【作者】 许海平； 郑庆华； 张岚； 王倩； 黄定明；

【Author】 Haiping Xu;Qinghua Zheng;Lang Zhang;Qian Wang;Dingming Huang;State Key Laboratory of Oral Diseases,West China Hospital of Stomatology,Sichuan University;Department of Stomatology,the Affiliated Hospital of Qingdao University;Department of Conservative Dentistry and Endodontics,West China School of Stomatology,Sichuan University;

【机构】 口腔疾病研究国家重点实验室,四川大学； 青岛大学附属医院口腔科； 四川大学华西口腔医院牙体牙髓病科；

【摘要】 目的:采用三维有限元法研究磨耗对下颌第一磨牙牙根受力的影响。方法:建立下颌第一磨牙的三维有限元模型,将(牙合)面分别自舌侧向颊侧、自近中向远中由浅及深依次均匀磨除0.5~1.5mm和2~3mm,建立舌颊向和近远中向不均匀磨耗的模型,模拟(牙合)平面的改变。在(牙合)面加载200N垂直和斜向45°的静态载荷,分析年龄相关性磨耗对牙根受力状况的影响。结果:1.根面应力主要集中在颊、舌面,加载方式对根面受力状况影响很大,垂直载荷下,近中根面应力值高于远中根,而斜向载荷时根面最大von Mises值位于远中根舌面。2.随磨耗发生,垂直载荷下,根面应力向抗折力较小的根下方转移,高应力区面积也增大;但斜向载荷下,胎面磨耗反而使根面应力变小。结论:磨耗牙齿在垂直载荷下,近中根下段颊舌面应力增大而易折裂,这可是能原发性牙根纵裂患牙常见严重磨耗的原因。提示老年磨耗牙齿,应及时修复咬合面形态。更多还原

【Abstract】 Objective:To evaluate the stress distribution in root of mandibular first molar with worn occlusal surface by three dimensional finite element analysis.Methods:Three dimensional finite element model of mandibular first molar was established.The occlusal worn became more and more serious from lingual to buccal aspect or from mesial to distal aspect.All the models were loaded under 200 N forming 0° or 45° with long axis.The von Mises stress and distribution in root were recorded.Results:The von Mises stresses were distributed mainly in the buccal and lingual surfaces.Loading directions had great effect on stress distributions,thus on root fracture.Under vertical load,mesial root had higher stress value than distal root,while the maximum von Mises under 45° load was at the lingual surface of the distal root.Occlusal wear lead stress to transfer down towards the lower root and increase the area of high stress area under vertical load,while under oblique loading,occlusal wear reduced the root surface stress.Conclusion:Wear increases the stress level of the lower root part,leading it more prone to fracture under vertical loading,especially in mesial root.This might be the reason why spontaneous vertical root fracture occurs mainly in worn teeth.Thus,the occlusal morphology of teeth with serious wear should be repaired timely.更多还原