Finite element analysis of the influence of the offset placement of an implant-supported prosthesis on bone stress distribution.

The aim of this study was to evaluate the influence of the straight alignment versus distal offset placement of an implant-supported prosthesis (using implants with different diameters: 4 mm, 4.5 mm, and 5 mm) on bone stress distribution. 3D finite element models of a straight configuration and different offset configurations of the implant-supported prosthesis (until 2.4 mm distal offset) were evaluated for the three implant diameters. A mesial load of 200 N and a distal load of 230 N were applied to the prosthesis. Results showed that implant offset provokes an opposite effect in bone stress depending on the exposed mesial or distal force. The former increases stress whereas the latter induces a dissipation of bone stress proportional to the offset. From these two forces, an optimal offset is created in which maximum bone stress is reduced in the range of 7-8% compared with the straight configuration. Increasing implant diameter from 4 to 5 mm decreased bone stress in 30% for all configurations. These data suggests that offset implant placement apart from enabling an optimal aesthetic restoration, reduces bone stress compared with the straight configuration. The use of wider implants permitted the reduction of the maximum bone stress in all the simulated configurations. (c) 2008 Wiley Periodicals, Inc.