Effects of food simulating solutions on the mechanical properties of different prostodontic framework materials

Objective: This study compared the mechanical and structural stability of high-performance polymers, 3Y-TZP zirconia, and metallic framework materials used in tooth- and implant-supported restorations after medium-term exposure to foodsimulating chemical environments. Method: Standardized specimens were conditioned at 37 °C for 60 days in food-simulating liquids (heptane, ethanol, citric acid, and distilled water). Leeb hardness (HL) was measured before and after conditioning. Dynamic mechanical analysis (single-cantilever bending at 37 °C) yielded storage modulus (E′), loss modulus (E″), and damping factor (tan δ). Surface/topographical changes were examined using scanning electron microscopy (SEM). Results: Baseline HL values were comparable across groups. Following exposure, titanium and milled Co-Cr exhibited minimal HL change, with no overt chemical attack on SEM. In laser-sintered Co-Cr, citric acid caused limited, shallow, selective attack within carbide-rich domains; in heptane, ethanol, and water, melt-pool traces and lack-of-fusion porosity largely persisted without notable deterioration. In high-performance polymers, ethanol (and to a lesser extent heptane) was associated with slight decreases in HL and E′ and a tendency toward increased tan δ; surface degradation remained limited. Overall, responses were material- and medium-specific, with small-to-moderate magnitude. Conclusion: All investigated framework materials demonstrated clinically acceptable stability after 60-day chemical aging. Where high exposure to foodsimulating solvents is anticipated, titanium or milled Co-Cr appear more stable options, while high-performance polymers remain viable with appropriate case selection and surface management. Keywords: prosthodontic framework materials, high-performance polymer, Leeb hardness, damping, dynamic mechanical analysis.