The effects of recycling on the tensile bond strength of new and clinically used stainless steel orthodontic brackets: an in vitro study.

The tensile bond strength was evaluated for three different types of stainless steel orthodontic bracket/base combinations (both cast and machined integral bases, and a foil-mesh base). The cast base gave a significantly higher initial bond strength than the other two brackets. Following recycling by either chemical or thermal methods, all the bases demonstrated a significant reduction in bond strength. However, thermal recycling produced an unacceptably large reduction in the bond strength of the cast base and this method of reconditioning should be avoided with these brackets. Recycling the brackets an additional four times was found to result in a further reduction in bond strength, but this was not statistically significant. Clinically used brackets demonstrated a slightly lower, though not statistically significant, bond strength compared to unused brackets following one recycling with either the chemical or thermal method.