COMPARING THE MECHANICAL PROPERTIES OF CONVENTIONAL, MILLED, AND 3D-PRINTED OCCLUSAL SPLINT MATERIALS: AN IN VITRO STUDY

Aim: Evidence on the mechanical properties of digitally manufactured occlusal splint materials remains scarce. The aim of this study was to evaluate and compare the mechanical properties of CAD/CAM fabricated occlusal splint materials versus conventionally heat-cured acrylic resin materials. Materials and Methods: A total of 100 specimens were manufactured for the present study. One CAD-CAM milled (ProArt CAD Splint), one heat-polymerized (SR IVOcap Clear), and three 3D-Printed (KeySplint Hard, NightGuard Firm2 and RoDIN Splint 2.0) resin materials were evaluated. Flexural strength, flexural modulus and surface hardness were measured. The three-point flexure test was used for the determination of flexural strength and modulus values, while Vickers hardness and Shore D hardness were measured to determine surface hardness. Twenty specimens (n = 20) of each material were tested using these procedures. Results were analyzed using analysis of variance (ANOVA) followed by Tukey’s post-hoc test. Results are presented as mean±SD and p-values less than 0.05 were considered statistically significant. Results: The values of flexural strength ranged from 9.8 ± 7.0 MPa to 121.0 ± 3.0 MPa. The values of flexural modulus ranged from 0.2 ± 0.2 GPa to 3.0 ± 0.2 GPa. The Vickers hardness values ranged from 10.1 ± 0.4 VHN to 22.9 ± 1.0 VHN, while the values of Shore D hardness ranged from 55.3 ± 0.5 HD to 95 ± 0 HD. Significant differences were found among the tested materials for flexural strength, flexural modulus and surface hardness (p < 0.0001). Conclusion: There are differences in the mechanical properties of the various tested occlusal splint materials. 3D-printed resins demonstrated adequate mechanical performance for occlusal splints when compared to conventional and milled PMMA, with the exception of surface hardness.