GaAlAs Laser Therapy in Dentin Hypersensitivity and Histopathological Changes of the Dental Pulp Tissues

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Recent studies have shown the effects of diode laser irradiation in treatment for dentin hypersensitivities. However,the system of the effects still remains unsolved. The conditions and indications of irradiation in the diseases are, therefore, not defined in detail, which decreases clinical reliability of the laser therapy for pain.The study was designed to examine histopathological change of dental pulp tissue by laser irradiation to know the mechanism of the effects.Continuous irradiation at 30mW was performed for 60 and 90 seconds under direct contact of a probe to occlusal surface of the first molars of male Wistar rats by using Ga-Al-As diode laser(<lambda>: 830nm, Osada Electric Co.). The rats were sacrificed 2 weeks after irradiation and the pulp tissues were routinely examined histopathologically under light microscope. Clinical examination also done on the patients having hypersensitive dentinunder their consents.Experiments indicate ; 1) No differences were detected in histopathological appearance of pulp tissues between irradiated and non-irradiated groups in this study. Since loss of pain by laser irradiation may give some histological change to pulp tissue, ultratine structure investigation would find the changes in future. 2) In clinical experiment, of 61 cases, the findings showing remarkable effective, effective, and non-effective were 10(16%), 29(48%), and 22(36%) cases, respectively. Though the laser irradiation yielded immediate effect, pain returned in some cases. This uncertain clinical results suggested further study on informations of dentin hypersensitivity to get higher clinical reliability.