Antibacterial effects of children's and adults' toothpastes containing different amounts of fluoride: An in vitro study.

Background: In recent years, fluoride concentrations in toothpaste for children and adults have increased. However, the effects of different concentrations on bacterial activity have rarely been compared. We aimed to investigate and compare the antibacterial activity of children's and adults' toothpaste containing 500, 1000‒1100, and 1450‒1500 ppm fluoride. Methods: Three strains of bacteria (Streptococcus mutans, Streptococcus salivarius, and Lactobacillus casei) were cultured in brain heart infusion agar. Thirty commercially available toothpaste products for children and adults containing 500, 1000‒1100, and 1450‒1500 ppm fluoride were selected and tested. Toothpaste's ability to inhibit bacterial growth was evaluated by agar diffusion assay, in which plates were incubated for 24 hours, and then the diameter of the microbial inhibition zone was measured. Comparisons between children's and adults' fluoride toothpastes were made using the Mann-Whitney U test. The association between bacterial growth inhibition and sodium lauryl sulfate (SLS) was analyzed by the chi-square test. A P value of <0.05 was considered statistically significant. Results: No difference in the inhibition zone was observed for different fluoride concentrations. However, there were significant differences between toothpastes for children and adults, with higher inhibition zones for adults' toothpastes. Most toothpastes for adults contained SLS, which was associated with antibacterial activity. Conclusion: Fluoride concentrations ranging from 500 to 1500 ppm did not affect bacterial growth. The antibacterial activity of toothpastes for adults was significantly higher than that of toothpastes for children, which was mainly attributed to the SLS usually added to adult formulations.

Efficacy of Biofilm Removal on the Dental Implant Surface by Sodium Bicarbonate and Erythritol Powder Airflow System.

OBJECTIVE: Peri-implantitis is a common complication in implant therapy and it is one of the main contributing factors to implant failure. This can be prevented by regular maintenance with mechanical debridement. One of the recent mechanical debridement methods is air abrasion therapy using different abrasive powders. This study aimed to evaluate the two common abrasive powders of different sizes (sodium bicarbonate and erythritol) for their biofilm cleaning efficacy on dental implant surfaces. MATERIALS AND METHODS: In an in vitro setting, a total of 33 implants were divided into three groups: Group 1 (n =11) = no treatment; group 2 (n = 11) = air abrasion therapy treated group using a sodium bicarbonate powder (AIRFLOW Powder Classic Comfort, EMS Electro Medical Systems, Nyon, Switzerland); and group 3 (n = 11) = air abrasion therapy treated group using an erythritol powder (AIRFLOW Powder Plus, EMS Electro Medical Systems, Nyon, Switzerland). The implants in each group were subjected to biofilm formation, and group 2 and group 3 were treated with air abrasion therapy of two different powders having different sizes with the same settings. The particle sizes were sodium bicarbonate (40 µm) and erythritol (14µm). The surface characteristics of the dental implants in three groups were studied from a digital camera and under the scanning electron microscope at different magnifications. The comparison of biofilm-removal efficacy between the three groups was performed by using a one-way analysis of variance with post-hoc Dunnett's T3 test. A p-value less than 0.05 was chosen to indicate statistical significance. RESULTS: There were no statistical differences (p > 0.05) between the two powder-treated groups for the biofilm cleaning efficacy. However, both groups showed significantly better biofilm-cleaning efficacy than the control group (p < 0.05). CONCLUSION: This suggests that both powders are effective in removing biofilm from the implant surface under ideal conditions. However, there was no clear distinction between the cleaning potential of the two powders, as both performed in a similar manner.

Genotyping of Candida albicans and Candida dubliniensis by 25S rDNA analysis shows association with virulence attributes in oral candidiasis.

OBJECTIVES: This study genotyped oral isolates of Candida albicans and C. dubliniensis by analyzing 25S rDNA transposable intron and evaluated their virulence attributes in oral candidiasis. DESIGN: C. albicans and C. dubliniensis were isolated from oral cavity of normal carriers (n = 100) and oral candidiasis patients (n = 100), genotyped by PCR, and virulence properties, namely, secreted phospholipase and proteinase activities (using an agar plate method) and binding to buccal epithelial cells, were determined. In addition, antifungal sensitivity was assayed for all Candida isolates. RESULTS: C. albicans genotypes A, B, C and D (C. dubliniensis) were identified. Genotype B was the most prevalent in both healthy and candidiasis groups and had highest buccal epithelial cell binding ability but lowest secreted phospholipase activity. Genotype C was the third most prevalent, with higher frequency in patients than normal carriers. Genotype A, the second most prevalent, was equally found in both groups. There were no significant differences in secreted proteinase activity among the three C. albicans genotypes. C. dubliniensis, the least prevalent, was more frequent in healthy carriers and demonstrated minimal levels of the virulence properties. When all Candida isolates were compared based on groups of subjects, only secreted phospholipase activity was significantly higher in isolates from candidiasis patients. All Candida isolates were susceptible to clotrimazole, fluconazole, miconazole and nystatin. CONCLUSIONS: Genotyping based on the 25S rDNA transposable intron region provided a simple method allowing studies of the pathogenicity of each genotype.

Multilocus sequence typing analysis of Streptococcus mutans strains with the cnm gene encoding collagen-binding adhesin.

Streptococcus mutans is one of the oral pathogens associated with infective endocarditis (IE). With respect to bacterial binding ability to the extracellular matrix, the Cnm protein, a cell surface collagen-binding adhesin of S. mutans, is known as one of the possible virulence factors with regard to IE. In this study, we aimed to determine the distribution of the cnm gene, which encodes Cnm, in a large number of clinical isolates of S. mutans from Thai subjects. Then, the cnm-positive strains were classified using a multilocus sequence typing (MLST) scheme, which we constructed previously. In addition, the data were analysed together with our previous MLST data of cnm-positive strains from Japan and Finland in order to evaluate the clonal relationship among S. mutans strains harbouring the cnm gene. The cnm gene was detected in 12.4 % of all 750 Thai isolates, and serotype f showed the highest rate of detection (54.5 %). According to the MLST data, two clonal complex groups were revealed as the important clones related to cnm-positive S. mutans from various origins of isolation. Moreover, the collagen-binding properties of S. mutans strains with the cnm gene were significantly greater than those of strains without the gene, although four cnm-negative strains classified into two sequence types (STs), ST110 and ST136, showed extremely high collagen-binding rates suggesting the presence of additional genes involved with collagen binding in these STs. Taken together, these results provided information on both epidemiological as well as evolutional aspects of S. mutans possessing the cnm gene.