Evolution of the force generated by gradual deflection of orthodontic wires in conventional and self-ligating brackets

• Grant number: 10/15686-7
• Support Opportunities: Scholarships in Brazil - Scientific Initiation
• Start date: January 01, 2011
• End date: December 31, 2011
• Field of knowledge: Health Sciences - Dentistry - Orthodontics
• Principal Investigator: José Fernando Castanha Henriques
• Grantee: Nayara Thiago Semenara
• Host Institution: Faculdade de Odontologia de Bauru (FOB). Universidade de São Paulo (USP). Bauru , SP, Brazil

Abstract

The aim of the study will be the evaluation of the deflection of orthodontic wires of rectangular section (0.019 "x 0.025") on conventional brackets (Morelli) and self-ligating brackets (Damon and Speed). Two trademarks of wires will be used (Morelli and GAC), in three different alloys: stainless steel, Nitinol and CooperNiti. The specimens will be assembled in a clinical simulation model, specially designed for this study, and evaluated in a Universal Testing Machine (EMIC). In an acrylic resin plate 14 devices will be attached and the brackets will placed on them. The intention is attach these devices in resemblance to the positioning of teeth in the upper dental arch, in the form of a parabola. The interval of space between them will be kept constant to avoid errors during the measurement of the force generated by the deflection of the wires. Three of these models will be made for the bonding of each set of accessories to be tested (Morelli, Damon and Speed). Then, the wires will be latched and locked by means of elastic modules (Morelli) in the case of conventional brackets. In the case of the self-ligating brackets, the seizure of the wire will be made only by closing the system, either passive (Damon) or active (Speed). For the procedures of the testing, the acrylic device representative of the right central incisor will be moved lingually, in activations of 1 to 3mm, with readings of the resistance generated by the deflection at every 0.1 mm with constant speed of 0.5 mm / min. After the deflection tests, the results will be evaluated by analysis of variance (ANOVA) to one or more criteria, with a significance level of 5% (p <0.05) for comparison between groups. In the case of significant difference, the comparative analysis of the averages will be made by using the Tukey test (p <0.05).