Efficacy of clear aligners on mandibular molar distalization: A retrospective study

Abstract

Background: Clear aligners (CAs) can distalize mandibular molars. The present study aimed to study the efficiency and influencing the factors of CAs for mandibular molar distalization and to provide guidance for clinical design. Materials and Methods: The present study evaluated 32 adult orthodontic patients who needed mandibular molar distalization and were treated with CAs between September 2018 and September 2020 at the school of medicine. The cone-beam computed tomography images of T0 (before orthodontic treatment) and T1 (after mandibular molars were fully distalized) were collected, and the actual movements of mandibular molars were measured and compared with the expected movements. The efficiency of mandibular molar distalization during treatment was comprehensively evaluated, and the relevant factors were analyzed. Results: For mandibular first molar distalization, the average efficiency of the crown was 67.19% 9swn. 13%, and that of the root was 37.87% 7stn. 72%. There was a significant difference between the achieved movement amount and the expected amount (P < 0.05). For mandibular second molars, the average efficiency of the crown was 58.47% 7swn. 07%, and that of the root was 57.03% 3stn. 48%. There was a statistically significant difference between the achieved movement amount and the expected amount (P < 0.05). There was a significant negative correlation between the expected movement and the efficiency of the crown. Conclusions: CAs can achieve mandibular molar distalization, and the movement pattern of molars is mainly a tipping movement. To accomplish bodily movement, overcorrection should be fully considered. In addition, it is suggested that close attention should be given to observing root movement during molar distalization.