Effects of storage and toothbrush simulation on Martens hardness of CAD/CAM, hand-cast, thermoforming, and 3D-printed splint materials

Clin Oral Investig. 2023 Nov 13. doi: 10.1007/s00784-023-05378-4. Online ahead of print.

ABSTRACT

OBJECTIVES: To investigate Martens hardness parameters of splint materials after storage in liquids and toothbrush simulation.

MATERIALS AND METHODS: Ten specimens per material and group were fabricated (hand-cast CAST, thermoformed TF, CAD/CAM-milled CAM, 3D-printed PS, PL, PK, PV), stored in air, water, coffee, red wine, and cleaning tablets and investigated after fabrication, 24 h, 2- and 4-week storage or toothbrushing. Martens hardness (HM), indentation hardness (H_IT), indentation modulus (E_IT), the elastic part of indentation work (η_IT), and indentation creep (C_IT) were calculated (ISO 14577-1).

STATISTICS: ANOVA, Bonferroni post hoc test, between-subjects effects, Pearson correlation (α = 0.05).

RESULTS: HM varied between 30.8 N/mm² for PS (water 4 weeks) and 164.0 N/mm² for CAM (toothbrush). H_IT values between 34.9 N/mm² for PS (water 4 weeks) and 238.9 N/mm² for CAM (toothbrush) were found. E_IT varied between 4.3 kN/mm² for CAM (toothbrush) and 1.8 kN/mm² for PK (water 2 weeks). η_IT was found to vary between 16.9% for PS (water 4 weeks) and 42.8% for PL (toothbrush). C_IT varied between 2.5% for PL (toothbrush) and 11.4% for PS (water 4 weeks). The highest impact was identified for the material (p ≤ 0.001).

CONCLUSIONS: Storage and toothbrushing influenced Martens parameters. The properties of splints can be influenced by the choice of materials, based on different elastic and viscoelastic parameters. High HM and E_IT and low C_IT might be beneficial for splint applications.

CLINICAL RELEVANCE: Martens parameters HM, E_IT, and C_IT might help to evaluate clinically relevant splint properties such as hardness, elasticity, and creep.

PMID:37957307 | DOI:10.1007/s00784-023-05378-4