种植材料表面龈下菌斑生物膜形成过程的力学机制研究

Peri-implantitis is one of the main causes of failure for oral implants. The bacterial adhesion and biofilm formation on the implant surface is the essential step and the prerequisite in the pathogenesis of the infection. The aim of this study is to investigate the process of bacterial adhesion on implant surface and the subgingival plaque biofilm formation by atomic force microscopy (AFM). The bacterial adhesion forces for subgingival strains to the implant surface are measured in nearly physiological conditions. According to the statistical analysis of AFM force-distance curve, the mechanism of initial adhesion, bond strengthening and bacteria gather for the different strains to implant biomaterials are clarified. Furthermore, the morphology and adhesion forces of bacterial cells in the early to mature stages of biofilm formation are demonstrated . So the force map is created over the forming biofilm. It is a complicated process influenced by many factors, including the bacterial properties, the material surface characteristics and the environment. Integrated with the measurement of the cohesive energy, this study discusses the mechanism of subgingival plaque biofilm formation of implant materials. This results will help the design optimization of material type and surface to reduce bacterial adhesion of implant surface and control the subgingival plaque formation. It will elucidate the mechanical mechanism for reducing the incidence of per-implantitis. Moreover, the method of analyzing adhesion forces and cohesive strength in the process of bacterial adhesion will be a new idea for the mechanism study of biofilm formation.

口腔种植体周围炎是导致种植失败的主要原因之一，细菌在种植体表面的黏附定植及生物膜形成是致病性的首要步骤和前提条件。本课题采用原子力显微镜技术（AFM）研究细菌对种植材料表面的黏附及菌斑生物膜形成机制，在近生理条件下检测细菌对种植材料的黏附力，通过对力-距曲线的统计学分析，研究不同细菌对种植材料初期黏附、黏附强化及细菌集聚的机制；在此基础上分析生物膜形成早期到成熟阶段的形貌及细菌黏附力，获得生物膜表面的力分布图，讨论影响生物膜形成及处理的因素；综合分析菌斑生物膜的黏附能，探讨种植材料表面菌斑生物膜形成的机制。本课题有助于种植材料种类和表面设计优化，减少细菌黏附，控制牙菌斑的形成，降低种植体周围炎的发病率；通过分析黏附力及黏附能研究细菌黏附过程，为菌斑生物膜的形成机制研究提供新的思路。

本课题组探索并优化了制备高质量原子力显微镜（AFM）用多细菌细胞探针的方法，在近生理条件的液相下采用AFM研究了口腔细菌对牙体组织和种植材料表面的初期黏附和黏附强化的过程，结果表明牙体组织和材料化学组成、表面粗糙度和微观形貌影响细菌定植黏附,特别是表面粗糙度的影响较大，对于特定材料存在阈值；分析细菌对材料表面的集聚过程，检测先锋菌与牙周致病菌之间相互的黏附力，探索细菌与细胞外基质或基质内的微观相互作用机制；研究分析龈下细菌生物膜形成早期到成熟阶段的形貌及细菌细胞的黏附力，获得生物膜表面的力分布图，讨论影响细菌生物膜形成及处理的因素包括pH值、溶液离子浓度等；建立了口腔单细菌细胞黏附力测试平台，可用于研究单个活细胞的黏附行为和过程，对阐明细菌黏附的分子机制有明显的优势，为后续进一步利用原子力显微镜从细菌黏附行为及生物膜形成力学机制开展系统的创新性研究工作奠定了良好的基础。