[Effects of bite raising on fine structure of condylar cartilage in rats].
[Effects of bite raising on fine structure of condylar cartilage in rats].
复制标题
咬合抬高对大鼠髁突软骨精细结构的影响
DOI：
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发表时间：
1989
期刊：
影响因子：
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通讯作者：
O. Honzawa
中科院分区：
文献类型：
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作者：
O. Honzawa
本研究探讨了下颌骨在发育过程中，咬合在磨牙上抬起，下颌骨持续向后下移的情况下，髁状突软骨的早期反应和成熟期的适应性。本研究选用3周龄雄性SD大鼠。双侧第一磨牙和第二磨牙的咬合量约为1 mm。分别于短期(1周、2周、3周、4周)和远期(8周、12周、16周)进行组织学观察。1.观察短期效果，2-3周成熟区和肥厚区厚度明显减薄，纤维区软骨细胞层比例增加，肥厚区软骨细胞层比例降低。光镜下可见2周时成熟区和肥大区的细胞数量减少，3周时细胞排列不规则，4周时部分区域出现无细胞层。根据这些发现和解剖结构，推测托槽对髁突软骨施加了压力。2.短期电镜观察显示，术后3周软骨基质内可见空泡样结构，细胞有部分空泡化。这似乎表明短期内下颌突软骨的生长受到抑制。3.随着时间的推移，成熟区和肥厚区的细胞层厚度和比例减小，纤维区的细胞层厚度和比例增加。光镜下可见肥厚区细胞数量减少，小梁形成不良。这些似乎表明，在目前的实验条件下，下颌骨的髁突软骨也受到长期抬高的影响。4.长期的电子显微镜观察显示，在肥大带内存在形态上与成熟带内的细胞十分相似的细胞。同时观察到正常钙化的紊乱。提示下颌骨髁状突软骨的生长长期呈抑制趋势。上述结果提示，幼年大鼠持续咬合抬高对髁状突软骨产生压迫力，对其生长有较快的抑制作用，且作用持续时间较长，但作用随时间延长而减弱。
The present study was investigated the response in the early stage and the adaptability in the maturation stage of condylar cartilage, when the bite was raised at the molars so that the mandible was continuously displaced posteroinferiorly during the developmental stage. 3-week-old male SD rats were used in this study. Amount of the bite raising was approximately 1 mm at the bilateral first and second molars. The short-term (1, 2, 3 and 4 weeks) and long-term (8, 12 and 16 weeks) effects were histologically examined by electron and light microscopy. 1. On examining the short-term effects, at 2-3 weeks the thickness of the maturative and hypertrophic zones was markedly reduced, and the ratio of cartilaginous cell layer was increased in the fibrous zone and decreased in the hypertrophic zone. Light microscopy revealed a reduction of the cell count in the maturative and hypertrophic zones at 2 weeks, an irregularity of cell arrangement at 3 weeks and a cell-less layer in some areas at 4 weeks. From these findings and the anatomical structure, it is presumed that the brackets exerted a compressive force on the condylar cartilage. 2. Short-term electron microscopic observation disclosed a vacuole-like structure in the cartilaginous matrix and some vacuolation of cell at 3 weeks. This seems to suggest the inhibited growth of mandibular condylar cartilage in the short-term. 3. Throughout the long-term, the thickness and ratio of the cell layer was reduced in the maturative and hypertrophic zones and were increased in the fibrous zone. Light microscopy revealed a decrease in the cell count and poor trabecular formation in the hypertrophic zone. These seem to suggest that, under the present experimental conditions, the mandibular condylar cartilage is also affected by long-term elevation. 4. Long-term electron microscopic observation disclosed in the hypertrophic zone the cells that rather morphologically resembled cells existing in the maturative zone. Disturbance of normal calcification was also observed. These seem to indicate that the growth of mandibular condylar cartilage tended to be inhibited in long-term. The above results suggested that continuous bite raising in juvenile rats caused a compressive force to the condylar cartilage, inhibited the growth relatively fast and continued to exert its effect for a long time, though the effect is diminished with time.