Visual evaluation of the color adjustment of single-shade and group shade resin composites in restorations with different cavity configurations

Objective: To evaluate the influence of the tooth shade, type of resin composite and cavity configuration on the color adjustment of single-shade and group shade resin composites. Methods: Class I and V cavities were prepared in artificial acrylic mandibular right molars with different shades A1, A2, A3, A3.5 and A4. Three single-shade (OMN, UNI, CHA) and two group shade (FIL, HAR) resin composites were evaluated. Seventy-five observers, including dentists, dental students and laypersons (n = 25), participated in the study. A psychophysical experiment based on visual assessments of the color matching between each tooth and each restoration was ranked from 0 (excellent match) to 4 (huge mismatch), and mean frequencies (%) were calculated. Visual color differences among composite materials and tooth shades were statistically tested (P < 0.05). Results: The results showed highest percentages of unacceptable color mismatches for class V compared to class I restorations, especially for more chromatic tooth shades (A3.5 and A4). The percentage of ratings of acceptability was higher for laypersons group. For class V, OMN presented significant difference only from UNI in tooth shades A1, A2, A3 and A4. However, for class I, OMN presented significant differences with CHA for A1, A2 and A4, and with HAR and FIL for A1. Conclusions: Class I resin composite restorations exhibit superior color matching than Class V, with lighter and low chroma tooth shades demonstrating better color adjustment. The color matching of both cavity configurations is comparable for single and group shade resin composites. Clinical significance: Cavity configuration and tooth shade may impact color matching of single and group shade resin composites. This study demonstrates superior color matching in class I configurations over class V for both single and group shade resin composites. Additionally, restorations placed in teeth with lighter shades exhibit more favorable color adjustment.