混合层树脂水解析出和裸露胶原酶解变性是临床树脂充填体脱落的主要原因，如何重建其结构和功能并改善树脂牙本质粘接耐久性是亟待解决的问题。本课题组前期研究表明，多聚磷酸钠和聚丙烯酸能模拟非胶原蛋白对生物矿化的双向调控作用，诱导脱矿牙本质胶原纤维内再矿化，重现天然矿化胶原磷灰石晶体的尺寸及迭序排列特征。本研究拟进一步探讨多聚磷酸钠与I型胶原的分子作用机理，通过无定形磷酸钙纳米粒度分析及单层重组胶原矿化诱导实验，优化含多聚磷酸钠和聚丙烯酸的仿生改性MTA Plus树脂洞衬剂，改建混合层原位再矿化模型。应用酶联免疫吸附法探讨仿生矿化对I型胶原代谢的抑制作用，透射电镜和激光共聚焦扫描电镜定性分析微观形态学变化，纳米动态力学分析与微拉伸测试定量评价粘接界面的硬度和微拉伸强度等生物力学指标改变，深入揭示混合层矿化调控机理及其在改善树脂牙本质粘接耐久性中的意义，为仿生再矿化策略的最终临床应用提供充分科学依据。

Hydrolytic degradation of adhesive resin and enzymatic degradation of exposed collagen fibrils within the bonded interface are known as the key factors contrubuting to bond failure.Clearly, improving the durability of resin-dentin bonds is a significant health issue that affects the quality of life of individuals. Using sodium tripolyphosphate(STTP) and polyacrylic acid (PAA) as dual biomimetic analogs of non-collagenous proteins(NCPs), we successfully achieved remineralization of demineralized dentin, with evidence of intrafibrillar apatite nanoplatelets deposited in an ordered manner observed in natural mineralized collagen fibrils.In this proposal, we aim to examine the binding characteristics as well as mechanism of STTP to type I collagen of dentin, to establish a clinical relevant in-situ biomimetic remineralization model of hybrid layer by developing a biomimetically modified MTA plus resin liner.This will enable STTP, PAA, calcium and hydroxyl ions to diffuse into hybrid layer,resulting in biomimetic remineralization and self-repair of poorly resin-infiltrated collagen matrices. The C-terminal telopeptides (ICTP) released by MMP degradation of hybrid layers will be detected with ELISA to quantitate enzymatic activity on the naked type I collagen fibrils.Representative remineralized specimens will be evaluated with transmission electron microscopy (TEM)and confocal laser scanning microscopy (CLSM) for changes in the ultrastructure of hybrid layers and ability of apatite backfilling of water-filled defects in hybrid layers.Nano-dynamic mechanical analysis (nano-DMA) and microtensile strength testing will be used to quantitatively probe the mechanical behavior of biomimetic remineralized dentin hybrid layers. The success of the proposed vertically-diffusing, in-situ remineralization protocol in resisting the degradation of resin-dentin bonds may warrant the role of biomimetic remineralizaiton technology in imrpoving the integrity of hybrid layers, and benifiting clinicians by providing a means for extending the durability of resin-dentin bonds via a biomimetic scheme.