SD大鼠单侧髁突颈横行截骨对下颌骨生长发育的影响

Unilateral condylar neck ostrotomy affects mandibular growth in rats

目的应力刺激与髁突生长发育密切相关,髁突是下颌骨的生长区。文中建立年轻SD大鼠单侧髁突颈部截骨的动物模型,探讨应力改变对大鼠健、患侧下颌骨生长发育的影响。方法 72只雄性SD大鼠按完全随机法分为3组,每组24只。建立大鼠单侧髁突颈部横行截骨的动物模型,观察截骨组手术侧、截骨组非手术侧、假手术组手术侧和对照组术后1、3、5、9周髁突影像学、组织学及下颌骨解剖学的变化。检测与髁突生长发育关系密切的结缔组织生长因子(connective tissue growth factor,CTGF)及X型胶原在髁突软骨中表达的变化。结果单侧髁突颈截骨后髁突在术后1周代偿性增大。截骨组手术侧术后4个时间点下颌骨生长发育受到限制,非手术侧下颌骨长度、高度、下颌升支高度超过手术侧,导致下颌骨的不对称。HE染色显示截骨组手术侧髁突软骨总厚度代偿性增厚,后明显变薄。免疫组化测定CTGF、X型胶原定量分析结果显示,截骨组手术侧CTGF的表达在术后1、3、5周时强于截骨组非手术侧、假手术组手术侧和对照组。截骨组手术侧X型胶原表达在术后1周时,强于截骨组非手术侧和假手术组手术侧和对照组。结论本研究的动物模型建立具备良好的可行性及可重复性。单侧髁突颈截骨,致应力改变明显,影响下颌骨及髁突生长发育,可导致手术侧、非手术侧下颌骨的不对称,并影响CTGF及X型胶原在髁突软骨的表达。

Objective Stress stimulation is closely related with the growth of the condyle, one of the growth sites of the mandi- ble. The aim of this study is to investigate the influence of condylar neck osteotomy on the growth of the condyle in the rat model. Methods Seventy-two 4-week-old SD rats were equally randomized to an osteotomy, a sham-operation and a blank control group, Models of unilateral condylar process osteotomv were established usin~ snecial blood vessel forcens. All of the rats were killed a~ 1 _ 3 5 and 9 weeks after operation for observing the imageological, histological and anatomical changes in the condylar process, and detecting the expression of the connective tissue growth factor （CTGF） associated with condylar growth and that of type-X collagen （ColX） in the condy- lar cartilage. Results The condylar process on the operation side showed compensatory enlargement at 1 week after unilateral condylar osteotomy, and the growth of the mandible was inhibited at 1,3, 5 and 9 weeks. The length and height of the mandible and the height of the mandibular ascending ramus in the non-osteotomy were significantly in- creased, resulting in the asymmetry of the mandible. HE staining re- vealed a compensatory enlargement in the total thickness of thecondylar cartilage on the osteotomy side at 1 week, which then became thinner. Quantitative analysis showed a significant increase in the expression of CTGF at 1, 3 and 5 weeks as well as in that of Col X at 1 week on the operation side in the osteotomy group as com- pared with the sham-operation and a blank control groups. Conclusion This rat model of condylar neck osteotomy has obvious feasi- bility and repeatability. Unilateral condylar neck osteotomy produces a series of physical responses from the mandible and condyle, af- fects their growth and results in their asymmetry. It also affects the expressions of CTGF and Col X in the condylar cartilage.