根切术后单根牙应力分布变化及力方向对其影响的有限元研究

Stress distribution of single-root tooth after apicoectomy and its influencing factors

目的本课题利用三维有限元法,模拟上颌中切牙根切术后模型,并进行应力分析,继而评估不同咬合形态造成的不同咬合力方向,可能对此带来的影响。以期对临床病例的选择和预后提供理论依据。方法建立上颌中切牙三维模型,继而根据根切术基本要求,模拟出根切术后模型和根切术骨完全愈合后模型,计3个模型;在Ansys Workbench有限元软件中按照一定的载荷条件,观测根切术前、后,不同受力方向下的应力分布和大小,并进行对比分析,了解应力变化趋势。结果当加载情况相同时,根切术后即刻受力,牙颈部以及整体应力的最大值、分布情况,最大位移值均较完整牙齿增大,当根尖骨组织愈合完全,上述参数又有改善,但仍高于完整牙齿状态。而当所有条件一致时,载荷方向与牙长轴所成角度越大,整体应力水平越大,应力集中区域范围越大,总体位移值也越大。结论根切术后即刻至根尖牙槽骨质完全愈合之前,较完整牙齿生物力学稳定性下降。在完全愈合后,稳定性又获得一定程度的改善。所以根尖区骨质的再生是关乎根切术成败也是维持术后牙齿机械稳定性的关键。咬合状态使患牙承受水平力较大,根切术后带来的应力增加越大,选择根切术作为治疗方案时建议将咬合形态纳入考虑因素,避免造成应力集中,松动等不良后果。

Objective To determine the stress distribution of single-root tooth after apicoectomy and its influencing factors with three-dimensional finite element method（fem）.Methods A 3D-model of maxillary incisor was established before simulation of the apicoectomy according to the standard requirements.The distribution and maximum of Von-mises stress and displacement were recorded and analyzed with the finite element software（Ansys Workbench）.Results The root-end resection immediately increased von-mises stress and maximum displacement compared to the intact teeth,while bone tissue completely healing around the apical root improved the above parameters.Stress concentration area and overall displacement value grewwith the increase of angle between loading direction and axis of the tooth under the same conditions.Conclusion The study shows that root-end resection compromises the stability of the teeth;however,after complete healing the stability would obtain a certain of improvement.