RESUMEN

The aim of this study was to define the relation between load distribution and the number of implants supporting mandibular implant-supported screw-retained complete prostheses (ISCP). It is a three-dimensional (3-D) finite element study. Three models were simulated. The first one represents a 4-implant supported prosthesis (4ISP), the second one is a 3-implant supported prosthesis (3ISP) and the third one is a 6-implant supported prosthesis (6ISP). The 6ISP model showed the best bone stress distribution among all models. Its maximum stress value was 63.3 MPa. The 4ISP (98.9 MPa) showed a better bone stress distribution than the 3ISP (122.9 MPa). A flexion of the prosthesis was more important for the 4ISP than 3ISP and then 6ISP model at 10 MPa. In the 4 ISP and the 3ISP models, the anterior implants were more solicited. However, the stress was evenly distributed on the 6 implants, in the 6ISP model. Concerning, the stress distribution in bone, the uppermost stress was found in the 3ISP, then the 4ISP and then the 6ISP model. The increase of implants number reduces the stress on the bone and prosthesis and implants. The use of 6 implants to support screw-retained complete prostheses showed a better biomechanical behavior.