恒磨牙窝沟菌斑结构的研究

Study on the structure of fissure plaque of permanent molars

目的比较有龋窝沟和无龋窝沟的菌斑结构。方法首先将拔除的双尖牙或磨牙进行双固定,通过窝沟,颊舌向连续切两张牙片,锇酸固定后,一张牙片做显微放射照相分析,确定有龋和无龋牙各5颗,另一张牙片用环氧树脂包埋;部分磨除表层的环氧树脂以暴露牙本质和釉质,10%EDTA脱钙,将菌斑包埋、切片,透射电镜观察。结果有龋窝沟和无龋窝沟的菌斑结构有明显的区别:有龋窝沟菌斑中细胞成分较多,细胞形态变化较多,多数细胞形态完整、包膜清晰,细胞间的基质成分较少,在基质中可见大量的膜样结构;无龋窝沟菌斑中细胞成分较少,细胞形态变化较少,多为圆形,细胞间的基质成分较多,细胞之间可见明显的基质间隔。二者也有相同的特点:菌斑与釉质界面上有连续的高电子密度的条带,未见明显的细胞分裂,无龋窝沟菌斑在整个菌斑的不同区域均可见到细胞壁的增厚、细胞内钙化、细胞内空泡变性等现象,并且明显多于有龋窝沟菌斑。结论有龋窝沟菌斑和无龋窝沟菌斑的结构有显著差别,有龋窝沟菌斑中细胞数量多,体积大。

Objective To investigate the structure of permanent molar fissure plaque by transmission electron microscope （TEM）. Methods The fresh extracted molars was immediately fixed for 24 hours and then fixed again in 2% osmic acid for 2 hours. Fissure specimen was made by buccolingually sectioning the fissure one by one, and two sections were obtained for each tooth, one for micro-radiography and another （containing fissure plaque） was immediately fixed again in 2% osmic acid for 1 hour. After embedding and grinding the specimen, fissure enamel was exposed and removed in 10% EDTA, and then the plaque was embedded once again. The ultra thin sections were made and the plaque was observed under TEM. Results The structure of plaque in caries fissure was different to that in non-caries fissure. The plaque in carious fissure was mainly comprised by less matrix between cells, a structure similar to cell membrane, and more cells with various shape compared to the plaque in non-caries fissure which contained less, smaller, circle cells. They had same structural appearance, such as a continuous high electron dense hand, intercellular and intracellular calcification, thicker cell membrane, intracellular vesicles and without cell divisions. Conclusion Structure differences between plaques in carious and non-caries fissure suggest that the plaque in carious fissure was more cariogenic than plaque in non-caries fissure.