Stiffness and stress fluctuations in dental cement paste: a continuum micromechanics approach

• Published in: Mechanics of advanced materials and structures 2023-06, Vol.30 (16), p.3332-3350
• Main Authors: Dohnalík, Petr, Hellmich, Christian, Richard, Gilles, Pichler, Bernhard L. A.
• Format: Article
• Language: English
• Subjects: Calcite; Cement paste; continuum micromechanics; Crystal defects; Dental cement; dental cement paste; Grain boundaries; Hydrates; lognormal microelasticity model; Mechanical properties; Microcracks; Micromechanics; Nanoindentation; piecewise uniform microelasticity model; Poisson's ratio; Stiffness; stiffness fluctuations; Stiffness homogenization; stress fluctuations
• ISSN: 1537-6494; 1537-6532
• DOI: 10.1080/15376494.2022.2073493

Calcite-reinforced hydrates provide the superior mechanical properties of Biodentine, a cementitious material used in dentistry. Herein, a self-consistent micromechanics model links two nanoindentation-probed, lognormally distributed microstiffness distributions of infinitely many hydrate phases, to the material's macrostiffness, quantified from longitudinal and transverse ultrasonic wave transmission experiments. Thereby, the model provides values for the Poisson's ratio of the hydrates and for a microcrack density reflecting grain boundary defects. Moreover, the model-predicted hydrate microstresses turn out as beta-distributed, while the overall stiffness can be equally well upscaled from only two, piecewise uniform, hydrate phases exhibiting median microstiffness values. Highlights Grid nanoindentation provides lognormal distributions of hydrate stiffness They enter a microelastic model for dental cement paste This model considers grain boundary defects as isotropically-oriented closed cracks It provides micro-stress fluctuations resulting from hydrate stiffness distributions Median values of hydrate stiffness govern the overall paste stiffness