The effect of different surface treatment and denture cleansers on the bond strenght and color stability of PEKK-composite structure

The purpose of this study was; to evaluate the effect of various surface treatment methods and denture cleansers on the bond strength and color of the PEKK-composite structure. One hundred and ninety-six discs with a diameter of 10 mm and a height of 4 mm were fabricated from PEKK blocks. The specimens were randomly divided into 4 different surface treatment groups: Acid (9.5% Hydrofluoric acid), Er-YAG laser (150 mJ, 10 Hz, 1.5 W), Kojet (30 µm Al2O3) and Control (No-surface treatment) (n = 48). The roughness measurements were recorded on all specimens baseline and after surface treatments. According to the roughness measurement results from all surface treatment groups, 4 specimens closest to the average were selected and SEM (Scanning electron microscope) analyzes were observed. After surface treatments, PEKK bond was applied to the specimens, with the help of Teflon mold, a pink composite resin with a diameter of 3 mm and a height of 4 mm was veneered on the surface of the PEKK. Specimens of each roughening group are divided into 4 according to the solutions to be immersed. Groups are; Corega, Protefix, Curaprox and Distilled water (n = 12). All specimens were immersed to denture cleaners or distilled water for 8 hours a day for 140 days. Color measurements of the specimens were determined with spectrophotometer by measuring at baseline, and again after immersion of denture cleansers. Color parameters (L *, a *, b *, ΔE) are calculated according to the CIE Lab (Comission Internationale de L'Eclairage) system. On the specimens, force was applied with a loading speed of 1mm / min until fracture occurred to performed shear bond strenght (SBS) tests. The shear bond strength was measured by recording the force at the moment of rupture. Failure types after SBS test were classified as adhesive, cohesive and mixed. Statistical analyzes were analyzed by using Two-Way Anova and One-Way Anova) to determine the differences between groups, and Post-Hoc Tukey HSD Multiple Comparison Test and Tamhane's T2 tests to determine intra-group differences. Paired t test was used if there was a homogeneous distribution in the data before and after, and Wilcoxon test was used if there was no homogeneous distribution. Results were analyzed at p≤0.05 significance level. According to the results of the study; It was seen that there was no statistically difference between all groups (p≥0.05). When the groups were evaluated within themselves, it was seen that HF acid and Er-YAG groups were statistically significant (p≤0.05). The roughness values increased statistically in both groups. The Cojet group increased the roughness, but this difference was not statistically significant (p≥0.05). When the shear bond strength values of our study was examined in terms of surface treatments, statistically significantly higher bond strength values were observed in all surface treatment groups compared to the control group (p≤0.05). The shear bond strength average values belongs to HF acid, Kojet, Er-YAG laser and Control group from highest to lowest. When the shear bond strength values of our study are examined in terms of denture cleansers; There was no statistically significant difference in Corega, Protefix and Curaprox groups in terms of shear bond strength values (p≥0.05). The shaer bond strength values in the distilled water group were found to be significantly lower than all other denture cleansers (p≤0.05). The color change values (ΔE) of the specimens immersed to the Corega and Curaprox group were statistically significantly higher than the Protefix and Distilled water groups (p≤0.05). While the effect of cleaning solutions prepared with Corega and Curaprox on the color change of the PEKK-composite structure is not clinically acceptable, the effect of Distilled water and Protefix solution is within clinically acceptable limits. Keywords: Polyetherketoneketone (PEKK), Surface treatment, Denture cleansers, Composite, SEM.