The effects of different surface treatments on shear bond strength of polyetheretherketone (PEEK) and polyetherketoneketone (PEKKTON) materials to veneering composite

Purpose: The purpose of this in vitro study was to evaluate the effects of four different surface treatments and thermocycling process on shear bond strength between PEEK/PEKKTON and indirect composite. Materials and Methods: 115 PEEK and 115 PEKKTON discs were divided into five groups according to surface treatment methods; no treatment (control), air abrasion with 50 µm Al2O3, air abrasion with 110 µm Al2O3, silica coating with 3M Cojet, etching with 98% sulfuric acid.. The surface roughness was examined with profilometer and scanning electron microscopy (SEM). After surface treatments, Visio.link adhesive with GC Gradia veneering composite was applied on PEEK and PEKKTON surfaces and light-cured. Then, all groups were divided into two subgroups according to whether thermocycling process was applied or not (n=11). Shear bond strength was measured and failure analysis was performed. The data were analyzed using a Two-Way ANOVA, Three-Way ANOVA. Results: The highest surface roughness values in PEEK and PEKKTON samples were seen in the air abrasion with 110 µm Al2O3 groups (p<0.05). In the PEEK samples, the group with the highest shear bond strength values was in the air abrasion with 50 µm Al2O3 group, while the highest values in the PEKKTON samples were observed in the air abrasion with 110 µm Al2O3 group (p<0.05). Shear bond strength values decreased in all groups after thermocycling. Adhesive failure is the most common in PEEK samples, while mixed failure in PEKKTON samples. Conclusions: In the samples of PEEK and PEKKTON, the most effective surface treatment in terms of surface roughness and shear bond strength is air abrasion with Al2O3 particles. The bond strength decreased in the thermocycled samples. Keywords: PEEK, PEKKTON, air abrasion, SEM, shear bond strength.