Comparative evaluation of mechanical and thermal properties of 3D-printed restorative polymers: Effects of resin...

This study evaluated how resin type, printer technology, and post-curing time influence the mechanical and thermal properties of 3D-printed polymers for dental restorations. Bar-shaped specimens were printed with digital light processing (DLP) and liquid crystal display (LCD) printers using provisional and long-term resins. The post-curing times tested were 5 and 30 min. Response variables (n = 10) included fracture toughness (K_IC, MPa√m), Knoop microhardness (kgf/mm²), and degree of C=C conversion (%DC). Thermal analyses were carried out via differential scanning calorimetry (DSC) and dynamic mechanical analysis (DMA). Data were analyzed via three-way ANOVA (α = 0.05). Compared with the long-term resin, the provisional resin generally presented a superior K_IC. The 30-min the post-curing time was linked to an increase in K_IC in most conditions. No differences in microhardness were detected across any group. The long-term resin generally had a greater DC, and the DC was greater for the 30-min post-curing time than for the 5-min time for the provisional resin printed by the DLP printer. Longer post-curing times resulted in more complete curing of the resins. DSC and DMA analyses revealed that the 30 min post-curing time enhanced the thermal stability of both provisional and long-term resins, indicating more homogeneous polymer network formation with reduced residual monomers. The printer type had a minor effect on the performance of the restorative polymers. In conclusion, the resin material is key for 3D-printed dental restoratives, and longer curing times improved their mechanical and thermal properties.