The use of debonding microspheres in electrothermal debonding

The aim of this study was to investigate if debonding microspheres (DM) could enhance electrothermal orthodontic debonding, and specifically to evaluate if the addition of DM, in varying concentrations to the orthodontic adhesive process, will affect bond strength. Bovine teeth (n=8) were mounted in acrylic using a silicone mould. Four test groups of three preparations of primer (Rely-a-Bond) with DM and a control were examined. Five incisor brackets were bonded to each tooth using the assigned primer and cold cure composite (Rely-a-Bond). Bracket tensile bond strength was measured in vitro in an Instron machine and recorded as debonding force (N). Differences between the groups were statistically analysed using analysis of variance, and repeatability was assessed. The mean debonding force of the control group was statistically significantly greater than all the other groups to which DM had been added (P<0.001). Comparison of the mean debonding forces of 1, 2.5, and 5 per cent concentrations of DM revealed no statistically significant difference between the groups. The addition of DM to orthodontic adhesive produced a highly statistically significant reduction in debonding force. There was no statistical difference in debonding force between varying concentrations of DM.