• Restorative Dentistry and Endodontics
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• 제44권1호
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• pp.7.1-7.10
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• 2019

Apical periodontitis is a biofilm-mediated infection. The biofilm protects bacteria from host defenses and increase their resistance to intracanal disinfecting protocols. Understanding the virulence of these endodontic microbiota within biofilm is essential for the development of novel therapeutic procedures for intracanal disinfection. Both the disruption of biofilms and the killing of their bacteria are necessary to effectively treat apical periodontitis. Accordingly, a review of endodontic biofilm types, antimicrobial resistance mechanisms, and current and future therapeutic procedures for endodontic biofilm is provided.

• International Journal of Oral Biology
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• 제44권2호
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• pp.31-36
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• 2019

Streptococcus mutans is one of the important bacteria that forms dental biofilm and cause dental caries. Virulence genes in S. mutans can be classified into the genes involved in bacterial adhesion, extracellular polysaccharide formation, biofilm formation, sugar uptake and metabolism, acid tolerance, and regulation. The genes involved in bacterial adhesion are gbps (gbpA, gbpB, and gbpC) and spaP. The gbp genes encode glucan-binding protein (GBP) A, GBP B, and GBP C. The spaP gene encodes cell surface antigen, SpaP. The genes involved in extracellular polysaccharide formation are gtfs (gtfB, gtfC, and gtfD) and ftf, which encode glycosyltransferase (GTF) B, GTF C, and GTF D and fructosyltransferase, respectively. The genes involved in biofilm formation are smu630, relA, and comDE. The smu630 gene is important for biofilm formation. The relA and comDE genes contribute to quorumsensing and biofilm formation. The genes involved in sugar uptake and metabolism are eno, ldh, and relA. The eno gene encodes bacterial enolase, which catalyzes the formation of phosphoenolpyruvate. The ldh gene encodes lactic acid dehydrogenase. The relA gene contributes to the regulation of the glucose phosphotransferase system. The genes related to acid tolerance are atpD, aguD, brpA, and relA. The atpD gene encodes $F_1F_0$-ATPase, a proton pump that discharges $H^+$ from within the bacterium to the outside. The aguD gene encodes agmatine deiminase system and produces alkali to overcome acid stress. The genes involved in regulation are vicR, brpA, and relA.

• 한국치위생학회지
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• 제19권3호
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• pp.351-362
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• 2019

Objectives: The study aimed to analyze the factors affecting the maturity of dental biofilm, which was assessed with quantitative light-induced fluorescence-digital(QLF-D), in a sample of Korean older adults. Methods: This cross-sectional study included 67 participants, aged 65 years and older. All participants completed a questionnaire and tests to measure their manual dexterity and handgrip strength, which are parameters that indicate hand function abilities. To evaluate dental biofilm maturity, 804 surfaces of six index teeth were imaged using QLF-D and then quantified as ${\Delta}R$ values. All data were collected from May 25, 2017 to April 30, 2018. The independent t-test, one-way analysis of variance, and step-wise multiple linear regression were performed to analyze the factors associated with the maturity of dental biofilm (${\Delta}R$). Results: The multivariate linear regression analysis revealed that the factor most strongly related to dental biofilm maturity(${\Delta}R$) was manual dexterity (${\beta}=-0.326$), followed by handgrip strength (${\beta}=-0.303$) and use of interdental cleaning devices (${\beta}=-0.283$) (p<0.05). Conclusions: Manual dexterity, handgrip strength, and use of interdental cleaning devices are factors that can predict dental biofilm maturity in adults aged 65 years or older. Therefore, the hand function of a patient should be evaluated first, before assessing the oral hygiene status of the patient or providing him/her with oral health education, and the dental hygienist should provide differentiated oral hygiene care depending on the patient's hand function ability. Finally, dental hygienists should help older adults to recognize the importance of auxiliary oral hygiene devices such as interdental brushes and keep motivating them to use the devices more frequently.

• Restorative Dentistry and Endodontics
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• 제39권4호
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• pp.288-295
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• 2014

Objectives: This study was designed to evaluate the synergistic antibacterial effect of xylitol and ursolic acid (UA) against oral biofilms in vitro. Materials and Methods: S. mutans UA 159 (wild type), S. mutans KCOM 1207, KCOM 1128 and S. sobrinus ATCC 33478 were used. The susceptibility of S. mutans to UA and xylitol was evaluated using a broth microdilution method. Based on the results, combined susceptibility was evaluated using optimal inhibitory combinations (OIC), optimal bactericidal combinations (OBC), and fractional inhibitory concentrations (FIC). The anti-biofilm activity of xylitol and UA on Streptococcus spp. was evaluated by growing cells in 24-well polystyrene microtiter plates for the biofilm assay. Significant mean differences among experimental groups were determined by Fisher's Least Significant Difference (p < 0.05). Results: The synergistic interactions between xylitol and UA were observed against all tested strains, showing the FICs < 1. The combined treatment of xylitol and UA inhibited the biofilm formation significantly and also prevented pH decline to critical value of 5.5 effectively. The biofilm disassembly was substantially influenced by different age of biofilm when exposed to the combined treatment of xylitol and UA. Comparing to the single strain, relatively higher concentration of xylitol and UA was needed for inhibiting and disassembling biofilm formed by a mixed culture of S. mutans 159 and S. sobrinus 33478. Conclusions: This study demonstrated that xylitol and UA, synergistic inhibitors, can be a potential agent for enhancing the antimicrobial and anti-biofilm efficacy against S. mutans and S. sobrinus in the oral environment.

• 대한소아치과학회지
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• 제44권2호
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• pp.170-179
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• 2017

본 연구의 목적은 국내 상품화된 일반 우유와 저지방 우유의 우식원성을 CDC Biofilm Reactor를 사용한 세균막 모델을 통해 비교하는 것이다. 소의 법랑질 시편에 Streptococcus mutans ATCC 25175 세균막을 형성하였다. 하루에 3번 일반 우유, 저지방 우유와 0.9% 생리식염수를 세균막에 노출시켰다. 시간의 흐름에 따른 배지의 pH 변화를 측정하였다. 실험 5일째 시편에서 세균막을 분리하여 세균의 집락 형성단위를 측정하였다. 세균막의 두께는 공초점현미경으로 관찰하였다. 실험 전, 후의 표면미세경도를 측정하여 시편의 미세경도변화율을 평가하였다. 세 군 간의 pH 변화 양상과 세균막 두께는 유사하였으며 미세경도변화율과 세균의 집락형성단위는 유의한 차이를 보이지 않았다(p > 0.05). 본 연구 결과, 일반 우유와 저지방 우유의 우식원성은 차이를 보이지 않았으며, 우유는 우식에 대해 안전한 식품임을 확인하였다.

• 대한치과교정학회지
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• 제53권6호
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• pp.345-357
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• 2023

Enamel demineralization represents the most prevalent complication arising from fixed orthodontic treatment. Its main etiology is the development of cariogenic biofilms formed around orthodontic appliances. Ordinarily, oral biofilms exist in a dynamic equilibrium with the host's defense mechanisms. However, the equilibrium can be disrupted by environmental changes, such as the introduction of a fixed orthodontic appliance, resulting in a shift in the biofilm's microbial composition from non-pathogenic to pathogenic. This alteration leads to an increased prevalence of cariogenic bacteria, notably mutans streptococci, within the biofilm. This article examines the relationships between oral biofilms and orthodontic appliances, with a particular focus on strategies for effectively managing oral biofilms to mitigate enamel demineralization around orthodontic appliances.

• 한국치위생학회지
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• 제20권3호
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• pp.387-397
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• 2020

Objectives: This study aimed to evaluate the inhibitory effects of probiotics containing Lactobacillus reuteri on Streptococcus mutans and Aggregatibacter actinomycetemcomitans. In addition, the degree of biofilm formation, initial acidity, buffering ability, and acid production performance were measured to confirm the dental caries-inducing ability. Methods: S. mutans (KCTC3065) and A. actinomycetemcomitans (KCTC2581) were used as experimental strains. The number of viable cells, degree of biofilm formation, initial pH, buffering capacity, and production performance were measured for comparing L. reuteri-containing probiotics and Bulgaris. Results: The viability of S. mutans in the groups was reduced in the following order: Bulgaris, probiotics, control. The degree of biofilm formation was significantly higher at 0% and gradually reduced at different concentrations (p<0.01). At 2.5%, the absorbance of the probiotics and Bulgaris groups differed significantly (p<0.01). The acid formation ability differed significantly based on the performance of S. mutans in each product (p<0.05). The absorbance of the probiotics group was significantly lower than that of the Bulgaris group (p<0.01). Conclusions: This study suggests that the use of L. reuteri-containing probiotics as an adjuvant for the prevention and decreasing of oral diseases may reduce their incidence, which can be considered one of the benefits of using probiotics.

• 치위생과학회지
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• 제18권2호
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• pp.69-75
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• 2018

우리 연구의 목적은 DUWL에서 배출되는 물에서 분리한 균주의 부착 능력과 바이오필름 형성 능력을 확인하고 두 능력 사이 관계를 확인하는 것이다. DUWL로부터 분리한 12균주를 실험에 사용하였다. 각 균주의 부착 능력을 확인하기 위해, 12-well plates의 각 well에 멸균된 glass coverslip, R2A 액체 배지, 그리고 $1{\times}10^8CFU/ml$의 농도로 조정된 세균 현탁액을 넣고 $26^{\circ}C$ 배양기에서 7일 동안 배양하였다. 배양 후, glass coverslip에 부착한 정도에 따라 1~3점으로 점수를 부여하였다. 분리 균주의 바이오필름 형성 능력을 확인하기 위해, 96-well polystyrene flat-bottom microtiter plate에 R2A 액체 배지와 세균 현탁액을 넣고 $26^{\circ}C$에서 7일 동안 배양하였다. 배양 후, plate에 형성된 바이오필름은 R2A 액체 배지에 현탁했고, 현탁액을 R2A 고체 배지에 도말하였다. $26^{\circ}C$에서 7일 배양한 후 세균의 집락을 계수하고 CFU/ml를 계산하였다. DUWL로부터 총 56균주가 분리되었으며, 12속과 31종을 포함하였다. 실험에는 속당 1균주씩 선택하여 총 12균주가 사용되었다. 12균주 중에 S. echinoides, M. aquaticum, C. pauculus의 부착 능력 점수는 +3으로 가장 높았다. 바이오필름 축적량은 C. pauculus가 가장 많았고, M. testaceum이 가장 적었다. 대부분의 부착 능력이 높은 균주는 바이오필름 형성 능력 또한 높았다. 본 연구의 결과는 DUWL 바이오필름의 형성 기전을 파악하는데 도움을 주며 나아가 바이오필름 형성을 억제하는 방법의 개발에 기본적인 정보를 제공할 수 있을 것이다.

• 대한소아치과학회지
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• 제46권2호
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• pp.135-138
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• 2019

이 연구의 목적은 부유 및 바이오필름 상태의 Mutans streptococci에서 치태와 치석 착색제로 치과 진료실에서 사용하는 식용색소인 에리스로신에 대한 감수성을 조사하는 것이다. 세균은 호기성 조건에 배양하였고, 에리스로신은 $0.02-10000{\mu}g/L$의 농도로 희석하였다. 부유 상태 S. mutans의 최소 억제 농도(MIC)와 최소 살균 농도(MBC)를 측정하였다. 세균을 배양하여 바이오필름을 형성한 후, 최소 바이오필름 억제 농도(MBIC) 및 최소 바이오필름 박멸 농도(MBEC)를 측정하였다. MIC와 MBC는 $19.5{\mu}g/L$로 동일하게 측정되었으며 따라서 에리스로신은 부유 상태의 S. mutans에 대해 살균 효과를 가지는 것으로 나타났다. MBIC, MBEC 값은 각각 $313{\mu}g/L$, $2500{\mu}g/L$로 측정되었다. 측정된 MIC, MBC, MBIC는 실제로 치과에서 사용되는 농도에 비해 낮은 값이며 따라서 인체에 무해한 농도에서 S. mutans를 억제할 수 있을 것으로 보인다.