Improvement of the biological performance of filling materials for primary teeth after pulpectomy by incorporating Ca-polyP microparticles

Polyphosphate is incorporated into Calcium Hydroxide to prepare a modified paste (CH-PP-I). • CH-PP-I exhibits sustained ion release properties (Ca 2+ , OH - ). • CH-PP-I has less volume loss compared to Vitapex. • CH-PP-I has better antimicrobial activity and a lower degradation rate than CH-I and Vitapex. • CH-PP-I can be a promising filling paste for primary teeth. Objectives Calcium Hydroxide/Iodoform pastes (CH-I) are used for pulpectomy in primary teeth. To alleviate the rapid degradation of CH-I, polyphosphate (poly P) was incorporated with CH to form a modified paste (CH-PP-I), which was evaluated against CH-I and a commercial paste (Vitapex®). Methods Vitapex, CH-I and CH-PP-I were compared for injectability, viscosity, pH, Ca 2 + release and solubility. Antimicrobial properties of the pastes were tested using Enterococcus faecalis (E. faecalis). Their effects on human periodontal ligament cells (hPDLCs) were explored using CCK-8, Edu and TUNEL assays. Their impact on osteogenic and osteoclastic differentiation was detected on dental follicle stem cells (DFSCs) and bone marrow mononuclear cells (BMMs). The test materials were implanted subcutaneously to assess in vivo biocompatibility and degradation rates. Results CH-PP-I released calcium more slowly and consistently than CH-I. CH-PP-I showed superior bacteriostatic properties than Vitapex, similar to CH-I. CH-PP-I exhibited lower cytotoxicity on hPDLCs compared to Vitapex and CH-I, with cell proliferation and apoptosis barely affected. CH-PP-I also promoted osteogenic differentiation of DFSCs and inhibited osteoclast differentiation of BMMs. Subcutaneous implantation revealed moderate inflammation in CH-PP-I and CH-I groups, while severe inflammation in the Vitapex group on day 15. After 60 days, all groups showed mild to moderate inflammation, and CH-PP-I had the lowest degradation rate on day 90. Significance CH-PP-I exhibited more excellent antimicrobial activity and a lower degradation rate than CH-I and Vitapex, highlighting its potential as a promising filling paste for primary teeth.