Effects of High-Calcium/Phosphorus Bioactive Glass on Human Dental Pulp Stem Cells and Interfacial Reactivity Observed by 31P Nuclear Magnetic Resonance

Introduction and aims This study aimed to evaluate the biocompatibility and regenerative potential of a novel bioactive glass with high calcium and phosphorus contents (HCaP-BG) in human dental pulp stem cells (hDPSCs), and to investigate the formation of apatite-like calcium phosphate on the bioactive glass surface using ³¹P solid-state magic-angle spinning nuclear magnetic resonance (NMR). Methods HCaP-BG was synthesized via the melt-quench method. Its effect on hDPSCs proliferation was assessed using a colourimetric cell viability assay (CCK-8), and cytotoxicity was evaluated using a lactate dehydrogenase assay. Cell morphology was observed using field-emission scanning electron microscope. Mineral deposition was examined using Alizarin Red S staining. Odontogenic differentiation was assessed by real-time quantitative PCR analysis of dentin matrix protein 1 expression. To evaluate interfacial reactivity, HCaP-BG was immersed in simulated body fluid for 21 days, followed by analysis via solid-state 31 P NMR spectroscopy. Results HCaP-BG demonstrated no significant effect on the proliferation of hDPSCs and exhibited no cytotoxicity. hDPSCs directly exposed to HCaP-BG maintained normal morphology. Alizarin Red S staining showed visible calcium deposits in the experimental group. Expression of dentin matrix protein 1 was significantly upregulated at days 14 and 21 following HCaP-BG exposure. Solid-state 31 P NMR analysis indicated the formation of amorphous calcium phosphate. Conclusions HCaP-BG demonstrated good biocompatibility and promoted the formation of a biomimetic layer primarily composed of amorphous calcium phosphate, with minor hydroxyapatite component. Clinical relevance HCaP-BG exhibited biocompatibility and modulation of hDPSC behaviour, indicating its potential for dentin repair.