Class II Distalisation Staging Comparison in Twins Using the Invisalign System

Case Report

Dr Mike Anderson BDS (Hons), MDSc (Orthodontics)

This case report is intended for dental and healthcare professionals, and is subject to applicable local laws, regulations and guidelines. INVISALIGN, CLINCHECK, and ITERO ELEMENT, among others, are trademarks and/or service marks of Align Technology, Inc. or one of its subsidiaries or affiliated companies and may be registered in the U.S. and/or other countries. Clinical findings • Both twins required approximately Refinement phase 5 mm A-P correction. Segmental • Twin A presented with a Class II division New records were taken with the distalisation was used for Twin A Twin brothers (Twin A and Twin B), aged 14 years and 8 months, presented with Class II 1 dental relationship accompanied iTero Element Scanner for refinement and en-masse distalisation for with Class II buccal segments. He had treatment. The 3-month refinement Twin B. Pre-Invisalign sagittal malocclusions. The boys sought treatment to improve their dental aesthetics. Neither wanted an overjet of 12 mm and a deep bite phase aimed to achieve better settling correctors can be used in severe with mild crowding of both arches. All of the posterior occlusion and further to be treated with fixed orthodontic appliances or functional appliances. Hence, moderately cases (4+ mm); however, with close his third molars remained unerupted, torque control of the upper incisors. monitoring, aligners and elastics alone heavy Class II elastics with aligners were recommended to correct their dental malocclusion. there was a lower lip trap at rest and a can also achieve the A-P correction. brachyfacial tendency pattern. • Control of the deep bite was undertaken Treatment details • Twin B presented with a Class II division to ensure A-P correction was not Active treatment time for both patients 1 dental relationship accompanied with hindered. Optimised Attachments and • Initial treatment phase: 14 months. Class II buccal segments. He had an horizontal rectangular attachments • Refinement phase: 3 months overjet of 9 mm and a deep bite with were used to extrude premolars. I. Intra- and extra-oral images before treatment Clinical presentation pronounced crowding. All his third Overcorrection of the deep bite was built Aligners and attachments Both twins presented with large molars remained unerupted, there was a into the ClinCheck treatment plan. lower lip trap at rest and a brachyfacial Initial treatment phase Instructions were given to wear the overjets, deep bites and crowding tendency pattern. • aligners with Class II elastics at all Composite resin attachments were Pre-Treatment of their teeth. times during the treatment period. bonded at the start of aligner treatment. (Twin A) Treatment goals • Class II elastics were attached to Twin A III. Cephalometric radiograph • Correct large overjet. Precision Cuts hooks on the upper • 85 active upper aligners, 19 active before treatment • Obtain near Class I occlusion. canines and on the lower first molars. and 66 passive lower aligners plus 3 Attachments were used on the lower • Correct deep bite. virtual c-chain aligners were planned. molars to prevent the elastics from However, not all aligners were used • Relieve crowding. lifting the lower aligner off the teeth. prior to refinement. Aligners were The elastics were worn from the changed every 5 days. time the first aligner was prescribed. Treatment approach • Optimised Attachments, conventional Each elastic was 1/4” 3.5 oz and after attachments, Precision Cuts hooks and Initial treatment phase approximately 6 months of treatment, button cutouts were used. • Impressions with polyvinyl siloxane they were advanced to 3/16” 3.5 oz. (PVS), intra-oral images and dental Both patients were advised to use new Twin B radiographs (orthopantomogram and elastics every day. • 60 active upper aligners, 46 active lateral cephalogram) were used for Pre-Treatment developing a ClinCheck treatment plan. V. Intra- and extra-oral images after treatment (Twin B) • Dental expansion and incisor Twin A Twin B proclination are preferred over interproximal reduction (IPR) in teenagers. Therefore, for these IV. Staging patterns patients, no IPR was planned. No Post-Treatment additional auxiliaries, except Class (Twin A) II elastics, were used to treat either patient. No partially fixed appliances were used. • The ClinCheck 3D models showed that the upper central incisors required more intrusion than the upper lateral II. Initial ClinCheck treatment plan incisors. To prevent over-intrusion of the upper lateral incisors, conventional attachments were added to them. • The ‘Tooth Movement Assessment’ (TMA) showed that the Twin A – Segmental distalisation anteroposterior (A-P) correction was more than 4 mm and, therefore, classified as a ‘black’ advanced Post-Treatment movement on the TMA. The rotation (Twin B) Twin A on tooth 42 for Twin B was greater than 50º. A vertical rectangular attachment was added to improve the predictability of this movement. The ClinCheck treatment plan for Twin A revealed that teeth 31 and 41 required intrusion of greater than 3 mm. This was supported by conventional rectangular attachments on the lower Twin B Twin B – En-masse distalisation premolar teeth.

This case report is intended for dental and healthcare professionals, and is subject to applicable local laws, regulations and guidelines. This case report is intended for dental and healthcare professionals, and is subject to applicable local laws, regulations and guidelines. INVISALIGN, CLINCHECK, and ITERO ELEMENT, among others, are trademarks and/or service marks of Align Technology, Inc. or one of INVISALIGN, CLINCHECK, and ITERO ELEMENT, among others, are trademarks and/or service marks of Align Technology, Inc. or one of its subsidiaries or affiliated companies and may be registered in the U.S. and/or other countries. its subsidiaries or affiliated companies and may be registered in the U.S. and/or other countries. VI. Final ClinCheck treatment plan VII. Cephalometric radiograph after treatment

Twin A

Twin A Twin B

features could have been used for these Twin B cases, but were not available at the time. The benefit of using these features would have and 16 passive lower aligners plus 3 Clinical tips been that Class II elastics would not have virtual c-chain aligners were planned. been required, increasing the predictability of • The twins presented for orthodontic the outcome by eliminating the compliance However, not all aligners were used treatment at the age of 14 years and 8 factor associated with wearing elastics. prior to refinement. Aligners were months. Ideally, orthodontic treatment changed weekly. should have commenced approximately • Optimised Attachments, conventional 2 years earlier to ensure continued Conclusion attachments, Power Ridge features, growth over the treatment period. Twin brothers (Twin A and Twin B) aged 14 Precision Cuts hooks and button • A clinician’s choice of either elastic hooks years and 8 months presented with Class cutouts were used. or buttons for anchorage of the elastics II malocclusions. Their overjets measured • Deep bite pressure area for intrusion is unlikely to affect the magnitude of the 12 mm and 9 mm, respectively, and the on teeth 12–22 and 33–43. A-P correction. Elastic hooks can cause buccal segments required A-P correction Refinement phase the aligners to lift off the teeth and some of approximately 5 mm. In addition, both patients may find it difficult to re-attach cases had deep bites, which required Twin A the elastics. The alternative use of careful control for the correction of Class II • 14 upper and lower additional aligners. buttons are subject to bond failure, but malocclusions. Treatment involved the use The aligners were changed weekly. can ease placing of the elastics. of Invisalign aligners and Class II elastics; • Optimised Attachments, a conventional • Both en-masse and segmental no Class II correctors or other auxillaries attachment, Precision Cuts hooks and distalisation, supported by Class II elastics, were used. Total treatment duration was button cutouts were used. resulted in significant A-P correction 17 months, which included one refinement Twin B with similar outcomes for both patients. phase. Clinical photos reveal correction • 13 upper and lower additional aligners. Significant A-P correction was achieved of the overjet and deep bite, and the The aligners were changed weekly. with only the aligners and Class II elastics. buccal segments finished in a near Class • Optimised Attachments, conventional • Class II malocclusions can be I relationship. Invisalign treatment with attachments, Precision Cuts hooks and successfully treated with Invisalign distalisation and Class II elastics resulted button cutouts were used. aligners when the deep bite is controlled in a favourable outcome for both twins with from the start of treatment. severe Class II malocclusions. Treatment outcome Author disclosure Impact on clinical practice • The comparison of pre-treatment and Dr Mike Anderson was provided an honorarium from The results for both twins compare Align Technology, Inc., for his contribution towards the post-treatment results indicated that the creation of this case report. large overjet, deep bite and crowding were favourably with what would have been fully corrected in both boys. In addition, obtained with the use of fixed appliances Dr Mike Anderson and Class II correctors. The results are they both achieved near Class I buccal Mike Anderson graduated with a Bachelor of Dental segments and significant improvement in also comparable with what would have Science with Honours at the University of Queensland, been obtained with two phase orthodontic where he went on to also complete his Master of Dental the Class II dental relationship. treatment, where a functional appliance is Science (Orthodontics). Upon graduating, Dr Anderson • The A-P was successfully corrected in worked at two major public hospitals and was a visiting used for the first phase. The treatment time lecturer at the University of Queensland Dental School. both cases with en-masse distalisation in both cases was equivalent or less than Dr Anderson has Australian Orthodontic Board for Twin A and segmental distalisation for that achievable with fixed appliances or two- certification and lives in Brisbane, where he runs three Twin B. busy single-provider practices. He has treated close to phase treatment. With regard to treatment 1,000 Invisalign cases and is a Diamond Tier Provider. • Further settling of the posterior teeth methods, the use of en-masse or segmental Dr Anderson was selected to be a moderator at the was required. The patients chose to be distalisation with Class II elastics, for 2016 Asia Pacific Invisalign Summit and has presented treated with bonded lingual retainers, to Australian and New Zealand orthodontists on the growing patients, will likely yield equivalent Invisalign System in several online education sessions which would help with the settling of the results . Invisalign treatment with Mandibular in 2017. Dr Anderson was chosen as a moderator at the posterior occlusion over time. Advancement and the new Precision Wings EMEA Invisalign Summit 2017.