Comparison of flexural properties and cytotoxicity of interim materials printed from mono-LCD and DLP 3D printers

Because few 3D-printing resins have been specifically developed for liquid crystal display (LCD) 3D printers, mono-LCD users may use digital light processing (DLP) 3D-printing resins. However, the suitability of these resins requires evaluation.The purpose of this in vitro study was to evaluate whether 3D-printing resins designed for DLP 3D printers can be used successfully in a mono-LCD 3D printer.3D printers based on photopolymerization and 3D-printing resin for interim restorations were used in this study. Enlighten AA temp and NextDent C&B MFH were printed from both the MiiCraft Ultra 125 and Phrozen Sonic printers, followed by postpolymerization by using the FormCure and PhrozenCure units for different times. The flexural strength and cytotoxicity of the specimens were evaluated.After postpolymerization treatment, the flexural strength of Enlighten AA temp and NextDent C&B MFH from both 3D printers was over the 50-MPa minimal requirement for the flexural strength of interim resins specified in the International Standards Organization (ISO) 10477 standard. With 15 minutes of FormCure and 1 minute of PhrozenCure postpolymerization, 4 material-printer combinations reached nearly 100% in cell viability.Interim resins designed for DLP 3D printers can be successfully used in mono-LCD 3D printers if the printed specimens are postpolymerized in a more powerful postpolymerization unit or in a less powerful postpolymerization unit for a longer time.