酪蛋白磷酸肽-无定形磷酸钙对牙本质粘接界面耐pH循环老化的影响

目的 研究局部应用酪蛋白磷酸肽-无定形磷酸钙（CPP-ACP）对牙本质粘接界面耐pH循环老化的影响。方法 常规制备牙本质粘接试件，将其随机分为3组，其中2组行pH循环，期间每日分别加用CPP-ACP、去离子蒸馏水（DDW）处理，15 d后测定微拉伸粘接强度，观察断裂模式、界面形貌及纳米渗漏，并确定混合层内元素含量。另一组试件制备完成后即刻测试。结果 无pH循环组及pH循环/CPP-ACP组微拉伸粘接强度差异无统计学意义，但二者均显著高于pH循环/DDW组（P＜0.05）。试件均以混合破坏为主。pH循环/CPP-ACP组混合层质量优于pH循环/DDW组，纳米渗漏少。无pH循环组及pH循环/CPP-ACP组混合层内Ca含量显著高于pH循环/DDW组，Ag含量显著低于pH循环/DDW组（P＜0.05）。结论 牙本质粘接界面局部应用CPP-ACP可增强界面耐pH循环老化的能力，延缓界面退变。

Effect of casein phosphopeptide-amorphous calcium phosphate on the stability of resin-dentin bonds against pH cycling

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.