Effect of Pulse Nd:YAG Laser on Bond Strength and Microleakage of Resin to Human Dentine

Abstract

The purpose of this study was to investigate the effect of pulse Nd:YAG laser on human dentine adhesion by optimizing the laser parameter combination and comparing it with other pretreatment methods for dentine adhesion. In recent decades, many scholars have been seeking an optimal method to enhance the bond strength of resin to human dentine. However, little improvement has been achieved. In this study, pulse Nd:YAG laser was studied as a pretreatment method for dentine adhesion. Two-hundred ten freshly extracted, caries-free human premolars were used in this study, which was conducted after approval from the IRB. Ninety of them were selected and randomly divided into nine groups, according to parameter combinations of pulse Nd:YAG laser. Tensile-bond strength was tested, and the laser parameter combination was optimized for later experiments. The other teeth were randomly divided into six groups: laser-irradiated, acid-etched, laser + acid, 10-3 solution, laser + 10-3 solution, and negative control (unconditioned). Each group had 20 specimens: 10 for tensile-bond strength tests and the other 10 for microleakage examination. After the bond-strength test, the fractured surfaces were examined under scanning electronic microscopy. The bond strengths fluctuated with different laser-parameter combinations applied and showed significant differences in different laser-parameter groups (p < 0.01). The highest mean of tensile-bond strength was found in the group irradiated with the parameter combination of 1 W/15 Hz. In the contrasting experiments, the laser-irradiated group, the 10-3 solution group, and the laser + 10-3 solution groups showed higher tensile-bond strength and lower microleakage than did the other three groups (p < 0.05). Pulse Nd:YAG laser, 10-3 solution, and their combination showed favorable effects on bond strength and adaptation of resin to human dentine and can be used to pretreat dentine surfaces before adhesion. The optimal parameter combination of pulse Nd:YAG laser was determined to be 1 W/15 Hz in this study.