The purpose of this study is to evaluate the deflection forces of orthodontic wires, of round 0.016" and rectangular 0.019" x 0.025", placed in conventional metallic, porcelain, sapphire (Ormco) and self-ligated (Damon Q/Ormco e In-Ovation R/GAC) brackets. Ormco's trademark wires will be used in two different alloys, stainless steel and Nitinol. The specimens will be mounted in a clinical simulation model created especially for this study evaluated in an Universal Testing Machine (EMIC). Brackets will be bonded to 14 acrylic devices, which will be fixed in an also acrylic resin plate. These devices will be fixed to resemble the positioning of the teeth in the maxillary dental arch, in parable form, and space interval between them will be kept constant to avoid errors in measuring the force generated by the deflection of the wires. Five of these models will be made for the bonding of each set of accessories to be tested: metallic (Mini Diamond), porcelain (Inspire), sapphire (Inspire ICE), and passive (Damon Q / Ormco) and active self-ligated (In-Ovation R/ GAC). Then, wires will be fit and fixed, with the aid of elastic modules, in the wings of the conventional brackets. For either the passive (Damon) or the active (GAC) self-ligating brackets, wire fixing will be accomplished only by closing the system. For performing the tests, the acrylic device corresponding to the right central incisor will be moved in the buccal-lingual direction, in activations from 1 to 3 mm, and values of resistance generated by the deflection every 0.1 mm, at a constant speed of 0.5mm/min, will be registered. Data will be subjected to analysis of variance (Three-way ANOVA), at a significance level of 5% (p <0.05), for comparison among groups. If significant differences are observed, comparative analysis of mean values will be performed by the Tukey test (p <0.05).
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