Effect of the combination of chemical-physical pretreatments for bonding PEEK to resin composites.

Objective: Surface pretreatment of polyetheretherketone (PEEK) is necessary to increase the bond strength between PEEK and veneering materials. The objective of this in vitro study was to evaluate the effect of a combination of chemical and physical pretreatments on the surface of PEEK for the adhesion of resin composite.

Materials and methods: Five pretreatments were evaluated: grit-blasting (Al2O3), grit-blasting (Al2O3)+primer adhesive, 98% sulfuric acid, 98% sulfuric acid+primer adhesive, and an untreated control. The PEEK surface was evaluated with a scanning electron microscope, and the tensile bond strength (TBS) of the PEEK with the veneering resin composite interface was measured with a universal test machine at a crosshead speed of 5 mm/min. The failure was categorized as adhesive, cohesive or mixed.

Results: Pretreatment with grit-blasting+primer adhesive obtained the highest mean ± standard deviation TBS value (19.10±1.70 MPa) followed by 98% sulfuric acid+primer adhesive (17.90±1.20 MPa), while the pretreatments with grit-blasting (13.97±2.33 MPa) and 98% sulfuric acid (12.18±0.70 MPa) showed the lowest values. All pretreatments showed statistically significant differences with respect to the untreated PEEK control and the combined pretreatments with respect to the pretreatment with grit-blasting and 98% sulfuric acid (p≤0.05). A higher number of adhesive failures were observed except in the grit-blasting+primer adhesive group, which had 80% mixed failures. No cohesive failures were seen.

Conclusion: The combination of chemical-physical pretreatments induced an increased in the TBS values between PEEK and resin composite because of the topographical roughness and the micro-mechanical anchoring in the PEEK surface.