Three-unit reinforced polyetheretherketone composite FDPs: influence of fabrication method on load-bearing capacity and failure types.

To investigate the influence of different fabrication methods of three-unit reinforced polyetheretherketone composite (PEEK/C) fixed dental prostheses (FDPs) on fracture load. Forty-five three-unit anatomically supported PEEK/C FDPs were fabricated as follows: i. milled using a CAD/CAM system from an industrially fabricated PEEK/C blank, ii. pressed from industrially fabricated PEEK/C pellets, and iii. pressed from granular PEEK/C. Fracture load was measured and data were statistically analysed (p<0.05). CAD/CAM fabricated FDPs (2,354 N) presented a higher mean fracture load than those pressed from granular PEEK/C material (1,738 N) (p<0.001). CAD/CAM milled FDPs and those pressed from PEEK/C-pellets showed spontaneous and brittle fractures near the pontic without deformation of the FDP. In contrast, granulate pressed FDPs showed some plastic deformation without fracture. CAD/CAM fabricated FDPs, and FDPs pressed from PEEK/C pellets showed higher Weibull moduli compared to FDPs pressed in granular form. Industrial pre-pressing of blanks (CAD/CAM/pellet) increased the stability and reliability of PEEK restorations.