MgHDT500 was synthesized by heating magnesium (Mg)-aluminum (Al) hydrotalcite (HDT), a highly adsorptive layered and microporous compound, at 500 ℃, and ZnHDT was synthesized by substituting Mg with zinc (Zn). Using obligate anaerobic bacterial cultures (Fusobacterium nucleatum ATCC25586 (F. nucleatum), Porphyromonas gingivalis ATCC33277, Prevotella intermedia ATCC25611, and Streptococcus mutans ATCC25175), the concentrations of H2S in mixtures with various HDTs were measured by gas chromatography to examine their inhibitory effects on H2S production and their antibacterial effects on the growth of F. nucleatum. Numerical data were statistically analyzed using one-way ANOVA and Fisher’s PLSD test (α＝0.05). As a result, H2S was produced in all bacterial cultures, as determined using H2S concentrations for each test culture, with the highest H2S production with F. nucleatum. The H2S concentration changes in the F. nucleatum cultures mixed with various HDTs demonstrated that no H2S was detected at 2 hours for ZnHDT. The effects of various HDTs on the growth of F. nucleatum was examined, demonstrating a reduction in colony-forming units with ZnHDT. Thus, the significantly reduced concentrations of H2S produced by F. nucleatum were caused by the sulfide adsorption and antibacterial effects of ZnHDT.
ISO is an independent international non-governmental organization, founded in Geneva, Switzerland in 1947. TC 106 (Dentistry) is in charge of the dental material instrument standards, as the ISO document is prepared by the Technical Committee (TC). The creation of ISO standards at TC 106 in Japan involves the Japan Research Council on Dental Products, which conducts domestic committee services entrusted to it by the Japanese Industrial Standards Committee. There are four types of ISO documents：International Standards, Technical Specifications, Technical Reports, and Publicly Available Specification, and work is carried out according to the procedures described in “ISO/IEC Directives” regarding the preparation of each document. Many countries operate with national interests, and Japan needs to acquire as many chairpersons and convenors as possible. Since it is highly specialized work and requires much experience, the recruitment of young persons is essential.
The most typical international standardization organizations for medical devices might be International Organization for Standardization (ISO) and the American Society for Testing and Materials (ASTM International). The author is responsible to report the activities of ISO/TC 150 (Implants for Surgery) in asking the supports and understanding for the relationship between standards and regulation, as Chairman of the Japanese Committee for ISO/TC 150.There are six working groups (WG) under TC 150, and seven sub-committees (SC). Among them, WG 14 (Models of tissues for mechanical testing of implants) and SC 7 (Tissue engineered medical products) were established by Japanese proposal and the chairman and secretariat of them were selected from Japan.One of the recent movements is continuous discussions to seek directions determine the standard values so as to be the minimum safety requirements for the regulation.