Faltin R M, Arana-Chavez V E, Faltin K, Sander F G, Wichelhaus A
Department of Orthodontics, University of Ulm, Germany.
J Orofac Orthop. 1998;59(4):208-19. doi: 10.1007/BF01579165.
A scanning electron microscopy study of possible root resorptions and their localization after application of continuous forces of different magnitudes was conducted. Twelve upper first premolars, indicated for extraction, were previously intruded with constant forces. The teeth were divided into 3 groups: 1. non-moved control teeth, 2. continuous force application of 50 cN for 4 weeks, 3. continuous force application of 100 cN for 4 weeks. Specially designed NiTi-SE-stainless steel springs were utilized to exert the actual forces. After experimental tooth movement, the extracted teeth were dehydrated, metal-coated and examined by scanning electron microscopy. The intruded teeth showed resorptive areas consisting of lacunae (concavities) in the mineralized root surface. The teeth moved with 50 cN showed in the apical third several, in the medial third few, and in the cervical third no resorptive areas. In the case of the teeth moved with 100 cN, we observed resorptive areas in most of the apical third--including the apex contour-, several in the medial third, and none in the cervical third. In the control group no resorptions were observed. Thus, our results suggest that intrusion of human teeth with continuous forces induces root resorption, depending on the magnitude of force applied.
进行了一项扫描电子显微镜研究，以观察在施加不同大小的持续力后可能出现的牙根吸收及其定位情况。选取了12颗拟拔除的上颌第一前磨牙，预先用恒定力使其侵入。这些牙齿被分为3组：1. 未移动的对照牙；2. 以50 cN的持续力施加4周；3. 以100 cN的持续力施加4周。使用专门设计的镍钛-SE-不锈钢弹簧来施加实际力。在实验性牙齿移动后，将拔除的牙齿脱水、镀金属并通过扫描电子显微镜检查。侵入的牙齿显示出在矿化牙根表面有由凹陷（凹坑）组成的吸收区域。以50 cN移动的牙齿在根尖三分之一处有几个吸收区域，在中间三分之一处有少量吸收区域，在颈部三分之一处没有吸收区域。在以100 cN移动的牙齿中，我们观察到大部分根尖三分之一区域包括根尖轮廓处有吸收区域，中间三分之一处有几个吸收区域，颈部三分之一处没有吸收区域。在对照组中未观察到吸收情况。因此，我们的结果表明，持续力使人类牙齿侵入会导致牙根吸收，这取决于所施加力的大小。
