Ren Yijin, Maltha Jaap C, Stokroos Lets, Liem Robert S B, Kuijpers-Jagtman Anne Marie
Department of Orthodontics, University Medical Centre Groningen, University of Groningen, Groningen, The Netherlands.
Angle Orthod. 2008 Nov;78(6):1000-5. doi: 10.2319/080107-357.1.
To investigate the age-dependent morphology of the periodontal ligament (PDL) tissue and changes in its surface area (SA) during force application provided with a standardized orthodontic setup for a period of 12 weeks in young and adult rats.
Two groups of 30 rats, age 6 weeks and 9 to 12 months, were used. Orthodontic appliances were placed to move the maxillary molars mesially with the contralateral sides used as controls. At 1, 2, 4, 8, and 12 weeks, groups of animals were killed. The PDL SA and the PDL SA ratio between pressure and tension regions were determined.
An age-related decrease in the PDL SA was noted at control sides. Significant changes during the experimental period occurred only at experimental sides: The PDL SA was smaller at pressure than at tension regions only at week 1 in young rats; in adult rats, the difference between the two regions was significant at week 8. These changes were confirmed by the morphologic disorganization of the PDL and alterations in the PDL SA ratio.
During force application, the PDL at the pressure regions became disorganized and subsequently was reorganized, as is shown by the histologic changes and SA of the PDL over time. This process occurred earlier and was more prominent in young rats; it occurred later and was more prolonged in adult animals.
利用标准化正畸装置，对年轻和成年大鼠施加力12周，研究牙周膜（PDL）组织随年龄变化的形态及其表面积（SA）的改变。
使用两组大鼠，每组30只，分别为6周龄和9至12月龄。放置正畸矫治器使上颌磨牙向近中移动，对侧作为对照。在1、2、4、8和12周时，处死每组动物。测定牙周膜表面积以及压力区与张力区的牙周膜表面积比值。
对照侧观察到牙周膜表面积随年龄下降。实验期间仅在实验侧出现显著变化：年轻大鼠仅在第1周时压力区的牙周膜表面积小于张力区；成年大鼠在第8周时两个区域的差异显著。这些变化通过牙周膜的形态紊乱和牙周膜表面积比值的改变得到证实。
在施加力的过程中，压力区的牙周膜变得紊乱，随后重新组织，这通过牙周膜的组织学变化和表面积随时间的变化得以体现。这个过程在年轻大鼠中发生得更早且更明显；在成年动物中发生得更晚且持续时间更长。
