Color Stability and Polymerization Behavior of Direct Esthetic Restorations

Objectives The current study evaluated the effect of accelerated artificial aging (AAA) on the color stability (CS) and degree of conversion (DC) of nanofilled and nanohybrid resin composites associated to different adhesive systems in direct esthetic restorations. Material and Methods Eighty bovine incisors were used to obtained dentin blocks (4 × 4 × 1 mm). The restorative systems were bonded to the blocks and photoactivated according to the manufacturer's instructions. Three adhesive systems were used: Adper Scotchbond Multi‐Purpose (conventional of three steps), Tetric N‐Bond (conventional of two steps) and ClearFill SE Bond (self‐etching). Also, two composites were used: Filtek Z350 XT (nanofilled) and IPS Empress Direct (nanohybrid). The restorations were made using a silicone mold placed on top of the prepared dentin blocks (N = 10). CS was measured after 300 hours of AAA by means of ultraviolet light using a spectrophotometer and CIE L*a*b* parameters on the top surface of the composite and at the bonded interface. The DC was performed using Fourier transform infrared spectroscopy (N = 10). Data were analyzed using two‐way analysis of variance and Tukey's test (α = 0.05). Results The adhesive systems had no significant influence on the color stability (ΔE) of either the restoration surface (α = 0.90) or the bonded interface (α = 0.78). However, composite influenced the color as measured by ΔE and isolated coordinates (α