An in vitro investigation of the effectiveness of bioactive glass air-abrasion in the 'selective' removal of orthodontic resin adhesive

The process of clinically debonding orthodontic brackets causes histomorphological damage to enamel that needs to be quantified and minimized. This study compared three methods for removing residual resin adhesive following bracket debonding. The surface finish following removal of residual adhesive using a slow-speed eight-bladed tungsten carbide bur (group 1), alumina air-abrasion (group 2), and bioactive-glass air-abrasion (group 3) and following polishing, was examined using scanning electron microscopy imaging of resin replicas. Contact profilometry was used to image surfaces before and after debonding for quantifiable volumetric analysis of enamel damage. Surface scarring was seen on scanning electron micrographs from group 1, a sharp pitted surface was identified in group 2, while group 3 exhibited similar, but subjectively smoother, pits. The surface finish following polishing was similar for groups 2 and 3 but did not completely remove the scarring evident from group 1. Quantifiable enamel lost was as follows: group 1, 0.285 mm(3); group 2, 0.386 mm(3); and group 3, 0.135 mm(3); statistical differences were observed between groups 2 and 3. From these results, bioactive-glass air-abrasion more consistently caused less physical damage to enamel and achieved a clinically smooth surface finish following polishing and is therefore to be recommended for clinical use