Mavridou Athina M, Hauben Esther, Wevers Martine, Schepers Evert, Bergmans Lars, Lambrechts Paul
Department of Oral Health Sciences, BIOMAT Research Cluster, KU Leuven and University Hospitals Leuven, Leuven, Belgium; Private Practice, Endo Rotterdam, Rotterdam, The Netherlands.
Department of Imaging and Pathology, KU Leuven and University Hospitals Leuven, Leuven, Belgium.
J Endod. 2016 Dec;42(12):1737-1751. doi: 10.1016/j.joen.2016.06.007. Epub 2016 Oct 21.
The aim of this study was to investigate the 3-dimensional (3D) structure and the cellular and tissue characteristics of external cervical resorption (ECR) in vital teeth and to understand the phenomenon of ECR by combining histomorphological and radiographic findings.
Twenty-seven cases of vital permanent teeth displaying ECR were investigated. ECR diagnosis was based on clinical and radiographic examination with cone-beam computed tomographic imaging. The extracted teeth were further analyzed by using nanofocus computed tomographic imaging, hard tissue histology, and scanning electron microscopy.
All examined teeth showed some common characteristics. Based on the clinical and experimental findings, a 3-stage mechanism of ECR was proposed. At the first stage (ie, the initiation stage), ECR was initiated at the cementum below the gingival epithelial attachment. At the second stage (ie, the resorption stage), the resorption invaded the tooth structure 3-dimensionally toward the pulp space. However, it did not penetrate the pulp space because of the presence of a pericanalar resorption-resistant sheet. This layer was observed to consist of predentin, dentin, and occasionally reparative mineralized (bonelike) tissue, having a fluctuating thickness averaging 210 μm. At the last advanced stage (ie, the repair stage), repair took place by an ingrowth and apposition of bonelike tissue into the resorption cavity. During the reparative stage, repair and remodeling phenomena evolve simultaneously, whereas both resorption and reparative stages progress in parallel at different areas of the tooth.
ECR is a dynamic and complex condition that involves periodontal and endodontic tissues. Using clinical, histologic, radiographic, and scanning microscopic analysis, a better understanding of the evolution of ECR is possible. Based on the experimental findings, a 3-stage mechanism for the initiation and growth of ECR is proposed.
本研究旨在探究活髓牙颈部外吸收（ECR）的三维（3D）结构以及细胞和组织特征，并通过结合组织形态学和影像学结果来理解ECR现象。
对27例显示有ECR的活髓恒牙进行了研究。ECR诊断基于临床检查和锥束计算机断层扫描成像。提取的牙齿进一步通过纳米聚焦计算机断层扫描成像、硬组织组织学和扫描电子显微镜进行分析。
所有检查的牙齿都表现出一些共同特征。基于临床和实验结果，提出了ECR的三阶段机制。在第一阶段（即起始阶段），ECR始于牙龈上皮附着下方的牙骨质。在第二阶段（即吸收阶段），吸收向牙髓腔三维方向侵入牙体结构。然而，由于存在根管周围抗吸收层，它并未穿透牙髓腔。观察到该层由前期牙本质、牙本质以及偶尔的修复性矿化（骨样）组织组成，厚度波动，平均为210μm。在最后一个晚期阶段（即修复阶段），通过骨样组织向内生长并沉积到吸收腔中进行修复。在修复阶段，修复和重塑现象同时发生，而吸收和修复阶段在牙齿的不同区域并行进展。
ECR是一种涉及牙周和牙髓组织的动态且复杂的情况。通过临床、组织学、影像学和扫描显微镜分析，可以更好地理解ECR的演变。基于实验结果，提出了ECR起始和发展的三阶段机制。
