下颌骨牵引成骨区即刻牙移动的实验研究

Experimental study on immediate tooth movement into newly distracted bone after mandibular distraction osteogenesis

目的:研究下颌骨牵引成骨后在新骨区即刻牙移动时牙周组织的改建行为及牙移动规律。方法:选择4只牙列完整的Beagle犬,其中2只犬建立双侧下颌骨牵引成骨动物模型,牵引完成后,即刻以30g力远中移动下颌第三前磨牙进入牵引成骨区;另外2只犬拔除双侧下颌第四前磨牙后3个月,以30g力远中移动下颌第三前磨牙。实验中,每周加力1次拍摄X线片,并记录牙移动速率。牙移动8周后,观察实验牙及其牙周组织特点。测量数据采用SPSS12.0软件包进行t检验。结果:实验牙借助自制的持续加力装置移动进入牵引成骨区,实验牙未产生倾斜,牙无明显松动,牙根未见明显吸收。实验组牙移动速度显著快于对照组,P<0.01。组组织学观察发现,牙槽骨和牙周膜未出现不可逆性损伤。结论:牵引成骨区的新生骨质中,牙可以快速而平稳地移动。

PURPOSE： To study the periodontium and tooth response to immediate tooth movement into newly distracted bone after mandibular distraction osteogenesis. METHODS： The experimental group consisting of 2 Beagle dogs and the control group including two dogs with complete dentition were used in this study. The animal model of bilateral mandibular distraction osteogenesis was established in experimental dogs. Custom-made appliances with 30 g orthodontic force were applied to move mandibular third premolars into distracted bone immediately after mandibular distraction osteogenesis. In the control group, bilateral mandibular fourth premolars were extracted and the mandibular third premolars were moved distally with the same force 3 months later. The devices were activated and radiographs were taken and the distance of tooth movement was recorded every week in the experimental group .The characteristics of experimental tooth and periodontal tissue were studied at 8-week following appliance activation. The data were analyzed by Student’s t test with SPSS12.0 software package. RESULTS： With self-made intraoral appliance, the experimental teeth were moved into the distracted bone. Tipping movement, tooth mobility and root resorption were not evident. Tooth movement was significantly faster in the experimental group than in the control group, P〈0.01. No obvious irreversible injury of alveolar bone and periodontal ligament occurred on histological examination. CONCLUSIONS： Immediate orthodontic tooth movement is feasible by moving a tooth into the distracted bone newly formed by distraction osteogenesis.