An In-Vitro Evaluation of Strength, Hardness, and Color Stability of Heat-Polymerized and 3D-Printed Denture Base...

This study evaluated the strength, hardness, and color stability of 3D-printed denture base resins and compared the outcome with conventional heat-cured denture base resins after aging by thermocycling. A total of 72 specimens from conventional and 3D-printed materials were fabricated in different shapes and dimensions based on the mechanical and color tests performed. The specimens were divided into five groups: flexural, tensile, and compressive strengths (n = 20), hardness, and color stability (n = 6). In all these groups, half of the specimens were stored in a distilled water bath at 37 °C for 24 h, and the remaining half of the specimens were subjected to aging by thermocycling. The 3D-printed specimens demonstrated the highest means of tensile strength (32.20 ± 3.8 MPa), compressive strength (106.31 ± 4.07 MPa), and Vickers hardness number (24.51 ± 0.36), and the lowest means of flexural strength (54.29 ± 13.17 MPa) and color difference (ΔE = 2.18 ± 1.09). Conventional heat-cured specimens demonstrated the highest means of flexural strength (59.96 ± 8.39 MPa) and color difference (ΔE = 4.74 ± 2.37) and the lowest means of tensile strength (32.17 ± 9.06 MPa), compressive strength (46.05 ± 4.98 MPa), and Vickers hardness number (10.42 ± 1.05). Aging significantly reduced the flexural strength (-27%), tensile strength (-44%), and hardness (-7%) of 3D-printed resins in contrast to the conventional resin's compressive strength (-15%) and color stability (p < 0.05). The 3D-printed resin had comparable flexural and tensile strength and significantly superior compressive strength, hardness, and color stability compared with conventional resins. Aging significantly and negatively affected the flexural strength, tensile strength, and hardness of 3D-printed resin.