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

ABSTRACT 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 t-test 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.

Efficacy of swm appliance in the expression of first-, second- and third-order information in Class I and Class II.

BACKGROUND: To assess the efficacy of a multibracket appliance-Straight-wire Mirabella (SWM) prescription-in terms of achieving the ideal first-, second- and third-order values proposed by Andrews. MATERIAL AND METHODS: A total sample of 46 Caucasian subjects was divided into two groups: 23 with class I malocclusion (Group 1), and 23 with class II malocclusion (Group 2). The treatment protocol involved fixed multibracket appliances-SWM prescription-for both groups, with the addition of class II elastics for Group 2. Values for ΔU1-PP, ΔIMPA, in-out, tip and torque were measured on digital scans, and the results obtained were compared with the ideal values proposed by Andrews. RESULTS: Statistically significant differences were revealed between the entire sample and Andrews' values for: in-out on upper lateral incisors and upper canines; tip on the upper first premolars, upper second premolars, upper first molars and upper canines; and torque on the lower central incisors, lower lateral incisors, lower canines and lower first premolars. However, comparison of Groups 1 and 2 revealed statistically significant differences only at the lower lateral incisors. The use of class II elastics influenced ΔIMPA values, but not ΔU1-PP. CONCLUSIONS: The efficacy of the multibracket appliance-SWM prescription-in expressing first- second- and, to a lesser extent, third-order information was demonstrated in both class I and class II malocclusions. Class II elastics only influenced the third-order expression on the lower lateral incisors and the ΔIMPA. Key words:Straight wire fixed appliances, prescription efficacy, Class I malocclusions, Class II malocclusions.