Effect Of Desensitizer And Laser Desensitization On Surface Morphology,Hardness And Composition Of Dentin

Objective:To investigate the effects of Aominqing desensitizer and two laser(Er:YAG and Nd:YAG)treatments on the dentin surface morphology,hardness,and calcium(Ca)and phosphorus(P)contents and Ca/P ratio,to clarify the possible mechanisms,and to provide reference for its clinical application in the treatment of dentin sensitivity.Methods:The fresh third molars extracted because of impaction from the volunteers aged 18-20 years old were collected.A total of 32 dentin slices of 2mm were prepared;the samples were divided into blank control group,Aominqing group Er:YAG group and Nd:YAG group,and there were eight samples in each group.Except blank control group,the samples in other groups were used to establish the dentin hypersensitivity models by purifying the polluted layer with 17% EDTA.Each sample was cut by linear cutting machine from the middle symmetry into two semicircle dentin;the half was used to observe the surface morphology and analyze the Ca and P contents with SEM and EDS was observed.Results:There were no significant differences in the SMH values of dentin samples between various groups(P>0.05).In blank control group,there was no smear layer on the dentin surface with wide tubules and smooth and clean surface;the dentin tubules of the samples in Aominqing group were partially closed,and obstructions were seen in the tubuless in Er:YAG group the dentin tubules were little or no open,most of them were partially or completely closed tubules,the surface had the melting changes in Nd:YAG group,the dentin tubules were partially or completely closed with few open tubules and the surface was molten.Compared with blank control group and Aominqing group,the Ca and P contents in the samples in Er:YAG group and Nd:YAG were significantly increased;there was no statistically significant difference in the contents of Ca and P between and blank control group and Aominqing group(P>0.05),and the difference between Er:YAG group and Nd:YAG group was not significant(P>0.05).The differences in the Ca/P ratios between various groups were not statistically significant(P>0.05).Conclusion:The application of Aominqing desensitization agent,Er:YAG laser and Nd:YAG laser can not cause the changes of dentin SMH and the Ca/P ratio,but the application of Er:YAG and Nd:YAG laser to dentin can significantly increase the contents of Ca and P and change the morphology,composition and structure of dentin surface.