In vitro study of dentin hypersensitivity treated with Nd: YAG laser

Objective: To observe the structural changes of dentin irradiated with Nd: YAG laser under different parameters and the changes of calcium-phosphorus ration, and evaluate the optimal parameters of Nd: YAG laser in treating dentin hypersensitivity (DH). Methods: The model of dentin hypersensitivity was established by acid etching method. Samples were irradiated with Nd: YAG laser under different parameters. The morphological alterations of the dentin surfaces and Ca-P ratio were examined with scanning electron microscopy (SEM) combined with energy dispersive X-ray microanalysis. Results: Compared with those in the control group, dentinal tubules could be blocked partially or totally with no cracks in A-C (30 mj, 5 Hz), (30 mj, 10 Hz) and (50 mj, 5 Hz) groups. Dentinal tubules could be entirely blocked but with cracks in D (50 mj, 10 Hz) and E (80 mj, 5 Hz) groups. Dentin was carbonized in F (80 mj, 10 Hz) group. Compared with that in the control group, Ca-P ratio was decreased significantly (P<0.05). Conclusion: The suitable energy parameter of Nd: YAG laser in treating dentin hypersensitivity is (30 mj, 10 Hz) and (50 mj, 5 Hz).