Failure of Fiber Reinforced Composite Archwires

Abstract

The objective of this article is to investigate the mechanical properties and surface morphology of fiber-reinforced composite (FRC) wires. FRC (Optis) wire and a NiTi 0.016 in diameter were evaluated with a 3-point bending test on a universal testing machine at temperatures of 23±1oC and 37±1oC. The sample was cut to a size of 30mm and divided into 5 groups, each consisting of 6 specimens. Group 1, 2 and 5 were tested at 3.1-mm deflection, groups 3 and 4 at 1.5mm deflection. The hysteresis curves were compared and the surface morphology of the FRC wires was observed by SEM. Clear breakages occurred between fibers and Polymethylmethacrylate (PMMA) matrix union between 1.5-mm and 2.0-mm deflection. Before 1.5-mm, the wires showed no significant changes in their surface structure. The flexural load required to produce a deflection of 1.5 mm on NiTi was near double that for the FRC wires. ANOVA indicated differences (P .05). FRC wires displayed comparable load-deflection curves to NiTi until deflection of 2.0mm, whereas it could be considered a viable alternative to metallic wires during mild irregular alignment situations. Failure occurs due to fibers pullout and breakage at the fiber/composite matrix interface.