Effect of Chlorinated Water on the Color Stability of Different Resin Composites: An In Vitro Comparative Study

ABSTRACT Objective This study evaluated the effect of chlorinated water on the color stability of different resin composites, simulating prolonged exposure experienced by frequent swimmers. Materials and Methods Sixty disk‐shaped samples of microhybrid (Arabesk Top), nanohybrid (Grandio) and Ormocer‐based (Admira Fusion) composites ( n = 20) were prepared. Each group was randomly divided into two subgroups, immersed in either chlorinated (≈3.5 ppm) or distilled water. Spectral reflectance was measured at baseline, 2 weeks, and 2 months using a Datacolor 600 spectrophotometer, and CIE L*a*b* coordinates were calculated using the 2° standard observer. Color stability was assessed with CIEDE2000 (Δ E 00 ) and the Whiteness Index for Dentistry (WI D ). Two‐way MANOVA analyzed the effects of composite type, storage medium, and their interaction with Bonferroni‐adjusted post hoc tests ( α = 0.05). Results All Δ E 00 and ΔWI D values were below the acceptability thresholds, though several exceeded perceptibility. Composite type and storage medium significantly influenced Δ E 00 and ΔWI D ( p < 0.05) with interactions. Overall, at 2 weeks, Admira ( p < 0.001) and Grandio ( p = 0.008) showed greater Δ E 00 in chlorine; Admira exhibited higher ΔWI D in chlorine than control (0–2 m p = 0.001; 2 w–2 m p < 0.001). Conclusion Chlorinated water caused greater short‐term discoloration in the Ormocer‐based composite, whereas the nanohybrid showed superior long‐term stability. The microhybrid composite presented progressive Δ E 00 increase with highest ΔWI D .