Comparison Of Two Total-etching Resin Adhesives On The Bonding Effect Of Normal Dentin To Glass Ceramic

Objective:The shear strength,fracture type and nano leakage of the specimens were observed after normal dentin(ND)and glass ceramics were bonded with two total acid etching resin adhesives.To evaluate its adhesive strength and interfacial closure,and provide reference for the selection of clinical adhesives Methods:Forty intact human molars without caries were selected.Under the condition of running water cooling,the enamel of the crown teeth and a small amount of dentin were polished with high-speed car needle to expose the dentin in the middle part of the crown,and the dentin surface was polished with car needle,to ensure that each dentin block obtained 4mm*4mm normal dentin surface,and a total of 40 normal dentin blocks were prepared.The prepared dentine blocks were divided into groups A and B by random number table method,and each group was randomly divided into two adhesive groups.The two bonding groups in group A were bonded with glass ceramics by the total acid etching system adhesives Variolink N and U.link respectively.After the specimens were bonded,they were stored in distilled water at 37? for 24 h.The shear strength of the specimens was tested by universal testing machine and the failure mode of the specimens was observed under a type microscope.The specimens were stained in the ammoniated silver nitrate solution and placed under field emission scanning electron microscopy(FESEM).In addition,energydispersive X-ray spectrometer(EDS)was used for energy spectrum analysis to observe the nano-leakage of the bonding interface.Results:1.the independent sample t test analyzed that the difference of shear strength between the two groups was statistically significant(P<0.05).variolink n group[(14.45±2.35)mpa] was significantly higher than u.link group [(6.39±1.43)mpa].There was no significant difference in fracture mode between the two groups by Fisher exact test(P>0.05).2.there was no significant difference in the analysis of nanomicroleakage by independent sample t test(P>0.05).Conclusion:1.The bonding strength of U.link is significantly lower than that of Variolink N;2.The interface closure effect of U.link is similar to that of Variolink N;3.No nano-leakage was found at the interface between the resin bonding layer and the porcelain block,which indicated that the surface treatment of the glass-ceramic interface with hydrofluoric acid corrosion and silane coupling agent was an effective method to improve the bonding effect between the resin adhesive and the glass ceramic.