Abstract:

Objective  To investigate the effect of casein phosphopeptide-amorphous calcium phosphate（CPP-ACP）on the stability of resin-dentin bonds against pH cycling. Methods Resin-bonded dentin specimens were prepared following manufacturers’instructions, and randomly divided into 3 groups. Among them, 2 groups experienced pH cycling, in which specimens applied CPP-ACP or distilled and deionized water（DDW） on the bonding interface, respectively.Microtensile bond strength（μTBS） testing, failure mode analysis, micromorphological and nanoleakage evaluation of bonding interface and elemental analysis within hybrid layer were performed after 15 days pH cycling. Theother group was tested immediately after specimens’preparation without pH cycling. Results  No significant differences were found in μTBS between no pH cycling and pH cycling/CPP-ACP group. Their μTBS were both significantly higher than that of pH cycling/DDW group（P<0.05）. Mixed fractures were the most prevalent failure mode. The qualityof hybrid layer in pH cycling/CPP-ACP group was better than that of pH cycling/DDW group, and the nanoleakage was also less severe. Comparing with pH cycling/DDW group, the atomic percentages of Ca in the other two groupswere both significantly higher, while those of Ag were statistically lower（P<0.05）. Conclusion Local application of CPP-ACP can promote the stability of resin-dentin bonding interface against pH cycling and prolong bonding degeneration.

Key words: casein phosphopeptide-amorphous calcium phosphate, resin-dentin bond, remineralization, bondstrength, nanoleakage