Asano T
Am J Orthod Dentofacial Orthop. 1986 Dec;90(6):464-74. doi: 10.1016/0889-5406(86)90106-x.
The purpose of this study was to investigate the three-dimensional effects of a mandibular retractive force on the growing rat mandible and mandibular growth after the force was removed. Eighty 4-week-old male Wistar rats served as experimental animals and 100 4-week-old male Wistar rats served as the control group. The experimental rats were divided into four groups. Thirty grams of retractive force was applied to each mandible for 4 weeks. Each group was then killed after 4-, 8-, 10-, 12-, or 16-week periods. At the time of death, tibia, skull, and mandible were removed, measurements of those bone specimens were taken, and histologic examinations were performed. Compared with the control group, the experimental group demonstrated no significant differences in body weight nor in the length of measurements of the tibia, skull, and proximal end of the tibia. The mandibles of the experimental group demonstrated shorter anteroposterior length, higher coronoid processes, and a thicker corpus in the retromolar region and condylar neck. The condylar cartilages of the experimental group showed moderate adaptation in the histologic sections. However, mandibles of the experimental animals did not show any catch-up growth behavior after removal of the force. It was concluded that the mandibular retractive force could produce overall growth retardation and transformation of growing rat mandibles, but the force had no effect on the growth behavior after the appliance was removed.
本研究的目的是调查下颌骨牵引力对生长中大鼠下颌骨的三维影响以及去除该力后下颌骨的生长情况。80只4周龄雄性Wistar大鼠作为实验动物，100只4周龄雄性Wistar大鼠作为对照组。实验大鼠被分为四组。对每只下颌骨施加30克的牵引力，持续4周。然后在4周、8周、10周、12周或16周后处死每组大鼠。在处死时，取出胫骨、颅骨和下颌骨，对这些骨标本进行测量，并进行组织学检查。与对照组相比，实验组在体重以及胫骨、颅骨和胫骨近端的测量长度方面均无显著差异。实验组的下颌骨显示出前后长度较短、冠突较高，以及磨牙后区和髁突颈部的下颌体较厚。实验组的髁突软骨在组织学切片中显示出适度的适应性。然而，实验动物的下颌骨在去除力后未表现出任何追赶生长行为。得出的结论是，下颌骨牵引力可导致生长中大鼠下颌骨整体生长迟缓及形态改变，但该力在去除矫治器后对生长行为无影响。
