Effect of conventional versus passive self-ligating vestibular appliances on torque, tip and transverse dental changes in patients affected by class I malocclusion: A retrospective study

Objective: To evaluate the effects of passive self-ligating appliances (PSLAs) and conventional ligating appliances (CLAs) during orthodontic treatment regarding torque, tip, and transversal dental changes. Material and Methods: Dental parameters were digitally acquired from pre-and post-treatment models of each subject belonging to two groups of patients treated with PSLAs (23 patients; 11 females and 12 males with a mean age of 14.2 ± 1.6 years) and CLAs (18 patients; 10 females and 8 males with a mean age of 14.3 ± 1.9 years), respectively. All subjects had Class I or slight Class II malocclusion (≤ 2mm), permanent dentition and no previous orthodontic treatment. After normality of data was assumed, a paired sample ttest rejected any side differences at T0 and, therefore, the data were grouped by tooth group. Statistical analyses were performed using a linear mixed-effect framework, assuming the appliance, time, and interactions as fixed effects and the tooth type as random effects. Finally, post-hoc effect analysis was used to contrast modeled marginal effects (p<0.05). Results: For both appliances, there is a general increase of both torque and transverse values at T1, especially for PSLAs. Tip shows a general reduction in the lateral sectors for both appliances is registered. The only significant statistical difference referred to appliances’ efficacy is located to mandibular intermolar width. Conclusion: Both appliances have an expansive potential for both torque and transverse dental changes. No evident differences are detectable between appliances except for the rate of the mandibular intermolar width increase.