幼龄犬的上颌骨延长

目的 探讨利用牵开成骨技术在幼儿发育期对发育不良的上颌骨进行诱导外科正颌的可能性，牵开成骨是否有碍幼儿上颌骨的继续生长发育。方法 4－6月龄杂种犬13只，行一侧上颌前部根尖下截骨，外置延长器固定，于1周后，按0．5－1mm/d的速度用延长装置牵开，牵开至10－20mm时，固定4－6周，卸下延长器，于术日，牵开前，牵开期间，固定期间定期摄X线片，分批处死动物，行咬合关系变化，三维立体测量及组织学等观察，结果 术侧有确切的延长效果，咬合关系发生变化，延长段经膜内成骨逐渐演谈正常骨组织，术侧的上颌骨除延长段外，生长发育基本与未术侧同步。结论 于颅面生长发育期的幼龄犬行 开成骨，进行诱导外科正颌治疗是有效的，且不致影响其继续生长发育。

Maxillary distraction of baby dogs

Objective To investigate the effects of distraction osteogenesis on the very young patients with hypoplasia maxillary and the possibility of inducing normal growth of the deformed maxillary. Methods Thirteen dogs, 4～6 months of old, underwent unilateral anterior maxillary subapical osteotomy with application of a unilateral extra-oral fixator specifically designed for distraction. After seven days,distraction was started at 0.5～1.0 mm/d and continued for 10～20 days up to approximately 10-20mm.Following a further 4～6 weeks of retention, the device was removed and the animals were observed for 8 weeks. The non-distracted side served as a control. Radial examinations were performed post-opera-tively, once a week during and after the distraction. The dogs were sacrificed in batch during the distraction and fixation period. Occlusion relationship was observed and the specimens were measured in three-di-mensions and were analyzed histologically. Results Radiographically and histologically, all dogs fully bridged the experimented gaps. Intramembranous ossification was detected. In comparison with the control side, a marked maxillary lengthening was noted on the distracted side. The occlusion relationship was changed simultaneously. Except for the distracted gap, the distracted maxillary grew approximately at the same speed as the control side. Conclusion The technique of distraction in baby dogs is effective and does not impair maxillary growth.