Biomechanical aspects in late implant failures: scanning electron microscopy analysis of four clinical cases.

AIM The aim of this work is to analyze by scanning electron microscopy implant components that have mechanically failed in vivo. MATERIALS AND METHODS Three clinical cases are presented relative to single lateral posterior restorations supported by implants and a case of a mandibular overdenture supported by two implants. In all the reported cases the presence of an incongruous occlusal load caused the fracture of the components of the implant supported restorations. CONCLUSION From the analysis of the cases examined in this study, it is deduced that the functional overload influences the biomechanical behavior of the prosthetic rehabilitation supported by an implant and may, in less fortunate cases, determine the failure following the fracture of the connecting screws and/or the fixture.