Biomechanical Comparison of All-on-Four and Interforaminal All-on-Six Concepts Using Titanium and Ti-Zr (Roxolid®): A...

The All-on-Four and All-on-Six concepts are widely used for full-arch rehabilitation in atrophic mandibles; however, limited biomechanical data exist comparing these protocols when restricted to the interforaminal region and using different implant materials. This finite element analysis (FEA) evaluated the influence of implant configuration and material (titanium vs. Ti-15Zr Roxolid) on stress distribution in an atrophic mandible. A three-dimensional mandibular model was created, and four implant-prosthesis configurations were simulated: interforaminal All-on-Six with Roxolid implants (Model I) or titanium implants (Model II), and All-on-Four with 30° angled posterior implants using Roxolid (Model III) or titanium (Model IV). Von Mises stresses in the mandible, implants, abutments, bar, and prosthesis were calculated using nonlinear FEA. The All-on-Four models exhibited lower mandibular stresses than the All-on-Six models. Implant stresses were lowest in the All-on-Four Roxolid model and highest in the All-on-Six titanium model. Roxolid implants showed generally reduced stresses in both implants and abutments compared with titanium. Within the limitations of this study, the All-on-Four concept-particularly with Roxolid implants-demonstrated more favorable biomechanical behavior than the interforaminal All-on-Six configuration. While implant material affected stress patterns, implant configuration had the greater overall influence. Further patient-specific and clinically validated studies are needed.