In Vitro Evaluation of Color and Surface Roughness Changes of Polyetheretherketone, Monolithic Zirconia, and Resin Nanoceramics Exposed to Staining Liquids

This study aims to investigate color stability and surface roughness of polyetheretherketone (PEEK), zirconia, and hybrid ceramics while stored in different liquids. A total of 240 specimens were prepared from monolithic zirconia, PEEK, and hybrid ceramics. All specimens were polished using rubber sets with different grain sizes. Color parameters (L*, a*, b*) were measured three times using a dental spectrophotometer in standard D65 lightning. Each group was divided into eight different groups to be kept in eight different solutions as distilled water, cola, red wine, tea, coffee, heptane, citric acid, and 50% ethanol. Specimens were held in solutions at 37°C for 12 days. Color measurements were repeated, and color change (ΔE) was calculated using the CIE Lab formula. The color difference of PEEK specimens was found above the clinically acceptable limit; however, color differences for monolithic zirconia produced by coffee were found within the clinically acceptable limits. ZR and HC specimens’ color change values were found between threshold values (1<ΔE < 3.3). The differences observed in surface roughness levels amongst the ZR specimens could be caused by the polishing instrument and procedure. The color change of the materials was within acceptable limits, whereas the surface roughness increased more than 0.2 µm. Especially cola, heptane, and red wine significantly increased the mean surface roughness.