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Stress in the bone and prosthetic components due to "all-on-4" system with polyether-ether-ketone screwing prosthesis. Analysis using 3D finite element method.

OBJECTIVE
To identify and analyze distribution of bone stress in the implant area using a PEEK prosthesis fixed on four dental implants depending on different positions of the functional loading point on a cantilever in a 3D modeled system.


MATERIAL AND METHODS
The fragment of the lower jaw with dental implants and over-the-implant prosthetic part was represented by geometrical 3D models and diagonal loads were placed on the distal cantilever of the prosthesis. 3D models were exported to SolidWorks® Student Edition 2018 (Dassault Systemes SE, France) software. Average von Mises stress around the outer perimeter of the implant was measured in MPa. Relative stress was identified using a graded color scale in relative units. A 0.95 confidence level (P), 0.05 significance level (p), maximum error of 10% (Δ) were set. The data was analyzed using Statistical Package for Social Sciences® (IBM, Armonk, USA) version 137.


RESULTS
The distal implant on the same side as the point of loading receives 45.01-53.88% of all forces created. Stress at the frontal implants is distributed almost evenly. The pair of implants on the same side of the loading force suffers 66.38-74.68% of all forces. The implant on the opposite side of the loading force receives the smallest stress which is hardly influenced by the length of the console.


CONCLUSION
A full arch restoration in an edentulous lower jaw using a four-implant fixed PEEK prosthesis system generates unevenly distributed internal stress in the bone next to the implants but does not go over the critical resistance of the bone.