Chayanupatkul Atinooch, Rabie A B M, Hägg Urban
Orthodontics, Faculty of Dentistry, The University of Hong Kong, Hong Kong SAR, China.
Eur J Orthod. 2003 Oct;25(5):465-70. doi: 10.1093/ejo/25.5.465.
This study was designed to monitor the amount of bone formed after 'early' and 'late' removal of bite-jumping devices and to compare it with that of normal growth. One hundred and thirty-five 35-day-old female Sprague-Dawley rats were randomly divided into seven control (n = 5) and 10 experimental (n = 10) groups. Appliances were fitted to position the mandible forward in the experimental groups. On day 30, the bite-jumping device was removed in two groups ('early' removal) and the rats were sacrificed on days 44 and 60. On day 44 the device was removed in one group ('late' removal) and the rats were sacrificed on day 60. The full-time wear and matched control animals were then sacrificed at different time points. Tissue sections (7 microm) were cut through the temporomandibular joint (TMJ) in the sagittal plane and stained with periodic acid and Schiff's reagent for the evaluation of new bone formation. Newly formed bone was measured using a computer-assisted image analysing system. The results showed that, in the condyle, early removal of the appliance resulted in less bone formation when compared with that of natural growth. Late removal of the appliance resulted in bone formation similar to that of natural growth. In the glenoid fossa, the level of bone formation was similar to that of the control at early and late removal of the appliance. In conclusion, early appliance removal results in subnormal growth of the posterior condyle but not of the glenoid fossa. Increasing the length of mandibular advancement secures normal levels of mandibular growth in the post-treatment period.
本研究旨在监测咬合跳跃装置“早期”和“晚期”拆除后形成的骨量，并将其与正常生长的骨量进行比较。135只35日龄雌性Sprague-Dawley大鼠被随机分为7个对照组（n = 5）和10个实验组（n = 10）。在实验组中安装矫治器以使下颌向前移位。在第30天，两组拆除咬合跳跃装置（“早期”拆除），并在第44天和第60天处死大鼠。在第44天，一组拆除装置（“晚期”拆除），并在第60天处死大鼠。然后在不同时间点处死全程佩戴矫治器的大鼠及其匹配的对照动物。在矢状面切取颞下颌关节（TMJ）的组织切片（7微米），并用高碘酸和席夫试剂染色，以评估新骨形成情况。使用计算机辅助图像分析系统测量新形成的骨量。结果表明，在髁突，与自然生长相比，早期拆除矫治器导致骨形成减少。晚期拆除矫治器导致的骨形成与自然生长相似。在关节窝，早期和晚期拆除矫治器时的骨形成水平与对照组相似。总之，早期拆除矫治器会导致髁突后部生长低于正常水平，但不会影响关节窝。增加下颌前伸的时间可确保治疗后阶段下颌生长达到正常水平。
