Finite element analysis on internal hexagonal and internal conical abutment

Implant-abutment connection plays an important role in the long-term success of dental implant. It should be able to resist bacterial leakage. Colonization of bacterial in microgaps along implant-abutment interfaces will lead to inflammatory reaction. One of the factor which have been identified to produce microgaps is micromotion. This study was conducted to analyse micromotion and stress distribution on mating surface of internal conical and internal hexagonal implant-abutment connections. Three dimensional (3D) model of mandible around the first molar was reconstructed from two dimensional (2D) CT data scan. The reconstructed 3D model includes a layer of cortical bone, cancellous bone, mucosa, prosthesis of first molar and adjacent teeth. Dental implant body and two-piece abutment with different implant-abutment connection were designed and inserted separately to simulate the replacement of the first molar. Axial load were applied on the top centre of the prosthesis and on the adjacent teeth to simulate occlusal force. Micromotion was observed to be lower around internal hexagonal abutments compared to internal conical. However, internal hexagonal connection produce stress concentration at its vertices, thus increase the possibility to be fractured.