• Journal of Korean society of Dental Hygiene
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• v.20 no.3
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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.

• Journal of Technologic Dentistry
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• v.21 no.1
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• pp.145-151
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• 1999

Titanium(Ti) alloys has been mostly concerned with biocompatibility, corrosion resistance, and biofunctionality. However, very little is known, about the biological effects of titanium on microorganism and in particular on the oral flora. So, the effect of titanium on the in vitro growth of oral microorganism forming dental caries was studied under either aerobic or anaerobic condition. In this study, the mostly bacterial species commonly found in dental plaque or gingival sulcus grew well in an aqueous medium containing $100{\mu}g/ml$ of titanium standard solution.

• Journal of the korean academy of Pediatric Dentistry
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• v.50 no.1
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• pp.65-74
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• 2023

This study compared the surface roughness and microbial adhesion characteristics of Omnichroma, a novel composite resin developed using "smart chromatic technology", with those of two other conventional composite resins with different filler compositions. A total of 144 specimens were fabricated using 3 types of composite resins: Omnichroma (nano-spherical), Filtek Z350XT (nanofill), and Tetric N-Ceram (nanohybrid) and, divided into 3 groups of 48. Finishing was performed using tungsten carbide burs. Specimens were then divided into 3 subgroups using different polishing methods: Control, SofLex, and PoGo. Surface roughness was analyzed quantitatively and qualitatively using an atomic force microscope and a scanning electron microscope. Microbial adhesion was assessed by culturing Streptococcus mutans on the specimens for 24 hours and then measuring colony-forming units attached to the upper surface. The surface roughness (Ra) of Omnichroma was 0.123 ㎛ after finishing, and it exhibited a smooth surface compared to the other resins. However, after polishing, there were no significant differences in the surface roughness between the three composite groups, regardless of the polishing methods. The surfaces of the Control subgroups were significantly rougher than those of the SofLex subgroups in all 3 composite groups. However, except for Tetric N-Ceram, there were no significant differences between the Control and PoGo subgroups in the other composite groups. Microbial adhesion assessment showed no significant differences between any of the 3 composite resin subgroups; however, Omnichroma exhibited higher microbial adhesion than the other two composites. No significant correlation was observed between surface roughness and microbial adhesion.

• Korean Journal of Microbiology
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• v.48 no.1
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• pp.52-56
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• 2012

The aim of this study was to evaluate the antimicrobial effect of carvacrol against periodontopathic and cariogenic bacteria and its cytotoxicity in human oral tissue cells. We tested their antibacterial properties against mutans streptococci and five major periodontopathic bacterial species involved in periodontal disease. The antimicrobial activity was evaluated by the minimal inhibitory concentration (MIC) and minimum bactericidal concentration (MBC). The cell viability of carvacrol on normal human gingival fibroblast (NHGF) cells was tested by metyl thiazolyl tetrazolium assay. The data showed that carvacrol had remarkable antimicrobial effect on tested bacteria with a MIC and MBC values ranged from 16 to $128{\mu}g/ml$ and from 32 to $128{\mu}g/ml$, respectively. In cell toxicity studies, carvacrol had significantly decreased cell viability when NHGF cells were treated at $128{\mu}g/ml$. These findings suggest that carvacrol has a strong antimicrobial activity against periodontopathic and cariogenic bacteria. However, in order to use it as a component of gargling solution or toothpaste, its concentration should be below $64{\mu}g/ml$ and other compounds having an antimicrobial activity against periodontopathic and cariogenic bacteria should be used together.

• Journal of dental hygiene science
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• v.2 no.2
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• pp.105-113
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• 2002

This study was aimed to investigate the practice on the infection control and dental waste disposal in dental clinic. The data used in this study had been collected in 100 dental clinics located in Seoul city from August to October, 2001. It was shown that examination instruments, oral surgery instruments, and periodontal instruments were almost sterilization in dental clinic. It was high in the recognition of individual protection but it was low in the degree of practice. Therefore, the practice in infection control is very important to dental team for safety of patients and operators.

• Journal of Life Science
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• v.31 no.12
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• pp.1072-1078
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• 2021

The oral pathogen Streptococcus mutans is considered a major causative agent of dental caries in humans. The use of dental hygiene products, including toothpaste and mouthwash, is used for caries control. However, food intake can lead to the recurrence of oral microorganisms. This study aimed to explore why this bacterium dies so quickly during prolonged incubation and to assess whether this growth characteristic is closely associated with the secretion of metabolic products. Notably, the number of live S. mutans cells rapidly declined after 24 hr during the entire period tested, whereas the number of Escherichia coli cells, an indicator strain, remained steady over the same period. To test whether the S. mutans supernatants contained possible signals that accelerated the death of neighbor cells, we obtained the individual supernatants at the above time points. Following pH neutralization, the cells in which the supernatant was supplemented with glucose grew well. However, pH adjustment alone could not fully recover cell growth in conditions in which the supernatant was supplemented, with or without glucose. These phenotypes of S. mutans may be associated with signaling, not only resulting from nutrient depletion. The findings on the survival phenotype of S. mutans provide new insights into cell-cell communication in the biology of this bacterium.

• Korean Journal of Microbiology
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• v.19 no.3
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• pp.137-141
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• 1981

Occurrence and distribution of sucrose metabolizing enzymes in oral streptococci had been studied. In these studies, the carbohydrate component of the culture medium had been glucose. I have extended these studies by analyzing bacterial culture supernatants for the relative content of hexosyltransferases, namely glucosyl and fructosyltransferase. As a carbohydrate, fructose was used. The growth measured for nine oral streptococci (Strptococcus mutans strains BHT, ING, AHT, 6715, LM-7, and SL-1 ; Streptococcus sanguis 903, 9811, and M-5) varied. The level of glucosyltansferase activity also varied among S. mutans strains, and its level in S. sanguis was relatively low. Fructosyltansferase activity of the various strains fluctuated more than of glucosyltransferase. S.mutans strain LM-7 had significantly higher level of both enzymes. As a whole, fructose-grown cultures had generally an agreeable trend of enzyme activity to those from glucose-grown cultures.

• Korean Journal of Microbiology
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• v.27 no.3
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• pp.259-264
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• 1989

The adherence of $^{3}H$-labeled oral streptococcal cells to protein-coated hydroxyapatite (HA) beads was studied by a standard adherence assay. The adherence equilibrium for S. mutans 10449 occured in about 2 hrs. The cell numbers adhering to SHA was 50% less than those on bare HA. Sailva from different subjects had varying effect on bacterial adherence. The use of saliva adsorbed with homologouis bacteria decreased S. mutans adherence by 38% ; this indicates the presence of salivary agglutinin in acquired pellicle formed on HA. Animal sera and BSA decreased S. sanguis adherence. BSA concentration as high as 10mg/ml caused up to 87% adherence inhibition. The desorption experiment of adhered bacteria confirmed the previous reports that the adhesive sites on HA beads for S. mutans were different from those for S. sanguis and that S. mutans could enhance the adherence of S. sanguis but not vice versa.

• Journal of Periodontal and Implant Science
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• v.37 no.1
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• pp.1-10
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• 2007

연구 목적 : 구취의 주된 화학적 요소는 휘발성 황 화합물 (VSCs)들이다. 이들은 치태, 설태, 타액과 혈액, 상피세포의 혐기성 그람 음성 세균에 의한 단백분해 변성으로 만들어 진다. 또한 구취는 치주질환과 타액내의 세균의 증가를 야기하는 불량한 구강 위생상태에서 기인한다고 보고되고 있다. 이 연구의 목적은 VSCs를 측정함으로 구취에 대한 비외과적 치주 치료의 영향을 평가하고, 타액내의 세균 수를 측정함으로써 VSCs와의 상관관계를 살펴보고자 하는 것이다. 연구 대상 및 방법 : 중등도의 만성치주염을 가지는 23명의 참가자들이 대조군과 실험군으로 분류되었다. 대조군은 구강위생교육 (치간청결기구와 혀세정 포함)만을 시행하였고 실험군은 구강위생교육과 함께 24시간 내에 전악 치석제거술과 치근활택술을 시행하였다. 치료 전과 치료 4주 후에 VSCs 농도를 $Halimeter^{(R)}$(Interscan Corp., CA, USA)를 사용하여 측정하였고 타액 시료는 혐기성과 호기성 조건에서 배양되었다. 결과 : 4주 후에 두 군 모두에서 휘발성 황화합물의 농도가 유의하게 감소하였고, 실험군에서의 감소량이 통계적으로 유의하게 더 크게 나타났다. 타액 내 세균의 배양에서 총세균수에 대한 혐기성 세균의 비율이 실험군에서만 통계적으로 유의하게 감소하였다. 그러나 세균의 비율과 휘발성 황화합물의 농도와의 상관관계는 낮게 나타났다. 즉 구취의 감소는 타액 요인 보다는 치주치료에 의한 다른 복합적인 인자의 작용에 의한 것으로 추론할 수 있었다. 결론 : 본 연구는 중등도의 치주염환자에서 구강위생교육만으로도 구취의 주요 화학적 요인인 휘발성 황화합물의 농도를 감소시킬 수 있으나 비외과적 치주치료를 동반하였을 때 더욱 큰 효과를 얻을 수 있는 것으로 해석된다. 그러나 실험 참가자의 수가 적었고 장기간의 분석이 이루어지지 않았으므로 앞으로 더 많은 연구가 구취에 대한 치주치료의 영향을 이해하기 위해서 필요할 것으로 사료된다.

• Journal of Dental Rehabilitation and Applied Science
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• v.37 no.4
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• pp.244-250
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• 2021

Purpose: The purpose of this study was to examine effects of culture conditions on the growth and antibacterial activity of Streptococcus salivarius K12. Materials and Methods: S. salivarius K12 was cultivated in medium containing animal and plant protein or in medium of neutral and acidic conditions. The growth of S. salivarius K12 was measured every 2 hours by a spectrophotometer. The antimicrobial activity of S. salivarius K12 against Streptococcus mutans and Porphyromonas gingivalis was investigated by the susceptibility assay using the spent culture medium. Results: the growth of S. salivarius K12 showed faster in medium containing plant protein and neutral pH condition. The antimicrobial and antifungal activity of S. salivarius K12 appeared stronger in medium containing plant protein than animal proteins. Conclusion: For application of S. salivarius K12 to bacterial oral disease, co-substances may be needed for S. salivarius K12 to colonize in the oral cavity and enhance the antimicrobial activity.