Biomaterials used in dental treatments are expected to have favorable properties such as biocompatibility and an ability to induce tissue formation in dental pulp and periapical tissue, as well as sealing to block external stimuli. Bioactive glasses have been applied in bone engineering, but rarely applied in the field of dentistry. In the present study, bioactive glass cement for dental treatment was developed, and then its physicochemical properties and effects on cell responses were analyzed. To clarify the physicochemical attributes of the cement, field emission scanning electron microscopy, X-ray diffraction, and pH measurement were carried out. Cell attachment, morphology, and viability to the cement were also examined to clarify the effects of the cement on odontoblast-like cells (KN-3 cells), osteoblastic cells (MC3T3-E1 cells), human periodontal ligament stem/progenitor cells and neuro-differentiative cells (PC-12 cells). Hydroxyapatite-like precipitation was formed on the surface of the hardened cement and the pH level changed from pH10 to pH9, then stabilized in simulate body fluid. The cement had no cytotxic effects on these cells, and particulary induced process elongation of PC-12 cells. Our results suggest that the newly developed bioactive glass cement have capability of the application in dental procedures as bioactive cement.

Introduction: Dentinogenesis is regulated by cytokines and growth factors, and modulated by alterations in the extracellular microenvironment. Dental matrix protein-1 (DMP-1), which is predominantly expressed in odontoblasts, is required during the early and late stages of odontogenesis. In the present study, we examined the involvement of proinflammatory cytokines in the expression of odontogenic markers in the rat odontoblast-like cell line KN-3. Methods: The expression of DMP-1 and p38 mitogen-activated protein kinase (MAPK) in proinflammatory cytokine-treated KN-3 cells was evaluated by immunoblot analysis. Alkaline phosphatase (ALP) activity in proinflammatory cytokine-treated KN-3 cells was measured by ALP staining and a colorimetric assay. Results: DMP-1 protein was downregulated in KN-3 cells treated with interferon-γ (IFN-γ) for 3 days, but not in interleukin-1β (IL-1β)-treated cells. The IFN-γ-induced downregulation of DMP-1 was rescued by treatment with IL-1β for 3 days. Interestingly, ALP activity was also suppressed in IFN-γtreated KN-3 cells and no significant change was induced by IL-1β treatment for 5 days. In addition, IFN-γ treatment for 3 days remarkably upregulated the phosphorylation of p38 MAPK in KN-3 cells. Conclusions: INF-γ treatment downregulated DMP-1 expression and ALP activity in KN-3 cells through prolonged phosphorylated p38 MAPK. IL-1β treatment restored these odontogenic reactions mediated by IFN-γ. Taken together, these findings suggest that IFN-γ and IL-β may be involved in the complex regulation of odontogenesis in the microenvironment of dental pulp. Rec.3/18/2015, Acc.5/24/2015, pp210-217