Shear bond strength of recycled orthodontic brackets treated by variable reconditioning methods

Yim, Jang Bin; Lee, Jin Woo; Cha, Kyung Suk

Abstract

The purpose of this study is to find the optimal reconditioning method for a debonded bracket base. In this study, metal brackets and ceramic brackets are used. There are devided into five groups by reconditioning methods (A : control(new bracket), B : heat treated, C : grinded with green stone, D : sandblasting for four seconds, E : sandblasting for eight seconds). Each reconditioned brackets were bonded and shear bond strength was measured by universal testing machine. After debonding, enamel surfaces were examined under stereoscopic microscope to determine the adhesive remnant index. The Microstructure of reconditioned bracket were examined by SEM (JSM 5200, Japan) and stereoscopic microscope (SZ-ST, Japan). 1. In metal bracket groups, sandblasting for eight seconds revealed the greatest shear bonding strength and its strength was above that of control group. 2. In ceramic bracket groups, sandblasting for eight seconds revealed the greatest shear bonding strength but its strength was below that of control group. 3. As sandblasting time was increased, shear bonding strengh of metal bracket was increased very much, but in ceramic brackets, shear bonding strength exhibited limited increase. This difference was caused by macro-mechanical retentive areas of ceramic brackets were broken for their brittle characteristics of material.