In vitro examination of fracture resistance of 3D-printed resin blocks in different diameters

The intraoral use of commercial printable polymers in dental patients is still a challenge due to the unknown physical properties of the materials. The present study aimed to comparably evaluate the maximum load and deflection values of three-dimensional-printed resin blocks in different diameters that can be used intraorally in dental patients. Forty-five cylindrical resin blocks in diameters of 2 mm (Group 1, n = 15), 3 mm (Group 2, n = 15), and 4 mm (Group 3, n = 15) and lengths of 20 mm were designed and printed. The samples were placed in the universal testing device to conduct the 3-point bending test. According to the Shapiro–Wilk normality test results, Kruskal–Wallis and Mann–Whitney U tests were performed for the statistical analysis. The level of statistical significance was accepted as P < 0.05. The values for the maximum load (N) and deflection (mm) in the study groups were 218.4 ± 31.9, 2.96 ± 0.86 in Group 3; 77.05 ± 61.5, 3.91 ± 0.92 in Group 2; and 19.67 ± 2.63, 4.06 ± 1.02 in Group 1, respectively. The mean values of maximum load for Group 3 were superior to Group 2 (P = 0.020) and Group 1 (P = 0.00). Group 2 revealed higher maximum load results than Group 1 (P = 0.003). The mean values of maximum deflection in Group 3 were lower compared to Group 2 (P = 0.014) and Group 1 (P = 005). The results of this in vitro study encourage the use of resin-printed intraoral appliances in place of conventional treatment modalities.