The aims of this study were to investigate the applicability of composite resin veneered polyetheretherketone（PEEK）crowns to dental restorations, and to evaluate fracture loads and failure modes of PEEK-based crowns with two framework designs.
A stainless-steel die was prepared for a maxillary molar crown restoration. Resin abutments were duplicated. Composite resin veneered PEEK crowns with two different PEEK framework designs (uniformthickness（STD）; supported-design（EXP））, and Computer-Aided Design/Computer-Aided Manufacturing （CAD/CAM）composite resin crowns（CRC）were fabricated. The restorations were cemented to abutments and loaded vertically until fracture. Fracture loads were recorded for each specimen. Failure modes were observed and statistically analyzed.
The fracture loads of the STD, EXP, and CRC specimens were 1610.9 N, 1680.8 N and 1698.0 N, respectively. There were no significant differences among the groups. For STD and EXP, almost all specimens showed restorable failure; however, CRC specimens showed a significantly higher ratio of non-restorable failure.
Composite resin veneered PEEK crowns can be applied to dental restorations in the molar regions and showed high fracture load, regardless of framework design. They also showed a failure mode with less influence on the abutment tooth at a high rate compared with CAD/CAM crowns.