Microtensile Bond Strength And SEM Evaluation Of Four Different Self-etching Adhesives To Caries-affected Dentine

Objective:To evaluate the microtensile bond strength of four 7th generation bonding system to caries-affected-dentine versus normal dentine.Methods:Twenty four extracted human molars with coronal medium carious lesions which form JiangXi were randomly divided to four groups. The softened carious dentine was removed with a slow-speed,carbon-steel bur and Caries Marker(Voco) was used as a guide. Normal dentin(ND) and caries-affected dentin (CAD) were bonded with self-etching adhesives AdperTM Easy One;Ibond;Clearfil S3 Bond;G bond.A crown was built up using resin composite(Filtek P60).Then these samples stored in water (37℃,24h).Rectangular sticks with resin-dentin bonded interfaces of 1.0 mm2 were obtained. The specimens were subjected to microtensile bond strength (μTBS) testing at a crosshead speed 0.8 mm/min. Interfacial morphologies were analyzed by Scanning Electron Microscopy (SEM).Result:Ibond showed significantly higher bond strengths in normal than in caries-affected dentine (P<0.01). Other adhensives attained higher bond strengths in normal than in caries-affected dentine (P<0.05).All the adhensives attained the similar strengths in caries-affected dentine (P>0.05).IBond and GBond showed higher bond strength values than GBond and AdperTM Easy One in normal dentine (P<0.05).Form SEM images, the hybrid layer in caries-affected dentine was thicker but more porous than that in normal dentine.Compared with normal dentine,there was fewer resin tag exhibited in caries-affected dentine.Conclusion:The four self-etching adhesives evaluated produced higher bond strengths in normal than in caries-affected dentine.All the adhensives attained the similar strengths in caries-affected dentine.