Evaluation of the force generated by gradual deflection of orthodontic wires in conventional mettalic, esthetic and self-ligated brackets

Author(s)

Manoela Fávaro Francisconi

• Document type: Doctoral Thesis
• Press: Bauru.
• Institution: Universidade de São Paulo (USP). Faculdade de Odontologia de Bauru (FOB/SDB)
• Defense date: 2014-07-21

Examining board members

Jose Fernando Castanha Henriques; Analu Giampietro Brandão; Daniela Gamba Garib Carreira; Alexandre Fortes Drummond; Karina Maria Salvatore de Freitas

• Advisor: Jose Fernando Castanha Henriques

Abstract

OBJECTIVE: The purpose of this study was to evaluate the deflection forces of Nitinol orthodontic wires, placed in different kinds of brackets by assessing strength values variation according to gradual increase in the diameter and the deflection of the wires, comparing the different combinations, in the different deflections. MATERIAL AND METHODS: Specimens were mounted in a clinical simulation model and evaluated in a Universal Testing Machine (INSTRON 3342), using a 10 N load cell and, as a protocol, ISO 15841. Five of these models were prepared, each one for the bonding of each set of accessories to be tested: metallic (Mini Diamond), reinforced polycarbonate with metallic slots (Spirit), sapphire (Inspire ICE), and passive (Damon Q/Ormco) and active self-ligated (In-Ovation R/GAC). For performing the tests, the acrylic device corresponding to the right central incisor was moved in the buccal-lingual direction, and values of resistance generated for 3, 2, 1 and 0.5mm deflections, at a constant speed of 2mm/min, were registered. Data were subjected to Oneand Two-way ANOVA; since significant differences were observed, comparative analysis of mean values was performed by Tukey\'s post hoc test (p<0.05). RESULTS: Elastic deflection results showed that deactivation force increased with increase in the diameter of the wires and deflection in the different brackets evaluated. For the combinations of the different types of brackets with the Nitinol wires, it was found that self-ligating brackets were those with the most similar results to each other, which decreased as the deflection was decreased. For Mini Diamond, Spirit and Inspire ICE conventional brackets there was no pattern for any of the deflections studied. CONCLUSIONS: Strength values evaluation according to gradual increase in the diameter and the deflection of the wires showed that it increased in all evaluated brackets. Self-ligating brackets were those which presented the most consistent and predictable results while for others kinds of brackets such pattern was not observed. (AU)

• FAPESP's process: 11/14346-0 - Evaluation of the force generated by gradual deflection of orthodontic wires in conventional mettalic, esthetic and self-ligated brackets
• Grantee: Manoela Fávaro Francisconi
• Support Opportunities: Scholarships in Brazil - Doctorate