[Three-dimensional finite element analysis of different framework materials in implant-supported fixed mandibular prosthesis]

Objective: To evaluate the biomechanical behaviors of different framework materials in implant-supported fixed mandibular prosthesis using three-dimensional finite element analysis. Methods: A model of implant-supported fixed mandibular prosthesis was established. The simulations were divided into six groups according to the framework materials: pure titanium, cobalt-chromium alloy, gold alloy, zirconia, polyether ether ketone (PEEK) and carbon fiber-reinforced PEEK. An oblique load of 300 N with a 75° angle to the occlusal plane was applied from the lingual side on the buccal cusps of the two premolars and the first molar teeth. The stresses on implants, surrounding bones and frameworks were analyzed and compared among the framework materials both quantitatively and qualitatively. Results: In implant-supported fixed mandibular prosthesis model, the highest stresses were located around the neck of the implants and cortical bone during oblique loading among six designs. In addition, the stresses were concentrated on the buccal and distal cortical bone around the implants of the posterior region. Stress values of implants and cortical bones from low to high were as follows: zirconia, cobalt-chromium alloy, pure titanium, gold alloy, carbon fiber-reinforced PEEK, PEEK. The von Mises stress values of implant and cortical bone in the first molar site of PEEK framework material were 44.96 and 29.13 MPa, while the von Mises stress values of implant and cortical bone in the first molar site of zirconia framework material were 21.29 and 17.79 MPa. The zirconia and medal framework materials were more advantageous in stress distribution around implants than PEEK framework material. Conclusions: In implant-supported fixed mandibular prostheses, biomechanical analysis showed that the zirconia and medal framework materials were more advantageous in stress distribution around implants than PEEK framework materials.