Rebonding of orthodontic metallic brackets: Comparative analysis of shear bond strength using different sandblasting particles

Abstract

IntroductionThis study aimed to evaluate the effect of two different sandblasting particles on the shear bond strength of rebonded metallic brackets to dental enamel. MethodsForty-eight metallic orthodontic brackets were divided into 4 experimental groups (n = 12) according to the surface treatment they received at their bases: positive control group (Metal), negative control group (MetalU), sandblasted with Rocatec Soft (MetalRoc) and sandblasted with Glass beads (MetalGlas). An elementary and topographic analysis of the base of the brackets was performed using scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS) after the surface treatment. The brackets rebonded to dental enamel were tested for their shear bond strength. The obtained data were subjected to statistical analysis one-way ANOVA and Tukey's test (α = 0.05). The fracture surfaces of the specimens after the mechanical test were analyzed using optical microscopy to classify the failure mode. ResultsSEM photomicrographs for the MetalRoc and MetalGlas groups showed efficient removal of the remaining resin composite. In both sandblasting treatments, the presence of silicon (Si) and oxygen (O) at the base of the brackets were verified by means of the EDS, suggesting the occurrence of silica coating. MetalGlas group showed greater bond strength (9.38 ± 2.78 MPa) compared to the MetalU group (5.31 ± 1.2Mpa). Metal (8.82 ± 4.14 MPa) and MetalRoc (8.29 ± 3.95 MPa) groups showed similar bond strengths. The failure mode predominantly found in the sandblasted groups was the totally adhesive failure between resin composite and tooth. SignificanceThe sandblasting treatment using the glass beads was efficient in removing the remaining resin composite of recycled brackets and generated fewer surface defects and topographic changes in the bracket bases.