下颌升支矢状截骨后不同固定方法稳定性的体外模型研究

The Stability of Various Fixation Patern in Bilaterial Sagittal Split Ramus Osteotomy: a Modeling Study in Vitro

目的 :比较下颌升支矢状截骨术 (bilateralsagittalsplitramusosteotomy ,BSSRO)后 3种固定方式产生的近远心骨段的稳定性。方法 :选牙列完整的成人下颌骨标本 9件 ,经标准术式的矢状截骨后 ,分别依次行双股钢丝结扎 (wirefixation ,WF)和两种形式的坚固内固定 (rigidinternalfixation ,RIF) :小夹板固定和双皮质螺钉固定。将试件两侧近心段妥善固定后 ,于两侧前磨牙区加载 ,记录不同载荷下远心骨段前端二维方向上的位移量。结果 :1)钢丝结扎后远心骨段在二维方向上的位移大于其它两组 ;2 )随载荷增加 ,远心骨段的位移增大 ;当载荷大于 2 0N时 ,钢丝固定组产生的位移明显大于其它两组 (P <0 .0 5 ) ;3)小夹板固定与双皮质螺钉固定组在二维方向上的位移情况相近 (P >0 .0 5 )。结论 :钢丝固定的稳定性最差 ,双皮质螺钉与小夹板固定的稳定性相似 ,但加载后远心骨段仍有不同程度的移位 ,提示术后应配合暂时性的颌间固定。

Objective: To compare the mandibular stability of the two fragments after BSSRO. Methods: Taking 9 human mandibles without missing teeth, after standard BSSRO procedure, secure the two fragments with wire、mini-plate、and bicortical screw accordingly. Fasten condyles carefully, then applying different loads on pre-molar regions and writing down the movement of distal fragement. Results: 1) The distal fragment's movement of wire fixation group in two directions is bigger than that of the other groups; 2) With increasing load, the distal fragment's movement increase; When the load is larger than 20N, the distal fragement's movement of wire fixation group is obviously longer than that of the other groups(P<0.05); 3)The fragement stability in mini-plate and bicortical screw group is similar(P>0.05). Conclusion: Fragements stability is unfavorable in wire fixation group. Mini-plate and bicortical screw group has a similar stability, but still some different degree movements are found when load is applied, and this suggest a transient maxillo-mandibular fixation is necessary after BSSRO.