Wang Shuang, Sun Jiang, Yu Yan-Yun
Dept. of Periodontics, Dalian Stomatological Hospital, Dalian 116021, China.
Faculty of Vehicle Engineering and Mechanics, Dalian University of Technology, Dalian 116023, China.
Hua Xi Kou Qiang Yi Xue Za Zhi. 2019 Feb 1;37(1):42-47. doi: 10.7518/hxkq.2019.01.008.
This study aims to explore the influence of three-wall osseous defects on periodontal ligament stress under normal occlusal forces.
A finite element model for mandibular total dentition, periodontal ligament and alveolar bone was created based on cone beam computed tomography (CBCT) DICOM images. Mesial or distal proximal three-wall osseous defects at varying depths (namely, 1/3, 2/3 and 3/3 of the root) were simulated by modifying the elastic modulus of elements within the defects area. Occlusal forces with an angle of 45° to the long axis of the tooth were applied to the finite element model. In addition, the equivalent stresses of the periodontal ligament were analysed.
In the case of no bone defect, the mean value of the periodontal ligament equivalent stress of 14 teeth was 5.71 MPa. The equivalent stresses of the periodontal ligament at different depths (namely, 1/3, 2/3 and 3/3 of the root) were 6.61, 7.14 and 7.42 MPa, respectively. With increasing depth of the osseous defects, stress on the periodontal ligament increased considerably, and the initial stress increment was greater than that of a later stage. Periodontal ligament stresses with mesial proximal three-wall osseous defects (at depths of 1/3, 2/3 and 3/3 of the root) were 6.62, 7.19 and 7.51 MPa respectively. Periodontal ligament stresses with distal proximal three-wall osseous defects (at depths of 1/3, 2/3 and 3/3 of the root) were 6.60, 7.10 and 7.33 MPa, respectively. For three-wall osseous defects located in the mesial surface and distal surface, a significant difference in periodontal ligament stress was lacking. In the case of the same absorption depth, the size relationship of periodontal ligament stress was in the following order: premolars>molars>incisors>canines.
Shallow three-wall osseous defects will likely cause a notable loss in strength of the periodontal ligament. Therefore, teeth with three-wall osseous defects should become the focus of clinical research. Treatment for these teeth should be administered as early as possible.
本研究旨在探讨正常咬合力下三壁骨缺损对牙周膜应力的影响。
基于锥形束计算机断层扫描（CBCT）的DICOM图像，创建下颌全牙列、牙周膜和牙槽骨的有限元模型。通过改变缺损区域内单元的弹性模量，模拟不同深度（即牙根的1/3、2/3和3/3）的近中或远中三壁骨缺损。将与牙长轴呈45°角的咬合力施加于有限元模型。此外，分析牙周膜的等效应力。
在无骨缺损的情况下，14颗牙的牙周膜等效应力平均值为5.71MPa。不同深度（即牙根的1/3、2/3和3/3）的牙周膜等效应力分别为6.61、7.14和7.42MPa。随着骨缺损深度的增加，牙周膜应力显著增加，且初期应力增量大于后期。近中三壁骨缺损（牙根深度为1/3、2/3和3/3）时的牙周膜应力分别为6.62、7.19和7.51MPa。远中三壁骨缺损（牙根深度为1/3、2/3和3/3）时的牙周膜应力分别为6.60、7.10和7.33MPa。对于位于近中面和远中面的三壁骨缺损，牙周膜应力无显著差异。在相同吸收深度的情况下，牙周膜应力大小关系依次为：前磨牙>磨牙>切牙>尖牙。
浅三壁骨缺损可能会导致牙周膜强度显著降低。因此，有三壁骨缺损的牙齿应成为临床研究的重点。应对这些牙齿尽早进行治疗。
