Francini E, Mancini G, Vichi M, Tollaro I, Romagnoli P
Department of Human Anatomy and Histology, University of Florence, Italy.
Ital J Anat Embryol. 1992 Jul-Sep;97(3):189-201.
In order to obtain detailed information on the tissue changes which occur during physiological root resorption, 52 human deciduous teeth at various stages of resorption were studied under light microscopy. The early stage of root resorption was defined as resorption of not more than one third of the root length; the late stage was defined as resorption of more than one third. A close topographical interrelationship was found among che sites of pressure of the permanent tooth, the extent of root resorption and the types of tissue changes. Linear resorption (which reflects suspension or marked slowing down of resorption) and redeposition of hard tissue were more pronounced at the early stage of resorption, while lacunar resorption was more pronounced at the late stage. There were pronounced haemorrhagic and inflammatory infiltrates within the pulp at the late stage of resorption and the subodontoblastic cells disappeared as the infiltrates took over the tooth. False denticles were found frequently, especially at the early stage of resorption. Unexpectedly, acellular cementum was found to be deposited against secondary dentine at the cuspidal tip of the pulp chamber of seven teeth, independently of any sign of resorption nearby. These data indicate that: 1) the pressure exerted by a permanent tooth is the most important factor in the differentiation of odontoclasts. 2) the extent of lacunar (i.e., active) resorption correlates directly with the resorption rate, which is higher at the late stage of root resorption. 3) inflammation is a consequence, rather than a cause, of resorption; it may lead to the loss of subodontoblastic cells and a consequent decrease in the ability of the pulp cells to replace damaged odontoblasts. 4) the pulp of the deciduous tooth might be cementogenic in some way, given that about 13% of the samples were found to be so.
为了获取有关生理性牙根吸收过程中发生的组织变化的详细信息，对52颗处于不同吸收阶段的人乳牙进行了光学显微镜研究。牙根吸收的早期定义为牙根长度吸收不超过三分之一；晚期定义为吸收超过三分之一。在恒牙的压力部位、牙根吸收程度和组织变化类型之间发现了密切的地形学相互关系。线性吸收（反映吸收的暂停或明显减缓）和硬组织的再沉积在吸收早期更为明显，而腔隙性吸收在晚期更为明显。在吸收晚期，牙髓内有明显的出血和炎症浸润，随着浸润占据牙齿，成牙本质细胞下层细胞消失。假牙本质经常被发现，尤其是在吸收早期。出乎意料的是，在七颗牙齿的牙髓腔尖部，无细胞牙骨质被发现沉积在继发性牙本质上，与附近任何吸收迹象无关。这些数据表明：1）恒牙施加的压力是破骨细胞分化的最重要因素。2）腔隙性（即活跃的）吸收程度与吸收速率直接相关，牙根吸收晚期的吸收速率更高。3）炎症是吸收的结果而非原因；它可能导致成牙本质细胞下层细胞的丧失，从而导致牙髓细胞替代受损成牙本质细胞的能力下降。4）鉴于约13%的样本被发现如此，乳牙牙髓可能在某种程度上具有牙骨质生成能力。
