Biomechanics of the implant-supported full arch fixed complete denture manufactured by milling and injection techniques: An experimental and FEA study.

Abstract

Purpose: This study aims to characterize the mechanical properties of implant-supported full arch fixed complete dentures manufactured by milling and injection techniques.

Materials and methods: Twenty-two samples with milling and injection manufacturing techniques were fabricated. Twenty-two titanium samples were manufactured to be used as the control group. Additionally, eight PEEK samples from both the injection and milling groups were manufactured and tested using a uniaxial tensile test, and the obtained results were used as input data for finite element analysis (FEA). All-on-four PEEK hybrid prostheses supported with 2 implants on the mandible were used for the simulations. The FEA computations were performed for a bilateral 150 N force applied in both vertical and oblique directions.

Results: A significant difference was observed between the injection and milled PEEK groups in terms of modulus of elasticity (Injection PEEK group: 3.1 ± 0.6 GPa, Milling PEEK: 4.6 ± 0.9 GPa) and flexural rigidity (Injection PEEK group: 28.0 ± 5.8 kNmm², Milling PEEK: 41.2 ± 8.4 kNmm²) (p < 0.05), while no significant differences were observed between the injection and milled PEEK groups in terms of other parameters (p > 0.05). The finite element results showed that the highest stresses were observed in the Injection PEEK group, while the lowest were observed in the Milling Titanium group. Both injection and milled PEEK frameworks exceeded the yield stress limit during vertical and oblique loading.

Conclusion: It was concluded that the forces implemented on rigid framework material such as titanium were better distributed to the implants supporting the all-on-four prosthesis.