Alom Ghaith, Kwon Ho-Beom, Lim Young-Jun, Kim Myung-Joo
Department of Prosthodontics, School of Dentistry, Seoul National University, Seoul, Republic of Korea.
Dental Research Institute and Department of Prosthodontics, School of Dentistry, Seoul National University, Seoul, Republic of Korea.
J Adv Prosthodont. 2021 Feb;13(1):12-23. doi: 10.4047/jap.2021.13.1.12. Epub 2021 Feb 23.
The aim of the study was to compare the lingualized implant placement creating a buccal cantilever with prosthetic-driven implant placement exhibiting excessive crown-to-implant ratio.
Based on patient's CT scan data, two finite element models were created. Both models were composed of the severely resorbed posterior mandible with first premolar and second molar and missing second premolar and first molar, a two-unit prosthesis supported by two implants. The differences were in implants position and crown-to-implant ratio; lingualized implants creating lingually overcontoured prosthesis (Model CP2) and prosthetic-driven implants creatingan excessive crown-to-implant ratio (Model PD2). A screw preload of 466.4 N and a buccal occlusal load of 262 N were applied. The contacts between the implant components were set to a frictional contact with a friction coefficient of 0.3. The maximum von Mises stress and strain and maximum equivalent plastic strain were analyzed and compared, as well as volumes of the materials under specified stress and strain ranges.
The results revealed that the highest maximum von Mises stress in each model was 1091 MPa for CP2 and 1085 MPa for PD2. In the cortical bone, CP2 showed a lower peak stress and a similar peak strain. Besides, volume calculation confirmed that CP2 presented lower volumes undergoing stress and strain. The stresses in implant components were slightly lower in value in PD2. However, CP2 exhibited a noticeably higher plastic strain.
Prosthetic-driven implant placement might biomechanically be more advantageous than bone quantity-based implant placement that creates a buccal cantilever.
本研究旨在比较形成颊侧悬臂的舌侧种植体植入与表现出过大冠根比的修复驱动种植体植入情况。
基于患者的CT扫描数据，创建了两个有限元模型。两个模型均由严重吸收的下颌后牙区组成，包含第一前磨牙和第二磨牙，缺失第二前磨牙和第一磨牙，由两颗种植体支持的双单位修复体。不同之处在于种植体位置和冠根比；舌侧种植体形成舌侧轮廓过高的修复体（模型CP2），修复驱动种植体形成过大的冠根比（模型PD2）。施加466.4 N的螺钉预紧力和262 N的颊侧咬合负荷。种植体部件之间的接触设置为摩擦系数为0.3的摩擦接触。分析并比较最大von Mises应力和应变以及最大等效塑性应变，以及在指定应力和应变范围内的材料体积。
结果显示，每个模型中的最高最大von Mises应力，CP2为1091 MPa，PD2为1085 MPa。在皮质骨中，CP2显示出较低的峰值应力和相似的峰值应变。此外，体积计算证实CP2承受应力和应变的体积较低。PD2中种植体部件的应力值略低。然而，CP2表现出明显更高的塑性应变。
修复驱动的种植体植入在生物力学方面可能比形成颊侧悬臂的基于骨量的种植体植入更具优势。
