牙髓－牙本质复合体超微结构的老年性改变

Age-related changes of the ultrastructures in dental pulp-dentin complex

目的研究牙髓－牙本质复合体超微结构的老年性特征，探讨牙衰老临床表现的机理，并为抗衰老研究提供形态学基础。方法应用透射电镜观察青幼组（１～６月龄）和老年组（１８～２４月龄）Ｗｉｓｔａｒ大鼠切牙牙髓－牙本质复合体主要成分的超微结构。结果老年大鼠造牙本质细胞核出现切迹，内含大量异染色质；高尔基复合体、粗面内质网和线粒体水肿、空泡化，最后消失，胞浆内未见脂褐素；相邻细胞间隙扩大，并出现环层样小体，最后细胞连接松解、分离；牙本质钙盐增加，脱钙时间延长；胶原原纤维增粗、横纹消失、数量增加；牙本质小管缩窄、阻塞、减少，界膜退变。结论牙髓－牙本质复合体超微结构的衰变与其它组织基本相同，细胞内不出现脂褐素和细胞间隙出现环层小体可能是该组织衰老的独有特征。

Objective Age-related changes of the ultrastructures in dental pulp-dentin complex were studied and the mechanism of clinical manifestations due to aging of teeth was approached,so as to provide the morphological basis for anti-aging study.Methods A group of 7 young Wistars rats(1-6 months old) and a group of 7 old(18-24 months old) were used for this study.The ultrastructures of the main components in dental pulp-dentin complex of the incisors were examined under transmission electron microscope.Results The nuclei of the odontoblasts of the aging rats were notched and contained a large amount of heterochromatins.The Golgi complexes,mitochondria and rough endoplasmic reticula showed edema, became gradually vacuolized and finally disappeared.There was no lipofuscin in the cytoplasm.The space between the odontoblasts was enlarged and filled with ring-layered figures.The odontoblasts were finally separated after the connections were destroyed.Calcium depositions in the dentinal matrix increased in amount and the time required for decalcification of the dentin prolonged.The cross striations of collagen fibrilles in the predentin and the dentin could not be found.The collagen fibriles increased in diameter and amount.The number of dentinal tubule reduced obviously.The lumina of the dentinal tubule were either narrowed or occluded.The lumina limilems in the tubules degenerated.Couclusions The changes of the ultrastructures in dental pulpdentin complex of aging teeth are basically similar to other tissues, but there is no lipofuscin in the cytoplasm.Ring-layered figures appearing in the spaces between aging odontoblasts might be a distinctive feature of the aging teeth tissue.