Comparison of the physico-mechanical properties of 3D-printed resins used as permanent indirect restoration materials

Aim: The aim of this study is to compare the physico-mechanical properties (microhardness, surface roughness, and flexural strength) of permanent 3D-printed dental resins with those of a resin nanoceramic CAD/CAM block and a composite resin Material and Method: Four different material groups were included in the study: a composite resin (Clearfil Majesty Esthetic), a resin nanoceramic CAD/CAM block (Cerasmart), and two 3D-printed resins (Saremco Print Crowntec and Varseo Smile Crown Plus). The specimens were prepared in disk form (10 mm in diameter and 2 mm in thickness) for microhardness and surface roughness tests, and in dimensions of 2 × 2 × 25 mm in accordance with ISO 4049 standards for the flexural strength test. Composite specimens were fabricated using Teflon molds and polymerized with an LED light-curing unit. Specimens of the 3D-printed resins were digitally designed and exported in .STL format, then sliced using Chitubox software and printed with a Sonic Mini 8K printer. Specimens from the CAD/CAM block were designed using Exocad software and fabricated with a 5-axis milling machine. Microhardness measurements were performed using the Vickers test at three different points on each specimen. Surface roughness values were measured three times with an optical profilometer and recorded as Ra values. Flexural strength was evaluated using the three-point bending test on a universal testing machine. Statistical analysis was performed using one-way analysis of variance (ANOVA) and Tukey's post hoc tests. Results: Cerasmart exhibited the highest microhardness (85.53 ± 3.97) and flexural strength (184.45 ± 9.42) values, whereas Saremco Crowntec showed the lowest microhardness value (38.63 ± 2.14). Clearfil Majesty demonstrated the highest surface roughness value (1.24 ± 0.35). All materials, except for the composite resin, exhibited flexural strength values above the threshold specified in ISO 4049. Conclusions: 3D-printed resins exhibited clinically acceptable physico-mechanical properties. Their performance in terms of flexural strength and surface roughness was comparable to, or in some cases superior to, that of conventional materials; however, their microhardness values remained lower than those of CAD/CAM blocks. Keywords: 3D printing, dental resin, CAD/CAM, microhardness, surface roughness, flexural strength