불화나트륨 및 흡연이 인공 Streptococcus mutans 치면세균막 형성에 미치는 영향 = Effects of sodium fluoride and cigarettes smoking exposure on Streptococcus mutans biofilm formation

다국어 초록 (Multilingual Abstract)

This thesis is divided into two chapters to introduce the effects of two common substances on the growth of oral caries biofilm. In chapter 1, the effects of fluoride on the development of cariogenic biofilms were introduced. Streptococcus mutans (S. mutans) biofilms were cultured in vitro and treated with F- at different concentrations (250~2000 ppm) in the early and mature stages. To evaluate the effect of sodium fluoride on the growth of S. mutans biofilm, biochemical (dry weight accumulation, water-insoluble/soluble extracellular polysaccharides (EPSs), intracellular polysaccharides (IPS), acid production), microbiological (viable cell counting) and confocal image (live/dead assay, biofilm architecture) analyses were conducted. The experimental results showed that all fluoride treatment groups significantly inhibited the dry weight accumulation, viable cell counts, and total EPSs formation of 46 h-old S. mutans biofilm in a concentration-dependent manner. In the mature stage of biofilm growth, only the fluoride treatment at 2000 ppm significantly inhibited the biomass accumulation, bacterial activity, and EPSs formation of S. mutans biofilm compared with those of the other groups. Thus, the effect of fluoride treatment on the disruption of S. mutans biofilm was related to the stage of biofilm development and in turn, treatment of fluoride at the early stage of biofilm may control the cariogenic biofilm formation and prevent caries.
The second chapter introduces the effect of cigarette smoking (CS) on the growth of cariogenic biofilms. S. mutans biofilms were cultured in vitro and exposed to CS one, three, and six times per day, respectively. To examine the effect of CS　on S. mutans biofilm formation, biofilms were exposed to CS for 5 min using a custom-made smoking device. The total biomass, viable cell counts, contents of water-soluble/insoluble EPSs and IPS, acid production, and three-dimensional architecture of S. mutans biofilms at 74 h were analyzed. The experimental results showed the 6 times/day CS exposure group showed the lowest biofilm accumulation and EPS values compared with those of other groups in 74 h-old S. mutans biofilms. CS exposure inhibited the S. mutans biofilm formation in vitro study, the formation of anti-cariogenic biofilm was enhanced in a frequency-dependent manner.
In this study, the effect of fluoride and CS on the growth of S. mutans biofilm were conducted and the results suggested that fluoride treatment in the early stage of cariogenic biofilm formation may control the cariogenic biofilm formation and prevent caries, CS exposure inhibited the growth of S. mutans biofilms, the anti-cariogenic biofilm formation was increased with a frequency-dependent manner.

목차 (Table of Contents)

• General Abstract 1
• General Introduction 4
• I. Chapter 1:Effects of brief sodium fluoride treatments on the growth of early and mature cariogenic biofilms 7
• 1. Introduction 7
• 2. Materials and Methods 8
• 2.1 Microbiological and biochemical biofilm analyses 8
• 2.2 CLSM analysis 9
• 2.3 Statistical Analysis 10
• 3. Results 10
• 4. Discussion 12
• 5. Conclusion 13
• 6. Figures 14
• II. Chapter 2:Effects of brief sodium fluoride treatments on the growth of early and mature cariogenic biofilms 28
• 1. Introduction 28
• 2. Materials and Methods 29
• 3. Results 30
• 4. Discussion 31
• 5. Conclusion 33
• 6. Figures 34
• III. References 47
• IV. Abstract in Korean 50

참고문헌 (Reference)

1. Relationship between fluoride concentration and activity against virulence factors and viability of a cariogenic biofilm : in vitro study, Pandit , S. , Kim , H. J. , Song , K. Y . & Jeon , J. G., 47 , 539-547 (, , 2013

2. Comparison of Flavorless Electronic Cigarette-Generated Aerosol and Conventional Cigarette Smoke on the Survival and Growth of Common Oral Commensal Streptococci, Cuadr , G. A. , Smith , M. T. , Nelson , J. M. , Loh , E. K. & Palazzolo , D. L. A, 16 , 1669, , 2019