Comparison of Arch Expansion Changes Between Passive Self-ligating and Conventional Brackets With Broad Arches After Alignment and Levelling With the Same Arch Protocol: A Randomized Controlled Trial

Fifty-four subjects were randomly with an electronic randomization program allocated to treatment with either a self-ligating bracket system (Damon Q-slot 0.022", Ormco Corp,) or a conventional bracket system (Orthos-slot 0.022", Ormco Corp). All patients were treated following the same protocol and arch wire sequence: 0.014-inch, 0.018-inch and 0.014x0.025-inch Damon copper nickel-titanium arch wires (Cu-NiTi; Ormco). Lateral cephalograms and study models, taken at prior to treatment (T0) and after alignment and levelling (T1), were used to compare the amount of arch expansion and incisor angulation changes that took place. In the analysis of results in a single observer analyzes the data blindly without knowing which group the patients belonged. Results: Models and cephalograms of the patients and both stages(T0-T1) were measured at the data were analyzed in STATA S.E. Treatment produce statistically significant increases in transverse arch dimensions especially in premolars maxillary (2.8-4.3mm) and mandibullary (2.0-4.2mm) of both group. The expansion in the maxillary arch was similar for both groups, but in the mandibular arch was greater in the self ligation group in about 2 mm more. Conclusions: The treatment with self ligation brackets produced more expansion in the mandibular arch than the conventional ligation brackets when used the same arch Damon protocols.