Evaluation of the mechanical and the physical properties for resin 3D printed material and machinable composite

Abstract

OBJECTIVES: This in vitro study assessed the mechanical and physical properties of various 3D-printed resin materials and a machinable hybrid resin. MATERIALS AND METHODS: Eight 3D printing resin materials were selected for evaluation: Pac-Dent Rodin Sculpture 2.0 (RS), Pac-Dent Rodin Titan (RT), BEGO VarseoSmile Crown Plus (BVS), Desktop Health Flexcera Smile Ultra Plus (DHF), SprintRay OnX tough 2 (SROnX), SprintRay Ceramic Crown (SCC), Saremco Crowntec (SC), GC Dental Cerasmart Universal 270 (CS). These materials were tested to evaluate their flexural strength, flexural modulus, biaxial flexural strength, thermocycling, fatigue, fracture toughness, and wear resistance. The specimens still intact after thermocycling and fatigue were subjected to a biaxial flexural strength test. A DLP 3D printer, Asiga Max, was used to print 12 specimens from each printable material to determine three-point flexural strength, biaxial flexural strength, and fracture toughness using a single-edge V-notched beam. and wear resistance was measured using a pin on plate two-body system. The pins acted as test material, and VitaMKII was used as the tooth analog plate material. For the machinable block, bar specimens were prepared by sectioning with an Isomet 5000 diamond saw. A core drill press was also used to prepare pins of the specimens for wear resistance testing and discs for biaxial flexural strength, thermocycling, and fatigue tests. The filler weight percentage of each material was determined using the ash-burning method. The microstructure of a wear rod from each material was examined under a scanning electron microscope (SEM), and the elemental composition was investigated by Energy Dispersive Spectroscopy (EDS). To compare means, a one-way ANOVA (α=0.05) with Tukey's HSD posthoc tests was performed using Excel 365 and JMP Pro 17. RESULTS: Utilizing the three-point method, the flexural strength test results reveal significant differences among the materials tested. The flexural modulus also exhibited significant differences, with the highest to the lowest average observed in CS, RS, SCC, SC, RT, BVS, SROnX and DHF, measuring 8.23, 8.20, 7.33, 6.70, 6.63, 5.65, 4.84 and 4.47 GPa, respectively. The resin materials with the highest biaxial flexural strength were DHF, which demonstrated the highest mean value of 236.89 MPa, followed by CS 229.13 MPa and SROnX 216.85 MPa, with no significant distinction. CS exhibited the highest biaxial flexural strength at 205.52 MPa, while BVS demonstrated the lowest at 117.29 MPa. The thermocycling test presented no significant differences in strength between SROnX, DHF, CS, SC, and SCC. In contrast, BVS displayed the statistically lowest biaxial flexural strength. The fracture toughness test presented no significant differences between CS, RT, and SCC, with values of 3.18, 2.74, and 2.63 MPa·m^0.5, respectively, exceeding the remaining materials. In the wear test, SC showed the least weight loss of 0.0025 g, and SC exhibited the smallest height reduction of 0.040 mm after undergoing the same number of cycles. In contrast, SROnX experienced the highest weight loss of 0.0051 g and height reduction of 0.091mm after 200k cycles. CONCLUSION: The study results demonstrate significant differences in the mechanical properties of 3D-printed resin materials compared to machined hybrid resin materials. These properties included flexural strength, flexural modulus fracture toughness, wear resistance, biaxial flexural strength before and after thermocycling, and cyclic fatigue.