Influence of non-thermal plasma systems and two favorable surface treatments on the shear bond strength of PAEKs to composite resin

This study aimed to investigate the effect of non-thermal plasma systems with and without two favorable surface treatment techniques on the surface roughness (Ra) and shear bond strength (SBS) of polyaryletherketone (PAEK) polymers to veneering composite resin material. A total of 288 (n = 144 for each polymer) Polyetheretherketone (PEEK) and Polyetherketoneketone (PEKK) samples (7 × 7×3mm) were divided into the surface treatment methods (n = 16): untreated (CNT); dielectric barrier discharge air plasma treatment (DBD); atmospheric pressure plasma treatment with a plasma brush (APB); 98% sulfuric acid etching (SA); SA_DBD; SA_APB; tribochemical silica coating (TBC); TBC_DBD; TBC_APB. The Ra (n = 5) and scanning electron microscope (SEM) analyses (n = 1) were performed. A bonding agent was applied to the remaining samples (n = 10) and veneered with a composite resin. After storing in distilled water for 24 h at 37 °C, the SBS test was applied with a universal test machine, and the failure modes were examined with an optical microscope. The SBS and Ra data were statistically analyzed with Kruskal Wallis, two-way analysis of variance (ANOVA), and compared with Mann-Whitney_U and Tamhane tests (α = 0.05). The highest SBS value was observed in Groups SA (22.67 ± 1.48 MPa) for PEEK, Group TBC (18.91 ± 1.09 MPa) for PEKK polymer groups. The highest Ra values were determined in Group TBC_DBD for both polymers. While the TBC may enhance the SBS values of both polymers, the SA application is more effective for PEEK polymer regarding the SBS value. In contrast to the effect of DBD, APB application is beneficial for improving the bonding capacity of PAEKs.