Federal Institute of Paraná, Londrina, PR, Brazil.
J Appl Oral Sci. 2012 May-Jun;20(3):362-8. doi: 10.1590/s1678-77572012000300012.
The non-homogenous aspect of periodontal ligament (PDL) has been examined using finite element analysis (FEA) to better simulate PDL behavior. The aim of this study was to assess, by 2-D FEA, the influence of non-homogenous PDL on the stress distribution when the free-end saddle removable partial denture (RPD) is partially supported by an osseointegrated implant.
Six finite element (FE) models of a partially edentulous mandible were created to represent two types of PDL (non-homogenous and homogenous) and two types of RPD (conventional RPD, supported by tooth and fibromucosa; and modified RPD, supported by tooth and implant [10.00x3.75 mm]). Two additional Fe models without RPD were used as control models. The non-homogenous PDL was modeled using beam elements to simulate the crest, horizontal, oblique and apical fibers. The load (50 N) was applied in each cusp simultaneously. Regarding boundary conditions the border of alveolar ridge was fixed along the x axis. The FE software (Ansys 10.0) was used to compute the stress fields, and the von Mises stress criterion (svM) was applied to analyze the results.
The peak of svM in non-homogenous PDL was higher than that for the homogenous condition. The benefits of implants were enhanced for the non-homogenous PDL condition, with drastic svM reduction on the posterior half of the alveolar ridge. The implant did not reduce the stress on the support tooth for both PDL conditions.
The PDL modeled in the non-homogeneous form increased the benefits of the osseointegrated implant in comparison with the homogeneous condition. Using the non-homogenous PDL, the presence of osseointegrated implant did not reduce the stress on the supporting tooth.
牙周韧带（PDL）的非均匀性已通过有限元分析（FEA）进行了研究，以更好地模拟 PDL 的行为。本研究的目的是通过二维有限元分析（FEA）评估当自由端鞍式可摘局部义齿（RPD）部分由骨整合种植体支撑时，非均匀 PDL 对应力分布的影响。
创建了六个部分缺牙下颌的有限元（FE）模型，以代表两种类型的 PDL（非均匀和均匀）和两种类型的 RPD（常规 RPD，由牙齿和纤维粘膜支撑；和改良 RPD，由牙齿和植入物[10.00x3.75mm]支撑）。另外两个没有 RPD 的 FE 模型用作对照模型。非均匀 PDL 使用梁元素建模，以模拟嵴、水平、斜向和根尖纤维。在每个牙尖上同时施加负载（50N）。关于边界条件，牙槽嵴的边界沿着 x 轴固定。FE 软件（Ansys 10.0）用于计算应力场，并应用 von Mises 应力准则（svM）分析结果。
非均匀 PDL 中的 svM 峰值高于均匀条件。对于非均匀 PDL 条件，植入物的益处得到增强，牙槽嵴后半部分的 svM 急剧减少。对于两种 PDL 条件，植入物都不会减少支撑牙的应力。
与均匀条件相比，以非均匀形式建模的 PDL 增加了骨整合植入物的益处。使用非均匀 PDL，骨整合植入物的存在并没有减轻支撑牙的应力。
