Resin materials for 3D-printing and milling of indirect restorations - Composition and leachables using an artificial...

Monomer leaching from resin-based restorations is a concern due to possible adverse effects on the oral environment. This study evaluated a validated artificial saliva model and a multi-instrument analytical workflow to characterize two liquid resins for 3D-printing, compare findings with manufacturers' SDSs, and determine leachable profiles from test specimens incubated in artificial saliva.

Liquid resins (Saremco print CROWNTEC, SCT; FREEPRINT® temp, FPT) were analyzed by UHPLC-HRMS and GC-MS. Disc-shaped specimens were 3D-printed and, as control, milled from Temp Premium Flexible (TPF) (n = 6). Samples were immersed in artificial saliva (surface area-to-volume ratio 1.2 cm²/mL, 37 °C). Aliquots were analyzed for methacrylate monomers and photoinitiators after 1 h, 24 h, 1 week, and 3 months using quantitative LC-MS/MS. Specimens incubated for 24 h and 3 months were further examined by untargeted UHPLC-HRMS.

SDSs identified BisEMA as the main methacrylate in both resins, confirmed by UHPLC-HRMS. FPT also contained nondisclosed UDMA. Targeted analysis showed significantly higher concentrations of leachables (P < 0.05) from FPT than SCT or TPF at all time points. Untargeted analysis supported this, revealing the greatest number of leachables in FPT incubations, with at least 67 putative compounds.

Most residual methacrylate monomers elute within 24 h after 3D-printing. However, untargeted results suggest different leaching dynamics for other substances, highlighting the importance of broader analytical approaches in assessing biocompatibility.