Color Adjustment and Fluorescence Matching of Single-Shade Composites: Spectrophotometric and Photographic Analysis Techniques

Background: Although the color adjustment of single-shade composites has been widely investigated, limited information is available regarding their fluorescence-matching performance. The aim of this study was to compare the optical performance of different composite resin systems by evaluating color adjustment under visible-light conditions and fluorescence matching under ultraviolet (UV) illumination. Methods: Standardized cervical cavities were prepared in 45 extracted human maxillary central incisors. Teeth were divided into nine groups (n = 5): five single-shade composites (Omnichroma, Charisma Topaz One, Vittra APS Unique, Zenchroma, and ONEshade), two simplified shade composites (Optishade and Clearfil Majesty ES-2), one multi-shade composite (Estelite Sigma Quick), and one group-shade composite (G-aenial A’chord). Color adjustment was evaluated using spectrophotometry (SP) and cross-polarized digital photography (CP), whereas fluorescence matching was evaluated using fluorescence-illuminated digital photography (FI). Data were analyzed using generalized estimating equations and Kruskal–Wallis tests. Results: FI showed significantly higher ΔE values (23.01 ± 7.04) than SP (3.34 ± 1.52) and CP (3.55 ± 1.35) (p < 0.001). G-aenial A’chord exhibited the lowest ΔE values (6.54 ± 5.01), whereas Charisma Topaz One showed the highest fluorescence mismatch (30.22 ± 10.92) (p < 0.001). A significant interaction was found between composite type and measurement method (p < 0.001). Conclusions: While single-shade composites exhibited favorable color adjustment under visible-light conditions, they showed greater fluorescence mismatch under UV illumination. In contrast, the group-shade composite demonstrated the most stable optical performance across different evaluation methods.