Effect Of Different Desensitization Methods On The Shear Bond Strength Between Dentin And Resin

Objective:This study evaluated the effects of three desensitization methods on bond strength to dentin,in order to provide reference for the choice of the desensitization method.Methods:Eighty extracted human third molars were selected(in the three months),removed the 1/3 occlusal surface of the tooth tissue,the remaining teeth were embeded in self-caring resin with the middle dentin exposed and made them into standard dentin specimens.The specimens were randomly divided into 4 groups(N=20),that is the control group where no desensitizing agent was used,the other group were treated with fluor varnish、bioactive glass、Er:YAG laser respectively.Then each group was randomly divided into 2 subgroups(n=10),were treated with self-etching adhesive Adper~TMM Easy One and the etch-and-rinse adhesives Adper~TMM Single Bond 2 respectively and randomly.All the specimens were bonded to composite resin.The shear bond strength of adhesive specimens was measured using a universal testing machine.The fracture modes were observed and recorded under a stereoscopic microscope.The experimental date was statistically analyzed using SPSS20.0 software package.Results:1.In self-etching adhesive group,the shear bond strength of the control group was greater than fluor varnish、bioactive glass、Er:YAG laser group,and there was a significant difference(P<0.05).The shear bond strength of fluor varnish was greater than bioactive glass and Er:YAG laser,and there was a significant difference(P<0.05).but there was no difference between the bioactive glass and Er:YAG laser groups(P>0.05).2.Inetch-and-rinse adhesives group,the shear bond strength from biggest to the smallest was as follows:bioactive glass、the control group、fluor varnish、Er:YAG laser.There was a significant difference in shear bond strength between any two groups.3.Treated with the same desensitization methods,the shear bond strength of etch-and-rinse adhesives group was greater than self-etching adhesive group,and there was a significant difference between the two groups(P<0.05).Conclusion:1.The bioactive glass could increase the shear bond strength with etch-and-rinse adhesives system,but decrease the shear bond strength with etch-and-rinse adhesives system.2.The fluor varnish and Er:YAG laser could both decrease the shear bond strength with self-etching adhesive system and etch-and-rinse adhesives system.