Minato Yukari, Yamaguchi Masaru, Shimizu Mami, Kikuta Jun, Hikida Takuji, Hikida Momoko, Suemitsu Masaaki, Kuyama Kayo, Kasai Kazutaka
Department of Orthodontics, Nihon University School of Dentistry at Matsudo, Chiba, Japan.
Department of Oral Pathology, Nihon University School of Dentistry at Matsudo, Chiba, Japan.
Korean J Orthod. 2018 Jul;48(4):253-261. doi: 10.4041/kjod.2018.48.4.253. Epub 2018 Jul 6.
Orthodontic root resorption (ORR) due to orthodontic tooth movement is a difficult treatment-related adverse event. Caspases are important effector molecules for apoptosis. At present, little is known about the mechanisms underlying ORR and apoptosis in the cementum. The aim of the present study was to investigate the expression of tartrate-resistant acid phosphatase (TRAP), caspase 3, caspase 8, and receptor activator of nuclear factor kappa-B ligand (RANKL) in the cementum in response to a heavy or an optimum orthodontic force.
The maxillary molars of male Wistar rats were subjected to an orthodontic force of 10 g or 50 g using a closed coil spring. The rats were sacrificed each experimental period on days 1, 3, 5, and 7 after orthodontic force application. And the rats were subjected to histopathological and immunohistochemical analyses.
On day 7 for the 50-g group, hematoxylin and eosin staining revealed numerous root resorption lacunae with odontoclasts on the root, while immunohistochemistry showed increased TRAP- and RANKL-positive cells. Caspase 3- and caspase 8-positive cells were increased on the cementum surfaces in the 50-g group on days 3 and 5. Moreover, the number of caspase 3- and caspase 8-positive cells and RANKL-positive cells was significantly higher in the 50-g group than in the 10-g group.
In our rat model, ORR occurred after apoptosis was induced in the cementum by a heavy orthodontic force. These findings suggest that apoptosis of cementoblasts is involved in ORR.
正畸牙齿移动导致的正畸牙根吸收（ORR）是一种与治疗相关的棘手不良事件。半胱天冬酶是细胞凋亡的重要效应分子。目前，关于牙骨质中ORR和细胞凋亡的潜在机制知之甚少。本研究的目的是调查在重度或最佳正畸力作用下，牙骨质中抗酒石酸酸性磷酸酶（TRAP）、半胱天冬酶3、半胱天冬酶8和核因子κB受体激活剂配体（RANKL）的表达情况。
使用闭合螺旋弹簧对雄性Wistar大鼠的上颌磨牙施加10 g或50 g的正畸力。在施加正畸力后的第1、3、5和7天的每个实验时间段处死大鼠。对大鼠进行组织病理学和免疫组织化学分析。
在50 g组的第7天，苏木精-伊红染色显示牙根上有大量牙根吸收腔隙，伴有破牙细胞，而免疫组织化学显示TRAP和RANKL阳性细胞增加。在50 g组的第3天和第5天，牙骨质表面的半胱天冬酶3和半胱天冬酶8阳性细胞增加。此外，50 g组中半胱天冬酶3和半胱天冬酶8阳性细胞以及RANKL阳性细胞的数量显著高于10 g组。
在我们的大鼠模型中，重度正畸力诱导牙骨质细胞凋亡后发生了ORR。这些发现表明成牙骨质细胞的凋亡与ORR有关。
