The effect of various types of sodium perborate bleaching agents on shear bond strength of composite resin Aim: The purpose of this study was to evaluate various types of sodium perborates mixtures effect on shear bond strength of composite resin. Material and Methods: Eighty extracted central teeth were used in this study. The crowns were splitted mesiodistally from the incisal edges to cervicals. Buccal parts of the teeth were mounted in a 4cm pipe with the use of cold acylic resin with their buccal surfaces downward. Dentin surfaces were polished and divided into main 2 groups according to the mixing solutions (n=40) (water or 30% hydrogen peroxide) and into four subgroups according to the sodium perborate type used (monohydrate, trihydrate, tetrahydrate and only the solution as control) (n=10). The dentin surfaces of the groups were treated with fresh bleaching pastes and stored in an incubator. Composites were placed onto the dentin surfaces by packing the material into cylindrical shaped matrix. Shear bond strength of each sample was measured and calculated in MPa. Results: Mixing with hydrogen peroxide decreased bond strength values significantly (p<0.05). Higher bond strength values were obtained in tetrahydrate mixed with water group. Conclusions: For the success of composite restorative treatment that will be applied to non-vital colored teeth, mixing bleaching agents with water may be preferential
