Application of Reactive Oxygen Species in Dental Treatment.

Reactive oxygen species (ROS) and free radicals, which have been implicated in inflammation, pain, carcinogenesis, and aging, are actually used in dental treatments such as tooth bleaching and composite resin polymerization. Recently, numerous studies have investigated the application of ROS in the medical and dental fields. In previous studies, ROS were generated intentionally through pathways such as photolysis, photocatalytic methods, and photodynamic therapy, which are used in the medical field to target cancer. In the field of dentistry, generated ROS are applied mainly for periodontal treatment and sterilization of the root canal, and its effectiveness as an antibacterial photodynamic therapy has been widely reported.. Given this background, the present article aimed to review the basic effects of ROS in dental medicine, especially endodontic therapy, and to discuss future applications of ROS.

Risk factors for abutment and implant fracture after loading.

PURPOSE: Implant component fractures are one of the most serious complications in implant treatment. With a better understanding of the risk factors for fracture in the preoperative, surgery, superstructure, and post-loading phases of implant treatment, low-risk treatment could reduce implant component fractures, leading to a better prognosis. The aim of this study was to clarify the risk factors for abutment and implant fractures that occur after loading, and to perform a retrospective, approximately 10-year follow-up study to explore the risk factors in each treatment phase. METHODS: Subjects were fitted with an implant prosthesis between January 2008 and December 2009. In total, 1,126 Ankylos implants in 430 patients were included for analysis. Binary logistic regression analysis was performed to extract factors related to non-fracture and fracture of the abutment or implant as a dependent variable. RESULTS: Gender (OR = 3.466, 95% CI 1.296-9.268, P = 0.013), gonial angle (OR = 3.420, 95% CI 1.308-8.945, P = 0.012), and splinting status of the superstructure (OR = 4.456, 95% CI 1.861-10.669, P = 0.001) were identified as significant risk factors. CONCLUSION: The risk of fracture is increased in males, especially those with a mandibular angle of less than 120° on panoramic radiographs, and those with a non-splinted superstructure.

Isolation and identification methods of Rothia species in oral cavities.

Rothia dentocariosa and Rothia mucilaginosa which are Gram-positive bacteria are part of the normal flora in the human oral cavity and pharynx. Furthermore, Rothia aeria, which was first isolated from air samples in the Russian space station Mir, is predicted to be an oral inhabitant. Immunocompromised patients are often infected by these organisms, leading to various systemic diseases. The involvement of these organisms in oral infections has attracted little attention, and their distribution in the oral cavity has not been fully clarified because of difficulties in accurately identifying these organisms. A suitable selective medium for oral Rothia species, including R. aeria, is necessary to assess the veritable prevalence of these organisms in the oral cavity. To examine the bacterial population in the oral cavity, a novel selective medium (ORSM) was developed for isolating oral Rothia species in this study. ORSM consists of tryptone, sodium gluconate, Lab-Lemco powder, sodium fluoride, neutral acriflavin, lincomycin, colistin, and agar. The average growth recovery of oral Rothia species on ORSM was 96.7% compared with that on BHI-Y agar. Growth of other representative oral bacteria, i.e. genera Streptococcus, Actinomyces, Neisseria, and Corynebacterium, was remarkably inhibited on the selective medium. PCR primers were designed based on partial sequences of the 16S rDNA genes of oral Rothia species. These primers reacted to each organism and did not react to other non-oral Rothia species or representative oral bacteria. These results indicated that these primers are useful for identifying oral Rothia species. A simple multiplex PCR procedure using these primers was a reliable method of identifying oral Rothia species. The proportion of oral Rothia species in saliva samples collected from 20 subjects was examined by culture method using ORSM. Rothia dentocariosa, Rothia mucilaginosa, and R. aeria accounted for 1.3%, 5.9%, and 0.8% of the total cultivable bacteria number on BHI-Y agar in the oral cavities of all subjects, respectively. It was indicated that among oral Rothia species, R. mucilaginosa is most predominant in the oral cavity of humans. A novel selective medium, ORSM, was useful for isolating each oral Rothia species.

Complete Genome Sequence of Rothia aeria Type Strain JCM 11412, Isolated from Air in the Russian Space Laboratory Mir.

Here, we present the complete genome sequence of Rothia aeria type strain JCM 11412, isolated from air in the Russian space laboratory Mir. Recently, there has been an increasing number of reports on infections caused by R. aeria The genomic information will enable researchers to identify the pathogenicity of this organism.

Complete Genome Sequence of Rothia mucilaginosa Strain NUM-Rm6536, Isolated from a Human Oral Cavity.

Here, we present the complete genome sequence of Rothia mucilaginosa NUM-Rm6536, a strain isolated from the tongue plaque of a healthy human adult. This strain is amenable to genetic manipulation by transformation and so provides a useful foundation for more detailed investigation of this species.

A selective medium for the isolation of Microbacterium species in oral cavities.

The genus Microbacterium has been isolated from the environment, dairy goods, and human clinical specimens. Although, in our previous studies, some Microbacterium species were infrequently detected in oral samples collected from humans, there is currently no report that these organisms, which are capable of causing serious systemic infections, were isolated from the human oral cavity. The aim of the present study was to develop a selective medium to isolate the representative Microbacterium species most frequently detected in human clinical specimens, and reveal the distribution of individual Microbacterium species in the oral cavity. The growth recoveries of representative Microbacterium species on the selective medium, designated as MSM, were sufficient. Moreover, the growth of other representative oral bacteria was markedly inhibited on the selective medium. The proportion of Microbacterium species in the saliva samples of 60 subjects, 20 of whom were removable denture wearers, was then examined. The proportion of these organisms was also examined in environmental samples obtained by swabbing 20 washstands. PCR primers were designed for representative Microbacterium species. The genus Microbacterium was detected in 45% of the saliva and denture plaque samples collected from the twenty removable denture wearers, but was absent in the saliva of the forty non-denture wearers. On the other hand, these organisms were detected in all environmental samples. The genus Microbacterium accounted for 0.00003%, 0.0001%, and 12.6% of the total cultivable bacteria number on the BHI medium in the saliva and denture plaque samples of removable denture wearers and in the environmental samples, respectively. The most predominant Microbacterium species in all positive samples was Microbacterium oxydans. These results indicated that the genus Microbacterium was not a part of the normal flora in the human oral cavity, except for subjects wearing dentures that were contaminated by the environment, and the selective medium, designated as MSM, was useful for isolating Microbacterium species, which are frequently encountered in human clinical specimens, from the various samples.

A selective medium for the isolation of Corynebacterium species in oral cavities.

Corynebacterium matruchotii is a microbial inhabitant in the oral cavity of humans and is associated with the formation of dental calculi. C. matruchotii forms highly specific morphological units, which are referred to as corn-cobs. Although other Corynebacterium species have frequently been isolated from the oral cavity of humans, their distribution has not been reported as extensively. The aim of the present study was to develop a selective medium to isolate the genus Corynebacterium and examine the distribution Corynebacterium species in the oral cavity of humans. The growth recoveries of representative Corynebacterium species on the selective medium were sufficient. Moreover, the growth of other representative oral bacteria was markedly inhibited on the selective medium. The proportion of Corynebacterium species in saliva samples collected from 20 subjects was examined. PCR primers were designed for the oral Corynebacterium species. C. matruchotii and Corynebacterium durum accounted for 0.3% and 1.5% of the total cultivable bacteria number on the BHI medium from saliva samples, respectively. The selective medium could distinguish C. matruchotii from C. durum by each colony color using differences in acid production from galactose. The selective medium, designated OCM, was useful for isolating oral Corynebacterium species.

A selective medium for Rothia mucilaginosa and its distribution in oral cavities.

A selective medium for Rothia mucilaginosa (RMSM) was developed to examine the population of R. mucilaginosa in oral cavities. The growth recovery of R. mucilaginosa on RMSM was 85.1% relative to HI medium. R. mucilaginosa was detected at 3.4% of total bacteria from stimulated saliva of 8 subjects.

A novel selective medium for the isolation and distribution of Rothia dentocariosa in oral cavities.

Rothia dentocariosa is an indigenous microbial flora of dental plaque. To examine the bacterium population in oral cavities, a novel selective medium, designated RDSM, was developed for the isolation of R. dentocariosa. RDSM was prepared by adding 0.5 µg/ml of lincomycin, 10 µg/ml of colistin, and 40% sucrose to Heart Infusion (HI). Average growth recovery of R. dentocariosa on RDSM was 93.8% that of HI medium. Growth of other bacteria including Rothia mucilaginosa, Neisseria, Actinomyces, or streptococci was remarkably inhibited on the selective medium. Clinical efficacy was evaluated by the recovery of R. dentocariosa on RDSM from the stimulated saliva samples of 8 volunteers. R. dentocariosa was detected at 2.6 (range: 1.0-4.6) % to total bacteria of 8.0×10(7)CFU/ml on BHI in their oral cavities. The new selective medium, RDSM, was highly selective for R. dentocariosa and was useful for the isolation of R. dentocariosa from clinical samples.