狗下颌骨牵张成骨稳定性的头影测量分析

THE CEPHALOMETRIC ANALYSIS OF STABILITY IN DOG MANDIBULAR DISTRACT-ION OSTEOGENESIS

目的 :通过头影测量方法研究狗下颌骨牵张成骨新骨形成及其稳定性。方法 :4只成年狗双侧下颌骨截断后经 7d间歇期 ,以 1m m/次、1次 /d的速度牵引 10 d,共延长 10 m m后固定。分别于牵张结束、固定 2、4、8周后行 X片检查及头影测量分析。结果 :牵张后固定 2周 ,两侧骨断端边缘模糊不清 ,牵张区仍为低密度影。牵张后固定 4周 ,两侧骨断端间透射影缩小 ,边界不清 ,牵张区密度明显升高 ,但仍表现为片状透光影 ,密度从两侧向中间逐渐增高。至固定 8周时接近正常骨组织密度 ,下颌骨长度在牵张结束后与 2、4、8周的差异均无统计学意义 (P >0 .0 5 )。结论 :牵张成骨可形成新的骨组织 ,对保持被延长的下颌骨长度的相对稳定起到重要的作用。

Objective:To study the stability of new bone formed in distraction osteogenesis by cephalometric analysis.Methods:Osteotomy was performed on bilateral mandibles in 4 adult dogs. After 7 days of latency, the mandibles were lengthened at a rate of 1 mm/d for 10 days(total 10mm elongation). The cephalometric and X-ray examination was taken respectively for the first day, 2,4,and 8 weeks after completion of distraction.Result:2 weeks after the completion of distraction,both edges of osteotomy appeared blurry, and the gap of distraction was still kept in low density image; in 4 weeks ,the interval of both sides reduced, the boundary was not clear,and the density of distraction gap was elevated obviously,but still remained in lower density.The density of new bone was enhanced gradually from both sides of osteotomy to the center of distraction gap, and was close to normal in 8 weeks. The mandibular length in 8 weeks after completion of distraction was not significantly different from those in other time points.Conclusion:The new bone formation and ossification in mandibular distraction osteogenesis was seen in X ray examination, and remained in stable length.