The Sealing Ability Of Infiltration Resin To Dentin Tubules And Effect Of Resin On Dentin Adhesion

Aim: The purpose of this study was to investigate the sealing ability of infiltration resin to dentin tubules and the effect of infiltration resin as desensitizer on microtensile bond strength and microleakage between dentin and resin filling in order to provide feasibility for the treatment of dentin hypersensitivity.Material and methods: 1.Nine dentin discs were used for the experiment of sealing dentin tubules,which were randomly divided into 3 groups(n=3): Single bond Universal(SBU)group,the dentin interface was coated with SBU adhesive and was cured by light;Wet bonding combined with infiltration resin group,dentin interface was etched by 37% phosphoric acid,and excess water was removed by dry tampons for keeping moist state.The interface was coated with infiltration resin and cured by light;Dry bonding combined with infiltration resin group,dentin interface was etched by 37% phosphoric acid and deproteinized by 10% Na Cl O solution.Then,the interface was dried by desiccant ethanol,coated by resin and cured by light.SEM was used to observe the tubules sealing in dentin surface and the morphology of the resin tags in the longitudinal section.The tubules sealing rate was calculated by using Image-Pro Plus 6.0 software.2.Thirty healthy and intact third molars were collected for microtensile bond strength.enamel and superficial dentin were removed by high-speed drill,and they were randomly divided into three groups(n=10).The groups and dentin interface treatment were the same as experiment 1.The dentine interface of wet and dry bond combined infiltration resin was coated with SBU,and the three groups were filled with Z350 resin to make microtensile specimens.The universal testing machine tested microtensile bonding strength,and fracture patterns under an optical microscope were recorded and analyzed.3.Thirty healthy and intact third molars were collected for microleakage.The Ⅴ type cavities were prepared on the buccal side of the teeth neck and randomly divided into 3 groups(n=10).The groups and treatment of cavities were the same as experiment 1.The holes in wet and dry bond group were coated with SBU,and the holes in the three groups were filled with Z350 resin.The specimen was immersed in 20g/L methylene blue solution for 24 h,and then cut in the center along the buccal and lingual surface of the filling.The depth of dye penetration into the gingival wall was observed and recorded under an optical microscope.Results: 1.The dentin interface after pretreatment was observed under SEM(x4000): the model of dentin hypersensitivity was successfully prepared,the surface smear layer was removed,and the dentin tubules were completely opened.Microscopically,it was confirmed that after the interface was deproteinized with 10%Na Cl O solution,the collagen fibers exposed by acid etching were removed,the diameter of the dentin tubules was significantly increased,and the dentin between the tubules was honeycombed.2.The dentin interface after three treatments of desensitization was observed under SEM(x2000): in the SBU group,the interface was flat and uniform,and the exposed dentin tubules were almost completely sealed.Most of the exposed dentin tubules in the wet adhesion combined infiltrated resin group were sealed,and some of the tubules were reduced in diameter or not sealed.The dentin interface was rough and most of exposed dentin tubules were sealed in the dry adhesion combined with infiltrated resin group.3.The dentin profile after three treatments of desensitization was observed under SEM(x300 and x1000): in the SBU group,the length of the resin tags were short at low magnification,while at high magnification,the dentin interface was covered with a uniform material layer,and the resin tags in the dentin tubules were sparse and short.At low magnification,the resin tags length of the wet adhesion combined infiltrated resin group was significantly larger than that of the SBU group.At high magnification,the dentin interface was covered with material layers of different thickness,and the number of resin tags were more than that of SBU adhesive group.At low magnification,the length of resin tags in tubules was larger than that in the first two groups,while at high magnification,the material layer of dentin interface was thinner,and the resin tags in tubules was denser than that in the first two groups.4.The sealing rates of dentin tubules in the three groups were 99.37±0.66%、85.91±5.65%和 96.89±1.94%,respectively,The difference between the wet adhesion combined with infiltrated resin group and the other two groups was statistically significant(P<0.05),and there was no statistical significance between the SBU group and the dry adhesion combined with infiltrated resin group(P>0.05).5.The microtensile bond strength of the three groups was 29.64±10.57 MPa 、32.26±10.14 MPa 和 31.18±8.89 MPa,respectively,and there was no statistically significant difference between the three groups(P>0.05).6.Fracture patterns: SBU group and dry bond combined with infiltration resin group were mainly adhesive surface fracture,while wet bond combined infiltration resin group were mainly adhesive surface fracture and cohesive fracture.7.The microleakage of gingival wall in SBU group was less than that in the other two groups,which was statistically significant(P<0.05).The microleakage in dry bond combined with infiltration resin group was smaller than that in the wet bond combined infiltration resin group,but the difference was not statistically significant(P>0.05).Conclusion: 1.Infiltration resin can seal dentin tubules effectively and has the potential of clinical application as a desensitizer in the treatment of dentin hypersensitivity.2.deproteinization and drying treatment to dentin can improve the sealing ability of infiltration resin to dentin tubules.3.As desensitizer,infiltration resin has no significant effect on the microtensile bond strength of dentin bond.4.As desensitizer,infiltration resin may aggravate microleakage of dentin bond.