Comparative analysis of microhardness of polymeric materials for temporary restorations manufactured using different technologies

Objective. Comparative study of the surface hardness of polymer materials for temporary crowns, differing in composition and manufacturing technology, in a dry state and after exposure to an aqueous medium. Material and methods. 4 materials were studied: Huge PMMA (CAD/CAM), Dental Sand Pro (3D printing), Sinma-M (hot curing), Tempocor (cold curing). The disc-shaped samples were polished and kept in dry conditions or distilled water (37 °C, 7 days). The Vickers hardness was measured on a Duramin-20 microhardness tester (load 25 g, exposure 15 s). Statistical processing is the Student’s t-test. Results. In the dry state, all materials showed similar hardness (19—22 HV). The smallest decrease in hardness after water was observed in Huge PMMA (<7%) and Sinma-M (~3%). Dental Sand Pro showed a decrease of 12.4%. The maximum drop was in Tempocor (by 17%: from 19.72 to 16.37 HV). Microstructurally, Dental Sand Pro and Tempocor have pores and inhomogeneities. Conclusion. It is most stable in the aquatic environment of Huge PMMA (CAD/CAM). Sinma-M (hot polymerization) also demonstrates high stability. Dental Sand Pro 3D printing material requires optimization of post-polymerization modes. Tempocor (cold curing) is the least water-resistant, and its use for long-term temporary restoration is limited. Surface hardness is an informative criterion for preclinical assessment of the reliability of temporary restorations.