Abstract: Objective: To evaluate the effect of pretreatment by Casein phosphopetide-amorphic calcium phosphate (CPP-ACP)and Casein phosphoetide-amorphic calcium fluoride phosphate complexes (CPP-ACFP) on the bond strength of resin cements and resin. Methods: Thirty-six specimens were randomly divided into self-etching and total-etching group, and each group was constituted with blank group, GC group and GC plus group (n = 6). After pretreated by CPP-ACP and CPP-ACFP on day 1 and day 7, the morphology of dentin surface was observed by scanning electron microscope (SEM). Calcium/phosphorus ratio was evaluated by energy dispersive spectroscopy analysis. A 4 mm-thick layer of Z350 resin was placed on each specimen, and the micro tensile strength was tested by the universal testing machine. The fracture mode of interface was observed. Results: results showed that the diameter of pretreatment dentin tubule decreased, and the dentin tubule almost completely closed after several times of repeated pretreatment. The Ca/P ratio changes were not statistically different between the pretreated dentin and normal dentine. The bond strengths of total-etching adhesive system (single bond2) were decreased (P<0.05) by pretreatment of CPP-ACP or CPP-ACFP. The pretreatment had no obvious effect on self-etching adhesive system (ibond). There were no differences between CPP-ACP and CPP-ACFP pretreatment in both etching adhesive systems. Stereoscopic microscope showed that the fracture mode of interface was mainly on the bonding surface. Conclusion: Pretreatment of dentine by CPP-ACP or CPP-ACFP before bonding could close the dentin tubule. Increase times of application might improve this effect. Pretreatment of dentine by CPP-ACP or CPP-ACFP had no obvious effect on self-etching adhesive system (ibond), while could reduce bond strength of total-etching adhesive system.

Key words: Dentine hypersensitivity , Bond strength , Tensile strength , Casein phosphoetide