MECHANISM OF ADHESION BETWEEN GINGIVAL JUNCTIONAL EPITHELIUM AND TOOTH ENAMEL

1)本研究对猕猴牙龈边界牙角质层的超微结构进行了详细观察。结果表明，牙角质层是在牙牙龈边缘由基底膜成分和一种生化性质不确定的深色无定形物质的积累而形成的，这种物质位于牙釉质侧的牙结上皮基底膜致密层。虽然黑色无定形物质可能来源于牙龈渗出液中的血清蛋白或降解红细胞中的血红蛋白，但仍需要进一步的研究来证明这种黑色物质的来源。2)在非哺乳动物物种中，牙基膜的表征仍有待进一步研究。本研究对鲨鱼不同发育阶段的牙齿基底膜进行了详细的超微结构观察。结果表明，发育中的鲨鱼牙齿的基底膜和哺乳动物牙齿的基底膜一样，发挥着多种作用，包括锚定、牢固结合，以及可能介导对牙齿发育至关重要的物质的运输。3)为了阐明牙龈与牙齿黏附的机制，我们对猴子牙龈边界进行了详细的超微结构研究。在边界处，内基底膜通过半底粒与连接上皮紧密结合。在牙釉质侧，有一附加层（补充层），具有牙釉质侧纹层致密的特征。在非脱矿组织中，基底膜的一部分，即补充层致密层优先矿化。该矿床与牙釉质中的矿床连续，构成矿化的前缘。因此，牢固的牙龈-牙齿粘连是通过内部基膜的部分矿化来建立的。

1) In this study the detailed ultrastructure of the dental cuticle at the dentogingival border in monkeys was observed. The results suggest that the dental cuticle, is formed at the dentogingival border by an accumulation of basement membrane components and a dark amorphous material of uncertain biochemical nature at the enamel side of the lamina densa of the basement membrane of the junctional epithelium. While the dark amorphous material may be derived, as has been suggested, from serum proteins in gingival exudates or hemoglobin from degraded red blood cells, further studies are still needed to demonstrate the origin of this dark material.2) In nonmammalian species, characterization of the tooth basement membranes is still to be advanced. In this study, detailed ultrastructural observations of the basement membranes of the tooth of the shark were made in its various developmental stages. The results indicate that basement membranes of the developing shark tooth, as those in the mammalian tooth, play various roles, including anchoring, firm binding, and possible mediation of the transport of substances that are known to be vital for the development of the tooth.3) In order to elucidate the mechanism of adhesion between the gingiva and the tooth, detailed ultrastructural studies of the dentogingival border were done in the monkey. At the border, the internal basement membrane is firmly bounded to the junctional epithelium through hemidesmosomes. The lamina densa was closely associated at its enamel side with an additional layer (supplementary lamina densa), which had characteristics of the lamina densa. In nondemineralized tissues a part of the basement membrane, that is, the supplementary lamina densa was preferentially mineralized. The mineral deposit was continuous with that in the enamel, thus constituting an advancing edge of mineralization. Therefore, strong gingiva-tooth adhesion is established by partial mineralization of the internal basement membrane.