The use of an appropriate drill is vital for achieving clinically sufficient osseointegration. In the present study, we evaluated the clinical results for dental implants placed with a trephine bar compared with those for dental implants placed with a regular drill. A total of 40 dental implants (20 patients, 7 males and 13 females) were evaluated. The experimental group consisted of 20 dental implants placed using a trephine bar, and the control group consisted of 20 implants placed using a regular drill in accordance with commercial protocol.During clinical examination, the bone loss and gingival infection around the dental implants, mobility of the implants, and discomfort on chewing were scored and evaluated. No significant differences were found between the two groups. These results suggest that usage of the trephine bar does not influence the prognosis of postoperative dental implant placement.
Although research on regenerative medicine using iPS cells has markedly progressed, no culture medium meeting the objective of studies on cell differentiation using iPS cells has been developed. The establishment of the in vitro cell growth method and development of MEM and DMEM as cell culture media have facilitated the stable growth of many types of cultured cell. These culture media are of marked historical value in cell culture methods, and they are used for the cell differentiation of iPS and ES cells without modification as the standard media. There are only a few reports providing a basis for the essential amino acid contents of these culture media.To develop a new culture medium for cell differentiation, we started a basic investigation of the essential amino acid contents using mouse-derived ES-D3 cells which do not require feeder cells. Dulbecco's Modified Eagle Medium (DMEM) is normally used for ES-D3 cell culture. The essential amino acid content of DMEM is higher than that of Minimum Essential Medium (MEM). Of the 7 essential amino acid contained in MEM, the contents of 6 amino acids are lower than those of DMEM excluding L-arginine. Thus, we investigated the influence of the 6 essential amino acids excluding L-arginine by adding them individually to MEM, and the viability and differentiation rate of ES-D3 cells were investigated. The addition of L-glutamine improved the cell viability and differentiation rate. It was clarified that the accumulation of data on the differentiation of various cells is necessary to determine the appropriate essential amino acid contents, aiming at the preparation of culture media for regenerative medicine.
It is well-known that nitric oxide resulting from the reduction of salivary nitrate plays a beneficial antimicrobial role in the oral cavity. Recent genomic analysis of nitrate reductase-positive bacteria in the oral cavity revealed that certain bacterial species (members of Veillonella, Actinomyces, Rothia, Staphylococcus, Corynebacterium, etc.) have the capacity to reduce nitrate. One such species that was notable for its high reducing activity was Rothia mucilaginosa. Recent metagenomics studies have shown a strong correlation between the presence of oral Rothia spp. within oral subgingival bacterial communities and periodontal health. We hypothesize that this correlation results partly from the microbicidal efficacy of the nitrate-reducing system in Rothia. In this study, we evaluated the nitrate reduction abilities of three R. mucilaginosa strains individually using a chromogenic substrate method based on the Griess reaction and a NOx analyzer. We found that, intriguingly, the three strains exhibited different levels of nitrate-reducing activity. This is the first study to reveal the variation in nitrate-reducing capacity among individual oral R. mucilaginosa strains.
The carcinogenicity of indium and its compounds is of concern, and so the Ministry of Health, Labour and Welfare specified these as chemicals which may be carcinogenic to humans by ministerial ordinance. Many carcinogens act on DNA and cause mutation, leading to cancerization. Accordingly, mutagenicity is closely involved in carcinogenicity. We extracted each component from alloy powders of prototype indium-containing silver alloy, alloy for porcelain bonding, and gold-silver-palladium alloy, and investigated their mutagenicity using the umu-test, which is a mutagenicity screening method. This test method utilizes expression of the SOS genes which repair injured DNA in bacteria, and the mutagenicity of many chemicals can be detected, similarly to the Ames test. A positive reaction was detected in the prototype Ag-indium alloy, but the alloy for porcelain bonding and gold-silver-palladium alloy were negative. It was clarified that close investigation of metal indium and commercial indium alloys is necessary.