The Invisalign Appliance Today a Thinking Person s Orthodontic Appliance 2017 Seminars in Orthodontics

The Invisaligns appliance today: A thin thinki king ng pers person on s orth orthod odon onti ticc appl applia ianc ncee ’

Eugene Chan, and M. Ali Darendeliler Darendeliler Since Since its inducti induction on in 199 1997, 7, the Invisa Invisalig lign n s appliance appliance has vastly vastly evolved evolved through the years. Having used this appliance since inception to its current form, we have learnt much through trial and error and accumulated much experience. The product had advanced substantially since the days of only treating simple Class I malocclusions. It is now possible to treat multiple extraction cases, skeletal asymmetries, as well as, surgical and non-surgical camou�age cases. This article summarises the experiences of two specialist orthodontists who had spent time to perfect the system through understandi standing ng the biolog biology y of tooth tooth moveme movement, nt, and also also utilis utilising ing smart smart biobiomechan mechanics ics to bypass bypass the inadeq inadequac uacies ies and furthe furtherr enhanc enhance e the patien patientt and and clinic clinician ian's 's experi experience ence in using using the applia appliance nce.. (Semin (Semin Orthod Orthod 201 2017; 7; 23:12 – 64.) & 2017 Published by Elsevier Inc.

Introduction

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rthodo rthodonti ntics cs has a strong strong histor historyy of indiindi vidual opinions; from the individual orthodontist to the orthodontic guru. However, the global trend is to gradually move towards a focus focus on evide eviden nce-based ce-based rather rather than opinionbased decisions.1 If treatment is needed, how do we decide what sort of treatment to use? Treatment procedures should be chosen on the basis of clear evidence and the most successful approach. Usually the better the evidence, the easier the decision. Yet, there are some innate problems with evidencebased orthodontics. Unlike the �eld of medicine, we are not dealing with a disease or diseased tiss tissue ues. s. In orde orderr to trea treatt a pres presen ente ted d malo maloccclusion, we primarily establish an individualised treatment goal and proceed to formulate a set of treatment plan(s). In the pursuit of these goals, our mechanical procedures can be very different for any given patient; hence, unlike medicine,

Department of Orthodontics, Faculty of Dentistry, University of Sydney, Sydney, Sydney, Sydney, Australia; Australia; Orthoworx, Orthoworx, Sydney, Sydney, Australia. Australia. Address correspondence to M. Ali Darendeliler, BDS, PhD, Dip Ortho, Certif. Orth, Priv. Doc, Department of Orthodontics, Faculty of Dentistry, University of Sydney, Sydney Dental Hospital, Sydney Lo cal Health District, Level 2, 2 Chalmers Street, Surry Hills, New South Wales 2010, Australia. Australia. E-mail: E-mail: [email protected] & 2017 Published by Elsevier Inc. 1073-8746/12/1801-$30.00/0 http://dx.doi.org/10.1053/j.sodo.2016.10.003

the endpoint, akin to the elimination of disease, may not be as precise. About 20 years ago, less than 3% of the world s popula populatio tion n had a mobile mobile phone. phone. Today, Today, twotwothirds thirds of the world s popula populatio tion n has a mobile mobile phon phonee of some some sort sort.. The The digi digita tall tech techno nolo logy gy around us have pushed us to learn and adapt to new new gadg gadget etss and and meth method odss in the the worl world d of orthodontic orthodontics. s. From digital digital records, records, treatment treatment planning, planning, applianc appliancee design design and manufactur manufacture, e, digital monitoring of treatment, computer aided orthodontic treatment has �nally arrived. However, there are road blocks and clinicians need to be full fullyy awar awaree of such such cons conseq eque uenc nces es befo before re embracing this technology fully, and blindly. '

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Diagnostics Training Training clinicians clinicians to use the Invisalig Invisalign n appliappliance has long been largely based on anecdotal evidence. There is an urgent need for systemic reviews and meta analyses to be conducted. We were able to collect data on 400 consecutively treated Invisalign cases by 1 clinician, and subsequen sequently tly analys analysee them. them.2 Thes Thesee case casess were were classi�ed under respective age groups, gender, type type of dental dental malocc malocclus lusion ions, s, and treatm treatment ent therapies therapies (extraction (extraction or non-extract non-extraction). ion). The trea treatm tmen entt dura durati tion on and and tota otal num number ber of appointments required were also noted. The following report draws evidence from the above �ndings.

Seminars in Orthodontics, Vol 23, No 1, 2017: pp 12 – 64 64

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The Invisalign s appliance today

Identifying road blocks The The comm common on feed feedba back ck from from new new clin clinic icia ians ns have foll follow owed ed all all the the include include the following following:: “ I have instructions given by the technicians, I have placed all the necessary attachments, and done all the necessary prescribed interproximal reduction (IPR). My patient wore all the aligners and used the Chewies as prescribed. They all wore them ‘ more than ’ ’ 20 hours per day but the result still differs from the ClinCheck plans. The product ” just ‘ does not ’ ’ work! work! ” Years of experience using the Invisalign appl applia ianc ncee have have allo allowe wed d us to conc conclu lude de that that treatm treatment ent progre progress ss is indeed indeed not as easy easy and predictable as the computer animation dictates. Ther Theree has has to be some some unde unders rsta tand ndin ing g of the the biol biolog ogyy and and mech mechan anic ical al invo involv lvem emen entt of the the aligners in order to produce repeatable, good clinical outcomes. The Invisalign product itself has evolved through through time and has become more user friendly. friendly. Have we, the clinicians, clinicians, evolved to understand its advanced applications too? The Invi Invisa sali lign gn appl applia ianc ncee has has inde indeed ed beco become me a thinking persons’ orthodontic appliance. One One of the the dif dif �culties that that new Invisalign Invisalign users face while using this appliance is the ability to identify challenging cases. The common factors affecting the predictability of treatment are (i) unders understan tandin ding g the anatom anatomyy of dentit dentition ion,, (ii) (ii) knowing the growth potential of the patient (or the lack of), (iii) the ability to place attachments (bas (based ed on aesth esthet etiic and biom biomec echa hani nica call requ requir irem emen ents ts), ), and and (iv) (iv) iden identi tify fying ing dif dif �cult dent dental al move moveme ment ntss and and how how to plan plan for for such such contingencies.

Case 1 Case Case 1 is an adult adult female female of Asian Asian extrac extractio tion n (Fig. 1A ). ). She � rst presented with chief concerns of an uneven bite, crooked front teeth, and some dental spacing. She was diagnosed as a Class-II dental malocclusion on a skeletal Class-I pattern, with a normal to horizontal direction of growth. Radiographic examination was nondescript. The road road blocks blocks with with treati treating ng this this patien patient t using the Invisalign appliance were as follows: (i) she had some degree of microdontia with short clinical crown heights, (ii) she was a non-growing Class-II dental malocclusion with upper crowding, and lower spacing, (iii) the antero-posterior (AP) correction would require good compliance with Class-II traction, and (iv) she also has a

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horizontal growth pattern with a tendency of her bite deepening as treatment progresses. A key to successful treatment with the Invisalign appliance is to ensure good surface area contacts between the aligner material and the dentit dentition ion.. Theref Therefore ore,, the succes successfu sfull planni planning ng and treatmen treatmentt of this this case case with with short short clinic clinical al crown heights involved (i) choosing the correct atta attach chme ment nts, s, (ii) (ii) have have them them appr appropr opria iate tely ly placed, (iii) decrease the velocity of the movement ment of the the dent dentit itio ion n whil whilst st desi design gnin ing g the the ClinCh ClinCheck eck plans, plans, (iv) (iv) the patie patient nt also also has to unders understan tand d the importa importance nce of using using Class-I Class-III elasti elastics, cs, (v) be prepar prepared ed for re�nement/additional tional aligne aligners, rs, and (vi) (vi) ensure ensure good good patien patient t compliance. The �rst ClinCheck plans presented a treatment ment plan plan with with 15 alig aligne ners rs and and atta attachm chmen ent t design as shown in Fig. in Fig. 1B. 1B. The ClinCheck plans were modi �ed to reduce the treatment velocity and a different attachment design (Fig. (Fig. 1C). 1C). The case treated out well in 21 months using a total of 46 (29 þ 17) aligners with 1 re �nement (Fig. 1D). 1D).

Case 2 Case Case 2 is an adul adultt fema female le Cauc Caucas asia ian n who who is extremely concerned with the aesthetics of the trea treatm tmen entt appl applia ianc ncee (Fig ig.. 2A ). Her chief conc concer erns ns were were the the rot rotated ated upp upper late latera rall incisors and also a lateral open bite on the left side. She is a Class-I dental malocclusion over a skeletal Class-I base with a normal direction of growth. There were no soft tissue parafunctions and radiographic examination was nondescript. Previo Previous us experi experienc ences es with with moving moving latera laterall incisors has noted it to be a great challenge. The nece necess ssit ityy of plac placin ing g an opti optimi mise sed d extr extrus usio ion n attachment in this case is almost imminent. The clear clear applia appliance nce that that is Invisa Invisalig lign n is a natura naturall choice for the patient, provided it was capable of executing the biomechanical forces necessary to extrude the lateral incisor and close down the lateral open bite successfully. Although matching tooth-colou tooth-coloured red composite composite attachment attachmentss may be selected, and if well placed and polished, almost invisible upon close scrutiny. However, when the actual aligner with the pushed out outline of the attachment is placed on the dentition, the visibility of the attachment highly increases. Out of


Identifying road blocks The The comm common on feed feedba back ck from from new new clin clinic icia ians ns have foll follow owed ed all all the the include include the following following:: “ I have instructions given by the technicians, I have placed all the necessary attachments, and done all the necessary prescribed interproximal reduction (IPR). My patient wore all the aligners and used the Chewies as prescribed. They all wore them ‘ more than ’ ’ 20 hours per day but the result still differs from the ClinCheck plans. The product ” just ‘ does not ’ ’ work! work! ” Years of experience using the Invisalign appl applia ianc ncee have have allo allowe wed d us to conc conclu lude de that that treatm treatment ent progre progress ss is indeed indeed not as easy easy and predictable as the computer animation dictates. Ther Theree has has to be some some unde unders rsta tand ndin ing g of the the biol biolog ogyy and and mech mechan anic ical al invo involv lvem emen entt of the the aligners in order to produce repeatable, good clinical outcomes. The Invisalign product itself has evolved through through time and has become more user friendly. friendly. Have we, the clinicians, clinicians, evolved to understand its advanced applications too? The Invi Invisa sali lign gn appl applia ianc ncee has has inde indeed ed beco become me a thinking persons’ orthodontic appliance. One One of the the dif dif �culties that that new Invisalign Invisalign users face while using this appliance is the ability to identify challenging cases. The common factors affecting the predictability of treatment are (i) unders understan tandin ding g the anatom anatomyy of dentit dentition ion,, (ii) (ii) knowing the growth potential of the patient (or the lack of), (iii) the ability to place attachments (bas (based ed on aesth esthet etiic and biom biomec echa hani nica call requ requir irem emen ents ts), ), and and (iv) (iv) iden identi tify fying ing dif dif �cult dent dental al move moveme ment ntss and and how how to plan plan for for such such contingencies.

Case 1 Case Case 1 is an adult adult female female of Asian Asian extrac extractio tion n (Fig. 1A ). ). She � rst presented with chief concerns of an uneven bite, crooked front teeth, and some dental spacing. She was diagnosed as a Class-II dental malocclusion on a skeletal Class-I pattern, with a normal to horizontal direction of growth. Radiographic examination was nondescript. The road road blocks blocks with with treati treating ng this this patien patient t using the Invisalign appliance were as follows: (i) she had some degree of microdontia with short clinical crown heights, (ii) she was a non-growing Class-II dental malocclusion with upper crowding, and lower spacing, (iii) the antero-posterior (AP) correction would require good compliance with Class-II traction, and (iv) she also has a

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horizontal growth pattern with a tendency of her bite deepening as treatment progresses. A key to successful treatment with the Invisalign appliance is to ensure good surface area contacts between the aligner material and the dentit dentition ion.. Theref Therefore ore,, the succes successfu sfull planni planning ng and treatmen treatmentt of this this case case with with short short clinic clinical al crown heights involved (i) choosing the correct atta attach chme ment nts, s, (ii) (ii) have have them them appr appropr opria iate tely ly placed, (iii) decrease the velocity of the movement ment of the the dent dentit itio ion n whil whilst st desi design gnin ing g the the ClinCh ClinCheck eck plans, plans, (iv) (iv) the patie patient nt also also has to unders understan tand d the importa importance nce of using using Class-I Class-III elasti elastics, cs, (v) be prepar prepared ed for re�nement/additional tional aligne aligners, rs, and (vi) (vi) ensure ensure good good patien patient t compliance. The �rst ClinCheck plans presented a treatment ment plan plan with with 15 alig aligne ners rs and and atta attachm chmen ent t design as shown in Fig. in Fig. 1B. 1B. The ClinCheck plans were modi �ed to reduce the treatment velocity and a different attachment design (Fig. (Fig. 1C). 1C). The case treated out well in 21 months using a total of 46 (29 þ 17) aligners with 1 re �nement (Fig. 1D). 1D).

Case 2 Case Case 2 is an adul adultt fema female le Cauc Caucas asia ian n who who is extremely concerned with the aesthetics of the trea treatm tmen entt appl applia ianc ncee (Fig ig.. 2A ). Her chief conc concer erns ns were were the the rot rotated ated upp upper late latera rall incisors and also a lateral open bite on the left side. She is a Class-I dental malocclusion over a skeletal Class-I base with a normal direction of growth. There were no soft tissue parafunctions and radiographic examination was nondescript. Previo Previous us experi experienc ences es with with moving moving latera laterall incisors has noted it to be a great challenge. The nece necess ssit ityy of plac placin ing g an opti optimi mise sed d extr extrus usio ion n attachment in this case is almost imminent. The clear clear applia appliance nce that that is Invisa Invisalig lign n is a natura naturall choice for the patient, provided it was capable of executing the biomechanical forces necessary to extrude the lateral incisor and close down the lateral open bite successfully. Although matching tooth-colou tooth-coloured red composite composite attachment attachmentss may be selected, and if well placed and polished, almost invisible upon close scrutiny. However, when the actual aligner with the pushed out outline of the attachment is placed on the dentition, the visibility of the attachment highly increases. Out of

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Chan and Darendeliler

social embarrassment, this often result in patients not not wear wearin ing g the the alig aligne ners rs for for the the pres prescr crib ibed ed number number of hours; hours; and hence, hence, disrup disruptin ting g the biomec biomechan hanica icall forces forces and not obtain obtaining ing the desired results. The road block of treating this case with the Invi Invisa sali lign gn appl applia ianc ncee incl includ udes es meet meetin ing g the the patient ’s expectations in terms of aesthetics and treatment outcomes. If attachments were to be placed on the buccal surfaces of the teeth, there might be a high chance that the patient might not ful�l the prescribed hours of aligner wear.

Is there any other way to design the ClinCheck plans and attachments? How do we extrude the dentition and close the lateral open bite on the left left sid side? Would ould we requ requir iree the the need need for for elastic bands? The �rst ClinCheck ClinCheck plan presented presented a treattreatment plan with upper 18 and lower 12 aligners and attachments on the buccal surfaces of the upper anterior teeth (Fig. (Fig. 2B). 2B). The ClinCh ClinCheck eck plan plan was modi modi�ed to place vertical rectangular attachments on the lingual surfac surfaces es of the upper upper latera laterall inciso incisors rs instea instead. d.

Figur Figuree 1. (A) Pre-treatment images of case 1. (B) Initial ClinCheck plans with only 15 active aligners and an elastic simulation. Precision cuts for elastic wear were not available as case was treated pre-G3. (C) Final ClinCheck plans with slower velocity and modi�cation of attachment designs. Precision cuts for elastic wear were not available as case was treated pre-G3. (D) Completion images of case 1.


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Figure 1. Continued.

The velocity velocity of the tooth tooth moveme movement nt was also redu reduce ced d (Fig ig.. 2C 2C). ). No elas elasttic band bandss were ere nece necess ssar aryy and and the the pati patien ent t ’s comp compli lian ance ce was was excellent throughout the treatment duration. The case treated out well in 15 months using a total of 32 (25 þ 7) aligners with 1 re �nement (Fig. 2D). 2D).

Case 3 Case Case 3 is an adul adultt Asia Asian n pati patien entt with with init initia iall concerns of crooked front teeth and impacted

lower second premolars premolars (Fig. 3A ). ). Radiographic examination was nondescript. She was a ClassClass-II II divisi division on 2 dental dental malocmalocclusion on a skeletal Class-I base with a normal direction of growth. The road block in this case hinges mainly on the disengagement of the lower second second premol premolar ar teeth, teeth, and extrud extruding ing them. them. There is a high chance that we would require the use of auxili auxiliari aries es to assist assist in these these extrus extrusion ion movements. Prior to onset of treatment, the patient gave her informed consent that there would be a high

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Figur Figuree 2. (A) Pre-treatment images of case 2. (B) Initial ClinCheck plans with only 18 upper active aligners and 12 lower lower active active aligne aligners. rs. Optimi Optimised sed attachm attachment entss are placed placed on the upper upper anterio anteriorr teeth. teeth. (C) Final Final modi modi�ed ClinCheck plans with 25 active aligners and vertical rectangular attachments placed on the lingual surfaces of the upper anterior teeth. (D) Completion images of case 2.

chance of using sectional �xed appliances on the lower lower quadra quadrants nts to assist assist in the dental dental movements. The initial ClinCheck plan set up by the technician had recognised the dif �culty in these extrusive movements and have decided to not extr extrud udee the the lowe lowerr seco second nd prem premol olar arss at all all (Fig ig.. 3B 3B). ). This This trea treatm tmen entt plan plan succ succes essf sful ully ly improves the tracking rate of the case as the dif �cult movements will be dealt with at a second, later stage. However, this will lengthen the total treatment duration and may not be of the best

inte intere rest st of the the pati patien ent. t. More Moreov over er,, when when the the sectional �xed xed appl applia ianc nces es are are plac placed ed,, the the orig origin inal al alig alignm nmen entt achi achiev eved ed on the the lowe lowerr ante anteri rior or segm segmen ents ts may may be lost lost as rela relaps psee quic quick kly sets sets in. in. Some ome sort sort of tempo empora rary ry retainers will have to be designed to prevent this. The Clin ClinCh Chec eck k plan planss were were subse subsequ quent ently ly modi�ed to allow expansion expansion of the dental arch forms, forms, increas increasing ing the dental dental arch arch perime perimeter ter to allo allow w suf suf �cien cientt spac spacee for for the the extr extrus usio ion n of the the lowe lowerr seco second nd prem premol olar arss (Fi Fig. g. 3C 3C). ).


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Appropriate attachments were placed to assist in the extrusion of the premolars and the contingency plan was that once the lower impacted premolar teeth were not tracking, sectional �xed appliances would be placed on the lower �rst premolars, second premolars, and �rst molars. The existing, remaining aligners will also be cut and adjusted to �t around these �xed appliances. The patient will still be changing her aligners every 2 weeks as previously planned. In this way, the extrusion with the �xed appliances are planned within the boundaries of the aligner movement and there will be “space” to allow this

extrusive movement to occur with the usual aligner wear. As such, any interim retainers will not be necessary. Some other considerations in this case include appropriate attachment designs in order to successfully extrude these premolars, clinical monitoring on suf �cient spacing, and light IPR where necessary to allow the planned movements to occur. Patient compliance has to be reinforced as well. The case treated out well in 26 months using a total of 58 (40 þ 18) aligners with 1 re�nement and Class-II elastics (Fig. 3D),

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Figure 3. (A) Pre-treatment images of case 3. (B) Initial ClinCheck plans with uncorrected impacted lower second premolars. (C) Final modi�ed ClinCheck plans with 40 active aligners and corrected lower second premolar positions. (D) Completion images of case 3.

surprisingly, without the need for any sectional braces.

ClinCheck treatment plans A ClinCheck treatment plan allows us to visualise the treatment progress and treatment outcome virtually. However, it is strongly guided by soft ware defaults and limitations. Trained align

technicians are often unaware of biology of tooth movement, biomechanics, and other clinical limitations and/or variations. Therefore, the following common trouble situations are often reported: (i) dif �culty in obtaining the correct amount of dental expansion (ii) inability to achieve suf �cient anterior torque in premolar extraction cases (iii) inability to fully correct deep overbite dental


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malocclusions and (iv) inability to resolve severe dental crowding without multiple re�nements. Recovery techniques therefore are formulated to overcome these situations. Sectional or full arch �xed appliances, �xed bonded power arms incorporated with power chains and/or pull coils, button, and elastics etc. are often the “get out of trouble” consequence. Clinicians have to spend more time and overheads to prepare and plan for such situations. Patients who are not pre warned of such situations are often not impressed with the prolonged treatment duration, extra costs involved, and the placement of a more

visible appliance in order to complete the case to perfection. We strive to achieve repeatable, outstanding results without the need for such predicaments. We can come close to avoiding such situations by going back to the basics—through understanding the true biology of tooth movement, and relating it back to aligner treatment and biomechanics.

Planning and execution With an expansive market within the �eld of dentistry, Invisalign has made orthodontics easily

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Figure 4. (A) Pre-treatment images of case 4. (B) ClinCheck plans showing sequential “ staggered” staging pattern. (C) Clinical images showing sequential molar distalisation augmented by using Class-II elastics. (D) Completion images of case 4.

available for the masses. As the product evolves into the cosmetic dental environment, the science behind dental movement is slowly eroded. “Is Invisalign orthodontics?” Using pre-set defaults within the ClinCheck software and allowing technicians to dictate clinical treatment may allow the new clinician to get away with treating simple Class-I cases. However, when faced with more complex situations, the age-old debate comes about “how much

orthodontics should you know before using the Invisalign appliance?”

Age-related treatment (a) Molar distalisation or elastic simulation The decision making in the type of orthodontic correction required in Class-II and/or Class-III dental malocclusions relate closely to the growth potential of the patient. Differential growth spurts


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and velocities in the growth of adolescences have been previously described.3 It is noted that girls have their growth spurt up to 2 years earlier than boys. However early-maturing boys will reach puberty before slow maturing girls. Therefore, it is essential to note the growth patterns and characteristics of each individual patient during

consultation appointments. The Burlington growth studies done in the early 70s looked at the various growth time points of children.4 The increments of mandibular length was also noted annually. Therefore, when it comes to the decision on whether the molar dental relationship should be corrected with “molar distalisation” or an “elastic

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Figure 5. (A) Pre-treatment images of case 5. (B) Images showing the ClinCheck plans and staging pattern of case 5. (C) Completed images of case 5.

simulation,” this understanding of the growth potential of the patient becomes rather important. (i) Sequential staging pattern This is one of the default staging patterns in the correction of molar dental relationships with the Invisalign appliance.

Case 4 Case 4 is a Caucasian non-growing adult female with a Class-II dental malocclusion (Fig. 4A ). She had undergone previous dental treatment with a single upper and lower premolar tooth extracted in quadrants 1 and 4. This has resulted in a deviated upper dental midline, moderate upper,


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and lower dental crowding, rather constricted upper and lower dental arch forms, a deep dental overbite, and a Class-II dental molar relationship. Her panoramic (OPG) radiograph demonstrates normal dental root anatomy, normal dentoalveolar bone heights, and normal bony density (Fig. 4B). The wisdom teeth on the left side have all been previously removed. The ClinCheck plans reveal a “staggered” staging pattern (Fig. 4C) that indicates a sequential staging treatment plan. The default staging pattern is as such the upper terminal molars are usually distalised from stage 1 for approximately 8 stages before the �rst molar starts distalising for another 8 stages and subsequent teeth distalised individually thereafter. The upper anterior teeth are usually stationary all this time while the molar distalisation is occurring. Although this staging pattern is predictable in non-growing patients, the treatment duration is usually prolonged. Moreover, the upper anterior crowding is usually not resolved till the later part of the treatment. Patients with anterior crowding as a chief concern would not like such a treatment plan. There are, however, several ways to overcome this staging problem.  The

digital ClinCheck plans do not take into considerations any inter-arch anchorage augmentation. The use of Class-II elastics in such treatment highly improves the predictability of

the treatment. The sequential staging of the upper molars may then be successfully reduced to every 4 stages instead of 8. This reduces the total number of active aligners signi �cantly.  The ClinCheck plans may also be modi �ed to allow early upper anterior alignment to alleviate the patients’ chief concerns. This usually involves, if allowed, an expansion and/ or proclination movement of the upper anterior teeth allowing an early aesthetic improvement. The upper anterior teeth will subsequently be retracted back once the molar distalisation has created suf �cient space. The case treated out well in 18 months using a total of 43 (39 þ 4) aligners with 1 re �nement (Fig. 4D). This staging pattern is predictable and suitable for adult non-growing patients with up to half unit A-P correction. The patient would require good clinical crown heights, good compliance with aligner wear, and dental elastics. There should not be any wisdom teeth present on the arch which we are distalising. However, treatment duration may be longer and anterior teeth may not be fully corrected till the later part of the treatment. (ii) En masse distalisation With the sequential staging pattern taking up a longer treatment duration, there will be certain

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Figure 6. (A) Pre-treatment images of case 6. (B) ClinCheck plans for case 6. (C) Completed images of case 6.

cases that will allow “en masse distalisation” pattern. This staging pattern is not an “elastic simulation” but rather right from the commencement of treatment, the whole dental arch distalises and achieves the desired AP correction.

Case 5 Case 5 is an adult Caucasian non-growing adult patient with a Class-II dental malocclusion (Fig. 5A and B). She had previous orthodontic treatment and 4 premolar teeth were previously

extracted. Her upper and lower dental arches have collapsed and constricted over time with upper and lower mild to moderate degrees of crowding noted. There is an increased overjet and a quarter unit Class-II dental relationship. Attachments were placed from stage 4, Class-II elastics were also applied then. This staging pattern is demonstrated in the ClinCheck plans as the upper arch is completely distalised as if via “an invisible” force. This could be applied either through inter-arch elastics or placement of temporary anchorage devices (TADs) at the appropriate areas.


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The en masse staging pattern allows simultaneous correction of the patients’ dental crowding as well as addressing the AP correction at the same time. The treatment duration, however, is much shorter. And clinical tracking may be slightly trickier. When the patient returns for a review/adjustment appointment, it is imperative to not only check the �t of the

aligners, but also remove the aligners, get the patient to bite into a maximum intercuspation to check for inter-arch relationships and adjust the anchorage control with Class-II elastics as required. The case treated out well in 12 months using a total of 27 (18 þ 9) aligners with 1 re �nement (Fig. 5C).

Figure 7. Pre- and post-dental arch expansionin adults using the Invisalign appliance. Case I (A and B) and Case II (C and D).

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Figure 8. Dental arch expansion. (A) Cases to avoid and (B) cases to select.

This staging pattern is predictable and suitable for adult non-growing patients with pre vious premolar extractions, and up to half unit AP correction. The presence of maxillary wisdom teeth may sometimes make the correction dif �cult when we are performing en masse distalising and it is highly recommended that they be removed. The patient would require good clinical crown heights, excellent compliance with aligner wear and dental elastics. Otherwise, 4-5 mm attachments on the premolars may be required to increase the surface area contacts between the aligner and the dentition. (iii) Elastic simulation Using inter-arch elastic traction to correct Class-II dental malocclusion is quite the “norm” in conventional orthodontics. Especially in growing children with the potential for vertical

Figure 9. Dental arch expansion: showing the centre of rotation and the expansion arc. (Image source: Wikimedia commons, free media repository).

dento-alveolar growth. In contrast, correcting a full Class-II dental malocclusion using elastics in an adult patient is like asking a toddler to walk across the Sydney Harbour Bridge.

Case 6 Case 6 is an adolescent Asian male with concerns of deviated upper and lower dental midlines, retroclined anterior teeth with moderate upper and lower dental crowding. He was diagnosed as a Class-II subdivision dental malocclusion on a mild skeletal 2 base (Fig. 6A ). The elastic simulation staging pattern is an ef �cient staging pattern to achieve alignment, space closure and vertical correction in growing patients. In such cases, it is essential to have good attachments placed due to their shorter clinical crown heights, and their passive eruption. In the ClinCheck plan, the staging pattern demonstrates a simultaneous movement of all teeth with a last stage aligner “ jump” at the end, just before the overcorrection aligners (if any were planned). It does not matter which arch does the jump as in the ClinCheck plans, dental movement occur in space. The default has set the arch with the most aligners to jump (Fig. 6B).

Figure 10. Overcoming the side effects of dental arch expansion: intruding and increasing the buccal root torque, placement of attachments, and over expansion. (Image source: Wikimedia commons, free media repository).


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Figure 11. (A) Pre-treatment images of case 7. (B) Pre-treatment OPG and lateral ceph of case 7. (C) ClinCheck plans for case 7. (D) Completed images of case 7. (E) Completed OPG and lateral ceph of case 7. (F) Overall and regional superimposition of case 7.

However, it has to be taken into account that the success of the treatment also relies heavily on the severity of the Class-II discrepancy, growth potential and patient cooperation. It is important to understand that although elastic simulation was performed at the last aligner, it is imperative to have the inter-arch dental elastics worn from the very early part of the treatment to have the desired treatment outcome. The strength and duration of the elastic wear will depend greatly on the severity of the discrepancy.

The case treated out well in 22 months using a total of 58 (39 þ 12 þ 7) aligners with 2 re�nements (Fig. 6C). Re�nement/additional aligners were changed weekly. This staging pattern is rather predictable and suitable for growing patients with up to half unit AP correction. Dental crowding is usually resolved early and simultaneous staging pattern keeps the treatment duration short. The patient would require good clinical crown heights, excellent compliance with aligner wear and dental elastics.

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(b) Dental arch expansion Dental arch expansion in growing and non-growing patients using removable appliances has previously been established.5,6 Studies on cadaver material have noted the cessation of growth and fusion of the palatal and pterygopalatine sutures at around 13–15 years of age.7 Accordingly, in the treatment of adult patients using the Invisalign appliance, one cannot expect skeletal transverse changes unless surgery is incorporated. Dental arch expansion in adults using the

Invisalign appliance is predictable and successful (Fig. 7A –D). However, there are limitations to how much expansion is achievable and it has to occur within the thickness of the dento-alveolus.8 Cases with thin gingival biotype and evident recession should be avoided (Fig. 8A ). Instead, try to select cases with lingually tipped buccal segments, with thick gingival biotype with minimal or no recession (Fig. 8B). During dental arch expansion of the maxilla, the centre of rotation of the


29


expansion is much higher than the palatal bone structures itself (Fig. 9). One of the worst side effect during this dental expansion is that the palatal cusps of the posterior teeth will extrude and hang down due to the tipping movement of the

dentition. The strong soft tissue resistance during expansion also does not allow suf �cient expansion clinically as planned. Understanding these side effects is therefore necessary in order to design a successful ClinCheck plan.

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Figure 12. (A) Pre-treatment images of case 8. (B) Pre-treatment OPG and lateral ceph of case 8. (C) ClinCheck plans for case 8. (D) Completed images of case 8. (E) Completed OPG and lateral ceph of case 8. (F) Overall and regional superimposition of case 8.

It is quite a common diagnostic error during the evaluation of the transverse discrepancy that the clinician only considered the dimensions of the upper dental arch, but has not considered if the lower arch was too wide instead. This transverse discrepancy can be corrected by not just expanding the upper arch, but with a combination with the constriction of the lower arch if necessary. This will reduce the amount of upper arch expansion and make the treatment more predictable. It is vital to have these following movements designed into the ClinCheck plan: (i) intrude

and increase the buccal root torque of the upper posterior teeth, (ii) place appropriate attachments in order to increase the surface area contact between the dentition and aligner material, (iii) over expansion of up to 20% of the required distance (Fig. 10). (c) Treatment in teenagers Using the Invisalign appliance in the orthodontic treatment of teenagers has been met with resistance. The number of Invisalign Teen cases shipped globally have stagnated at about 24% over the last few years. 9 The usual road blocks include (i) the


31


lack of patient compliance (despite the presence of compliance indicators), and (ii) short clinical crown heights disallowing good three-dimensional control. However, the physiology of teenage patients has been shown to respond better to various orthodontic appliances as compared to adults.10,11 The Ann Arbour Michigan Centre of Human Growth and Development

published data on the average changes in mandibular molar and canine widths over the childrens’ growing years. Maximum growth rates tend to peak just before the age of 12 years and the trend decreases thereafter. Therefore, while we are planning for a younger patient using the Invisalign appliance, we cannot forget the fact that the patient ’s growth is assisting the treatment

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while we are enhancing the growth potential of the child as well.

Case 7 Case 7 is an adolescent female patient of Caucasian decent. She was diagnosed as a Class-II dental

malocclusion on a mild skeletal Class-II base with a normal to horizontal direction of growth. She presented with a deep dental overbite, unilateral posterior crossbite and lower midline deviation to the right side (Fig. 11A –C). The ClinCheck plan included the use of both optimised and conventional attachments. Simultaneous staging


33

Figure 13. (A) Pre-treatment images of case 9. (B) Pre-treatment OPG and lateral ceph of case 9. (C) Post-twin block treatment images of case 9. (D) ClinCheck treatment plans of case 9. (E) Completion images of case 9. (F) Completion OPG and lateral ceph of case 9. (G) Overall and regional superimposition of case 9.

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was planned with an elastic simulation. Class-II elastics were worn from the upper canines to the lower �rst molars using a button-to-button method.

The case treated out well under 21 months using a total of 45 (33 þ 12) aligners with 1 re�nement (Fig. 11D–F).



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Shape-driven orthodontics The essence of orthodontic treatment is the application of forces and force systems to alter tooth positions or to produce physiologic bony changes. The application of scienti�c biomechanics improves the quality of treatment and treatment ef �ciency. However, biomechanics did not originate with orthodontics. It is based upon the pioneers of physics like Galileo and Newton. Recent research also included material science, mechanics of materials, beam theory, �nite-element, and computer science to get to where we are today. In orthodontics, we build on the foundation from these basic sciences of engineering and physics. In the biological system, we are dealing with constant bone resorption and bone remodelling through the periodontal

ligament within the periodontium. The tooth itself becomes the subject of interest as it tra verses through the dento-alveolar bone. Historically, orthodontic appliances were developed, described, and taught as shape driven. In the era of shape-driven appliances, we were taught how to bend or twist a wire or how to properly position a bracket. That is all geometry and driven by shape. The best approach is to �rst determine our orthodontic goal, what we want to achieve, and then determine the force system that is required to produce that result. Subsequent to that can we then design our appliance. It is important to have a shape, but it is more important that the shape produces the desired force system. Often, that resultant shape will look nothing like the ideal �nish.


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Figure 14. (A) Pre-treatment images of case 10. (B) Pre-treatment OPG of case 10. (C) ClinCheck plan for case 10 showing simultaneous staging and an elastic simulation. (D) Completed images of case 10. (E) Completed OPG of case 10. (F) Final restoration placed for case 10. (G) Periapical radiographs of implant and �nal restoration for case 10.

Compensatory movements Understanding the side effects and the inadequacies of the aligner system is extremely important in treating of complex cases. As Invisalign is also a removable appliance, the degree of “play ” between the appliance and the dentition affects the true tracking of the appliance.

Managing premolar extraction cases using the Invisalign appliance is challenging. Extraction cases in younger patients contribute to a greater challenge due to the lack of absolute threedimensional control of the dental movements with shorter clinical crown heights and less than ideal patient compliance. However, through good case selection, proper planning and design,

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premolar extractions in teenagers can be executed well. In such cases, not only good and suf �cient attachments need to be selected, compensatory movements also need to be planned. These are some of the compensatory movements required in handling such extraction cases. (i) Increase the upper anterior lingual root torque, further intrude the lower incisors: often an anterior open bite is seen in the �nal ClinCheck plans. During dental space closure, the anterior teeth are often extruded and retroclined contributing to an increase of dental overbite

often leading to an anterior interference and posterior open bite. These 2 compensatory movements will prevent the “dumping ” of the anterior teeth as the dental spaces are closed. G5 precision bite ramps should be included on the upper anterior teeth to assist in the control of the vertical dimension as space closes. (ii) Teeth mesial to the extraction site need increased distal root tip movements while teeth distal to the site require increased mesial root tip movements. Essentially, we are trying to counteract the crown the abutment teeth as the “dumping ” of extraction spaces are closed. Due to the damping


39


effect of the aligner system, the further away from the extraction space, the less of these increased tipping movements are required. This concept is further explained using the following 2 cases.

Case 8 Case 8 is an adolescent Asian female with a Class-II division 1 dental malocclusion with a skeletal 1 pattern and a vertical to normal direction of growth (Fig. 12A –B). Her chief concerns were that

her upper front teeth stuck out and she wanted to have them retracted with an improvement with her dento-facial pro�le. She also presented with severe upper and moderate lower dental crowding, a deep lower Curve of Spee and incompetent lips. Her dental midlines were non-coincident. The upper �rst premolar teeth (teeth #14, #24) were extracted and Invisalign Teen was prescribed. The ClinCheck plans with conventional attachment designs and staging patterns are shown (Fig. 12C). Class-II dental elastics were also used to control the anchorage during space closure. Precision buccal cut

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pattern (Fig. 13D). After obtaining a positive overjet and overbite at stage 23, night use of Class-II dental elastics was used to maintain the anchorage.12 An early re�nement was performed at stage 31 and posterior triangular elastics was used to settle the bite during these re�nement stages. The compensatory movements planned in this case were increased lower incisor intrusion by 0.8 mm, increased distal root tip of the lower canines 8 , increased mesial root tip of the lower second premolars, and �rst molars 8 and 6 , respectively. The case treated well in 17 months with a total of 42 (31 þ 11) aligners with 1 re�nement (Fig. 13E–G). The total active orthodontic treatment was 24 months. Despite reported dif �culties from new clinicians in obtaining repeatable good results using the Invisalign appliance in younger patients, the most common mistakes are that they have either not planned the treatment around the patients existing growth potential, or that they have failed to fully understand and counteract the side effects of tooth movement with aligner appliances. Favourable physiology and good growth potential in younger patients allow orthodontic treatment to be more “ forgiving. ” We could often achieve a reasonable result despite less than ideal compliance, and even more overwhelming results with excellent growth potential and compliance. 1

1


outs were designed and buttons were placed to enable controlled retraction and space closure. The compensatory movements planned in this case were: increased lower incisor intrusion by 0.8 mm, increased distal root tip of the upper canines 6 , increased mesial root tip of the upper second premolars, and �rst molars 8 and 6 , respectively. The case treated well in 24 months with a total of 51 (37 þ 14) aligners with 1 re�nement (Fig. 12D–F). 1

1

1

Case 9 Case 9 is an adolescent male patient with a mixed Asian and Caucasian ethnicity. He was a Class I dental on a skeletal 2 base with a horizontal direction of growth. His chief concerns were a mildly recessive chin and lower dental crowding (Fig. 13A –B). Due to his insuf �cient horizontal projection of his chin and a de�cient mandible, a functional twin block appliance was prescribed. Active treatment lasted 7 months and brought him into a reversed dental overjet and an improved facial appearance (Fig. 13C). Subsequently lower �rst premolars (teeth #34 and #44) were extracted and the Invisalign Teen appliance was prescribed. The treatment plan was to complete the case in a Class I canine and a ClassIII molar dental relationship. The ClinCheck plans demonstrate the use of optimised as well as con ventional attachments in a simultaneous staging

1

(d) AP correction Understanding the shortcoming of any orthodontic appliance allows us to think outside the usual treatment plans in order to achieve the desired result within a prescribed, limited range. The anterior–posterior correction of dental malocclusion using the Invisalign appliance will be described under the following subheadings: (i) Opening spaces

Case 10 Case 10 is an adult Caucasian male who lived many years with an absent upper right lateral incisor (Fig. 14A –B). His chief concerns were that his smile was asymmetrical, has an like to have his smile “underbite,” would improved, and missing dentition restored. He presented with a Class-III dental malocclusion on a skeletal 1 pattern with a normal direction of


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Figure 15. (A) Pre-treatment images of case 11. (B) Pre-treatment OPG of case 11. (C) ClinCheck plans for case 11. (D) Images of case 11 after the 31 þ9 aligners. Images taken at re �nement 2. (E) Completed images of case 11 after the placement of �nal restoration. (F) Completed OPG of case 11 after the placement of �nal restoration.

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growth. The upper dental midline was deviated to the right due to the missing upper right lateral incisor. There was a reversed overjet, an anterior functional shift, with increased wear and attrition to his anterior teeth. The patient also presented with a Bolton’s discrepancy with the upper left lateral incisor slightly diminished in size. As he was reluctant to have that built up, it was quite a challenge to allow a full dental implant to be placed in the site where the missing tooth was. The ClinCheck plan was designed with simultaneous staging. An elastic simulation was prescribed in order to achieve the Class-I occlusion after the elimination of the

functional shift (Fig. 14C). Class-III dental elastics were used clinically to achieve the AP correction. The �nal occlusion and dental space for the upper right lateral incisor was achieved after 13 months of active treatment with 27 (17 þ 10) aligners, 1 re�nement (Fig. 14D–E). The dental implant was successfully placed and the �nal restoration subsequently installed (Fig. 14F–G). Treatment planning in adults is challenging as patients do not often present with a full set of complete dentition. However, ClinCheck treatment planning is the best tool for such patients


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requiring interdisciplinary treatment. The precise virtual prediction of dental movements and implant site preparation allows the case to be planned and modi�ed where necessary with the input from the orthodontist, periodontist, prosthodontist, and also the patient him/herself. The same applies for orthognathic surgery cases in terms of arch co-ordination and anchorage management.

Case 11 Case 11 is an adult Caucasian female who had her lower left �rst premolar tooth previously extracted. The dental space had since closed resulting in the lower dental midline shifting

completely to the left side (Fig. 15A –B). Her chief concern was that she had a narrow smile and crooked front teeth. Multiple orthodontic plans for her were discussed. We could extract 3 more premolar teeth (one from each other quadrant) to balance the occlusion, or remove 2 upper premolar teeth and IPR the lower arch, or perform a non-extraction plan and IPR the upper arch and keep the dental midlines uncorrected. As the patient was also concerned with her narrow smile, the examination of her supporting periodontal tissues led us to a fourth treatment option. A non-extraction treatment was planned with the re-establishment of a dental space where the lower left �rst premolar was. This treatment

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Figure 16. (A) Pre-treatment images of case 12. (B) Pre-treatment OPG and lateral ceph for Case 12. (C) ClinCheck plans for case 12. (D) Completed images and CT scan of mandible of case 12.

would require the patient to have a dental implant placed post-orthodontic treatment. The ClinCheck plans with the attachment design (Fig. 15C), simultaneous staging pattern and use of Class-II elastics on the left side was prescribed. The implant space was favourably opened after the initial lot of 40 (31 þ 9) aligners (Fig. 15D). The stage I dental implant was placed while the patient was still undergoing active treatment with re�nement aligners. This

allowed no down time as osteointegration occurred. The �nal restoration was placed (Fig. 15E–F) after a total of 51 aligners.

Case 12 Case 12 is an adult male Caucasian patient with his dental spacing as his chief concern. He had a ClassII dental malocclusion with a skeletal Class-I facial pattern and a horizontal direction of growth


45


(Fig. 16A –B). He also presented with a mild degree of microdontia, a deep bite tendency, and noted wear and attrition on his dentition in general. Few treatment options were discussed and many included the closure of the dental spaces,

�xed

appliances with � xed functional appliances such as a Herbst. After considering his dentofacial pro�le and his preferred choice of appliance, the �nal treatment plan was to use the Invisalign appliance to open a third premolar

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Figure 17. (A) Pre-treatment images of case 13. (B) Pre-treatment OPG of case 13. (C) ClinCheck plans showing the establishment of 4 premolar spaces. (D) Completion images of case 13. (E) Comparison of pre- and posttreatment pro�les of case 13.

space on each of the lower quadrants, leaving the molars in full Class-II but canines in Class-I dental relationship. These spaces will then be restored with prosthodontic replacements, likely dental implants. Opening of a third premolar space in the lower arch to treat a Class-II dentition orthodontically is not common. However, the distraction of the periodontium provides good dental bony structures to allow implant placement. But it is necessary to examine if the surrounding supporting periodontal tissues are able

to contain the dental movements required to achieve the desired end result. With the Invisalign system, ClinCheck plans allow the visualisation of the dental movements, either expansion and/or proclination (in this case), and exact measurements and anchorage considerations can be made. Computer aided treatment decisions can then be made more precisely as such. A prosthodontist and periodontist were consulted and radiographs inspected. In order to keep the option of a dental implant placement open,


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the position of the mental nerve and its canal had to be considered. In this case, we decided to open a single premolar dental space between the lower �rst and second premolar teeth (Fig. 16C).

Treatment was supported with optimised and conventional attachments, and Class-II elastics. Treatment was completed in 21 months with 45 (26 þ 19) aligners and 1 re�nement (Fig. 16D).

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Case 13 Case 13 is an adult Caucasian female with chief concerns of dental spacing. She presented as a Class-I dental on a skeletal Class-I horizontal base. She had a certain degree of microdontia with upper and lower dental spacing. She also had a deep bite tendency, retroclined upper and lower anterior teeth with deviated dental midlines. Her dental pro�le was concaved and did not allow full dental space closure without either dishing in her pro�le further, or involving bimaxillary orthognathic surgery (Fig. 17A-B). After considering various treatment options using the virtual ClinCheck treatment plans, it was decided to have 4 premolar spaces opened up for prosthodontic replacement, one in each quadrant (Fig. 17C). On the upper arch, the third premolar spaces were opened between the upper �rst and second premolars. Whereas on the lower arch, the third premolar spaces were opened between the lower canines and the lower �rst premolars. Both Class-II and Class-III elastics were used to control the anchorage and midline correction. The completed dental occlusion was a Class-I canine and molar dental relationship. The

consolidation of dental spaces, closing of the anterior spacing, and establishing a full premolar space in this case has allowed an aesthetic outcome with the preservation of the patient ’s dento-facial pro�le (Fig. 17D-E). The treatment duration was 15 months with a total of 31 (22 þ 9) aligners and 1 re�nement. (ii) Closing spaces Premolar extraction cases in non-growing patients using the Invisalign appliance maintain a tough challenge to the new clinician. The same principles on compensatory movements mentioned as before should also be applied. The increased dif �culty in adult treatment is the lack of vertical dento-alveolar growth and often treatment duration could be longer.

Case 14 Case 14 is an adult female patient of Asian descent. Her chief concerns were her crowded dentition. She presented as a Class-III dental on a skeletal 3 pattern with a vertical growth pattern. She had bilateral posterior and anterior crossbites, moderately severe upper and lower dental


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Figure 18. (A) Pre-treatment images of case 14. (B) Pre-treatment OPG and lateral ceph of case 14. (C) ClinCheck plans of case 14. (D) Compensatory movements planned for case 14. (E) Completion images of case 14. (F) Completion OPG and lateral ceph of case 14. (G) Overall and regional superimposition of case 14.

crowding, minimal overbite, and overjet with deviated dental midlines (Fig. 18A-B). A camou�age treatment plan was designed with the extraction of the lower left �rst and lower right second premolars (teeth #34 and #45). The ClinCheck plans show a mixture of optimised and conventional attachment designs, IPR, and simultaneous staging (Fig. 18C). Compensatory movements were planned with increased mesial root tip of the immediate

dentition distal to the extraction spaces and increased distal root tip of the immediate dentition mesial to the extraction spaces (Fig. 18D). Class-III elastics were used to control the anchorage. The plan was to complete the occlusion with a Class I canine and Class-III molar dental relationship. The treatment duration was 22 months with 47 (32 þ 15) active aligners with 1 re �nement (Fig. 18E-G).

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Case 15 Case 15 is an adult male patient of Asian background. He presented with a bimaxillary protrusive Class-I dental malocclusion on a skeletal 1 base with a normal direction of growth. He had a protrusive dental pro�le, incompetent lips, an anterior crossbite with minimal overjet and overbite (Fig. 19A-B). The treatment plan was to have 4 �rst premolars extracted (teeth #14, #24, #34 and #44). The Invisalign ClinCheck treatment plan was set up with both optimised and conventional attachments with simultaneous staging. A vertical rectangular attachment was placed on the lingual surface of the upper right instanding lateral incisor for aesthetic reasons (Fig. 19C). The compensatory movements in this case included an increased upper incisor lingual root

torque of 4 , further intrusion of the lower incisors of 0.6 mm, increased mesial and distal root tip of the abutment teeth distal and mesial to the extraction sites respectively of between 4 and 8 (Fig. 19D). Class-II elastics were used initially to allow anchorage control and also to maintain a Class I canine relationship. During the re�nement stages, posterior box elastics were used in corporation with the upper anterior precision bite ramps (G5 feature) in order to control the vertical settling of the occlusion. (Fig. 19E) The total treatment duration was 26 months with 83 aligners (30 þ 17 þ 12 þ 24) and 3 re�nements. The re�nement aligners were changed weekly (Fig. 19F-H). Adult orthodontic treatment often constitutes dentitions with missing or absent teeth. While prosthodontic replacements are more 1

1

1


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common now, there remains additional surgical involvement and costs. Closure of large edentulous spaces with the Invisalign appliance alone is challenging and should be discouraged. However, the appliance could be incorporated with partial �xed appliances and TADs to enable us to dictate the dental movements required.

Case 16 Case 16 is an adult male patient with an Asian background. He had a missing lower left �rst molar

and wanted to have it closed orthodontically to avoid the placement of a dental implant. He was a mutilated Class-I dental malocclusion on a skeletal Class-I base with a normal direction of growth. He presented with a congenitally missing lower incisor, non-coincident dental midlines, missing upper right �rst molar (space almost all closed up) and lower left �rst molar, proclined upper incisors with mild upper and lower anterior crowding (Fig. 20A-B). The treatment plan was to use a TAD on the lower left quadrant, in concurrent with partial �xed appliance to close the lower left edentulous

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space; and do the rest of the other orthodontic movements with the Invisalign appliance. The ClinCheck plans demonstrated the use of optimised and conventional attachments with an initial upper 30 and lower 40 active aligners. We allowed mesial movement of the lower left molars within the �rst 30 active aligners as the upper dental treatment progressed. At the end of the �rst 30 aligners, partial braces and a TAD were placed and re�nement aligners were ordered to complete all the dental movements required (Fig. 20C). In the re�nement ClinCheck plans, precision cuts were designed to incorporate the partial �xed appliances and triangular elastics with elastomeric chains were also used to close the dental spaces as well as to settle the occlusion

vertically (Fig. 20D). Although the movement of the lower left molars were achieved with the partial �xed appliance, mesial movements were also planned in the ClinCheck treatment to facilitate the tracking of the dentition. Other �nishing orthodontic movements were occurring in concurrent with the partial �xed appliances. The treatment duration was 28 months with 61 (30 þ 31) active aligners and 1 re�nement (Fig. 20E-F). (iii) Orthognathic surgery Further AP correction in adult treatment that extends beyond the boundaries of the dentoalveolar segment will require the involvement of orthognathic surgery. More often than not, oral


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Figure 19. (A) Pre-treatment images of case 15. (B) Pre-treatment OPG and lateral ceph of case 15. (C) ClinCheck plans of case 15. (D) Compensatory movements planned for case 15. (E) Posterior box elastics with G5 precision bite ramps on the upper incisors. (F) Completion images of case 15. (G) Completion OPG and lateral ceph of case 15. (H) Overall and regional superimposition of case 15.

surgeons involved in the treatment planning and execution of these cases treated with the Invisalign appliance would still prefer to have �xed appliances placed a couple of months before the surgery is performed. The decompensatory, pre-surgical movements are clearly visualised and well executed by the Invisalign appliance. It is predictable and the patients and surgeons appreciate the “forecast ” of dental movements prior to the actual commencement of treatment. Surgical movements can be better planned as such.

Case 17 Case 17 is an adult Caucasian female patient that presented with an uneven bite. She was a Class-III dental and skeletal 3 base with a vertical growth pattern. There were mild degrees of upper and lower dental crowding, the lower midline and mandible were both deviated to the right side with anterior and posterior crossbites evident (Fig. 21A-B). The strength of the virtual ClinCheck treatment plan allows us to view the pre-surgical

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decompensatory movements clearly and plan the vertical and transverse corrections digitally prior to the commencement of treatment. Marginal ridge discrepancies, palatal cusps interferences, and transverse inter-arch discrepancies can all be eliminated early and ef �ciently. Optimised and conventional attachments were used; a simultaneous staging pattern was planned with a surgical simulation at the end of the active aligners (Fig. 21C). Treatment proceed with initial prescription with the Invisalign appliance. 2 months before the surgical date, �xed appliances were placed. The �xed appliances were removed 2 months after the completion of the orthognathic surgery

and re�nement aligners were ordered to complete the treatment. The surgical movements executed were maxillary advancement and posterior impaction, asymmetrical bilateral sagittal split osteotomy (BSSO), and autorotation of the mandible. After the �rst 17 aligners, �xed orthodontic appliances were placed and a surgical date was set. Model surgery and surgical splints were fabricated as usual, and the �nal surgical movements were con�rmed. 2 months postorthognathic surgery, the �xed orthodontic appliances were removed and re�nement aligners were ordered. During the re�nement stages, precision cuts were planned to allow further


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correction of the malocclusion and dental midlines (Fig. 21D). The treatment was completed in 17 months with 4þ months of �xed appliances and 27 (17 þ 10) active aligners with 1 re �nement (Fig. 21E-G).

Age-related treatment plans using the Invisalign appliance should be no different from using conventional orthodontic appliances. Considerations of treatment include the followings.  Sutural

maturity. age of the patient. Avoiding movement of teeth beyond the physiological boundaries of the dentoalveolar segments. Examine the periodontal support of the dentition. One of the advantages of using the Invisalign system is the ability to selectively orchestrate the dental movements. The velocities of every tooth can be dictated and

 Biological

Discussion Pre-treatment evaluation, case selection, and planning is of paramount importance in using the Invisalign appliance. The study of the anatomy of the dentition, biology of the subject and part psychological evaluation of the patient is the key to successful treatment.





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monitored as treatment is planned and executed. Periodontally compromised teeth can also be almost left stationary during treatment with minimum and/or no mechanical pressure.  Examine if the soft tissues can hold up against camou�age treatment.

 Examine

for suf �cient clinical crown heights for aligner adaptation.  Decide if it is necessary to have extractions.  Plan for suf �cient and appropriate attachments.  Plan for compensatory movements to overcome the side effects of the dental movements.


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Figure 20. (A) Pre-treatment images of case 16. (B) Pre-treatment OPG of case 16. (C) Images at re �nement, placement of partial �xed appliances and TAD. (D) ClinCheck plans at re�nement of case 16. (E) Completion images of case 16. (F) Completion OPG of case 16.

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Figure 20. Continued.  Do

not hesitate to use any other orthodontic auxiliaries to facilitate your aligner treatment plans.  Examine the need and extra costs involved if prosthodontic and orthognathic work were to be included.  Examine stability of the result achieved and plan for long term retention where necessary.

Conclusion With digital treatment planning and automated manufacturing, many traditional barriers of orthodontic treatment are removed. The threedimensional visualisation of the treatment outcomes, differential treatment plans and/or extraction/non-extraction treatment plans, and foreseeing Bolton’s discrepancies, assist the



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Figure 21. (A) Pre-treatment images of case 17. (B) Pre-treatment OPG and lateral ceph of case 17. (C) ClinCheck plans of case 17. (D) Re�nement arch co-ordination with precision cuts and elastic bands. (E) Completion images of case 17. (F) Completion OPG and lateral ceph of case 17. (G) Overall and regional superimposition of case 17.



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clinician in the orthodontic of �ce. However, many new clinicians tend to forget that the diagnosis and treatment planning still lies well within our responsibilities. Computer-aided treatment planning does not understand dental anatomy, biology of tooth movement, biomechanics and material properties as well as we do. The complete reliance on it will lead to undesirable treatment outcomes. We are ultimately responsible for the treatment of our patients and we must understand the strength and weaknesses of the appliance in order to exploit the best out of what is available, and offer our patients the best treatment modality possible. As with using any new appliance, treating complex cases using the Invisalign system would have a learning curve. However, thoroughly understanding the limitations of the appliance and defaults of the ClinCheck software, outstanding results can often be achieved predictably. Clear appliance therapy is here to stay.

Embracing technology without �rst applying basic orthodontic concepts is a dangerous affair and should be discouraged. Lateral thinking, and often, thinking outside the common box allows us to further our art and achieve quality treatment results, more ef �ciently.

References 1. Hampton JR. Evidence-based medicine, opinion-based medicine, and real-world medicine. Perspect Biol Med . 2002;45(4):549–568. 2. Chan E. Evaluation of 400 consecutively treated Invisalign cases in private practice setting. Unpublished data . 3. Marshall WA. The relationship of puberty to other maturity indicators and body composition in man. J Reprod Fertil . 1978;52(2):437–443. 4. Pileski RC, Woodside DG, James GA. Relationship of the ulnar sesamoid bone and maximum mandibular growth velocity. Angle Orthod . 1973;43(2):162–170. 5. Timms DJ. The dawn of rapid maxillary expansion. Angle Orthod . 1999;69(3):247–250.

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