In Vitro Study On The Safety And Effectiveness Of Dentin Hypersensitivity Treated By Three Different Laser

Objective:1.Three different kinds of laser Nd:YAP laser,diode laser,Nd:YAG laser was used to irradiate the teeth of artificial dentin hypersensitiveity on the power of 0.9w,1.4w and 1.8w respectively.Thermocouple temperature measuring instrument was used to test the changes of temperature in pulp chamber during the laser irradiation and to evaluate the safety the three laser on pulp tissue.And provide experimental basis for clinical application;2.After laser irradiation,2 samples of each group were randomly selected to be dried and sprayed,and then were texted by using of the scanning electron microscope about of the morphology of dentin tubule.10 pictures of SEM were got in each group.And the score of closed dentinal tubules in each picture were made,which can evaluate the effectiveness of desensitization of the three kinds of laser.3.According to the temperature change and the medullary of dentinal tubule occlusion results and the principle of the safety and effectiveness,the best laser parameters were choosed which can seal dentinal tubule to the maximum extent and not cause more temperature rises,to provide experimental basis for the treatment of dentin hypersensitivity safe and effective in clinical work.Methods:1.Fifty no damage,no caries and complete the third molars and fresh extracted from young patients were collected.The root of the teech and the enamel were removed.And the pulp was taken out from the pulp chamber.And then polishing wheel and polishing paper were used to polishing and finishing the dentin surface,with 35%phosphoric acid erosion of the dentin surface 15s,preparation of artificial tooth hypersensitivity model.These teeth were saved in 4℃ normal saline.2.The laser power meter was used to correct Nd:YAP laser,diode laser and Nd:YAG laser machines.The thermocouple temperature measuring instrument is corrected under 37 ℃ water.The error is within 0.01 ℃,and the machine can be used for the experiment.3.Three kinds of lasers irradiated the samples 30s by the power of 0.9w,1.4w and 1.8w respectively.As the same time,the thermocouple temperature measuring instrument was used to monited the temperature in pulp chamber to evaluation safety of three kinds of laser in treatment of dentin hypersensitivity.Then observe the morphological changes of dentinal tubules by scanning electron microscopy and made scores of the SEM picture to evaluation of the effectiveness.Results:1.These three laser could rinse the pulp chamber temperature in the treatment of dentine hypersensitivity under the experimental conditions,Nd:YAG laser increased most but the increased value of less than 5.5℃(P<0.05),the parameters of three kinds of laser is relatively safe.2.And form the SEM,Nd:YAG laser could cause most of the dentinal tubules to melt and block at the power of 0.9w,1.4w and 1.8w which was better than diode laser(P<0.05).And Nd:YAP laser could cause a little part of dentinal tubule diameter to melt and block.In general,the parameters used for the three lasers are effective.Conclusion:1.These three kind of lasser were safe and effective in the treatment of dentine hypersensitivity under the experimental conditions.2.When laser irradiation time was certain,the effect of laser is related to the power.The higher of the power,the better the effect.The effection and safety should be considered at the same time.Nd:YAG laser at power 0.9w and semiconductor laser at 1.4w can both get the safety and effectivies for the DH.3.The method of laser operation is simple and laser can locate accurately and not damage the surrounding tissue,safe and effective.Laser will have good clinical application prospects in oral medicine.