[Comparison of clear aligners and customized lingual appliance for bimaxillary dentoalveolar protrusion: a retrospective study].

PURPOSE:To compare the treatment effects of clear aligners and customized lingual appliance on treating bimaxillary dentoalveolar protrusion patients with first premolar extractions. METHODS:Fifty-four patients with bimaxillary dentoalveolar protrusion treated in Shanghai Ninth People Hospital were involved in the retrospective study. Twenty-five cases used clear aligners and 29 cases used customized lingual appliance. All of them were treated by extracting 4 first premolars and retracting anterior teeth with strong anchorage. The changes of anterior tooth and soft tissue adduction before and after treatment were compared by lateral cephalometric measurements. SPSS 26.0 software package was used for data analysis. RESULTS:The total course of treatment in the clear aligners group (46.32±7.37 months) was about 10.8 months longer than that in the customized lingual appliance group (35.55±5.90 months) (P＜0.05). There was no significant difference in upper incisor retraction, lower incisor inclination and overjet reduction between the two groups(P＞0.05). There were significant differences in upper lip retraction, lower lip retraction, upper incisor torque reduction, and overbite reduction between the two groups(P＜0.05). Customized lingual appliance group showed a significant improvement of lips retraction and overbite reduction in orthodontic treatment. For the correction of overjet, there was no significant difference between the two groups (P=0.337). The data of U1-OP (the distance between edge of the upper central incisor and the functional occlusal plane) was not in normal distribution, and there was no significant difference between the two groups(P=0.184). CONCLUSIONS:The two techniques can both retract the anterior teeth and lips to improve the profile. However, the customized lingual appliance was more effective in improving the soft tissue profile of patients with bimaxillary dentoalveolar protrusion, with shorter treatment course.