Long A, Loescher A R, Robinson P P
Department of Oral and Maxillofacial Surgery, School of Clinical Dentistry, Sheffield, U.K.
Arch Oral Biol. 1996 Aug-Sep;41(8-9):799-808. doi: 10.1016/s0003-9969(96)00057-x.
Using light microscopy, the numbers of myelinated axons in the periodontal ligament of the cat mandibular canine were counted after orthodontic forces had been applied for either 3 days or 12 weeks, and also 8 weeks after removal of a force that had been applied for the previous 12 weeks. After 3 days no significant changes in axon number were recorded, but after 12 weeks there were significantly fewer myelinated axons in the periodontal ligament of the experimental teeth than in the control teeth. This reduction was not reversed after an 8 week recovery period. The width of the ligament was measured in an attempt to correlate regions of nerve fibre degeneration with areas of compression or tension, and the tooth root circumference was measured to assess the extent of any root resorption. It appeared that axon degeneration occurred both in areas of compression and tension. Root resorption had occurred after 12 weeks of applied force and there was no significant change after the 8 week recovery period. These findings support the view that nerve injury occurs as a result of orthodontic force and may possibly be permanent.
利用光学显微镜，在对猫下颌尖牙施加正畸力3天或12周后，以及在去除先前施加12周的力8周后，对牙周膜中有髓轴突的数量进行计数。3天后，轴突数量未记录到显著变化，但12周后，实验牙牙周膜中有髓轴突的数量明显少于对照牙。在8周的恢复期后，这种减少并未逆转。测量韧带宽度以试图将神经纤维变性区域与压缩或拉伸区域相关联，并测量牙根周长以评估任何牙根吸收的程度。似乎轴突变性发生在压缩和拉伸区域。施加力12周后出现了牙根吸收，在8周的恢复期后没有显著变化。这些发现支持了正畸力会导致神经损伤且可能是永久性的这一观点。
