粘接问题导致临床复合树脂充填继发龋的比例高达75%，提高牙本质与树脂的粘接耐久性一直备受关注。磷酸酯单体10-MDP可与牙本质羟基磷灰石形成化学结合，有助于提高混合层的稳定性，然而目前对混合层内10-MDP-钙盐的形成、分布、水解机制尚不清楚，这限制了具有更好性能粘接产品的开发。课题组预实验发现，10-MDP处理的牙本质粘接界面MMPs活性表达显著降低，纳米渗漏更低，但10-MDP与牙本质羟基磷灰石形成钙盐前，存在与硅烷分子间的缩合反应，却可能干扰胶原纤维被树脂的包裹。以上结果提示10-MDP对混合层稳定性的提高是综合作用的结果。本课题拟从解释10-MDP-钙盐的形成、水解反应可行路径及反应条件的影响、10-MDP-钙盐在混合层内的形成区域以及对MMPs活性和对胶原纤维暴露的影响入手，揭示10-MDP增强混合层稳定性的作用环节及综合贡献，以期为寻找抑制混合层降解新的可行措施提供实验基础。

Efforts towards achieving durable resin–dentine bonds have been made for decades, however, the hybrid layer (HL) created on organic dentine phase is still not perfect, which may fail over long-term, inducing marginal leakage and subsequent loss of retention of the composite restoration. According to a recent study, almost 75% of dental resin composite restorations failed in clinic after a long-term use contributed by the resin–dentine bonds problem. Developing an idea strategy for inhibition of HL degradation is needed. Phosphate ester monomer 10-methacryloyloxydecyl dihydrogen phosphate (10-MDP) has been found that can form a chemical bond with dentine hydroxyapatite and be helpful for improving the stability of resin-dentine bonding. However, the formation mechanism, distribution and hydrolytic stability of 10-MDP-Ca salts in the dentine HL keep unknown, which limit developing effective ways to develop strategy to improve bonding performance of phosphate ester monomer containing products for resin-dentine bonding. We performed a series of preliminary experiments, which provided results that suggested that 10-MDP containing adhesive inhibited the activity of MMPs in the dentine HL, and lead to a decreased nano-leakage of resin-dentine bonding interface. Nevertheless, we also confirmed a condensation reaction between 10-MDP and silane molecules, which, in turn, may weaken the chemical affinity of 10-MDP to hydroxyapatite, as well as silane to collagen fibers in demineralized dentine. All these preliminary data suggested the multiple roles played by 10-MDP-Ca salts in improving stability of dentine HL. In order to identify all the possible influence of 10-MDP-Ca salts, the present project has been designed to embrace three contents, including the formation mechanism of 10-MDP-Ca salts between dentine hydroxyapatite and infiltrated 10-MDP, the hydrolysis tendency and reaction pathway of 10-MDP-Ca salts, and the effects of changes in reaction conditions (i); location the formation of 10-MDP-Ca salts in the dentine HL (ii); and the interaction effects of 10-MDP-Ca salts to activity of MMPs and exposure of the collagen fibrils (iii). The results of the present project can therefore reveal the unknown function of 10-MDP to underlying HL degradation, as well as develop of novel strategies for the preservation of the resin–dentine bonding.