A Novel Bioactive Endodontic Sealer Containing Surface-Reaction-Type Prereacted Glass-Ionomer Filler Induces Osteoblast Differentiation

Abstract

Surface-reaction-type prereacted glass-ionomer (S-PRG) fillers exhibit bioactive properties by the release of multiple ions. This study examined whether a novel endodontic sealer containing S-PRG fillers (PRG+) has the capacity to induce osteoblast differentiation. Kusa-A1 osteoblastic cells were cultured with extracts of PRG+, PRG− (an experimental sealer containing S-PRG-free silica fillers), AH Plus (an epoxy-resin-based sealer), and Canals N (a zinc-oxide noneugenol sealer). Cell viability and mineralized nodule formation were determined using WST-8 assay and Alizarin red staining, respectively. Osteoblastic-marker expression was analyzed with RT-qPCR and immunofluorescence. Phosphorylation of extracellular signal-regulated kinase (ERK) and p38 mitogen-activated protein kinase (MAPK) was determined with Western blotting. Extracts of freshly mixed PRG+, PRG−, and AH Plus significantly decreased cell growth, but extracts of the set samples were not significantly cytotoxic. Set PRG+ significantly upregulated mRNAs for alkaline phosphatase and bone sialoprotein (IBSP) compared to set PRG−, and upregulation was blocked by NPS2143, a calcium-sensing receptor antagonist. Set PRG+ significantly accelerated IBSP expression, mineralized nodule formation, and enhanced the phosphorylation of ERK and p38 compared with set PRG−. In conclusion, PRG+ induced the differentiation and mineralization of Kusa-A1 cells via the calcium-sensing receptor-induced activation of ERK and p38 MAPK.