• Journal of the korean academy of Pediatric Dentistry
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• v.30 no.4
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• pp.554-562
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• 2003

Xylitol has been used as sugar substitute to prevent dental caries. It is not fermented by most dental plaque bacteria and interferes with the growth of mutans streptococci. Therefore the production of acidic metabolites and the growth of mutans streptococci are inhibited. S. mutans strains which are inhibited to grow under the presence of xylitol are referred as xylitol-sensitive ($X^S$) strains. However, experimental and clinical studies have shown that there were mutated groups of S. mutans strains that are not affected by xylitol. They are referred as xylitol-resistant($X^R$) strains. The aim of the present study was to investigate that emergence of $X^R$ strain would effect on the anticariogenecity of xylitol by comparing the growth rate, the extracellular pH, hydroxyapatite adhesion and the agglutination of the $X^R/X^S$ strains. Overall we came out with following results : 1. No difference in the growth rate and the extracellular pH was found between the $X^S$ strain and the $X^R$ strain. 2. No difference in adhesion to hydroxyapatite surface was found between the $X^R$ strain and the $X^S$ strain (p>0.05) and adhesion of the $X^S$ strain was greater than that of $X^R$ strain in the sucrose-dependent adhesion to hydroxyapatite (p<0.05). 3. The $X^R$ strain was agglutinated in the lower concentration of saliva than that of $X^S$ strains.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.35 no.2
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• pp.191-195
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• 2002

In previous reports the authors have screened the inhibition effects of marine algae extracts on halitosis, and demonstrated that a brown algae, Eisenia bicyclis (' Daehwang') possess not only strong deodorant effect bug also considerable anticariogenic activities. In this study, we screened antibacterial effects of various marine algae, and measured minimum inhibitory concentration (MIC) value of them against mutans streptococci in vitro. Among the 27 species of marine algae, $80\%$ ethanol extract of dried sea-mustard, Laminaria japonica ('Dasima') showed the strongest inhibition activity against Streptococcus mutans KCTC 3300. The extracts of Ulva lactuca ('Galparae'), Codium fragile ('Cheonggak'), Ecklonia cava ('Gamtae'), E. stolonifera ('Gompi') and Undalia Pinnatifida ('Miyeok') showed slightly weaker inhibitory potency than L. japonica. Differences of MIC values in $80\%$ ethanol extract of some species of marine algae were observed depending on test bacterial species, i.e., S. mutans KCTC 3300 or S. sobrinus KCTC 3307. Eighty percent ethanol extract of dried L japonica was fractionated with diethyl ether, chloroform, ethyl acetate, n-buthanol and water successively, The ether-soluble fraction had inhibitory effect on S. mutans KCTC 3300, however the inhibitory effects were not found in the other fractions. The MIC values of $80\%$ ethanol extract and ether fraction were 180 and 105 $\mu$g/mL respectively, while no significant inhibition activity of water-soluble fraction was found even when the fraction was added up to 5,500 $\mu$g/mL.

• Journal of the korean academy of Pediatric Dentistry
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• v.30 no.4
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• pp.728-737
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• 2003

To evaluate microbial data and salivary measurements from clinically compatible, culture-based screening procedures employed with children younger than 36 months old. Plaque and stimulated saliva specimens were collected from 87 children. The pH of each saliva sample was measured before and after 0.94% lactic acid was added. Specimens were diluted and plated on selective media and non-selective media. Data collected were counts of mutans streptococci (MS) and lactobacilli (LB). In addition, total viable counts (TVC) of specimens, salivary pH and buffering capacity were also assessed. Each variable was compared to caries status of subjects. According to this study, the results were as followed: 1. Highly significant correlation with caries rates were found for counts of MS and LB. 2. The specific counts/ml saliva or plaque above which caries is predicted, or below which caries is not predicted were as follows: 1) Saliva MS; $10^5$ 2) Plaque MS; $2{\times}10^5$ 3) Saliva LB; $10^3$ 4) Plaque LB; $10^3$. 3. Salivary pH and buffering capacity versus caries status were not significant. 4. Microbial screening methods based on mutans streptococci had higher predictive values and odds ratios than methods for lactobacilli. 5. MS counts were clearly the best indicators of caries status in young children. This measurement can easily be obtained in a dental clinical setting both by conventional culture techniques, or commercial kits for MS recovery.

• The korean journal of orthodontics
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• v.35 no.4 s.111
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• pp.312-319
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• 2005

Streptococcus mutans and Streptococcus sobrinus are major etiological agents in enamel demineralization around orthodontic appliances. This study was designed to examine the prevalence of these streptococci on orthodontic brackets in vivo using polymerase chain reaction. Four incisor brackets in the upper and lower arches were removed and collected from 80 patients at the time of debonding. The genomic DMA of adhered bacteria was extracted and each dextranase gene of S. mutans and S. sobrinus was amplified using the specific oligonucleotide primers. The results showed that the maxillary incisor brackets were colonized by both cariogenic streptococci to a somewhat higher degree than that taken from the mandible. The prevalence of S. mutans was $50.0\%$ on the maxillary incisor brackets and $33.8\%$ on the mandibular incisor brackets, and that of S. sobrinus was $17.5\%$ and $15.0\%$, respectively. Both species were detected on the maxillary incisor brackets of 7 patients $(8.8\%)$ and the mandibular incisor brackets of 5 patients $(6.3\%)$. These results suggest that cariogenic streptococci can adhere to the incisor brackets and may be resident species on the incisor brackets.

• Journal of the korean academy of Pediatric Dentistry
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• v.33 no.4
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• pp.587-596
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• 2006

Most of oral streptococci express the Antigen I/II (AgI/II) proteins, cell wall anchored adhesions. AgI/II protein binds to salivary agglutinin glycoprotein, a component of tooth pellicle and to ligands in other bacteria. These associations play important roles in bacterial colonization. Recently, it was reported that diverse host molecules also interact with AgI/II protein and that these interactions induce inflammatory responses from host cells. Among mutans streptococci containing -type hemolytic activity, Streptococcus mutans is a causative agent for dental caries. Compared with many other strains of S. mutans, GS-5 strain is unique in that this bacterium expresses truncated secretory AgI/II protein due to the nonsense mutation in the agI/II gene. This indicates that S. mutans GS-5 has a different clinical role and a recent report supported this idea based on the results from clinically isolated S. mutans strains. Previously, we had cloned agI/II gene from S. mutans GS-5 and generated recombinant N-terminal AgI/II protein. In this study, we further produced a hybridoma line expressing anti-AgI/II monoclonal antibodies named as 1C11A. This antibody showed high sensitivity to AgI/II protein in Western blot and ELISA. This new reagent will provide a basis for investigating the mechanisms of AgI/II-related diseases.

• Journal of the korean academy of Pediatric Dentistry
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• v.35 no.1
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• pp.73-82
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• 2008

Dental caries is an infectious disease caused by mutans streptococci, and is a primary etiologic agent of dental caries in humans. The molecular pathogenesis of mutans streptococcal-associated dental caries occurs in three phases. Firstly, S. mutans attaches to tooth surface via a cell surface adhesion termed antigen I/II. In the second phase, the glucosyltransferase(GTFs) synthesize polymers like glucans in the presence of sucrose. In the third phase, the multivalent glucans interacts with glucan binding proteins (GBPs) and they make dental plaque and accumulation of microorganisms. Many studies and clinical trials have indicated that a mucosal immune response to these antigens(Ag I/II, GTFs, GBPs) of S. mutans can influence the pathogenesis of dental caries. So these antigens can be important vaccine candidates for immunologic intervention against dental caries. In this study, we cloned the genes for GTFb, GTFc, GTFd from S. mutans GS-5 and did the nucleotide sequence analysis. And the recombinant proteins of GTFd and N-terminus of GTFd were expressed. Intact GTF which we get from this experiment can be used for antibody production specific for any GTF activity domain through animal experiment.

• Restorative Dentistry and Endodontics
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• v.20 no.1
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• pp.275-288
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• 1995

The inhibitory effect of cell wall extracts of streptococci, have been investigated to know host-parasite relationship or pathogenesis of abscess formation. Streptococci isolated from the infected root canals were sonicated to get cell wall extracts which have been known as one of the factors of pyogenesis. Lymphocytes separated by density gradient were stimulated with phytohemagglutinin and exposed to cell wall extracts of Streptococcus sanguis, S. mitis, S. uberis, S. mutans (ATCC 10449), and S. faecalis (ATCC 19433). [$^3H$]-thymidine uptake of lymphocytes was analyzed with scintillation counter and lactate dehyrogenase (LD) activity was measured with autochemistry analyzer. S. faeealis had the strongest inhibitory effect. beginning at $100\;{\mu}g/ml$ concentration of sonic extracts. S. sanguis and S. mitis had inhibitory effect at $300\;{\mu}g/ml$, while S. uberis and S. mutans showed no inhibitory, effect on DNA syntheis even at $300\;{\mu}g/ml$. Each streptococci showed different inhibitory effect on the DNA synthesis of lymphocytes, which finding indicated wide spectrum of susceptibility of lymphocytes according to streptococcus spp. There were no significant difference of LD activities between control and each streptococcal extracts. Streptococcal sonic extracts did not affect the morphological findings or number of colonies activated lymphocytes. These finding suggested the inhibitory effect of sonic extract of streptococci to lymphocytes could be detected by DNA synthesis inhibition, not by cellular membrane damage.

• Journal of the korean academy of Pediatric Dentistry
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• v.32 no.2
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• pp.207-216
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• 2005

Mutans streptococci have been reported to be implicated in dental caries. Of these streptococcal species, Streptococcus mutans and Streptococcus sobrinus are most commonly found in human dental caries. Prevalence of these bacterial species in dental caries is found to be varied in different races and countries. Therefore, importance of these bacteria in dental caries remains to be determined. The present study was peformed to detect S. mutans and S. sobrinus in 52 Korean children with dental caries between 2 to 6 years of age. For the study, plaque samples were collected from caries-active(CA) and caries-free(CF) teeth of each subject. DNA was extracted from the plaques and amplified by polymerase chain reaction(PCR) using primers corresponding to dex and gtf genes. The results obtained from the study were as follows: 1. Of 52 children, 37 children (71.2%) were found to harbor S. mutans and/or S. sobrinus. 2. Of the MS-infected 37 children, 3 children (5.8%) harbored S. mutans and/or S. sobrinus in the CF plaques only, 22 children (42.3%) in the CA plaques only and 12 children (23.1%) in both CF and CA plaques. 3. S mutans and/or S. sobrinus were detected in 34 CA plaques (65.4%), while 15 in CF plaques (28.8%) 4. In the case of CF plaques, 8 plaques (15.4%) were observed to harbor S. mutans only, 6 plaques (11.5%) to harbor S. sobrinus only and 1 plaque (1.9%) to harbor both species. 5. Of CA plaques, 24 plaques (46.2%) were detected to have S. mutans only, 2 plaques (3.8%) to have S. sobrinus only and 8 plaques (15.4%) to have both species. 6. In comparison with the efficiency of two different primers for PCR, it was found that the primer based on gtf gene was more effective in detecting S. mutans, while the primer corresponding to dex gene was better for S. sobrinus. Overall results suggest that MS appears to be important in dental caries of the Korean children, and S. mutans is more closely associated with than dental caries as compared to S. sobrinus.

• Journal of the korean academy of Pediatric Dentistry
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• v.30 no.1
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• pp.69-79
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• 2003

The purpose of this present study was to develop a new way of self-curing acrylic resin, using commercially available polyphosphate, Calgon, which is known to be antimicrobial and safe. For the study, polyphosphate(polyP) was blended with acrylic powder and devided into four groups as follows: no polyP(control), 1% polyP, 2% polyP, and 3% polyP. For the experiment, Streptococcus mutans GS5, Streptococcus sobrinus 6715, Streptococcus gordonii G9B and Challis, Porphyromonas gingivalis 2561, and Candida albicans ATCC 90027 were used. Resin specimens in each group were tested in vitro for the purpose of investigating the effect of polyP on the microbial attachment, growth and hydrophobicity of the resin surface. The results were as follows. 1. PolyP added to the acrylic resin decreased attachment of S. mutans GS5, S. sobrinus 6715, S. gordonii G9B. The greater binding inhibition was found in acrylic resin polymerized with polyP at higher concentrations. 2. The addition of polyP to acrylic resin failed to significantly affect the growth of the tested microorganisms. 3. The addition of polyP to acrylic resin seemed to reduce hydrophobicity of the acrylic resin. PolyP in acrylic resin does not seem to exert a direct antibacterial activity, but rather inhibit attachment of oral bacteria, especially mutans streptococci to saliva-coated acrylic resin. The acrylic resin reduces attachment of streptococci may be due to the decreased hydrophobicity caused by polyP added to the resin. PolyP may be included to acrylic resin to inhibit dental caries which often occurs when removable acrylic resin appliance is placed.

• International Journal of Oral Biology
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• v.41 no.4
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• pp.209-215
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• 2016

Chlorhexidine has long been used in mouth washes for the control of dental caries, gingivitis and dental plaque. Minimal inhibitory concentration (MIC) is the lowest concentration of an antimicrobial substance to inhibit the growth of bacteria. Concentrations lower than the MIC are called sub minimal inhibitory concentrations (sub-MICs). Many studies have reported that sub-MICs of antimicrobial substances can affect the virulence of bacteria. The aim of this study was to investigate the effect of sub-MIC chlorhexidine on biofilm formation and coaggregation of oral early colonizers, such as Streptococcus gordonii, Actinomyces naeslundii and Actinomyces odontolyticus. The biofilm formation of S. gordonii, A. naeslundii and A. odontolyticus was not affected by sub-MIC chlorhexidine. However, the biofilm formation of S. mutans increased after incubation with sub-MIC chlorhexidine. In addition, cell surface hydrophobicity of S. mutans treated with sub-MIC of chlorhexidine, decreased when compared with the group not treated with chlorhexidine. However, significant differences were seen with other bacteria. Coaggregation of A. naeslundii with A. odontolyticus reduced by sub-MIC chlorhexidine, whereas the coaggreagation of A. naeslundii with S. gordonii remained unaffected. These results indicate that sub-MIC chlorhexidine could influence the binding properties, such as biofilm formation, hydrophobicity and coaggregation, in early colonizing streptococci and actinomycetes.