Abutment Angulation Affect On Stresses In Bone. 3D FE Analysis

Objectives: The aim of this study is to investigate the effect of different implant abutment angulations (0°, 15°, 30°, 37.5°) on the stress level and distribution in the bone around an implant-supported mandibular second premolar crown using 3-dimensional finite element (FE) analysis. Methods: A 3-D FE model of a dental implant (Ankylos; Dentsply Friadent, Germany) placed at the region of mandibular second premolar and restored with an all-ceramic crown was modeled using FE software (Pro/Engineer, Wildfire 2.0 parametric technology Corporation). The bony segment was modeled to simulate different inclinations relevant to clinical cases. The implants were placed along the long axis of the bone. Four types of standard abutments were modeled to receive the crown used in each case: (1) straight i.e. 0° (2) angulated 15° (3) angulated 30° (4) angulated 37.5° (lingually angulated abutments). Occlusal load of 150N was applied axially to the buccal cusp and distal fossa respectively to simulate occlusal loading during function. The ANSYS version 11.0 (ANSYS/Workbench, Ansys Inc, USA) was used to provide the loading simulation and stress profile prediction. Result: The result demonstrated that the maximum equivalent Von Mises stress in the model with straight (0°), 15°, 30° and 37.5° abutments were 26.4 MPa, 50.2 MPa, 64.3 MPa and 70 MPa respectively. High stresses were seen to concentrate at the cortical bone around the implant collar. A more homogenous stress distribution in the bone was seen along the entire implant fixture. Conclusion: Within the limitations of the present study, it is concluded that high level of stress is concentrated in the cortical bone surrounding the implant collar and it is directly proportional to the abutment angulation; theoretically, this stress has the potential to resorb the bone at this area and jeopardize the longevity of the implant.