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

Abstract

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.