FEM EVALUATION OF DIFFERENT CONFIGURATIONS OF FULL-ARCH MANDIBULAR IMPLANT PROSTHESIS

Purpose: A recent procedure called “All-on-four " provides the rehabilitation of atrophic edentulous jaws by means of a fixed prosthesis supported by 4 implants. Purpose of this work is the comparative evaluation between the biomechanical features of the All on Four versus traditional therapyMethods: it was created a 3D model (SolidWorks - Dessault Systems SolidWorks Corp - Concord, MA, USA) of a clinical case with 6 mandibular implants and a screwed framework. The FEM analysis was performed by varying the number and position of the implants and the superstructure material. 9 different models were analyzed. The load was 300 N on the distal part of the framework.Results: Implants closest to the application of the force are the more loaded. In the superstructure there was a stress peak that exceeds the plasticization value of one material (titanium), although the area is very limited. In the bone, maximum stress occurs in the cortical component, while the medullary component is less interested. The distal implant (closer to the force) has a compressive load, while the mesial one has a tractive stress.Conclusion: The strategic distribution of implants appears to be the key factor that governs the distribution of loads. A limited number of implants, strategically placed, can be an effective alternative rehabilitation in selected cases. This suggests a possible effectiveness of the fixed implant prosthesis on 4 implants, accompanying the reduction of, costs, post-operative morbidity and the difficulty of the prosthesis than other procedures.