Properties of 3D-Printed resins for interim restorations: effects of printing and post-curing protocols

This study analyzed the properties of three-dimensional (3D)-printed resins designed for interim restorations and subjected to different printing and post-curing protocols. Specimens were manufactured with two 3D-printed resins for interim restorations at varying exposure times per layer, in accordance with the manufacturer's recommendations (Tm) or using a calibrator (Tc). Subsequently, the specimens were post-cured for 5, 10, or 15 min. Trueness, surface roughness, and color analyses were performed. For biological characterization, the specimens were incubated for up to 72 h in a culture medium, and the extracts were applied at 24-h intervals to keratinocyte cells (NOK-Si). Cellular metabolism was evaluated after 1 and 3 days. Leaching of residual monomers from the extracts was evaluated. Data were analyzed using two-way analysis of variance (ANOVA) and Tukey's honestly significant difference (HSD) test (α = 5%). The exposure time beyond Tc resulted in specimens with increased trueness and smoother surfaces. Color stability was also influenced by the type of resin and post-curing time; the longer the time, the greater the color change, allowing for brighter and clearer specimens. The resins were cytocompatible with NOK-Si, regardless of the printing and post-curing parameters, although residual monomer leaching was affected by the parameters tested. The evaluated resins were cytocompatible; however, variations in the exposure times per layer and post-curing duration affected their roughness, leaching, trueness, and color stability.