A rapid-setting and bioactive sealer based on PSC bioactive glass and tristrontium silicate for root canal filling

Root canal sealers play a crucial role in maintaining intraradicular asepsis by filling microscopic gaps and complex irregularities between the gutta-percha and canal walls, thus ensuring successful endodontic therapy. However, current root canal sealers suffer from slow setting rate and poor bioactivity, increasing the risk of reinfection and treatment failure. Herein, we develop a rapid-setting and bioactive sealer, with tristrontium silicate, bioactive glass and zirconium dioxide powder and phosphate solution as the solid and liquid phases, respectively. Upon mixing, the resultant injectable paste exhibits a fast setting time (42 ± 5 min), while possessing superior flowability (20.0 ± 0.1 mm), low solubility (2.9 ± 0.2%), appropriate film thickness (46.9 ± 0.3 µm) and adequate radiopacity (>3 mm Al equivalent), complying with ISO 6876:2012. Moreover, the developed sealer displays rapid generation of hydroxyapatite and sustained release of Sr²⁺ ions, while maintaining neutral pH under physiological conditions, contributing to its biocompatibility and antibacterial activity. Notably, the rapid-setting and bioactive sealer achieves improved in vitro dye resistance in a dentin-disc model over time, indicating excellent sealing ability, which is desirable for clinical applications.