Development and in vitro evaluation of porous calcium silicate fillers: A pilot study

This study aims to develop porous calcium silicate fillers with bioactive mineralization properties for dental applications. The fillers were synthesized via pre-sintering of nanosilica particles, followed by calcium infiltration into the porous silica matrix. For comparison, non-porous calcium silicate fillers were also prepared. The structural and morphological characteristics were analyzed using scanning electron microscopy (SEM), atomic force microscopy (AFM), and porosity estimation via nitrogen sorption/desorption isotherm measurements. The calcium ion release capacity was evaluated by monitoring pH changes in an immersion solution. Surface activity of the filler was assessed by examining surface changes following immersion in simulated body fluid (SBF). In vitro biological properties were investigated using rat KN-3 cells, focusing on cytotoxicity and mineralization potential, assessed via Alizarin Red S staining. The results revealed that the porous calcium silicate fillers exhibited an amorphous phase with an average pore diameter of 17.3 nm and BET surface area of 19.5 m 2 /g, attributed to the consolidated nanosilica structure. Immersion tests demonstrated a significant increase in pH (>9.5), indicating a substantial release of calcium ions. Hydroxyapatite-like precipitates formed on the filler surfaces after SBF exposure, confirming their bioactivity. Cytotoxicity evaluation indicated acceptable biocompatibility, while Alizarin Red S staining confirmed enhanced mineralization. These findings suggest that porous calcium silicate fillers hold promise for applications in dental pulp and dentin regeneration therapies.