The effect of simulated oral and clinical conditions on the fracture strength of ceramic bracket tie-wings

Abstract

This study examined the effect of simulated oral and clinical conditions on the tie-wing fracture strength of a polycrystalline and a monocrystalline bracket. Fracture strength was measured for brackets as-received (control) and after 7- or 21-day exposure to phosphate buffered saline solution (PBS) with or without repetitive ligation. Scanning electron microscopy was used for qualitative evaluation of the fractured brackets. Based on a two-factor ANOVA and Dunnett's post hoc test ( = 0.05), monocrystalline bracket tie-wing fracture strength was significantly decreased as a function of PBS storage over time with and without ligation, while there was no significant effect on the polycrystalline bracket tie-wing fracture strength. With monocrystalline brackets, tie-wing fracture origin appeared to differ between brackets exposed to repetitive ligation and those with no ligation. The results suggest that monocrystalline bracket tie-wing fracture strength is more susceptible to degradation in the oral environment.