Evaluation of the Surface, Structural, And Optical Stability of a Single-Shade Universal Resin Composite After Exposure to Acidic Staining Solutions

1.Background/Objectives: Advances in adhesive dentistry have led to the development of single-shade universal resin composites (SsURCs), designed to simplify shade selection and enhance aesthetic outcomes, yet their long-term stability under acidic conditions remains a concern. This study aimed to evaluate the surface properties, zeta potential, Raman spectral characteristics, and color stability of Omnichroma, a single-shade universal resin composite, before and after immersion in staining solutions (coffee, Coca-Cola, and red wine). 2.Methods: A total of 20 disc-shaped specimens were prepared and divided into four subgroups: control (artificial saliva), coffee, Coca-Cola, and red wine. Surface roughness, contact angle, and color stability were assessed before and after immersion, while Raman spectroscopy analyzed structural modifications, and zeta potential measurements determined the point of zero charge (PZC). 3.Results: Coffee caused the most significant color change (ΔE = 10.84 ± 1.03) and roughness increase (SR = 1.53 ± 0.38), followed by red wine (ΔE = 5.33 ± 0.27; SR = 1.15 ± 0.08) and Coca-Cola (ΔE = 1.28 ± 0.44; SR = 1.21 ± 0.31). The PZC was identified at pH 3.8, indicating a predominance of anionic ionizable groups. Raman analysis revealed molecular alterations, particularly in C=O stretching and C=C aromatic ring vibrations. 4. Conclusions: These findings suggest that acidic beverages affect the structural and optical stability of Omnichroma, with coffee having the greatest impact. Further in vivo studies are needed to assess its long-term performance in clinical settings.