Comparison of residual monomer content in permanent crown materials fabricated by additive manufacturing at different thicknesses.

This in vitro study aimed to quantitatively evaluate residual monomer release at different time points from specimens with different thicknesses fabricated from five commercially available 3D-printed permanent crown resins manufactured using additive manufacturing technology. Specimens with thicknesses of 2 mm and 4 mm were prepared from five 3D-printed permanent crown resins [BEGO VarseoSmile Crown plus (BVS), NextDent C&B MFH (ND), Formlabs Permanent Crown Resin (FL), Saremco print CROWNTEC (SC), DentaFab PowerResins C&B (DF)] and from GC Cerasmart270 as a reference material (24 groups, n=8). The specimens were stored in a 75% ethanol/water solution for 1 week and 1 month. The elution of triethylene glycol dimethacrylate (TEGDMA), urethane dimethacrylate (UDMA), bisphenol A-glycidyl methacrylate (Bis-GMA) and 2-hydroxyethyl methacrylate (HEMA) was analyzed using high-performance liquid chromatography. Higher monomer release was observed for Bis-GMA and TEGDMA, particularly in the BEGO group. Increased specimen thickness was associated with higher TEGDMA release in the BVS group and higher Bis-GMA and TEGDMA release in the ND group. Prolonged storage duration generally increased Bis-GMA and TEGDMA release levels, particularly in the BVS, SC, and DF groups. Thickness- and time-dependent increases in UDMA and HEMA release were also observed in certain groups. These findings suggest that residual monomer release may be influenced by material type, specimen thickness and storage duration under the present experimental conditions.