Dentin Endogenous Moisture On Shear Bond Strenghth Of Different Adhesives Systems

Objective:To determine influence of dentin endogenous moisture on the shear bond strength of different adhesives systems under simulated pulpal pressure.Methods: Occlusal surfaces of 72 sound extracted non-carious human third molars were grounded to obtain flat dentin surfaces and randomly divided into three groups: Clearfil SE Bond(SE),Clearfil S3 Bond(S3)and Prime&Bond NT(PB).All of these samples were tested under simulated pulpal pressure of 15 cm H2 O.After bonding procedures with three different adhesives,all samples were covered with two coats of nail vanish.The shear bond strength were tested after storing for 24 h under simulated pulpal pressure.Results:The remaining dentin thickness of the three adhesive groups showed no significant difference(P>0.05).The remaining dentin thickness and the shear bond strengthsin the PB group was significant with a positive correlation(r=0.764,P<0.05).The remaining dentin thickness and the shear bond strengthsin the SE and S3 group,Pearson correlation analysis showed that,(r=-0.15,P>0.05)and(r=0.165,P>0.05),respectively,withoutsignificantcorre-lation.The shear bond strength in group S3 was lower than that of group SE and PB(P < 0.05),there is no significant difference between SE group and PB group(P>0.05).Conclusion:Under simulated pulp pressure,the shear bond strength of the adhesive PB in the total etching bonding system was related to the depth of dentin while there was no correlation between the bond strength and the dentin thickness in the SE group which suggesting that the depth of cavity had no obvious effect on the bond strength.Besidesthe shear strength of PB had no significance difference with SE.The shear bond strength of one-step self-adhesive was the lowestwhich imply the insufficiency of bonding strength.