下颌升支截骨去血供后牙槽骨内氧水平变化与骨改建的变化研究

Mandibular ramus osteotomy-induced changes of oxygen level and alveolar bone remodeling

目的研究下颌升支截骨手术去血供后牙槽骨骨内氧水平与骨代谢的变化规律,了解颌骨手术对牙槽骨改建的影响。方法30只7周龄雄性大鼠随机按时间点分成6组,即术前组、术后第1、3、5、7、14天组,每组5只。手术组行双侧下颌升支截骨手术。以下颌第一磨牙区牙槽骨作为观察区域。利用低氧探针(Hypoxyprobe-1)联合免疫荧光在分子水平检测骨内氧水平变化;利用抗酒石酸酸性磷酸酶(TRAP)及碱性磷酸酶(ALP)染色观察骨代谢变化。结果术后牙槽骨骨内氧含量下降,第1、3天牙槽骨低氧程度逐渐加强,第5天时低氧程度开始回落但仍较术前有统计学差异,术后第7天低氧状态缓解恢复至术前水平;术后牙槽骨骨代谢活跃。术后第1天牙槽骨破骨吸收活性显著增强并持续增加至术后第7天,第14天时下降至术前水平。术后第1至5天牙槽骨成骨活性不明显,在术后第7、14天时,牙槽骨早期成骨分化显著。结论手术引起早期牙槽骨骨内氧含量降低的同时骨吸收活跃,当低氧状态缓解后,成骨能力增强。

Objective To investigate the change rules of oxygen level and bone metabolism after mandibular ramus osteotomy and try to figure out the effects of jaw surgery on bone remodeling.Methods Thirty healthy seven-week-old male rats were randomly divided into 6 groups.A set of 5 rats were sacrificed at pre-operation and 1 d,3 d,5 d,7 d,14 d respectively.Operation groups were treated by bilateral mandibular ramus osteotomy.The area of alveolar bone between the roots of the first molar was examined as region of interest.Hypoxyprobe-1 combined immunofluorescence staining was used to detect changes of oxygen environment at molecular level.Tartrate-resistant acid phosphatase(TRAP)and alkaline phosphatase(ALP)staining were utilized to observe the changes in bone metabolism.Results Obvious hypoxia occurred at 1 d and was maintained at 3 d postoperatively.The degree of hypoxic condition began to decline at 5 d,but there was still a statistical difference compared to the preoperative period.The hypoxia status was relieved and returned to preoperative levels at 7 d.Alveolar bone metabolism was active after surgery.The alveolar bone resorption activity was significantly enhanced at 1 d,peaked at 7 d and decreased to preoperative levels at 14 d.Alveolar bone osteogenesis activity was not obvious from 1 d to 5 d after surgery.However,early osteogenic differentiation was significantly active at 7 d and 14 d.Conclusion Hypoxic microenvironment of the alveolar bone at an early stage after osteotomy promotes bone resorption.Osteogenesis is enhanced when hypoxic condition is relieved.