Influence of extraoral lateral force loading on the mandible in the mandibular development of growing rats
Influence of extraoral lateral force loading on the mandible in the mandibular development of growing rats
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DOI：
10.1016/j.ajodo.2006.10.032
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发表时间：
2008-12-01
影响因子：
3
通讯作者：
Yamaguchi, Hideharu
中科院分区：
文献类型：
--
作者：
Ishii, Takenobu;Yamaguchi, Hideharu
本研究的目的是阐明下颌口外侧向力负载对下颌发育的影响。方法：30只生长中的Wistar大鼠分为3组：对照组、假手术组和实验组。为了确定纵向发育变化，每只动物都被麻醉并固定在定制的身体固定器中，以便在实验前后进行微计算机断层扫描。在实验组中，将铝制固定装置安装到颧弓上。然后用开放线圈对下颌骨施加侧向力，持续两周。立体图像是根据 3 维微计算机断层扫描图像构建的。测量距下颌下缘基线的绝对长度和垂直高度。图像叠加在每只动物的基线平面上。最后观察后，处死大鼠，切除双侧髁突。按标准方法将髁突脱钙，用苏木精伊红和甲苯胺蓝染色，并在显微镜下观察。结果：侧向力导致下颌骨向无负载侧移动；施加负荷一侧的芒氏髁突处的绝对下颌长度大于对照组。无负载侧与对照组没有差异，垂直高度也没有显着差异。下颌骨侧向加载引起组织病理学变化：(1)受载侧髁突头最高缘软骨区肥大，糜烂区扩大，下颌颈宽度减小； (2)无负荷侧软骨细胞层向内侧移位，软骨细胞层正下方横向发生软骨骨化，使下颌颈向内侧变形，造成下颌骨发育不对称。结论：这些结果表明，生长阶段口外侧向力负荷导致下颌发育不对称。 （Am J Orthod Dentofacial Orthop 2008；134：782-91）
The objective of this study was to elucidate the influence of extraoral lateral force loading of the mandible on mandibular development. Methods: Thirty growing Wistar rats were divided into 3 groups: control, sham, and experimental. To determine longitudinal developmental changes, each animal was placed under anesthesia and immobilized in a custom-built body retainer to allow microcomputed tomography to be performed before and after the experiment. In the experimental group, a fixing device of aluminum was fitted to the zygomatic arch. Lateral force was then applied to the mandible with an open coil for 2 weeks. Stereoscopic images were constructed from 3-dimensional microcomputed tomography images. Absolute lengths and perpendicular heights from the baseline of the lower border of the mandible were measured. The images were superimposed at the baseline planes in each animal. After the final observation, the rats were killed, and the bilateral condyles excised. The condyles were decalcified by the standard method, stained with hematoxylin and eosin and toluidine blue, and observed under a microscope. Results: Lateral force induced the mandible to shift toward the nonloaded side; absolute mandibular length at menton-condylion on the side where the load was applied was greater than that in the control group. No difference from the control group was noted on the nonloaded side, and there were no significant differences in perpendicular heights. Lateral loading on the mandible resulted in histopathologic changes: (1) on the side where the load was applied, the cartilaginous zone hypertrophied in the highest margin of the condylar head, the erosive zone expanded, and the width of the mandibular neck decreased; (2) the chondrocyte layer shifted to the medial side on the nonloaded side, and cartilaginous ossification occurred in the lateral direction immediately below the chondrocyte layer, which deformed the mandibular neck toward the medial side and caused asymmetric development of the mandible. Conclusions: These results demonstrate that extraoral lateral force loading during the growth stage causes asymmetrical mandibular development. (Am J Orthod Dentofacial Orthop 2008; 134: 782-91)