Effects of various functional monomers' reaction on the surface characteristics and bonding performance of polyetheretherketone.

Purpose: Polyetheretherketone (PEEK) is a new polymeric material that has received significant attention in dentistry because of its mechanical properties, biocompatibility, and aesthetics. However, the bonding performance of PEEK to other materials is not preferable. This study aimed to analyze the variations in the surface characteristics of PEEK under the chemical action of primers containing different functional monomers or polymers and to evaluate the bonding performance of PEEK and dental cement.

Methods: Disk-shaped PEEK samples were prepared by dental milling, blasting with alumina oxide, and covering with primers containing functional monomers or polymers. The surface characteristics of the samples were analyzed by microscopy and spectroscopy. The shear bond strength (SBS) between PEEK and dental cement, with and without thermocycling, was tested using a universal testing machine. Finally, the data were statistically analyzed and compared.

Results: Functional monomers or polymers were successfully bonded to the surface of PEEK. This treatment significantly improved its hydrophilicity and surface free energy (P < 0.05). The primer containing pentaerythritol triacrylate had the highest SBS without thermocycling (13.89 MPa). Meanwhile, the primers containing urethane dimethacrylate (UDMA) and methyl methacrylate (MMA) (abbreviated as the HC group) showed the highest SBS and lowest reduction (25.51%) after thermocycling. Notably, all the testing groups achieved the ISO10477 standard of 5 MPa. After thermocycling, adhesive failure accounted for the largest proportion of failures in all the groups except the HC group.

Conclusions: The chemical priming treatment can significantly improve the SBS of PEEK and dental cement. Moreover, a primer containing both UDMA and MMA can provide improved bonding for PEEK materials.