A research on bond strength and interface of dentin adhesives

Objective:To evaluate bond strength and interface of various dentin adhesives by a modified interface processing method.Methods:Nine extracted human molars were ground to expose fresh dentin surface.Three dentin adhesives(Single Bond,Clearfil SE Bond and Clearfil S3 Bond) were applied respectively and a block of composite resin was built up.The specimens were then stored in distilled water for 24 h at 37 ℃ and sectioned into beams of 0.9 mm×0.9 mm cross-sectional area.The microtensile bond strength was determined with Microtensile Tester(n=15).In addition,the bonding specimens were conditioned with 6 mol/L HCl,5% NaOCl and 0.08 mg/ml hyaluronidase to observe the adhesive interfaces by SEM.Results:Significant differences in bond strength were observed among the three adhesives(P0.05):SE Bond(45.06±5.29) MPa Single Bond(35.50±6.40) MPa S3 Bond(30.46±3.82) MPa.Single Bond showed resin tags about 9-12 μm long and gaps between hybrid and adhesive layers.No obvious boundary between hybrid layer and adhesive were observed for both SE Bond and S3 Bond,while the length of resin tags were 9-14 μm and 4-7 μm for SE Bond and S3 Bond respectively.Conclusion:The morphology of the bond interface of dentin adhesive has a relationship with the bond strength.