An analysis of surface roughness, surface morphology and composite/dentin bond strength of human dentin following the application of the Nd:YAG laser

Objectives: This study was conducted to investigate the surface effects to dentin following laser “etching” with an Nd:YAG laser, and to determine the shear bond strengths of composite to untreated and laser-treated dentin. Methods: Dentin surfaces from freshly extracted permanent molar teeth were subjected to laser treatment with an Nd:YAG laser using different laser pulse rates and power settings. The effect of application of a laser enhancing gel was also investigated. Surface profile analysis of the dentin surfaces was undertaken with a perthometer. The results were analysed by SPSS/PC multiple range test. Specimens were examined using a scanning electron microscope (SEM). The shear bond strengths of laser-treated dentin/composite and untreated dentin/composite by conventional dentin bonding (Gold Standard, Chameleon Dental Products) were also determined. These results were also compared by SPSS/PC multiple range test. Results: The laser-treated dentin specimens exhibited a qualitatively different surface morphology when compared with untreated dentin. Laser treatment at higher exposures resulted in the formation of microcracks and fissures. Bonding of resin composite to the laser-treated dentin was not significantly different from untreated dentin despite the fact that the surface roughness of laser-treated dentin was significantly higher than untreated dentin (p<0.05). Significance: It was concluded from this study that the etched dentin surfaces produced by the Nd:YAG laser operated under the conditions described were not superior to those obtained with conventional dentin bonding.