The influence of post-curing protocols on the optical properties of provisional and long-term 3D-printable resin...

This study determined the influence of post-curing protocols on the color stability of provisional and long-term 3D-printable resin composites. Disc-shaped specimens were fabricated from a provisional (Prov)  and long-term (Crown) 3D-printable resin composites using a digital light processing printer. Post-curing protocols included exposure to 405 nm-based light sources (Anycubic for 30 or 60 min in the standard mode or Procure 1) and one 385 nm-based light source (Procure 2 with distinct protocols). Color parameters (L*, a*, b*) were measured at baseline, after 14 and 21 d of dry storage, and after 7 d of water immersion. Post-curing protocol, material, and storage condition significantly influenced color stability. High-irradiance protocols resulted in the highest color change values, exceeding the clinical acceptability threshold (ΔE₀₀ > 1.8). Water immersion induced a significant whitening effect and increased total color change in all groups. The long-term resin demonstrated superior color stability compared to the provisional one across all post-curing protocols. The choice of post-curing protocol is critical for aesthetic performance, as high-irradiance parameters, while potentially beneficial for mechanical properties, can compromise chromatic stability, particularly in materials with low filler content.