不同咀嚼压力对幼兔髁突软骨成骨的影响研究

Effect of altered mastication on the osteogenesis of condylar cartilage

目的分析生长发育期不同咀嚼模式下兔髁突软骨成骨形态学的差异,研究咀嚼压力对幼兔髁突生长发育的影响和作用机制。方法选取15天龄的未断奶幼兔16只,随机分为硬食组和软食组各8只,硬食组提供颗粒饲料,软食组提供由同种颗粒饲料碾磨而成的粉状饲料。幼兔28天龄断奶,分别于28天龄、33天龄肌肉注射四环素、钙黄绿素,38天龄处死幼兔。制作硬组织切片,荧光显微镜观察,独立t检验分析比较两组髁突软骨成骨厚度、骨形态学参数。结果硬食组的软骨成骨厚度、骨小梁相对体积、骨小梁数量、骨小梁厚度均大于软食组(P<0.05),硬食组骨小梁分离度小于软食组(P<0.05)。相同时间硬食组骨形成沉积率((3.25±0.02)μm/d)大于软食组((2.37±0.02)μm/d)。结论生长期软食组幼兔的髁突软骨成骨能力较硬食组弱,咀嚼负荷力是影响髁突软骨成骨生长的重要因素。

Objective To analyze the histomorphometry differences of condylar cartilage osteogenesis under altered masticatory loading,and to study the mechanism of masticatory loading on condylar development in growing rabbits. Methods Sixteen 15-day-old rabbits were randomly divided into two groups and fed with different kinds of food,solid diet （n = 8） and soft diet （n = 8）. The solid diet group was provided with pellet feed,while the soft diet group with powdery feed milled from the same kind of pellet feed. All the growing rabbits were weaned when they were 28-day-old. Tetracycline（50 mg/kg） and calcein（20 mg/kg） were given intramuscularly on the 28-day-old and 33-day-old rabbits. The rabbits were sacrificed when they were 38-day-old. The specimens of condyles were embedded in methylmethacrylate. Undecalcified hard tissue slicings（20 mm） were then made and observed with a fluorescence microscope.The cartilage osteogenesis thickness and the histomorphometry parameters of the condyle in two groups were analyzed and compared.Results The cartilage osteogenesis thickness,bone trabecular relative volume,trabecular number and trabecular thickness of the solid diet group were all larger than those of the soft diet group,but trabecular separation was smaller （P〈0.05）. The bone formation deposition rate of solid diet group（（3.25±0.02） μm/d） was higher than soft diet group（（2.37±0.02） μm/d） during the same time. Conclusion The condylar cartilage osteogenesis in growing rabbits of the soft diet group is weaker than solid diet group. Mastication carrying capability is an important factor affecting the growth of the condylar cartilage osteogenesis.