Wang Hang, Chen Meng-Shi, Fan Yu-Bo, Tang Wei, Tian Wei-Dong
Department of Oral and Maxillofacial Surgery, West China Stomatology College, Sichuan University, Sichuan, China.
J Oral Maxillofac Surg. 2007 Jun;65(6):1109-16. doi: 10.1016/j.joms.2006.10.020.
This study used a biomechanical model to examine fundamental questions about rigid plate fixation treatment for maxillary Le Fort I fractures. Specifically, we sought to elucidate the principal strain patterns generated in miniplates and bite force transducers secondary to all masticatory forces, as well as the amount of permanent deformations incurred due to these loading forces.
Forty polyurethane synthetic maxillary and mandibular replicas were used to simulate the mandible and maxilla. Ten replicas were controls (group A). The other 30 were divided into 3 groups (10 each), according to the fixation techniques of 3, 2, and 1 miniplates each side (groups B-D), that were osteotomized in the Le Fort I fracture line on the maxilla. Different forces of masseter medial pterygoid, temporalis, and lateral pterygoid muscles were loaded onto the replicas to simulate different functional conditions (anterior incisor, premolar, and molar clenching). Rosette strain gauges were attached at predefined points on the plates and the bite force transducer to compare the stability and bite force of the different fixation methods for maxillary Le Fort I fractures.
Statistically significant differences were found for the deformation of the plates among fixation techniques. The order of stability for each technique was: group B greater than group C greater than group D. In regard to bite force, no difference was found between those found with group A and group B (P > .05), whereas the bite forces of groups C and D were less than those of group A (P < .05).
The fixation of 3 miniplates on each side provides sufficient stability and restores the bite force to the level of the intact maxilla. "The ideal fixation" with 2 miniplates on each side restores 90% of the bite force, and there were more deformations of the miniplates with the "ideal fixation" compared to those found with group B. Group D fixation produced the worst effects for the treatment of maxillary Le Fort I fractures with a weak bite force and insufficient stability.
本研究使用生物力学模型来探讨关于上颌Le Fort I型骨折坚固内固定治疗的基本问题。具体而言，我们试图阐明在所有咀嚼力作用下微型钢板和咬力传感器中产生的主要应变模式，以及这些加载力导致的永久变形量。
使用40个聚氨酯合成的上颌和下颌模型来模拟下颌骨和上颌骨。10个模型为对照组（A组）。另外30个模型根据每侧使用3块、2块和1块微型钢板的固定技术分为3组（每组10个）（B - D组），在上颌骨的Le Fort I型骨折线处进行截骨。将咬肌、翼内肌、颞肌和翼外肌的不同力量加载到模型上，以模拟不同的功能状态（前牙、前磨牙和磨牙咬紧）。在钢板和咬力传感器上的预定义点处粘贴应变片，以比较上颌Le Fort I型骨折不同固定方法的稳定性和咬力。
在固定技术之间发现钢板变形存在统计学显著差异。每种技术的稳定性顺序为：B组大于C组大于D组。关于咬力，A组和B组之间未发现差异（P > 0.05），而C组和D组的咬力小于A组（P < 0.05）。
每侧使用3块微型钢板固定可提供足够的稳定性，并将咬力恢复到完整上颌骨的水平。每侧使用2块微型钢板的“理想固定”可恢复90%的咬力，与B组相比，“理想固定”的微型钢板变形更多。D组固定对上颌Le Fort I型骨折的治疗效果最差，咬力弱且稳定性不足。
