Residual Monomer Elution from Permanent Crown Materials at Different Storage Times

Three-dimensional (3D)-printed permanent crown resins are increasingly used in restorative dentistry, but their residual monomer elution compared with computer-aided design/computer-aided manufacturing (CAD/CAM) materials remains insufficiently characterized. This in vitro study compared residual monomer elution from three permanent crown materials at different storage times. A CAD/CAM hybrid ceramic (GC Cerasmart 270) and two 3D-printed permanent crown resins (Graphy Tera Harz and Saremco CrownTec) were evaluated. Specimens (12 × 14 × 2 mm; n = 5 per material) were stored in 75% ethanol, and the extraction solutions were analyzed by high-performance liquid chromatography (HPLC) on days 1 and 30. The eluted amounts of Bis-GMA, TEGDMA, UDMA, and HEMA were quantified and analyzed using repeated-measures ANOVA, Kruskal-Wallis, and Wilcoxon signed-rank tests (p < 0.05). Material, time, and their interaction were significant for Bis-GMA (p < 0.001). Material differences were also significant for TEGDMA and UDMA (p = 0.002), whereas the time-dependent increases in TEGDMA, UDMA, and HEMA did not reach statistical significance. Graphy showed the highest Bis-GMA and UDMA elution, Saremco the highest TEGDMA and HEMA elution, and Cerasmart the lowest values for all monomers. Both material characteristics and storage time should therefore be considered when evaluating residual monomer elution.