Facile synthesis and characterization of novel rapid-setting spherical sub-micron bioactive glasses cements and their biocompatibility in vitro

Dental pulp vitality is extremely important for the tooth viability, since it provides nutrition and forms the dentin. Bioactive glasses (BGs) may be promising materials for pulp repair due to their excellent abilities of rapidly bonding to bone and stimulating new bone growth. However, the unsatisfied handling property, low plasticity, and poor rapid-setting property of traditional BGs limit its application in vital pulp therapy. Spherical bioactive glasses (SBGs) exhibited higher osteogenesis and odontogenic differentiation than irregular BGs. This study focuses on the application of SBGs with rapid setting property for dental pulp repair. Here, SBGs with various compositions were successfully synthesized by a sol-gel process using dodecylamine (DDA) served as both a catalyst and a template. The maximum content of CaO in SBGs was about 15%. The non-bridge oxygen amounts of the Si[sbnd]O network and the apatite-forming ability increased with the content proportion of CaO and P₂O₅. Bioactive glass pulp capping materials (BGPCMs) were prepared by mixing the SBGs powders and the phosphate buffer solution (PBS). The K₃CaH(PO₄)₂ and hydroxyapatite (HA) formed between SBGs particles as soon as they were mixed with PBS solution. The compressive strengths of fully set BCPCM-2 molded were measured to be 31.76 ± 1.9577 MPa after setting for 24 h. The K₃CaH(PO₄)₂ and the low crystallinity HA phases at the initial stage of solidification transformed to crystalline HA for 3 days, and the compressive strength was still higher than 10 MPa. Additionally, SBG-2 with a designed molar composition of 35% SiO₂, 55% CaO and 10% P₂O₅ more promoted dental pulp cell proliferation, and could be potential pulp capping applications.