Effect of Polishing Systems and Accelerated Artificial Aging on the Optical Properties (Color and Translucency) and Surface Roughness of Single-Shade Resin Composites

This in vitro study aimed to evaluate the effects of different polishing systems and accelerated artificial aging on the optical properties and surface roughness of structurally different single-shade resin composites (SSRCs). Five SSRCs (Omnichroma (OM), Essentia Universal (EU), Admira Fusion X-tra Universal (AFX), Charisma Diamond ONE Shade (CDO), and Zenchroma (ZC)) were evaluated in this study. A total of 250 disc-shaped specimens were randomly assigned to five polishing groups: unpolished control, Sof-lex XT, Clearfil Twist Dia, Enhance-PoGo, and Opti One Step. Measurements were taken after a 24 h incubation in distilled water (37 °C) and repeated after accelerated aging. Changes in color and translucency were calculated using the CIEDE2000 formula. Statistical analyses included the Mann–Whitney U test with Bonferroni correction, the Kruskal–Wallis test, and Spearman’s correlation for interrelationships among ΔE00, ΔTP00, and ΔSR. CDO and AFX showed lower ΔE00 values across all polishing groups (p < 0.05). ΔSR differed among resin composites and was generally higher in CDO and AFX (p < 0.05). Polishing systems affected both ΔE00 and ΔSR within each SSRC group. ΔTP00 varied by resin composite, increasing in some groups and decreasing in others. Overall, ΔE00, ΔSR, and ΔTP00 depended on resin composite type and polishing system. Nano-hybrid resin composites generally demonstrated weaker color changes than microhybrid resin composites, whereas the color stability of the supra-nanofilled composite varied according to the polishing system. Multi-step and diamond-containing polishing systems generally yielded superior optical and surface performance, although their effectiveness depended on resin composite structure. The optical properties of SSRCs, including color, translucency, and surface roughness, were influenced not only by polishing protocols and accelerated artificial aging but also by the structural characteristics of the resin composites. Given the relationships among color, translucency, and surface roughness, careful selection of polishing systems is critical for maintaining the long-term esthetic and functional performance of SSRCs.