Effect of Beverages on the Surface Roughness and Staining of Modified Polyetheretherketone (PEEK) Materials

This study investigates color and surface alterations in neat and modified PEEK materials (10 × 3 mm, n = 140) immersed in various beverage solutions. Surface roughness (Ra) and color change (ΔE) were analyzed, supported by SEM and AFM evaluations. Specimens polished with 400–1200 grit sandpaper were measured via profilometry before a 30-day immersion in distilled water, coffee, tea, cola, and red wine (refreshed every 12 h). Post-immersion results indicated that material and solution types significantly influenced Ra and ΔE values (p < 0.05), with the TP group being the least affected. Statistically, tea caused the greatest discoloration. The GFP group exhibited the highest Ra, indicating inferior surface stability, whereas TP and CR groups remained below the 0.2 μm clinical threshold. Specifically, the TP group demonstrated the lowest Ra value. Although perceptible color changes occurred in all materials, a positive correlation was identified between material type and beverage solutions. SEM and AFM analyses confirmed the presence of surface micro-cracks and morphological irregularities.