Effect Of 810-nm Diode Laser On Dentinal Tubule Occlusion:An In Vitro Study

Objective:To investigate the ultrastructural changes of dentin irradiated with 810-nm diode laser under different parameters and to observe temperature changes of pulp tissue after 810-nm diode laser going through dentin slices in the treatment of dentin hypersensitivity(DH).Methods:Intact and caries-free molars were selected to prepare 2mm-thick dentin slices.Each slice was sectioned perpendicularly into four pieces and all the 21 pieces were randomly divided into 7 groups and been irradiated with 810-nm diode laser under various parameters and continuous wave(CW).Groupl:control group,0W,0s(0J/cm~2);Group2:0.2W/CW,2s(333.47J/cm~2);Group3:0.2W/CW,5s(833.67J/cm~2);Group4:0.2W/CW,10s(1667.34J/cm~2);Group5:0.3W/CW,2s(502.85J/cm~2);Group6:0.3W/CW,5s(1257.12J/cm~2);Group7:0.3W/CW,10s(2514.25J/cm~2).All the specimens were examined with scanning electron microscopy(SEM).The temperature changes of pulp tissue were measured with thermocouple thermometer under 0.3W/CW and 0.2W/CW with irradiation time 1s 2s 3s 4s 5s 10s,respectively.Results:?Under same power(0.2W/CW or 0.3W/CW),the degree of dentinal tubule occlusion was higher with the prolonging of irradiation time(P<0.05),while under certain irradiation time,there was no significant difference between the occlusion degree and the power.?Under same power(0.2W/CW or 0.3 W/CW),the temperature of the opposite of the dentin slice after being irradited by 810-nm diode laser continued to rise with the increase of irradiation time(P<0.05),under certain irradiation time,the temperate continued to rise with the increase of power(P<0.05).?T of irradiation group at 0.2W,4s;0.2W,5s;0.2W,10s;0.3W,3s;0.3W,4s;0.3W,5s;0.3W,10s were higher than 3?.?T of irradiation group at 0.2W,2s(333.47J/cm~2);0.2W,3s(500.20J/cm~2);0.3W,2s(502.85J/cm~2)were lower than 3?.Conclusion:When laser tip was 1mm away from dentin and perpendicularly irradiated at 0.2W/CW,less than 3s or 0.3W/CW,less than 2s,810-nm diode laser was able to be safely used in clinical to occlude dentinal tubules without significantly changes of pulp temperature.And 0.2W/CW with irradiation time 2s or 0.3W/CW with irradiation time 2s was suitable,meanwhile,the safety power density is 333.47J/cm~2?502.85J/cm~2.