Fluoride release kinetic from dental restorative materials affects Dental Pulp Stem Cells behavior

Fluoride-releasing restorative dental materials can be beneficial to remineralize dentin and help prevent secondary caries. However, commercialized fluoride-restorative materials (F-RMs) exhibit a non-constant rate of fluoride release depending mainly on the material composition and fluoride content. Here we investigate whether different fluoride release kinetics from new dental resins could influence the behavior of human dental pulp stem cells (hDPSCs). The innovation consists in using as dental composites fillers modified hydrotalcite intercalated with fluoride ions (LDH-F). The fillers were prepared via ion exchange procedure and the LDH-F inorganic particles (0.7, 5, 10, 20 wt.%) were mixed in a commercial light-activated restorative material (RK), provided by Kerr s.r.l. (Italy) to obtain the final resins (RK-F). The physical-chemical characteristics, the release profile and the biological effect on proliferation of hDPSCs of RK-F 0.7, 5, 10 were analyzed. Since RK-F10 and a commercial fluoride-glass filler (RK-FG10) contain the same concentration of fluoride, RK-F10 was chosen to investigate the regenerative capability induced by fluoride-controlled release. To evaluate the difference between RK-F10 and RK-FG10 in inducing cellular migration and differentiation, it was isolated the human dental pulp stem cell subpopulation (STRO-1 positive cells) known for its ability to differentiate towards an odontoblast-like phenotype. The release of fluoride ions was determined in physiological medium and artificial saliva medium using an ion chromatograph. The cell migration assay was performed in presence of transforming growth factor β1 (TGF-β1) and stromal cell-derived factor-1 (SDF-1) using a modified Boyden Chamber method on STRO-1+ cells cultured for 7 days on RK, RK-F10 and RK-FG10 materials. The expression patterns of dentin sialoprotein (dspp), dentin matrix protein 1 (dmp1), osteocalcin (ocn), and matrix extracellular phosphoglycoprotein (mepe) were assessed by quantitative RT-PCR. The incorporation of ...