Finite element stress analysis of cuneiform and cylindrical threaded implant geometries.

Statement of problem. Different implant geometries present different biomechanical behaviors and in this context, one arising question is how cuneiform implant geometry compares to clinical successful cylindrical threaded implant geometry. Purpose. The purpose of this work was to study stress distribution around cuneiform and cylindrical threaded implant geometries using three-dimensional finite element stress analysis taking the latter as a reference. Material and methods. A model was generated from a computerized tomography of a human edentulous mandible with implants placed in the left first premolar region. The model was supported by the mastication muscles and by temporomandibular joint. A vertical load of 100N was applied at the top of each implant in the direction of their long axes. The mandibular boundary conditions were modeled considering the actual muscle supporting system. Taking muscle forces intensities and directions, balance moment equations were employed to assess the system equilibrium. Cortical and medullary bones were assumed to be homogeneous, isotropic and linearly elastic. Results. The analysis provided results for maximum (S1) and minimum (S2) principal stress and Von Mises (SEQV) stress field. For both geometries, the results showed concentration on one side of the neck, smooth stress distribution along the body and no considerable concentration at the apical area. Conclusion. Results showed similar stress distribution pattern for cuneiform and cylindrical threaded geometries. The stresses profiles along the implants length reproduced their morphology. In both occurred stress concentration at one side of the neck and no body or apical stress concentration.