Effect of Simulated Toothbrushing on Surface Roughness, Color Stability, and Gloss of Two Single-Shade Composite Resins

< 0.001). Strong correlations were found between surface roughness and both gloss change (r = -0.919) and color change (r = 0.826). Material A demonstrated greater resistance to surface degradation and better preservation of optical properties compared to Material B. Surface roughness was identified as the common underlying factor driving both color instability and gloss reduction in single-shade composites. Clinical Significance: Not all single-shade composites perform equally under mechanical aging. Clinicians should consider the filler technology and long-term surface stability when selecting single-shade composite resins for clinical use.