下颌支矢状劈开术不同固定方式对下牙槽神经功能的影响

Evaluation of neurosensory functions of inferior alveolar never after two rigid internal fixations for sagittal split ramus osteotomy

目的研究下颌支矢状劈开术(SSRO)常用两种内固定方式对下齿槽神经(IAN)功能的影响。方法成年恒河猴12只,均行双侧SSRO后退术。左侧行双皮质骨螺钉固定,右侧行单皮质螺钉与夹板固定。于术前、术后即刻及术后2、4、8、12周时对两侧IAN行感觉神经动作电位(SNAP)检查。结果SSRO术后即刻SNAP检测示IAN潜伏期延长,波幅减小,较术前有显著差异(P<0.01),但两侧之间无显著差别。术后2周起,IAN功能逐渐恢复。至术后12周时右侧IAN的潜伏期基本恢复至术前水平,左侧IAN潜伏期较术前延长15.4%(P<0.05);右侧的波幅恢复也要优于左侧(P<0.05)。结论SSRO术中使用双皮质螺钉固定和单皮质螺钉夹板固定对IAN功能均有影响,但随着时间的延长,IAN功能均有恢复。单皮质骨螺钉与夹板固定相对于双皮质骨螺钉固定对IAN的功能影响要小。

Objective To evaluate the neurosensory functions of the inferior alveolar nerve （IAN） after two rigid internal fixations for the sagittal split of ramus osteotomy （SSRO） in monkeys, Methods Twelve adult male rhesus monkeys were subjected to bilateral SSRO to set back the mandible. The two segments of the left ramus were secured with two bicortical titanium positional screws, while a mini - plate and four titanium screws were used for monocortical osteosynthesis of the proximal and distal segments of the right ramus. The sensory nerve action potential （SNAP） of the IAN was measured before, immediately, and 2, 4, 8 and 12 weeks after operation. Results Immediately after the operation, all inferior alveolar nerves from the both sides of the ramus showed a significant latency delay and amplitude attenuation （ P 〈 0.01 ）, but no differences between the two sides （ P 〉 0.05）. The greatest increase in latency and decrease in amplitude were still observed at 2 weeks after operation. At 12 weeks after operation, the average latency of the inferior alveolar nerves of the right ramus almost restored to preoperative level, but the inferior alveolar nerves were still 15.4 % prolonged than the baseline （ P 〈 0.05）. Conclusion Both rigid internal fixations could lead to temporary but reversible damage to the inferior alveolar nerves after the S：~RO. The monoeortical fixation with a mini - plate and four titanium screws had less adverse effects on the nerve than the bicortical fixation.