# The Impact of Calcination on the Structure, Bioactivity, and Biocompatibility of Sol–Gel-Derived Glasses

## TL;DR

This study examines how calcination affects the properties of sol-gel-derived bioactive glasses and their potential for biomedical applications.

## Contribution

The novel contribution is the synthesis and evaluation of bioactive glasses with and without calcination for biomedical use.

## Key findings

- Calcination induced crystalline calcite formation and reduced specific surface area from 62 to 32 m² g⁻¹.
- Both samples formed hydroxyapatite layers and showed good bioactivity and cell proliferation in HaCaT keratinocytes.
- A toothpaste with calcined bioactive glass showed effective dentin hypersensitivity treatment and remineralization.

## Abstract

Bioactive glasses
(BG) are promising materials for bone tissue
engineering due to their bonding ability to biological tissues. In
this study, a BG was synthesized via a modified sol–gel method
that incorporated fumed silica. Two thermal treatments were applied:
stabilization at 36.5 °C and calcination at 700 °C. X-ray
diffraction analysis revealed the amorphous nature of BG stabilized
at 36.5 °C, while calcination induced the formation of crystalline
calcite. Nitrogen adsorption–desorption analysis revealed a
specific surface area of 62 m2 g–1 for
the stabilized BG, which decreased to 32 m2 g–1 after calcination. Thermogravimetric analysis indicated that the
calcined sample exhibited lower thermal stability than the stabilized
sample. Both BG samples exhibited the capacity to form a hydroxyapatite
layer upon immersion in a simulated body fluid for a period of 48
h, being corroborated by X-ray diffraction, FTIR, and scanning electron
microscopy. Additionally, cell viability assays with HaCaT keratinocytes
showed enhanced cell proliferation compared to the control at 1, 4,
and 7 days. A toothpaste containing 3 w/w% BG was also formulated
with the calcinated sample and tested for dentin hypersensitivity,
showing promising dentinal tubule occlusion, remineralization potential,
and cytocompatibility. These results indicate that both samples prepared
retains excellent surface properties, bioactivity, and cytocompatibility,
even without high-temperature processing, highlighting its potential
for biomedical applications.