Abstract
Proposition: The objective of this study was to compare changes in maxillary and mandibular dental arch dimensions in cases treated nonextraction with conventional appliances and self-ligating Damon System. Materials and Methods: initial (T1) and final (T2) dental casts of 45 patients with Class I malocclusion treated nonextraction, with slight to moderate crowding, divided into two groups. Group 1: 21 patients treated with self-ligating Damon appliances, at a mean initial age of 18.37 years and mean treatment time of 2.11 years. Group 2: 24 patients treated with conventional appliances, at a mean initial age of 19.50 years and mean treatment time of 1.99 years. The model analysis was performed; Little irregularity index was used to evaluate crowding and arch form was evaluated by measurements in maxillary and mandibular arches including intercanine, interpremolar (first and second premolars) and intermolar distances and arch length. The intragroup comparison was performed with dependent t or Wilcoxon tests and intergroup comparison, with independent t or Mann Whitney tests. Results: In intergroup comparison of treatment changes (T2-T1) the Damon group presented an increase in maxillary transversal dimensions significantly greater than the conventional group. The change in maxillary arch length did not show difference between the groups. Regarding the mandibular arch, the Damon group presented a significantly greater increase in intercanine and inter first premolars than the conventional group. In The mandibular arch length, the greater and significant increase was observed in the groups of patients treated with conventional appliances. Conclusions: The treatment with the Damon appliances resulted in a significantly greater increase of maxillary arch dimensions when compared to conventional appliances. Mandibular intercanine and interpremolar distances also presented greater increase in Damon than conventional appliances. The increase in mandibular arch length was greater in conventional than in Damon group.
Highlights
The self-ligating appliances, introduced in the 1930s by Stolzenberg, are bracket systems that do not use ligatures, featuring a built-in mechanical device for closing the slot [1]
The sample calculation was based on an alpha significance level of 5% (0.05) and a beta of 20% (0.2) to achieve 80% test power in order to detect a mean difference of 1.46mm with a standard deviation of 1.66 for the mandibular intercanine and intermolar distances [8], evidencing that 21 patients would be necessary for each group
For the maxillary intercanine distance, in the intergroup comparison, at the beginning and at the end of the treatment, there was no significant difference in the increase obtained (Table 4 and Table 5)
Summary
The self-ligating appliances, introduced in the 1930s by Stolzenberg, are bracket systems that do not use ligatures, featuring a built-in mechanical device for closing the slot [1]. The primary advantage of self-ligating brackets is the possibility of generating less friction with the orthodontic wire during tooth movement, allowing orthodontic movements to be achieved with the application of lighter forces, causing less damage to adjacent tissues, besides the less time of chair released in the appointments. The use of low-friction brackets such as the Damon System, associated with wires of lighter forces produces a greater expansion in the posterior region of the arch, with less alteration in the intercanine distance and position of the mandibular incisor than the conventional appliances [4, 5]
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