Dental Tribune Middle East & Africa Edition | 4/2020 ◊Page E2 ORTHO TRIBUNE E3 Key cephalometric values: Measurement (deg) Initial Progress Norm Std Dev SNA SNB ANB U1-NA L1-GoGn Interincisal SN-GoGn 82.3 75.5 6.9 17.4 100.8 127.2 32.3 84.0 79.3 4.7 23.4 102.9 120.1 29.6 82 80 2.0 22 93 135 32 2.0 2.0 1.5 2.0 3.0 6.0 4.0 Cephalometric superimposition (using Sella-Nasion registered at Sella) Final Records open bite during the mandibular advancement phase is common, and can be corrected through arch leveling with additional aligners, or by initially leveling the arches with aligners through a pre-mandibular advancement phase. to complete the sagittal correction to Class I. All remaining rotations were fully resolved during addi- tional aligners. The total treatment time for this patient was 21 months (11 months for the mandibular-ad- vancement phase, 1 month for tran- sitional aligners awaiting additional aligners, and 9 months for addition- al aligners with standard Invisalign treatment), which is well within the expected treatment time for this se- verity of Class II malocclusion. Bilateral Class I occlusion was achieved, along with coincident mid- lines and normal overbite and over- jet. A reduction in facial convexity resulted in a pleasing soft-tissue pro- fi le. The patient’s dental alignment, smile arc, and fi nal occlusion were all excellent. Cephalometric analysis summary (initial to fi nal): The ANB angle im- proved by 2.4˚. The interincisal angle decreased from 127.2˚ to 116.8˚, as a result of a +8˚ change in upper inci- sor inclination and +4˚ increase in lower incisor inclination. Mandibu- lar autorotation led to a -4.4˚ reduc- tion in SN-GoGn. Treatment Summary • Total treatment time: 21 months (includes 1 month in between man- dibular advancement phase and additional aligners) • Pre-mandibular advancement aligners: not used in this treatment • Mandibular advancement align- ers: upper: 27, lower: 27, changed biweekly (11 months total) • Additional aligners: Upper: 19, Lower: 19, changed weekly (9 months total) • Retention: Vivera retainers at night only Discussion The Invisalign treatment with man- dibular advancement can be a rou- tine treatment modality for any growing Class II teen. This treatment approach enables the incisors to be aligned at the same time that the bite is being advanced. Proper incisor alignment was the key to success in this case, since removing any ante- rior interferences allowed the man- dible to come forward into an ideal overbite and overjet relationship. Setting up the mandibular advance- ment in the ClinCheck treatment plan to a “super” Class I or mild Class III cuspid relationship would be rec- ommended for treating any similar cases in the future, in order to further reduce the use of Class II elastics dur- ing additional aligners. Adding suf- fi cient lingual root torque to the up- per incisors is also recommended, so that enough clearance in the overjet is present for a stable Class I position to be established. Having a posterior thoughts and Summary Overall learnings about how to be successful with us- ing the mandibular advancement feature, and what to focus on dur- ing the mandibular advancement phase: Remove interferences through dental alignment, leveling of the curve of Spee, and lingual root torque of the upper incisors. anterior Case selection recommendations when starting to use this feature: A good malocclusion to initially tar- get is a dental Class II with a skeletal Class I normo-divergent or mildly hyperdivergent growth pattern. An ANB < 5 degrees and mild-to-mod- erate mandibular retrognathism are also helpful. What kind of cases to try after that: As your familiarity with the mandib- ular advancement feature increases, try treating growing teens with more severe Class II malocclusions, and with more severe hyperdivergent growth patterns. Patients with se- vere skeletal Class II or severe vertical growth patterns can be treated, but results so far have been progressive- ly less predictable with worsening skeletal patterns. What kind of conditions are fa- vorable and unfavorable for treat- ment using this aligner feature? The more easily the lower jaw can move straight forward without inter- fering with the upper jaw, the better. Identify any interferences (anterior and transverse usually) and elimi- nate them as early as possible during the alignment phases of treatment. For patients with deeper overbites and/or retroclined upper incisors, using a series of pre-mandibular ad- vancement aligners to reduce ante- Key cephalometric values Measurement (deg) Initial Progress Final Norm Std Dev SNA SNB ANB U1-NA L1-GoGn Interincisal SN-GoGn 82.3 75.5 6.9 17.4 100.8 127.2 32.3 84 79.3 4.7 23.4 102.9 120.1 29.6 84.8 80.3 4.5 25.4 105.1 116.8 27.9 82 80 2.0 22 93 135 32 2.0 2.0 1.5 2.0 3.0 6.0 4.0 References 1. Janson, G., Sathler, R., Fernandes, T., Branco, N., de Freitas, M., Correction of Class II malocclusion with Class II elastics: A systematic review, Am J Orthod Dentofacial Orthop, 2013; 143: 383-392. 2. The current Invisalign product is now confi gured for 1-week aligner changes. At the time of treatment, the aligners were changed every two weeks. 3. After the mandibular advance- ment phase, the patient switched from 2-week aligner changes to the current 1-week aligner change inter- val. rior interferences is key to correcting the sagittal relationship. What was learned from treating this particular case? 1. Setting up the bite correction goal to a “super” Class I in the ClinCheck treatment plan may reduce or elimi- nate the need for Class II elastics dur- ing the additional aligner phase. 2. Greater leveling of the curve of Spee in a pre-mandibular advance- ment phase may reduce the likeli- hood of having a posterior open bite at the end of the mandibular advancement phase. Common challenges/problems ex- perienced during teen treatment with this aligner feature: Leveling the curve of Spee and man- dibular advancement cannot be ac- complished simultaneously during the bite correction phase, so these corrections need to be done sequen- tially instead. How to avoid or correct these is- sues? Spend the fi rst 3 to 5 months leveling and aligning the arches with aligners in a pre-mandibular advancement phase. About the author Dr Barry J. Glaser Barry J. Glaser, DMD received his doctorate in dental medicine from The University of Pennsylvania School of Dental Medi- cine and earned a certifi cate of Advanced Graduate Studies in Orthodontics from Boston University. He served as associate director of orthodontics at Montefi ore Medical Centre in New York City from 1992 to 1995. He has been in private prac- tice in Cortlandt Manor, NY, since 1994. Dr. Glaser was an early adopter of Invisalign Teen® and has extensive experience with treating teens and adults of all malocclu- sions using Invisalign aligners. Three key take away points: 1. A pre-mandibular advancement phase to level, align, and fl atten the curve of Spee can reduce the chances of having a posterior open bite after the bite correction phase. 2. Overcorrect the sagittal relationship in the ClinCheck setup to a “super” Class I during the mandibular advancement phase, in or- der to reduce the need for interarch elastics during refi nement. 3. Build precision cut elastic hooks into the additional aligners just in case Class II elastics are needed at or near the end of treatment. Having the majority of the Class II correction accomplished with the precision wings feature means that any Class II elastics used are mostly for stabilizing and fi ne tuning the bite during additional aligners.