Effect of enamel prism orientation after irradiation with Er:YAG laser on bond strength

The purpose of this study was to investigate the micro-shear bond strength of current adhesive systems to irradiated enamel surfaces with different orientation of enamel prism. Flat enamel discs with cross-cut and long-cut enamel prism were prepared from human third molars. The specimens were polished with 600 grit silicon carbide papers. Halves of specimens were further irradiated with Er:YAG laser with 200 mJ and 15 Hz. The non-irradiated and irradiated specimens were divided into two groups for bonding to Single Bond or Clearfil SE Bond. Small cylindrical composite resins (0.7 mm in diameter) were then bonded onto the bonded surfaces and cured. The micro-shear bond strength test was performed after 24 h storage on a universal testing machine. Statistical analysis was performed at α=0.05. The effect of laser irradiation, enamel prism orientation and adhesive systems on the bond strength were found at p<0.01. Bond to cross-cut enamel demonstrated higher bond strength than that to long-cut enamel. The application of laser demonstrated increasing of the bond strength significantly in the groups that bonded to long-cut enamel.