Combustion synthesis of nanostructured calcium silicates: A new approach to develop bioceramic cements in endodontics.

Calcium silicate is widely used in endodontics because its bioactivity precedes tissue regeneration. The synthesis of pure compounds is challenging, especially for the C 3 S phase (3CaO·SiO 2) because, despite the use of pure phases to understand the phenomena involved in the fresh and hardened states, its isolated production requires specific conditions. Synthesis by combustion is an alternative method for obtaining improved endodontic cements. This study presents an alternative method for obtaining C3S-based nanostructured cements with the smallest possible amounts of polymorphs and CaO. To obtain the powders, citric acid was used as the fuel, and tetraethylorthosilicate was used as the silica precursor. In addition, two calcium precursors—calcium carbonate and calcium nitrate—were evaluated as oxidizers. Different parameters were investigated, including combustion temperatures (400 and 600 °C), equivalence ratios (χ) (citrate/nitrate) of 3, 5, and 7, type of oxidizer, and heat treatment temperatures (800, 1000, and 1200 °C). The thermal and structural properties, functional groups, and surface area were evaluated. The results indicate that at the combustion temperature of 600 °C, followed by heat treatment at 1000 °C with an equivalence ratio (χ) of 7, it is possible to obtain a nanostructured cement based on the M3 polymorph of C3S with 23.62 nm. The obtained material shows potential for application in endodontics because of its highly reactive and bioactive behavior. [ABSTRACT FROM AUTHOR]