and Type AB). The level of statistical significance was set at P=.05. Results: Denture satisfaction of the patients with regard to esthetics, speaking ability, and masticatory func tion was affected by personality type. Statistically significant differences were found between Type A and types B and AB, as well as between types B and AB. Conclusion: The personality type of the patients had an effect on their satisfaction with dentures. The lowest denture satisfaction values were observed in the Type A patients. Reprinted with permission of Quintessence Publishing.
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