塩素化水が異なるレジンコンポジットの色安定性に及ぼす影響：インビトロ比較研究

This study evaluated the effect of chlorinated water on the color stability of different resin composites, simulating prolonged exposure experienced by frequent swimmers.

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 (ΔE₀₀) 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).

All ΔE₀₀ and ΔWI_D values were below the acceptability thresholds, though several exceeded perceptibility. Composite type and storage medium significantly influenced ΔE₀₀ and ΔWI_D (p < 0.05) with interactions. Overall, at 2 weeks, Admira (p < 0.001) and Grandio (p = 0.008) showed greater ΔE₀₀ in chlorine; Admira exhibited higher ΔWI_D in chlorine than control (0-2 m p = 0.001; 2 w-2 m p < 0.001).

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 ΔE₀₀ increase with highest ΔWI_D.