正畸中牙根形态对牙根应力分布的影响

Effects of Root Morphology on Stress Distribution at the Root Apex During Orthodontic Treatment

对比分析正常形态和牙根弯曲的牙齿在正畸力作用下牙根及牙周膜的应力分布,为临床上不同形态牙齿的正畸方案提供参考。选用正常形态和牙根弯曲的上颌侧切牙,考虑相同的牙槽骨,基于CT扫描分别建立三维有限元模型,施加与整体移动、倾斜移动和压入移动相对应的载荷,对两个模型在相同载荷作用下牙根和牙周膜的von M ises应力进行比较。结果表明,3种载荷工况下,两种形态牙根的应力分布规律相似,整体移动和倾斜移动的载荷作用下,应力都是自根尖向牙槽骨嵴顶处逐渐增大;压入移动的载荷作用下,在远中根尖附近都出现一个应力集中区,牙根应力的最大值就在这个区域。然而,各载荷工况下,弯曲牙根模型的牙根和牙周膜的应力值都明显高于正常形态牙根模型,特别是压入移动,很可能导致牙根吸收。牙根弯曲会导致牙根及牙周膜应力的增高,正畸治疗中应考虑牙根形态异常对某些移动方式不利的情况,以采取相应的措施。

The stress distributions of two teeth with normal shape and bent root were compared.Two three-dimensional finite element models of the teeth with normal shape and bent root were established according to CT.The loads corresponding to bodily,tipping,and intruded movements were applied to the two models.The von Mises stresses on the roots and periodontal ligaments of the two models were compared.The results showed that the stress distributions of the two models were similar.The stresses in the two models were ...