Comparison between all-on-four and all-on-six treatment concepts on stress distribution for full-mouth rehabilitation using three-dimensional finite element analysis: A biomechanical study

PURPOSE: The current study intended to provide a comparison of biomechanical behaviors of two different treatment concepts for full-mouth rehabilitation with dental implants placed according to the “All-on-four” concept and “All-on-six” concept with analysis of the stress patterns of the implant support system using three-dimensional finite element analysis (FEA). MATERIALS AND METHODS: The edentulous mandible was treated with two different implant designs. “All-on-Four” implant placement concept was used in Model 1 with two central axial implants and two distally tilted implants at 17° and in Model 2, “All-on-Six” concept was applied with six vertically placed implants. Individual vertical and horizontal load of 100 N and oblique load of 141 N at 45° was applied to all implants. To evaluate and compare the results in terms of maximum principal stress, we used FEA. RESULTS: All-on-six showed smaller maximum principal stress values on the cortical bone and implants. However, maximum principal stress values obtained on trabecular bone was smaller in the All-on-four design for vertical and horizontal loading conditions. CONCLUSIONS: The All-on-six approach showed more favorable biomechanical behavior.