Dynamic finite element analysis of stress distribution in edentulous fixed restorations: Effects of different implant...

The biomechanical effects of different implant configurations and framework materials in fixed restorations for edentulous jaws have not been clearly quantified. Furthermore, the characteristics of stress distribution under functional dynamic loading conditions require further clarification. This study utilized dynamic finite element analysis (FEA) to evaluate the effects of implant configurations and framework materials on stress distribution in mandibular fixed restorations.

Three-dimensional models of edentulous mandibles and frameworks were reconstructed. And three implant configurations (All-on-4, All-on-6, and All-on-6 with short implants) were established. These configurations were combined with four framework materials: titanium, zirconia, polyetheretherketone (PEEK), and carbon fiber-reinforced polyetheretherketone (CFR-PEEK) to form 12 experimental groups. A dynamic loading cycle (0.875 s) was applied, consisting of staged vertical and oblique loads under 600 N bilateral posterior loading (100 N per tooth). Comparative analyses were conducted on the Von Mises stress (VMS) distribution in bone tissue, implants, and frameworks, as well as the deformation of frameworks across different loading stages.

Under dynamic loading, the minimum stress distributions were recorded as follows: All-on-6+Zirconia for cortical bone, All-on-6-short+Zirconia for cancellous bone, All-on-6-short+CFR-PEEK for implants, and All-on-6+PEEK for frameworks. The minimum framework deformation was observed in All-on-6+Zirconia.

Under dynamic loading, the six-implant configurations significantly reduced VMS in bone, implants, and frameworks compared to the four-implant design. Compared to All-on-6, All-on-6-short was more prone to stress concentration under oblique loading. Stress and deformation in the All-on-4 framework primarily concentrated in the posterior cantilever area, Whereas All-on-6 and All-on-6-short utilized multisupport structure to distribute stress anteriorly. Furthermore, oblique loading significantly increased system stress. Zirconia reduced bone stress and suppressed framework deformation, while PEEK alleviated internal stress within frameworks and implants.