牙体硬组织仿生矿化功能多肽构建及其原位修复牙体龋损组织的实验研究

Dental caries is the most prevalent oral disease in the world, posing a serious threat to oral and general health. The repairment of caries lesions is one of the most common and important dental clinical treatment. However, there are still some problems need to be solved in the current treatment such as filling microleakage, excitant to pulp, material aging and so on. According to biomimetic mineralization rationale, we put forward the hypothesis that biomimetic mineralization can cause the regeneration of tooth hard tissue in carious lesions in situ, which may become a new ideal repairment mode of dental carious lesions. However, so far there is no evidences to prove this hypothesis, the application research of biomimetic mineralization in this fields havn't been carried out. It is well known that amelogenin and dentin phosphoprotein act as a significant accelerant in biomineralized process of the tooth. Our previous experiments had obtained some functional peptides based amelogenin and dentin phosphoprotein, and for the first time it had been proved these functional peptides based on amelogenin and dentin phosphoprotein can enhance the remineralization of initial enamel carious lesion. In view of successful synthesis of hydroxyapatite induced by the polymer in vitro, by molecular biotechnology the current project will modify previous functional peptides based on amelogenin and dentin phosphoprotein to become a kind of biomimetic mineralization peptides, and test the potential of modified peptides in repairing the enamel / dentin carious lesion by biomimetic regeneration teeth hard tissue. Parameters of Biomimetic mineralization peptides delivery will be systematically optimized, including the form of calcium and phosphate used, and the target interface between Biomimetic mineralization peptidesand dental caries. Finally, the efficiency of repairment to carious lesions in situ is evaluated and its mechanism is explored. This study will provide the theoretical basis for the application of biomimetic mineralization peptides to repair the enamel/dentin carious lesion via biomimetic regeneration of teeth hard tissue. And the study will lay the solid foundation for breaking new ground in caries repairment and treatment. At the meantime, the implementation of this project will push the remineralization as a anticaries method into a repairment method to carious lesion through biomimetic process.

龋损修复是口腔临床最常见的重要工作，目前存在边缘微漏、牙髓刺激性、材料老化等问题。借助仿生矿化思想，在龋损原位再生牙体硬组织可能成为龋损修复的理想新模式。迄今国内外尚缺乏这方面的系统研究，仿生矿化修复龋损牙体组织的应用仍是空白。基于釉原蛋白、牙本质磷蛋白在牙发育过程中的生物矿化调控作用及体外其他高分子诱导羟磷灰石合成的成功，申请人创新提出仿生矿化原位修复牙体龋损思想，对课题组前期获得的具有再矿化作用的釉原蛋白功能多肽和牙本质磷蛋白功能多肽8DSS进行结构优化，通过多体系仿生矿化活性筛选实验，构建牙体硬组织仿生矿化功能多肽，通过多肽作用界面、钙磷供给形式等的研究建立仿生体外模型，评估其原位修复龋损有效性，探索其作用机制。本研究为仿生矿化功能多肽修复牙体龋损的应用提供理论依据，为开辟一条新的安全有效的牙体龋损修复方法奠定基础。同时本项目的实施也将再矿化从防龋手段的研究发展为龋损修复方法的研究

基于釉原蛋白、牙本质磷蛋白在牙发育过程中的生物矿化作用，体外有机高分子诱导牙体组织样羟磷灰石仿生合成的成功，课题组前期促进早期龋再矿化的釉原蛋白功能多肽和牙本质磷蛋白功能多肽8DSS的获得，本项目创新性提出“将早期龋的再矿化发展为龋损牙体硬组织原位仿生矿化”思想，借鉴蛋白质和多肽对生物矿化的调控作用，对前期具有促早期龋再矿化作用的釉原蛋白功能多肽ADP和牙本质磷蛋白功能多肽8DSS的氨基酸序列和二级构型进行优化，通过多体系仿生矿化活性筛选实验，构建具有仿生修复牙体硬组织功能的基于釉原蛋白、牙本质磷蛋白的功能多肽ADP1、8DSS1；进一步系统研究牙体硬组织仿生功能多肽载体、使用浓度、作用时间、龋表面处理方法、钙磷供给形式，建立了仿生牙体硬组织功能多肽原位修复牙体龋损组织的仿生体外模型；同时观察牙体硬组织仿生功能多肽ADP1、8DSS1对不同龋损深度牙体硬组织的原位修复，证明了牙体硬组织仿生功能多肽原位修复不同龋损深度牙体龋损组织的有效性。通过形貌学、化学、晶体学性能分析，初步探索仿生牙体硬组织功能多肽原位修复牙体龋损组织的机制，提出ADP1、8DSS1可能以静电作用吸附龋损表面，进而吸附钙磷行成晶核，启动了仿生矿化过程。牙本质龋损部位由于胶原对矿化的支持作用更为显著，单纯的晶核促进启动化学矿化过程较早期龋而言修复中、深龋部位的牙体缺损能力尚待进一步加强。观察不同浓度氟化物对仿生牙体硬组织功能多肽原位修复牙体龋损组织的影响，明确了氟与仿生矿化多肽在仿生矿化功能上具有协同作用。.总之，通过本项目的实施，充分提高了前期釉原蛋白功能多肽和牙本质磷蛋白功能多肽防治龋病的效果，进一步为利用仿生方法获得再生牙体硬组织的研究奠定基础，为仿生矿化功能多肽修复牙体硬组织龋损的应用提供理论依据，为开辟一条新的安全有效的牙体硬组织缺损修复方法提供可能。