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Cellular events at the onset of physiological root resorption.

生理根吸收开始时的细胞事件。

基本信息

批准号：
13671924
负责人：
SAHARA Noriyuki
金额：
$ 1.86万
依托单位：
Matsumoto Dental University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
2001
资助国家：
日本
起止时间：
2001 至 2002
项目状态：
已结题

项目摘要

For elucidation of how physiological root resorption of deciduous teeth is initiated, the cellular events that occur surrounding the root of rabbit deciduous teeth prior to and at the onset of physiological root resorption were observed by means of light and electron microscopy.The present investigation was focus on the physiological root resorption of deciduous lower second molar in rabbit from day 0 to 5 postnatally. At birth, the deciduous molar has not erupted yet, and no TRAP-positive cell could be found surrounding tissue adjacent to the root of the deciduous tooth. TRAP-positive mononuclear cells were initially detected in the coronal portion of the dental follicle of the permanent tooth at day I postnatally. TRAP-positive mononuclear cells then appeared in the cementoblast layer immediately adjacent to the surface of deciduous roots. At that time, cell-cell contact was frequently observed between these mononuclear cells and cementoblasts. During 3-5 days postnatally, the number of TRAP-positive multinucleated cells on the root surface gradually increased. They had well-developed ruffled borders and made typical resorption lacunae on the root surface of deciduous tooth. During this early postnatal period, neither inflammatory cells nor necrotic tissue could be observed surrounding the deciduous root. This study demonstrates that the dental follicle of the permanent tooth as well as the connective tissue adjacent to the deciduous root might play important role on site- and time-specific recruitment, development and activation of odontoclasts prior to and at the onset of the physiological root resorption.

为阐明乳牙生理性根吸收是如何发生的，用光镜和电子显微镜观察了生理性根吸收发生前和生理性根吸收开始时兔乳牙根部周围的细胞事件。在出生时，乳磨牙还没有萌出，在乳牙根部附近的组织周围找不到TRAP阳性细胞。生后第1天，恒牙牙囊冠部首先检测到TRAP阳性的单个核细胞。然后，TRAP阳性的单个核细胞出现在紧邻落叶根表面的成牙骨质细胞层。当时，这些单个核细胞和成牙骨质细胞之间经常观察到细胞-细胞接触。出生后3-5天，根表面TRAP阳性多核细胞逐渐增多。乳牙根面有发达的皱纹边缘，形成典型的吸收陷窝。在出生后早期，乳根周围既没有炎性细胞，也没有坏死组织。本研究表明，在生理性牙根吸收之前和开始时，恒牙的牙囊以及与乳根相邻的结缔组织可能对破牙细胞的特定部位和时间的招募、发育和激活起重要作用。