Does single-shade technology impact the long-term mechanical and optical performance of resin composites?

Abstract In this in vitro study, the mechanical and optical properties of a conventional multi-shade resin composite, Charisma Topaz, were compared with a single-shade resin composite, Charisma Topaz ONE, over a period of 12 months. This investigation isolates the effect of adaptive light-matching filler technology by keeping the monomer matrix nearly constant. Vickers microhardness, flexural strength, and color stability (Δ E 00 ) were evaluated at baseline and after aging in distilled water. Charisma Topaz exhibited significantly higher Vickers microhardness than Charisma Topaz ONE at both baseline ( p = 0.042) and after 12 months ( p = 0.045). No statistically significant difference was found between the two materials in flexural strength at any time point ( p > 0.05). For color stability (Δ E 00 ), both resin composites exhibited clinically unacceptable color changes (Δ E 00 > 1.8). Notably, Charisma Topaz ONE exhibited significantly greater discoloration after 6 months than Charisma Topaz ( p = 0.006). The study concludes that although both materials maintain stable flexural strength, the conventional multi-shade resin composite Charisma Topaz demonstrates superior Vickers microhardness and medium-term color stability after long-term water aging under laboratory conditions. In contrast, although the optical benefits of ‘shade matching’ in Charisma Topaz ONE are evident, it may be more appropriate for less demanding scenarios where esthetic simplicity is more important.