Katada Hidenori, Arakawa Tomohisa, Ichimura Kenichiro, Sueishi Kenji, Sameshima Glenn T
Department of Orthodontics, Tokyo Dental College Suidobashi Hospital, Tokyo, Japan.
Bull Tokyo Dent Coll. 2009;50(4):161-8. doi: 10.2209/tdcpublication.50.161.
The effects of mandibular distraction on the mandible and its surrounding tissue remain to be clarified. Here, we used a 3-dimensional finite-element method to investigate the effects of unilateral horizontal lengthening of the mandibular body and vertical lengthening of the mandibular ramus on the mandible and temporomandibular joint (TMJ). With horizontal loading that assumed mandibular body lengthening, tensile and compressive stresses were great near the anterior region of the mandibular angle (the loading area). With vertical loading that assumed mandibular ramus lengthening, tensile and compressive stresses were great at the center of the mandibular ramus (the loading area). Under both loading conditions, stress distribution in the TMJ was greater on the loading side than on the non-loading side. With mandibular body lengthening, the center of the mandible deviated in the direction of the non-lengthened side to widen the mandible in the lateral direction. With mandibular ramus lengthening, the occlusal plane tilted in the inferior direction on the lengthened side. In the TMJ, stress was greatest on the affected side during mandibular ramus lengthening, suggesting the need to consider the mandibular condyle on the affected side during this procedure.
下颌骨牵张对下颌骨及其周围组织的影响仍有待阐明。在此，我们采用三维有限元方法，研究下颌体单侧水平延长和下颌支垂直延长对下颌骨及颞下颌关节（TMJ）的影响。在假设下颌体延长的水平加载下，下颌角前部区域（加载区域）附近的拉应力和压应力较大。在假设下颌支延长的垂直加载下，下颌支中心（加载区域）的拉应力和压应力较大。在两种加载条件下，TMJ中加载侧的应力分布均大于非加载侧。随着下颌体延长，下颌骨中心向未延长侧偏移，使下颌骨在侧向增宽。随着下颌支延长，咬合平面在延长侧向下倾斜。在TMJ中，下颌支延长过程中患侧应力最大，提示在此过程中需要考虑患侧的下颌髁突。
