The effect of different bonding and debonding techniques on debonding ceramic orthodontic brackets

Abstract

Previous studies have indicated that different bonding and debonding techniques affect the removal or detachment of polycrystalline ceramic brackets that use a mechanical mechanism of bonding to resin. The delamination type debonding forces have been shown to be more effective, compared with twisting and tensile type forces. Further, polycrystalline brackets bonded by the indirect techniques debond leaving minimal filled resin on the tooth surface and hence cleanup and enamel damage are minimized. The purpose of this research was to compare the effects of three bonding and debonding techniques on debonding two types of ceramic brackets, using different modes of bonding. The monocrystalline bracket used the chemical and the polycrystalline bracket used the mechanical mechanisms for bonding respectively. Brackets were bonded to 180 freshly extracted bovine teeth, divided into two groups of 90 each, based on the bracket employed, i.e., monocrystalline and polycrystalline brackets. These brackets were bonded with the direct and two different indirect bonding methods: the conventional indirect method (modified Thomas) and the indirect technique that used a thermally cured resin. Each bonding group was further divided into three groups of 10, based on the type of debonding technique used, i.e., lift off, delamination, and twisting. The variables evaluated were bracket failure and remnant adhesive on debonding. The data were subjected to an analysis of variance to determine existence of significant differences, followed by multiple comparisons of means. Bracket failure or fracture was significantly affected, based on the bonding technique and the debonding technique for the monocrystalline at p < 0.0001 and the polycrystalline ceramic brackets at p < 0.001 and p < 0.05, respectively. Remnant adhesive was significantly affected by bonding and debonding techniques for the polycrystalline brackets at p < 0.0001. Remnant adhesive was significantly ( p < 0.01) affected by the bonding technique for the monocrystalline brackets. The delamination debonding technique combined with the thermal-cured indirect bonding technique was shown to be a safe combination for debonding both types of ceramic brackets. Therefore both bonding and debonding techniques significantly affect bracket failure or fracture and remnant adhesive of ceramic orthodontic brackets during the debonding procedure.