ABSTRACT
Objective To compare the pulp chamber temperature changes of Nd:YAP laser, Nd:YAG laser and semiconductor laser with the same power during dentin hypersensitivity treatment, and to evaluate the safety of these three laser treatments for dentin hypersensitivity. Methods 50 intact third molars were collected to prepare the dentin hypersensitivity model. The samples were randomly divided into Nd:YAP laser group (n=15), Nd:YAG laser group (n=15), semiconductor laser group (n=15), and blank control group (n=5). Each experimental group was divided into three subgroups (n=5) of 0.9 W, 1.4 W, and 1.8 W according to the laser power. The experiments were conducted with the corresponding laser parameters and thermocouple thermometer was used to record the temperature changes in the pulp chamber. The control group does not do any processing. After laser irradiation, one sample was randomly taken from each group and the morphology of dentin tubules was observed by scanning electron microscopy. Results When different power lasers were used to irradiate the samples, the temperatures of the pulp chamber in each group were increased. Among them, the temperature rise of the pulp chamber was smallest in the Nd:YAP laser group, followed by the semiconductor laser group, and the temperature rise was highest in the Nd:YAG laser group, but it was still lower than 5.5 ° C that could cause pulp necrosis. Scanning electron microscopy results showed that after irradiation with different power lasers, the diameters of most dentinal tubules in the Nd:YAG laser group and the semiconductor laser group were narrowed or even melted, and the effect was better than that of the Nd:YAP laser group. Conclusion The treatment using Nd:YAP laser, Nd:YAG laser and semiconductor laser for dentin hypersensitivity will increase the temperature of the pulp chamber. However, the temperature rise is less than 5.5℃and that will not cause irreversible damage to the pulp tissue. Nd:YAG laser and semiconductor laser have better dentinal tubule blocking effect, which is more suitable for laser dentin desensitization treatment than Nd:YAP laser.