Class II Malocclusion in Adult Patients: What Are the Effects of the Intermaxillary Elastics with Clear Aligners? A Retrospective Single Center One-Group Longitudinal Study

Abstract

Aim: To evaluate the dental effects of the treatment with clear aligners and intermaxillary elastics in adult patients with Class II malocclusion. Material and methods: A sample of 20 Class II patients treated with Invisalign aligners (5 M and 15 F; mean age of 27.6 ± 6.3 years) was included in this single-center one-group longitudinal study. Dental cast and cephalometric records were analyzed before (T0) and after treatment (T1). Data were analyzed with a T-test for paired data (p < 0.05). Results: There was a significant reduction of the Overjet (OVJ= −1.4 ± 0.2; p = <0.001) and a retroposition of upper incisors (U1-NPo = −1.3 ± 1.7; p < 0.001). Furthermore, distalization of upper molars with an improvement of molar class (U6-PT Vertical = −0.93 ± 0.97; p < 0.001; Molar Relation = −0.75 ± 0.45; p < 0.001) was observed. A good control of the lower and upper incisor inclination was present, highlighted by the non-significant changes in these values (L1-GoGn = −0.12 ± 5.4; p = 0.923; U1-AnsPns = −1.1 ± 8.1; p = 0.551). In the lower arch, an increase in the intermolar diameter (0.6 ± 1.0; p = 0.01) was present. Finally, there were no statistically significant changes in all the skeletal variables (ANPg = 0.005 ± 0.687; p = 0.974; SN/MP = −0.47 ± 1.9; p = 0.298). Conclusions: Treatment with Invisalign aligners shows a reduction of the Overjet, a retroposition of the upper incisors, good control of the lower incisors, and an improvement of the molar relationship.

Predictability of Maxillary Molar Distalization and Derotation with Clear Aligners: A Prospective Study

“…In our study, patients were asked to wear elastics bilaterally for 24 h of the day. Often, in clinical settings, Class II elastics are used as anchorage reinforcement and to improve the distalization achieved by the aligners, [21,22] but it is difficult to evaluate how much distalization is due to the aligner and how much is due to the elastics.…”

“…Intraoral fixed appliances, such as the pendulum appliance and distal jet [17,18], were introduced as more aesthetically-acceptable alternatives to headgear, since they minimize or eliminate the need for compliance; by using the palate, teeth, or both as sources of anchorage, the main side effect is anterior anchorage loss [19]. Moreover, intermaxillary Class II elastics and other intraoral fixed appliances (Herbst, Forsus) could be used to improve a molar Class II relationship in children and adolescents, but the main outcomes involve dental advancement of the mandibular arch [20][21][22].…”

Clear Aligners Treatment of Class III Subdivision with an Extraction of a Lower Bicuspid

“…Consequentially, they opted for an alternative approach with the extraction of two lower and one upper premolar in order to center the lower dental midline with the upper one and to obtain a molar and canine Class I on the Class I side and a molar Class III and canine Class I relationship on Class III side, with a minimal use of inter-maxillary elastics. Brunetto et al [ 25 ] presented a case of Class III subdivision malocclusion, managed as a non-extractive treatment, with the use of Class III elastics 24 hours per day applied on one side only; however, the long-term use of unilateral inter-maxillary elastics may lead to undesired effects on both arches, such as the extrusion of the teeth involved, resulting in a canting of the occlusal plane [ 27 ]. Zimmer et al [ 26 ] demonstrated that treating Class III malocclusion by the isolated extraction of lower premolars could be a valid alternative.…”

Predictability of tooth rotations in patients treated with clear aligners

“…Clear aligner therapy has become quite popular and nowadays are used to treat various kinds of malocclusion such as Class II, Class III and interdisciplinary cases 1 – 6 also considering some of their advantages such as greater ease to maintain good gingival health, lower impact on general well-being and less visibility 7 , 8 . However, despite the wide use of aligners, they still present an extreme variability in the movement accuracy 9 .…”