中文摘要：

目的将基于应变能密度（SED）的骨组织改建理论与有限元方法相结合，研究不同牙周附着水平下颌后牙在咬合力作用下，牙槽骨组织功能性改建的过程及其规律。方法构建不同牙周附着水平的下颌第一磨牙及其牙周组织的三维有限元模型，结合基于SED的骨组织改建理论，通过自主开发的ABAQUS有限元分析软件中的用户材料子程序（UMAT），建立能够模拟牙槽骨组织改建过程的生物力学模型，分析不同咬合力作用下牙槽骨组织应力及密度的变化情况，揭示咬合力对不同附着水平下颌第一磨牙牙槽骨组织改建过程的影响。结果下颌后牙牙槽骨Von Mises应力分布主要集中在颊舌侧颈部及根尖区。随着载荷的增加，牙槽骨所受应力值逐渐增大。牙槽骨密度在应力较大的区域随着载荷的增大先增加，随后出现下降。当牙周附着水平从正常降至根长1／2时，引起牙槽骨密度下降的载荷也由420N降至240N，同时牙槽骨组织的改建速度加快。结论随着牙周附着水平的降低，牙周组织承受咬合力的能力明显下降，牙槽骨组织密度的降低也会在较早的时间出现。在牙槽骨组织改建的过程中，咬合力与骨组织密度变化的关系密切，适当降低咬合力有利于临床牙周病患者的治疗和预后。

英文摘要：

Objective The theory of strain energy density （SED） was combined with finite element analysis to in- vestigate alveolar bone remodeling of the mandibular first molar with different levels of periodontal attachment under mastication loading. Methods Three-dimensional finite element models of the mandibular first molar with different levels of periodontal attachment were established. Based on SED theory, the user material subroutine （UMAT） （used by ABAQUS software） was developed by ourselves to simulate the remodeling process of mandibular bone. The stress distributions and bone density changes were analyzed under different mastication loading. The influence of loading magnitude on alveolar bone remodeling with different levels of periodontal attachment was investigated. Results The results showed that the neck of buccal, lingual regions and root apex area experienced a higher stress. The stress and the density of alveolar bone increased gradually with the enhancing of the bite force at the beginning. Then the density would appear declining when the bite force exceeded the extreme load. The extreme load reduced from 420 N to 240 N with the periodontal attachment falling from normal to 1/2 of root length also. And the remodeling rate of the bone was faster as the loading increasing. Conclusion The capability of the periodontal tissue for supporting the teeth will drop gradually as the periodontal attachment level dropping. And the decline of bone density also appeared in earlier time. The change of density is associated with mastication loading during the bone remodelling. And reducing the occlusal force properly to the molar with different attachment level is benefit for clinical treatment and prognosis of periodon- tal disease.