Heat-assisted vat-polymerization and light irradiance impact on 3D-printed dental resin composites

To evaluate the influence of temperature and light irradiance on the accuracy and physicochemical properties of available 3D-printed resin composites for long-term dental restorations.

Three resin composites with distinct filler contents (PriZma BioCrown Diamond, VarseoSmile Crown Plus, and Saremco Crowntec) were printed using a DLP device with chamber heating. Specimens were fabricated using three temperatures (30, 35, and 40 °C) and four irradiances (5.0, 7.5, 10.0, and 12.5 mW/cm²). Resin viscosity, temperature during printing, degree of conversion, dimensional accuracy, flexural strength, flexural modulus, Martens hardness, and indentation modulus were assessed. Mixed-effects regression models were applied to quantify the contribution of each variable.

Increasing temperature reduced resin viscosity by up to 250% in the highest-filler resin (PBD). Chamber temperature did not significantly affect the degree of conversion before or after post-curing. Higher irradiance produced specimens closer to the designed dimensions and increased flexural modulus (R² = 87.4%). Flexural strength and surface hardness were unaffected by such parameters. Material-dependent responses were observed, with the highest-filler resin (PBD) showing the greatest impact on viscosity reduction and dimensional accuracy.

Increasing chamber temperature reduced resin viscosity and influenced the dimensional accuracy of the printed specimens, whereas higher light irradiance increased the flexural modulus. Optimizing irradiance and temperature during printing can be controlled to modulate viscosity, dimensional accuracy, and stiffness of 3D-printed resin composites.

Optimizing light irradiance and printing temperature during DLP printing enhances the dimensional accuracy and stiffness of resin composites intended for long-term dental restorations.