Enhancing the Bond: A Comparative Study of Surface Treatments on PEEK– Composite Adhesion

Polyetheretherketone (PEEK) is a promising dental material due to its superior mechanical and biocompatible properties. However, its low surface energy presents challenges in achieving reliable adhesion with composite resin. This in vitro study aims to evaluate and compare the shear bond strength (SBS) between PEEK and composite resin following different surface treatment protocols. One hundred CAD/CAM-milled dental-grade PEEK specimens (5×5×2 mm) were divided into four groups: • Group A: Air abrasion with 110 µm Al2O3 • Group B: 5% hydrofluoric acid (HF) etching for 30 seconds • Group C: Air abrasion followed by 5% HF etching • Group D (Control): No surface treatment Composite resin (Te-Econom Plus) was bonded using a light-cured adhesive, and SBS was measured using a universal testing machine. SEM analysis was conducted to examine surface morphology and failure modes. Group C (air abrasion + HF) exhibited the highest bond strength (6.20 ± 0.69 MPa), followed by Group A (4.95 ± 0.62 MPa), Group B (2.91 ± 0.48 MPa), and Group D (1.10 ± 0.27 MPa). Statistical analysis confirmed significant differences among all groups (p < 0.001). SEM analysis revealed enhanced micromechanical retention and mixed/cohesive failures in Group C. Surface treatment significantly improves the bonding between PEEK and composite resin. The combination of air abrasion and 5% HF etching showed the highest efficacy. This protocol offers a clinically applicable and effective strategy for enhancing the adhesion of PEEK-based prosthetic restorations. Key Words Air abrasion, CAD/CAM, Composite resin, Hydrofluoric acid, PEEK, Shear bond strength, Surface treatment