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Background Enamel matrix derivative (EMD) is widely used for regeneration therapy in dental clinical situations, but the mechanism of EMD bioactivity remains obscure. To clarify this mechanism, we focused on the formation of connective tissue and blood vessels. The aim of this study was to confirm whether EMD induces the formation of connective tissue and blood vessels by using the diffusion chamber (DC) technique. Materials and methods Individual DCs containing EMD (DC-EMD) or propylene glycol alginate (PGA) were implanted subcutaneously in rat dorsum. At 4 weeks after the implantation, histological analysis of DCs was performed using azan staining. Results DC-EMD induced the formation of much larger amounts of connective tissue containing abundant blood vessels than did DC-PGA. Conclusion The results indicated that EMD can induce the formation of both connective tissue and blood vessels. This bioactivity may contribute to the mechanism whereby EMD induces tissue regeneration.

Background/Aim: Enterococcus faecalis is responsible for most cases of endodontic treatment failure. Despite various conventional disinfection methods, root canals are not completely free of microorganisms. Photodynamic therapy (PDT) is a new antimicrobial strategy that involves the use of a non-toxic photosensitizer (PS) and a light source. The aim of this study was to evaluate the antimicrobial effect of PDT using diode laser and pyoktanin blue (PB) and confirm the nontoxicity of PB as a PS. Materials and Methods: Laser irradiation with an output power of 3 W was performed with PB as the PS to a bacterial solution containing E. faecalis. Then, the number of colony-forming units was counted. PB cytotoxicity was also assessed by the MTT assay. Results: E. faecalis counts were reduced after laser irradiation, laser irradiation with PB, or the combination thereof compared to the control, non-irradiation or water. The 50% cytotoxic concentration value for adult human dermal fibroblasts incubated with PB for 1 min was 108 μg/ml. Conclusion: Diode laser irradiation in combination with PB as the PS is efficacious for the elimination of E. faecalis without toxic effects to human dermal fibroblasts. This strategy might be useful for root canal irrigants.