インプラント-骨界面を再現した力学解析法の検討： 実験モデルと有限要素解析モデルの比較

抄録

Objectives: Proper amount of stress produced by mastication around dental implants is an important factor to ensure their long-term stability. 3D-finite element analysis (FEA) is an effective tool for analyzing the distribution of stress in and around dental implants. Recent advances in CT technology have made it possible to create 3D-FEA models directly from CT data, but these models do not precisely reproduce the implant-bone interface contact. This study compared the displacement of implants under pressure in experimental models with those of a 3D-FEA model created using only CT data and 3D-FEA models which reflected implant-bone interface contact.
Methods: Five experimental models were manufactured, consisting of dummy jaw bones with inserted implants. These models were scanned using a micro CT, and three types of FEA model were created using an FEA software program (Mechanical Finder^®): FEA model A with the implant in full contact with the dummy jaw bone; FEA model B with a hollow under the tip of the implant; and FEA model C with the implant in partial contact with the dummy jaw bone. The displacement of implants under pressure in the experimental models was measured by applying a vertical pressure of 200 N. Three FEA models were also analyzed under the same conditions, comparing the experimental models and the FEA models for the displacement of implants under pressure.
Results:
1. A significant difference (p<0.01) was observed between the experimental model (35.7 ± 2.0 μm) and FEA model A (27.4 ± 2.4 μm), but not with FEA models B (34.9 ± 3.4 μm) and C (38.5 ± 3.8 μm).
2. The stress was concentrated in the cancellous bone of the implant bottom in FEA model A, but was concentrated in the cortical bone of the implant in FEA models B and C.
Discussion and Conclusions: It seems possible to create a 3D-FEA model that precisely reproduces the displacement of an implant under pressure, if the implant-bone interface contact is correctly reflected.