ABSTRACT
Objective To study the effects of pulsed Nd:YAG laser radiation on the marginal microleakage of porcelain-fused-to-metal crowns. Methods Twenty in vitro premolar teeth were selected and processed by standard porcelain crown preparation. The porcelain-fused-to-metal crowns were made based on the relevant repair technical requirements. The restorations were randomly divided into control group (group A) and experimental group (group B). The restorations in the group B were treated by external Nd:YAG laser irradiation with power of 1.25 W and irradiation time of 20 s. All the restorations were fixed with composite resin cement, and then put into normal saline under 37℃for 20 d, during which 300 times thermal cycling were performed. After that, the restorations were placed into 0.5％ pinkish red solution for 24 hours to dyeing, and then dissected along the longitudinal axis. The marginal microleakage of the restoration was observed by a stereomicroscopy. The data were processed by the SPSS 19.0 software. Results The degree of marginal microleakage of the restorations after Nd:YAG laser irradiation was significantly lower than that in the control group (P<0.05). Conclusions The pulsed Nd:YAG laser irradiation can effectively improve the adhesion between the resin and the hard tissue of the teeth, and reduce the marginal microleakage of the porcelain-fused-to-metal crowns.