Original Article
Influence of proximal two-wall bone defect on periodontal ligament stresses under normal occlusal forces
Shuang Wang, Jiang Sun, Yanyun Yu
Published 2018-07-09
Cite as Chin J Stomatol, 2018, 53(7): 448-452. DOI: 10.3760/cma.j.issn.1002-0098.2018.07.004
Abstract
ObjectiveTo study the influence of two-wall bone defect on periodontal ligament stresses under normal occlusal forces, and to analyze the influence of depth and width of bone defect to periodontal ligament stresses.
MethodsThree-dimensional finite element models of teeth, periodontal ligament and alveolar bone were created based on cone beam CT images. Proximal two-wall bone defect with different depths (bone defect occupies one third, two thirds, and full length of root) and widths (bone defect occupies one fourth, two fourths, three fourths and full width of buccal lingual width) were simulated by modifying the elastic modulus of elements within defect areas. Occlusal forces with magnitudes of half of the maximum occlusal forces were applied to the model at an angle of 45° to the long axis of tooth, and equivalent stresses of periodontal ligament were analyzed.
ResultsIn the model of no bone defect, the equivalent stresses of periodontal ligament of incisors, canines, premolars and molars were 2.88, 2.31, 8.67 and 7.53 MPa respectively. The equivalent stresses of periodontal ligament increased with the enlargement of depth and width of bone defect. The equivalent stresses of periodontal ligament with maximum bone defect in both depth and width for incisors, canines, premolars and molars were 4.47, 3.62, 11.66 and 8.72 MPa respectively. In the model of width of bone defect was consistent and bone defect develops vertically, the increments of equivalent stresses of periodontal ligament were significantly greater in the early stage bone defect model (from no defect to one third of root length bone defect) than that in the later stage bone defect model (from two thirds to full length of root length bone defect). In the model of bone defect depth was consistent and bone defect develops transversely, the increments of equivalent stresses of periodontal ligament in the early stage bone defect model (from no defect to one fourth of buccal lingual width bone defect) were significantly smaller than that in the later stage bone defect model (from three fourths to full width of buccal lingual width bone defect).
ConclusionsBone defect with shallow depth and that with large width would increase periodontal ligament stresses. Therefore, more attention should be paid to occlusion evaluation and adjustment for teeth with shallow and wide two-wall bone defect.
Key words:
Periodontal ligament; Finite element analysis; Alveolar bone loss
Contributor Information
Shuang Wang
Department of Periodontology, Dalian Stomatological Hospital, Dalian Liaoning 116021, China
Jiang Sun
Department of Periodontology, Dalian Stomatological Hospital, Dalian Liaoning 116021, China
Yanyun Yu
Faculty of Vehicle Engineering and Mechanics, Dalian University of Technology, Dalian Liaoning 116023, China
力下下颌牙列牙周膜应力的影响，分析骨缺损深度及颊舌向宽度对牙周膜应力的影响，为临床提供参考。
力（大小为相应牙位最大
力的一半），分析牙周膜等效应力。
力可影响牙周组织修复甚至造成牙周组织损伤。机械力刺激通过牙齿传递至牙周膜，牙周膜将机械信号转化为生物信号，激活效应细胞活性，产生牙周组织改建。因此准确获取伴牙槽骨吸收的牙周膜受力情况是探究牙周组织改建的先决条件，也为精准的咬合调整提供理论基础。近年国内外学者通过删除有限元网格的方法，建立个别牙齿水平型骨吸收的简化模型，分析其牙周膜受力[1,2]。牙周炎患者牙槽骨常表现为垂直型骨吸收。二壁骨缺损多见于相邻牙齿的牙槽间隔破坏，仅剩颊、舌两个骨壁。已有研究显示，此类缺损约占全部骨缺损的35.2%，在下颌牙约占62.0%[3]。因此建立具有良好几何相似性的模型可提高力学分析的准确性。本项研究在建立下颌牙列有限元模型的基础上建立不同深度、不同颊舌向宽度的邻面二壁骨缺损模型，定量分析邻面二壁骨缺损模型上各牙位牙周膜应力的变化特点，为临床提供参考。
