Preventive Effect of Tooth Fracture by Pulsed Nd:YAG Laser Irradiation with Diamine Silver Fluoride Solution

Objective: The purpose of the present study was to evaluate the preventive effect of pulsed Nd:YAG laser irradiation with 38% diamine silver fluoride [Ag(NH₃)₂F] solution for the fracture of endodontically treated teeth in vitro. Background Data: There have been no reports on the preventive effect of tooth fracture using Nd:YAG laser with Ag(NH₃)₂F solution. Materials and Methods: Twenty-eight human extracted teeth were used in this study. The teeth were randomly classified into four groups: control group, where tooth surfaces were not submitted to any treatment; group 1, where tooth surfaces were coated with 38% Ag(NH₃)₂F solution; group 2, where tooth surfaces were coated with Ag(NH₃)₂F solution and irradiated by pulsed Nd:YAG laser for 2 sec; and group 3, where tooth surfaces were coated with Ag(NH₃)₂F solution and irradiated by pulsed Nd:YAG laser for 10 sec. After preparation, shear tests were performed and the maximum load for the fracture was measured. Results were analyzed using the Scheffe test, and difference at p < 0.05 was considered significant. Results: The failure load for group 2 (mean, 182.5 kg) had the highest mean value and differed significantly from those for the control group (mean, 146.3 kg) and group 1 (mean, 147.1 kg; p < 0.05). The failure loads for groups 1 and 3 (mean, 150.0 kg) did not differ significantly from that for the control group (p > 0.05). Conclusion: The results show that the application of 38% Ag(NH₃)₂F solution followed by pulsed Nd:YAG laser irradiation for 2 sec is useful for prevention of tooth fracture at endodontically treated teeth.