下颌骨可压缩性的动物实验研究

Mandibular Condensability and Length Contraction: An Animal Experimental Study

目的 探讨下颌骨长度的可压缩性。方法 山羊 6只 ,单侧实验 ,口外进路 ,下颌角区保留骨松质连续性的颊舌侧骨皮质切开术 ,采用特制压缩器械 ,每 3d加力 1次 ,每次压缩 0 5mm。结果 压缩 4 8～ 78d后 ,下颌骨缩短 0 8～ 1 3cm ,下颌骨升支下段前移 ,下颌角变钝 ,但因对侧下颌的缩结 ,咬合变化不大 ;X线片见压缩区显示骨质密度先是减低 ,然后逐渐增高 ,最后完全与正常区一致 ;HE染色显微镜下可见 ,在整个压缩和固定阶段 ,骨切口线一直存在并充满不同成熟程度的成纤维细胞、软骨组织和骨组织。 3种结构之间可见组织过度表现。随着固定时间的逐渐延长 ,纤维组织和软骨组织逐渐变窄 ,最后骨切口线消失 ,并为骨组织所完全取代。结论 下颌骨在采用颊舌侧骨皮质切开术并配合外力加压的情况下其长度是可以缩短的 。

Objective To investigate the condensability of mandibular length.Methods In six goats were used in the study. Corticotomy at right mandibular angles was performed via extral-oral accession. Special devices were applied to shorten the mandible by 0 5 mm per three days respectively.Results ①Mandibular angles of the six goats were shorten by 0 8 cm to 1 3 cm respectively in 48 days to 78 days;②In spite of the lower ascending ramus moving forward and angles being blunt, the occulusion scarcely varied because of contralateral bite-lock;③X-ray demonstrated that, at first, bone density in contracted areas declined ,and then increased gradually to almost normal density;④Under microscope there were three tissues layers from central to lateral within the bone gap: fiber layer, cartilage layer and bone layer, and fiber layer gradually transform into cartilage layer with the fixed time. At the end of fixation they all transform into bone tissue.Conclusion Contraction osteogenesis is actually a process of compression, absorption and rebuilding. It is feasible that using contraction osteogenesis to shorten the mandible via cortcotomy.