Ren Yijin, Maltha Jaap C, Stokroos Ietse, Liem Robert S B, Kuijpers-Jagtman Anne Marie
Department of Orthodontics, University Medical Centre Groningen, University of Groningen, Groningen, the Netherlands.
Am J Orthod Dentofacial Orthop. 2008 May;133(5):752-7. doi: 10.1016/j.ajodo.2007.10.030.
Age effects on orthodontically induced periodontal vascular reactions have not been studied. The aim of the present study was to test the hypothesis that prolonged tooth movement induces age-related increases in periodontal vascularity.
A standardized orthodontic appliance was placed in 2 groups of 30 rats aged 6 weeks and 9 to 12 months. At 1, 2, 4, 8, and 12 weeks, animals were killed. Blood vessels (BV) were identified based on their morphology and by immunohistochemical staining for alpha-smooth muscle actin. At each study region, surface areas (SA) of the periodontal ligament space and each BV were measured; BV mean SA, BV relative SA (the summed BV SA as a percentage of the periodontal ligament SA), and BV numbers were calculated.
Pressure and tension regions showed similar vascular changes. Young rats had lower BV relative SA and BV mean SA in the early phase of force application (< 4 weeks); this increased in the late phase, reaching the same level as adult rats. In the late phase (4-12 weeks), young rats had increases of both small- and large-sized BV that did not affect the BV mean SA; adult rats had an increase of small-sized BV only; this resulted in decreased BV mean SA.
The hypothesis was confirmed that prolonged tooth movement increases periodontal vascularity, which is age related. These results suggest that clinicians should consider age-related difference in tissue reactions during orthodontic tooth movement.
年龄对正畸诱导的牙周血管反应的影响尚未得到研究。本研究的目的是检验这一假设，即长时间的牙齿移动会导致与年龄相关的牙周血管增多。
将标准化的正畸矫治器放置在两组大鼠中，一组30只，年龄为6周，另一组30只，年龄为9至12个月。在第1、2、4、8和12周时，将动物处死。根据血管的形态并通过α-平滑肌肌动蛋白的免疫组织化学染色来识别血管。在每个研究区域，测量牙周膜间隙和每条血管的表面积；计算血管平均表面积、血管相对表面积（血管总表面积占牙周膜表面积的百分比）和血管数量。
压力区和张力区显示出相似的血管变化。幼鼠在施力早期（<4周）的血管相对表面积和血管平均表面积较低；在后期增加，达到与成年大鼠相同的水平。在后期（4 - 12周），幼鼠的小血管和大血管均增加，但不影响血管平均表面积；成年大鼠仅小血管增加；这导致血管平均表面积降低。
长时间的牙齿移动会增加牙周血管数量，且与年龄相关，这一假设得到了证实。这些结果表明，临床医生在正畸牙齿移动过程中应考虑组织反应的年龄差异。
