Analysis of the factor which promotes teeth eruption with using the dog model of mandibular allograft

目的：衰老在临床上与牙萌出有关，目前还没有已知的研究阐明这种关系。我们检查了成熟受试者是否会正常地发生牙萌出。材料和方法：采用带血管的下颌复合组织移植技术，从幼年Beagle犬的下颌骨中取出包括牙胚在内的部分未成熟下颌骨，植入无亲缘关系的Bejagle犬体内。我们对移植的下颌骨中的下第一磨牙萌出进行了检查，并对结果进行了临床、放射学和组织学的比较。结果：年轻犬移植的下颌骨有正常的牙萌出现象。成年犬下颌骨牙槽骨萌出延迟，而牙槽骨萌出正常。此外，成年犬的整个牙冠上覆盖着一层牙龈组织帽，尽管这顶帽不是牙龈过度生长。结论：牙齿萌出受到一些与年龄相关的未知因素的影响。显然，在成熟受试者中，在减少的釉质上皮和覆盖在牙齿上的口腔上皮之间的结缔组织中没有发生细胞凋亡。

Purpose: Aging is clinically related to tooth eruption; there are no known studies that have elucidated the relationship. We examined whether tooth eruption would occur normally in a mature subject. Materials and Methods: Using vascularized composite tissue mandibular transplantation, we extracted portions of immature mandibles including the tooth germs from young beagle dogs and placed them into unrelated immature and mature bejagle dogs. we examined eruption of lower first molar in the grafted mandibular bone and compared the results clinically, radiographically, and histologically.Results: Normal tooth eruption was observed in the transplanted mandibles in the young dogs. In the mature dogs, eruption from the gmungiva was delayed, Whereas that from alveolar bone occurred normally in the transplanted mandibles. Further, the whole crown was covered with a cap of gingival tissue in the mature dogs, although this cap was not gingival overgrowth.Conclusion: Tooth eruption is influenced by some unknown factors related to aging. Apparently, apotosis did not occur in the connective tissues between the reduced enamel epithelia and oral epithelia that overlay the teeth in the mature subjects.