天然牙菌斑生物膜中死菌和活菌的空间分布

Spatial distribution of dead and vital bacteria in the native dental biofilm

目的研究天然牙菌斑生物膜初期形成中死菌和活菌的空间分布,为预防龋病及牙周病提供依据。方法通过釉质磨片从牙齿表面获得完整的1、4、8、12、24h 天然牙菌斑生物膜标本,应用激光共聚焦扫描显微镜及死菌和活菌荧光染色技术相结合的方法,对各时段的天然菌斑生物膜中死菌和活菌进行原位、实时的动态观察。结果天然牙菌斑生物膜形成初期,底层结构稀疏,主要由死菌组成,约占70%～80%;中间层细菌密集,主要由活菌组成,约占40%～70%,包括许多周围有活菌围绕的管道和空隙;顶层结构同底层,活菌较少,约占20%～40%。结论天然牙菌斑生物膜中死菌和活菌分布不均匀,顶层和底层主要由死菌组成,中间层主要由活菌组成;死菌是牙菌斑生物膜形成初期的组成部分之一;生物膜中的细菌排列随时间的延长而逐渐密集,形成了丰富的管道系统。

Objective To examine the spatial distribution of dead and vital bacteria in the early formation of native dental biofilm. Methods An experimental dental biofilm model in the oral cavity was established by enamel slabs and the spatial distribution of dead and vital bacteria in the early colonization of native dental biofilm on the enamel surface was observed by in situ real-time and dynamic observations and optical sections utilizing confocal laser scanning microscope （CLSM） and live and dead bacterial fluorescence staining technique. Results At the initial stage of dental biofilm formation, the structure was sparse and the percentage of dead cells reached 70% -80% at the inner layers. In the middle layers the structure became denser than in the inner layers, which was mainly composed of vital cells （40%-70% ）, and void-like structures were surrounded by vital bacteria. In the outer layers, the structure was sparse and vital cells occupied 20% -40%. Conduslons Native dental biofilms showed an uneven spatial distribution of vital and dead microorganisms. The percentage of vital microorganisms was lower adjacent to the enamel surface, increased in the z-axis towards the central parts, and decreased again towards the outer layers. The dead bacteria is an integral component in the early formation of native dental biofilm. Bacteria in the biofilms increased with time forming abundant channels.