Effect of Different Cantilever Lengths in Polyether Ether Ketone Prosthetic Framework in All-on-Four Technique on Stress Distribution: A Three-Dimensional (3D) Finite Element Analysis.

Background: Determining the distal cantilever length in All-on-Four (All-on-4) implant-supported prostheses is a major factor in the long-term success of these prostheses. The difference in mechanical properties of materials used in the fabrication of these prostheses, such as polyether ether ketone (PEEK), may have an impact on the determination of the cantilever length that best distributes stress.

Aim: To study the distribution of stress in All-on-4 mandibular prostheses in the bone, implants, and framework according to difference cantilever length in PEEK prosthetic framework using three-dimensional finite element analysis.

Materials And Methods: A three-dimensional (3D) model of an edentulous mandible was constructed, implants and abutments models were designed by the All-on-4 concept, and two frameworks were constructed from PEEK with different cantilever lengths of 10 and 15 mm. Two study groups were created. Occlusal oblique forces of 600N were applied from the right side at a 45-degree angle, and finite element analysis was performed to obtain the stress distribution in the bone, implants, and framework.

Results: At cantilever length of 10 mm, in the PEEK model, this study found an increase in stress compared to PEEK model at cantilever length of 15 mm in the cortical bone and implants and framework, but PEEK models showed a similar distribution of stress in the spongy bone.

Conclusions: Decreasing the cantilever length in the PEEK model will increase the stress. PEEK models showed deformation of the structure material