Effects of polishing protocols on the surface roughness and color stability of polyetheretherketone (PEEK).

Purpose: This study aimed to evaluate the effects of different polishing protocols on the surface properties and color stability of the polyetheretherketone (PEEK).

Materials and methods: A total of 96 disc-shaped specimens were fabricated from PEEK material and divided into 6 different groups: control (CN), ''Abraso-Starglanz'' polishing paste (A), ''Yildiz'' polishing paste (Y), ''Enhance'' polishing system (EN), ''Super snap'' polishing kit (SS), and silicone polisher (SP). Surface roughness (Ra) were measured with a profilometer and the surface topography was examined under scanning electron microscope. Color differences were measured with a spectrophotometer according to the CIEDE2000 (∆E00) formulation before and after coffee immersion. Data were statistically analyzed with Kruskall-Wallis and Spearman's correlation analysis (p<0.05, p<0.001).

Results: A statistically significant difference was observed between the Ra measurements of the polishing protocols (p<0.001). Ra measurements except A, Y, and SS groups were found to be higher than the clinical acceptable threshold of surface roughness (0.20 μm). In ΔE00 measurements, statistically significant differences were observed between the CN and SP (p=0.041), EN (p=0.001), and A (p=0.002) polishing protocols. No correlation was found between Ra and color stability.

Conclusion: Only in the A, Y and SS polishing protocols, Ra measurements were not found to be risky in terms of acceptable threshold of surface roughness. Polishing protocols have also generally failed to maintain the color stability. Considering the surface roughness and color stability, the ''Abraso-Starglanz'' paste may be suitable method for PEEK material.