Influence of Composite Viscosity and Application Techniques (Snowplow and Preheating) on Surface Roughness and Color Stability

Objective: This study aims to compare the effects of four application techniques performed with packable and flowable composites from two different manufacturers on the color stability and surface roughness of composite restorations.Materials and Methods: Eighty cylindrical specimens (8 × 2 mm) were prepared, forming eight groups (n = 10) using packable and flowable composites from two manufacturers. Four different methods were used: packable, flowable, snowplow, and preheating. After polishing and baseline measurements, specimens were kept in coffee for 12 days. A Vita Easyshade V spectrophotometer was used to measure colour (ΔE, ΔE₀₀). A Surtronic S-128 profilometer was used to measure surface roughness (Ra). Data were analyzed using Welch ANOVA, paired t-test, Pearson correlation, and regression (α = 0.05).Results: The highest ΔE₀₀ values were noted in the Charisma Packable (CP) and Charisma PreHeated (CH) groups, followed by the Tetric PreHeated (TH) group, while the lowest values were found in the Tetric Flow (TF) and Tetric Snowplow (TS) groups (p < 0.005). A strong positive correlation was identified between ΔE and ΔE₀₀ (r = 0.893, p < 0.001). The Snowplow technique reduced the initial surface roughness in the Charisma Snowplow (CS). After the coloring procedure, roughness increased in all groups; however, it was found to be significant only in the CS, CF, and CH groups (p < 0.05). Preheating slightly decreased discoloration in CH, while it resulted in higher in TH.Conclusion: The impact of application technique on color stability and surface roughness is strongly influenced by composite composition. While preheating and Snowplow techniques showed beneficial effects in the Bis-GMA–based system, similar improvements were not observed in the UDMA-containing composite. The importance of material-specific technique selection in clinical practice was demonstrated by these findings.