Mesoporous Silicate Nanoparticles With Phosphates Regulate Calcium Silicate Cement Hydration

Objectives: Although porous calcium silicate cement (CSC) synthesized via sol-gel method demonstrated much faster setting time if compared to that of mineral trioxide aggregate, the loosening microstructure of CSC, causing by fast hydration, limited its applications in dental treatment. Mesoporous silicate nanoparticles carried with phosphates (PO₄@MSN) may regulate hydration behaviors of CSC by releasing calcium, silicate and phosphates ions during hydration to reinforce the microstructure of hydrated products. The purpose of this study is to investigate the effects of PO₄@MSN on CSC hydration behavior.
Methods: Sol-gel CSC powders were mixed with MSN and PO₄@MSN in weight of 0%, 2% and 10%, respectively, and then mixed with distilled water for hydration at 37°C, 100% humidity for 1 day and 7 days. The hydrated products were investigated using XRD, FTIR and SEM analysis.
Results: The results of XRD demonstrated that both MSN and PO₄@MSN as additives inhibited the formation of Ca(OH)₂ during hydration. Compared to other groups, more shifting to high wave number of SiO^-4 stretching was observed in PO₄@MSN group, indicating more calcium-silicate hydrates (CSH) formation. In addition, PO₄^-3 stretching was only observed in PO₄@MSN group, implying the formation of new hydrated products with calcium phosphate. Unlike the porous structure of hydrated CSC, CSC with MSN and PO₄@MSN presented more packed microstructure with less pores.
Conclusions: The additives of MSN and PO₄@MSN affected the hydration of CSC to form a more packed microstructure via enhancing CSH formation and inhibiting the production of byproducts.