Liu Chang, Kaneko Sawa, Soma Kunimichi
Department of Orofacial Development and Function, Graduate School, Tokyo Medical and Dental University, Japan.
Angle Orthod. 2007 Sep;77(5):787-93. doi: 10.2319/091806-377.
To examine the effects of mandibular lateral shift on the growth and morphology of the condyle and mandibular bone in growing rats.
A maxillary resin plate was designed to displace 4-week-old rat mandibles 2 mm to the left during closure. The plate was cemented, and the rats were killed after 2, 4, 8, or 12 weeks. Gross dimensions of the condylar head were measured. Radiographic films of the mandibles were exposed, and selected measurements were made. The newly formed bone in the condyle was evaluated with periodic acid and Schiff's reagent (PAS) staining.
The length of the condylar head was greater on the ipsilateral side compared with the contralateral side. The experimental rats developed an asymmetric mandible, shorter in horizontal dimension but longer in the vertical dimension on the ipsilateral side. The mandibular growth direction was also affected, with the mandible on the ipsilateral side growing in a more anterior and superior direction. The amount of newly formed bone was greater in the superior subchondral region but lower in the posterior subchondral region on the ipsilateral side compared with the contralateral side.
Mechanical stimuli delivered by a functional shift produce a series of morphological and histological responses in the condyle and lead to condylar and mandibular asymmetry in rats.
研究下颌侧向移位对生长发育期大鼠髁突及下颌骨生长和形态的影响。
设计一种上颌树脂板，在闭口时将4周龄大鼠的下颌向左移位2毫米。将该板粘结固定，分别在2周、4周、8周或12周后处死大鼠。测量髁突头部的总体尺寸。拍摄下颌骨的X线片并进行选定的测量。用高碘酸和席夫试剂（PAS）染色评估髁突中新形成的骨组织。
与对侧相比，髁突头部同侧的长度更长。实验大鼠出现不对称下颌骨，同侧水平方向较短但垂直方向较长。下颌生长方向也受到影响，同侧下颌骨向前上方生长。与对侧相比，同侧髁突软骨下区域上方新形成的骨量较多，而软骨下区域后方较少。
功能性移位产生的机械刺激在髁突中引发一系列形态学和组织学反应，并导致大鼠髁突及下颌骨不对称。
