Red fluorescence of oral bacteria interacting with Porphyromonas gingivalis / 대한구강보건학회지

OBJECTIVES: Dental plaque is composed of 700 bacterial species. It is known that some oral microorganisms produce porphyrin, and thus, they emit red fluorescence when illuminated with blue light at a specific wavelength of <410 nm. Porphyromonas gingivalis belongs to the genus Porphyromonas, which is characterized by the production of porphyrin. The aim of this study was to evaluate red fluorescence emission of some oral microorganisms interacting with P. gingivalis. METHODS: Five bacterial strains (P. gingivalis, Streptococcus mutans, Lactobacillus casei, Actinomyces naeslundii, and Fusobacterium nucleatum) were used for this study. Tryptic soy agar medium supplemented with hemin, vitamin K3, and sheep blood was used as a growth medium. The fluorescence emission of bacterial colonies was evaluated under 405 nm-wavelength blue light using a Quantitative Light-induced Fluorescence Digital (QLF-D) camera system. Each bacterium was cultured alone and co-cultured in close proximity with P. gingivalis. The red/green (R/G) ratio of fluorescence image was calculated and the differences of R/G ratio according to each growth condition were compared using the Mann-Whitney test (P<0.05). RESULTS: Single cultured S. mutans, L. casei and A. naeslundii colonies emitted red fluorescence (R/G ratio=2.15±0.06, 4.31±0.17, 5.52±1.29, respectively). Fusobacterium nucleatum colonies emitted green fluorescence (R/G ratio=1.36±0.06). The R/G ratios of A. naeslundii and F. nucleatum were increased when P. gingivalis was co-cultured with each bacterium (P<0.05). In contrast, the R/G ratios of S. mutans and L. casei were decreased when P. gingivalis was co-cultured with each bacterium (P=0.002, 0.003). CONCLUSIONS: This study confirmed that P. gingivalis could affect the red fluorescence of other oral bacteria under 405 nm-wavelength blue light. Our findings concluded that P. gingivalis has an important role for red fluorescence emission of dental biofilm.

Risk indicators of periodontal disease in Korean adults / 대한구강보건학회지

OBJECTIVES: The purpose of this study was to evaluate the risk indicators of periodontal disease in a representative sample of Korean adults aged between 18 and 44 years. METHODS: Data of 6,485 adults were derived from the Fourth Korean National Health and Nutrition Examination Survey, which was conducted from 2007 to 2009. Demographic, socioeconomic, and oral health-related behavioral data were collected as independent variables. The Community Periodontal Index (CPI) was used as a dependent variable. The chi-square test and logistic regression analysis were performed to identify the relationship between the CPI and the other variables. RESULTS: Multiple logistic regression analysis revealed that periodontal pocket formation (4 mm or more) was related with sex, age, and income level, irrespective of whether the mother engaged in economic activities in childhood, smoking experience, dental flossing, and use of interdental brushes. The subjects in the lowest-income quartile and those who were current smokers had a higher risk of pocket formation (odds ratios, 1.43 and 1.74, respectively) than those in the highest-income quartile and those who had no smoking experience, respectively. CONCLUSIONS: This study confirmed various risk indicators of periodontal disease in Korean adults, using Korean national survey data. Smoking cessation, dental flossing, and efforts to decrease socioeconomic inequality should be encouraged to decrease the risk of periodontal disease.