单侧下颌骨牵引成骨术对颞下颌关节的影响

目的 :探讨单侧下颌骨牵引成骨术 (mandibulardistractionosteogenesis,MDO)对颞下颌关节 (temporo mandibularjoint,TMJ)的影响。方法 :恒河猴 1 0只行右侧MDO ,间歇期 5d ,牵引速度 0 .5mm× 2次·d-1 ,共 1 5d。分别于牵引完成时、牵引后 2、4、6、1 2周时拍摄X线片并处死一组动物 ,取双侧TMJ制作脱钙石蜡切片 ,行HE染色及TGF β1免疫组化染色。结果 :术后恒河猴下颌中线明显偏向左侧 ,前牙开牙合、反牙合 ,右侧后牙重度开牙合 ,左侧后牙为反牙合。X线片上见右侧髁状突向后上方移位 ,左侧髁状突向前下方移位。切片上见术后早期双侧TMJ均发生变化 ,右侧髁状突退行性变及增生活动均较左侧明显 ,且变化累及软骨各层及软骨下骨组织。稳定期开牙合逐渐关闭 ,髁状突逐渐向正常位置移动。牵引完成后 1 2周右侧后牙开牙合基本关闭 ,前牙开牙合及反牙合仍较明显 ,髁状突位置略偏后 ,仍存在退行性变 ;左侧髁状突除软骨肥大层仍较厚外 ,其位置及组织学表现接近正常。稳定期不同阶段髁状突TGF β1阳性着色均较对照组显著增强。 结论 :MDO可造成TMJ解剖位置变化及组织形态较轻微的退行性变 ,但远期这些变化可以得到逐步修复。TGF β1在TMJ退行性变的修复重建过程中 ,可能发挥了一定作用。

Effects of unilateral mandibular distraction osteogenesis on temporomandibular joint

OBJECTIVE: To study the effects of unilateral mandibular distraction osteogenesis(MDO) on the temporomandibular joint(TMJ). METHODS: Ten rhesus monkeys were used to perform right MDO. After 5 days, latency period, the distractor was initiated at the rate of 0.5 mmx2/day, totally 15 days. When MDO completed, and 2,4,6,and 12 weeks after MDO, X-ray films of bilateral TMJ were taken and one group of animals was sacrificed. Bilateral TMJ were obtained and paraffin slices were made HE and immunohistochemistry stains of TGF-beta1 were done on the slices. RESULTS: After MDO, the monkeys' mandible midline obviously deflected to the left side. The front teeth had open bite and reverse bite. The right molars were severely open bite and the left molars were reverse bite. From the X-ray film, we can see that the right condylar process moved backward and upward in the acetabulum, while the left condylar process moved forward and downward. On the slices, both sides of the TMJ showed different degrees of degeneration and proliferation, but the changes on the right side were more severe and obvious than the left side, and had involved all the cartilage's layers and the bone tissues under the cartilage. In some animals, there even appeared cartilage erosion and light histological changes of acetabulum. During the consolidation period, the open bite gradually closed, and the condylar process gradually moved to normal position. Twelve weeks after MDO, the open bite at the right side disappeared, but the front teeth open bite and reverse bite still existed. The right condylar process still lay a little backward and had some degree of degeneration. The left TMJ had the normal position and histology except for cartilage hypertrophy layer thickness. At different times during consolidation period, the positive stains of TGF-beta1 in condylar process on both sides were all more obvious than that of the control group. CONCLUSION: MDO can cause TMJ position change and light histological degeneration, but these changes can gradually rehabilitate in the future. TGF-beta1 may play a role in the reconstructive process of TMJ degeneration.