上颌骨Le Fort-Ⅰ型截骨术坚强内固定的有限元研究

摘要

Objective To study the biomechanical characteristic of maxillary Le fort- I osteotomy with rigid internal fixation (RIF), so as to choose best fixation method. Methods The 3-dimensional finite element models of maxillary Le Fort- I osteotomy with 9 kinds of RIF methods were established. Then the models were divided into three groups to calculate the stress distribution of the maxilla and the displacement of bone segment under 3 kinds of occlusion condition. The fixation stability of the different RIF methods was evaluated. Results Under the incisor occlusion condition, the stress of the cranio maxillary complex transmits mainly along the nasal-maxillary buttress. Under the premolar and molar occlusion condition, the stress transmits along the alveolar process first, then turns to the nasal-maxillary and zygomatic-maxillary buttress. The focused stress position of the internal fixation system is at the connection between the screws and the plate and at the plate near the osteotomy line. Under the premolar occlusion condition, the displacement of bone segment with different RIF methods was (in a decreasing order) 0.396509 mm ( with bio-absorbable plate), 0.148393 mm (with micro-plate ), 0.078436 mm (with mini-plate ) in group 1;0.188791 mm (fixing at the nasal-maxillary buttress), 0.121718 mm (fixing at the zygomatic-maxillary buttress) , 0.078436 mm (fixing at the both buttress) in group 2;0.091023 mm (with straight plate), 0.078436 mm (with L shape plate), 0.072450 mm (with Y shape plate) , 0. 065617 mm (with T shape plate) in group 3. Conclusions The fixation stability of using the bio-absorbable plate in Le Fort-Ⅰ osteotomy is less stable than using the titanium plate. Fixing at the zygomatic-maxillary buttress is more stable than at the naso-maxillary buttress. The fixation stability is different by using different shapes of plates.%目的 研究不同接骨板在上颌骨Le Fort-Ⅰ型截骨正颌手术中固定的生物力学特性,以期找出最佳固定方法.方法 建立正颌Le Fort-Ⅰ型截骨9种内固定方式的三维有限元模型,并分为3组,计算不同固定方法在3种咬合情况下上颌骨的应力及截骨段的位移,对比不同内固定系统,不同形状接骨板,以及接骨板不同放置位置的固定效果.结果 前牙咬合时,颅、上颌复合体中应力主要循双侧鼻上颌支柱向上传递,前磨牙和磨牙咬合时,应力先自咬合处向牙槽突两侧传递,再分别循颈上颌支柱和鼻上颌支柱传递;内固定系统中螺钉与接骨板交接处及接骨板近截骨线处,为应力集中部位.前磨牙咬合时,不同固定方法截骨段位移从大到小依次为:组1 生物可吸收小型板系统(0.396 509 mm)、微型钛板(0.148 393 mm)、小型钛板(0.078 436 mm);组2 单纯鼻上颌支柱固定(0.188 791 mm)、颧上颌支柱固定(0.12l 718 mm)、双支柱固定(0.078 436 mm);组3 直形板(0.091 023 mm)、L形板(0.078 436 mm)、Y形板(0.072 450 mm)、T形板(O.065 617 ram).结论 正颌Le Fort-Ⅰ型截骨术生物可吸收接骨板固定的稳定性和强度相对钛板较小;颧上颌支柱固定效果好于鼻上颌支柱固定;不同形状的钛板在鼻上颌支柱固定的稳定性有差异.