Tensile bond strength and failure location were evaluated in vitro for metal plastic and ceramic brackets bonded to human premolar teeth with a low filled no-mix orthodontic bonding resin. The Kruskal-Wallis and Mann-Whitney U tests were used to determine whether any statistical significance existed among the tensile bond strength values recorded for three different brackets. The differences between the mean values of tensile bond strength for metal and plastic brackets, and for plastic and ceramic brackets were statistically significant, whereas the difference between the mean values of tensile bond strength for metal and ceramic brackets was not statistically significant. The highest values of bond strength were obtained from ceramic brackets when compared with plastic and metal brackets. The site of failure was commonly adhesive type and located at the resin/bracket interface for all of the bracket types evaluated.

Keywords: Orthodontic brackets, direct bonding, tensile bond strength