Do modeling liquid and glycerin gel compromise the color stability of one-shade composites

This study aims to investigate the effect of modeling liquid and glycerin gel on the color stability of one-shade composites. 120 specimens were prepared using four one-shade resin composites, one conventional composite, one modeling liquid, and one glycerin gel. The specimens were divided into four groups: Group 1, only polished; Group 2, modeling liquid applied followed by polishing; Group 3, modeling liquid applied without polishing; and Group 4, modeling liquid and glycerin gel applied without polishing. All specimens were stored in a coffee solution for one week. Color measurements were performed using a spectrophotometer at baseline and after coffee staining. Data were analyzed using the Kruskal-Wallis test and Post Hoc Dunn-Bonferroni test. Clinically unacceptable color differences were obtained in all composite resins after coffee immersion. In Group 1, Omnichroma and Zenchroma Universal exhibited significantly lower ΔE₀₀ values compared to Vittra APS Unique. In Group 2, Zenchroma Universal showed significantly lower ΔE₀₀ values than Charisma Topaz ONE. In Group 3, the ΔE₀₀ value of Charisma Topaz ONE was lower than that of Vittra APS Unique. In Group 4, Zenchroma Universal showed significantly lower values compared to Vittra APS Unique. The susceptibility of composites to discoloration varied based on surface treatment. Material selection should consider not only esthetic and mechanical properties but also long-term color stability. Modeling liquids facilitate composite handling and improve surface adaptation; however, optimal restoration longevity requires proper finishing and polishing. Combining modeling liquid with glycerin gel and Mylar strips without subsequent polishing may increase surface roughness and susceptibility to staining. This can compromise long-term esthetics and plaque resistance. Polishing not only removes residual inhibition layers but also enhances surface smoothness, reducing discoloration risk. Clinicians should integrate polishing into restorative protocols when using surface wetting agents to ensure improved manipulation during placement and optimal esthetic and functional outcomes over time.