• Journal of the korean academy of Pediatric Dentistry
• /
• v.30 no.1
• /
• pp.33-40
• /
• 2003

Fusobacterium nucleatum, one of the bacteria causing halitosis, produces the volatile sulfur compounds (VSC) such as $H_2S$ in the media containing sulfur components, and forms FeS by binding with iron component. The various factors of oral cavity affect the concentration of sulfur compounds produced by Fusobacterium nucleatum. In this study, the effect of nutrients and pH on the production of sulfur compounds by Fusobacterium nucleatum was studied with the following results. 1. The optical density of broth was increased to $0.817{\pm}0.032$ and $1.297{\pm}0.024$ by adding 1.0% sodium thiosulfate and 0.05% L-cysteine hydrochloride in the media, respectively. 2. Though the optical density of broth was $0.799{\pm}0.032$ by adding volatile sulfur compounds (VSC) only in the media, it was increased to $1.775{\pm}0.003$ and $1.648{\pm}0.022$ by adding xylitol combined with glucose and fructose, respectively. 3. The concentration of VSC was above 20,000 ppb in the media above pH 5.5. The optical density of broth was still high in the media with L-cysteine hydrochloride of higher concentration, being low in the media of lower pH. 4. The concentration of VSC was high when there was distilled water or saline solution on the media, and their amount was small. These results suggest that the production of sulfur compounds by Fusobacterium nucleatum was inhibited by xylitol and acid.

• Journal of the korean academy of Pediatric Dentistry
• /
• v.47 no.4
• /
• pp.397-405
• /
• 2020

The aim of this study is to compare cariogenic characteristics of fluoride-sensitive Streptococcus mutans [fluoride-sensitive (FS) S. mutans ] and fluoride-resistant Streptococcus mutans [fluoride-resistant (FR) S. mutans] in the presence of sucrose, and to evaluate its effect on cariogenic biofilm formation. S. mutans ATCC 25175 was continuously cultured in trypticase soy broth (TSB) containing NaF (70 ppm) for 40 days to generate FR S. mutans. FS and FR S. mutans were inoculated in TSB with or without 2% sucrose, and optical density and pH were measured every hour. An oral biofilm was formed using saliva bacteria and analyzed through confocal laser scanning microscopy and CFU count. Finally, the expression of glucosyltransferases genes of both S. mutans was investigated through RT-PCR. FR S. mutans exhibited slower growth and lower acidogenicity in the presence of sucrose compared to FS S. mutans . Both cariogenic and single species biofilm formation was lower in the presence of FR S. mutans, along with reduced number of bacteria. FR S. mutans showed significantly low levels of gtfB, gtfC, and gtfD expression compared to FS S. mutans . On the basis of results, FR S. mutans may be less virulent in the induction of dental caries.

• Restorative Dentistry and Endodontics
• /
• v.35 no.4
• /
• pp.295-301
• /
• 2010

Recent studies demonstrated that the combination of chlorhexidine (CHX) and sodium hypochlorite (NaOCl) resulted in the formation of a precipitate, para-chloroaniline (PCA). Alexdidine (ALX) is a kind of biguanides like CHX, and has stronger detoxification effect against the bacterial virulence factors such as lipoteichoic acid and lipopolysacchardide compared with CHX. The purpose of this study was to determine whether PCA was formed after chemical interaction between ALX and NaOCl using mass spectrometry. Mass spectrometry was performed for the mixture of five different concentrations of ALX (1, 0.5, 0.25, 0.125, 0.0625%) and 4% NaOCl. Results showed that the peak of PCA was not detected in mixed solutions of ALX and NaOCl in mass spectrometry analysis. The color of mixed solution of ALX and NaOCl after chemical interaction was light yellow to white, but there wasn't any precipitate found.

• Korean Journal of Microbiology
• /
• v.40 no.3
• /
• pp.237-243
• /
• 2004

The aim of this study is to investigate the detection rate of putative periodontopathogens, Porphyromonas gingivalis, Tannerella forsythia, and Actiobacillus actinomycetemcomitans, related to cardiovascular diseases(CVD). Plaques were sampled from 15 subjects (4 sites of denture base and/or tooth) with sterilized explorers and were transported in IX PBS. The detection of periodontopathogens was performed by polymerase chain reaction with species-specific primers based on 16S rDNA. The PCR products were cloned into pGEM-T easy vector and its nucleotides were sequenced in order to confirm the specificity. Our data showed that the detection rate of P. gingivalis and T forsythia in denture base of edentulous patients was 25％ and 75％, respectively. And the detection rate of P. gingivalis and T.forsythia in denture base of patient having one more tooth was 91％. The results indicate that plaque of denture base may serve as reservoirs of oral bacteria related to CVD.

• Journal of the korean academy of Pediatric Dentistry
• /
• v.34 no.1
• /
• pp.130-139
• /
• 2007

This study investigated the relationship between dental caries and various oral factors in subjects with Down's syndrome. We compared 25 subjects with Down's syndrome with 63 healthy control. The dental caries index and plaque index were examined, and the total salivary immunoglobulin A and S. mutans specific salivary immunoglobulin A concentration were measured using ELISA. The S. mutans counts, Lactobacillus counts and buffer capacity were measured with Dentocult test medium. The decayed and filled surface index of deciduous teeth in subjects with Down's syndrome was lower than in controls(p<0.001). The plaque index and total salivary immunoglobulin A concentration showed no difference, S. mutans specific salivary immunoglobulin A concentration and buffer capacity in subjects with Down's syndrome were lower than in controls(p<0.001). There was no significant difference between two groups in the S. mutans counts and Lactobacillus counts. In 9-11 year age group, S. mutans counts in subjects with Down's syndrome was lower than in controls(p<0.001) and S. mutans specific salivary immunoglobulin A concentration was lower(p<0.05). There was a high correlation among deciduous dental caries index and buffering capacity and S. mutans counts.

• Journal of the korean academy of Pediatric Dentistry
• /
• v.38 no.4
• /
• pp.368-375
• /
• 2011

The aim of this study was to evaluate the position of the mandibular foramen in panoramic radiographs of Korean children to provide information for successful inferior alveolar nerve block anesthesia. 240 panoramic radiographs of 7 to 15-year-old boys and girls were analyzed. The subjects were divided into 4 groups in boys and girls according to their age.; 7-8, 9-10, 11-12 and 13-15 years old. The shortest distances from the center of the mandibular foramen to the anterior border of ramus, to the posterior border of ramus, to the antegonial notch and to the mandibular notch and the perpendicular distances from the center of the mandibular foramen to the occlusal plane were measured. The following results were obtained. 1) Although the relative position of the mandibular foramen in the ramus of mandible tended to move anteriorly for both genders with age, the vertical position did not correlate with age. 2) The mandibular foramen moved upward in relation to the occlusal plane with age, and showed statistically significant correlation with age(p<0.05). 3) The mandibular foramina of boys, when compared to those of girls, were located more superiorly in relation to the occlusal plane and more superiorly and posteriorly in the ramus of mandible.

• Food Science of Animal Resources
• /
• v.36 no.6
• /
• pp.779-786
• /
• 2016

This study aimed to evaluate the prevalence of Listeria monocytogenes on livestock farms in Korea and determine their serotypes and genetic correlations. Twenty-five livestock farms in Korea (central: 15, south west: 7, south east: 3) were visited 2-3 times, and 2,018 samples (feces: 677, soil: 680, silage: 647, sludge: 14) were collected. Samples were enriched in LEB (Listeria enrichment broth) and Fraser broth media, and then plated on Palcam agar. The isolates were identified by PCR and 16S rRNA gene sequencing. Then, the sero-types, presence of virulence genes (actA, inlA, inlB, plcB, and hlyA), and antibiotic resistance were determined. Genetic correlations among the isolates were evaluated by analyzing the restriction digest pattern with AscI. Of the 2,018 samples, only 3 (0.15%) soil samples (FI-1-FI-3) from 1 farm in the south east region were positive for L. monocytogenes. Based on biochemical tests and multiplex PCR, the serotype of the isolates were 4ab (FI-1 and FI-3) and 3a (FI-2), which are not common in foodborne L. monocytogenes. The 3a sero-type isolate was positive for all tested virulence genes, whereas the 4ab serotype isolates were only positive for hlyA, actA, and inlA. The isolates were resistant to all 12 tested antibiotics, especially FI-3. The genetic correlations among the isolates were 100% for those of the same serotype and 26.3% for those of different serotypes. These results indicate that the prevalence of L. monocytogenes on livestock farms in Korea is low; however, the isolates are pathogenic and antibiotic resistant.

• Food Science of Animal Resources
• /
• v.36 no.6
• /
• pp.752-759
• /
• 2016

The objective of this study was to describe the growth patterns of Staphylococcus aureus in combinations of NaCl and $NaNO_2$, using a probabilistic model. A mixture of S. aureus strains (NCCP10826, ATCC13565, ATCC14458, ATCC23235, and ATCC27664) was inoculated into nutrient broth plus NaCl (0, 0.25, 0.5, 0.75, 1, 1.25, 1.5, and 1.75%) and $NaNO_2$ (0, 15, 30, 45, 60, 75, 90, 105, and 120 ppm). The samples were then incubated at 4, 7, 10, 12 and $15^{\circ}C$ for up to 60 d under aerobic or vacuum conditions. Growth responses [growth (1) or no growth (0)] were then determined every 24 h by turbidity, and analyzed to select significant parameters (p<0.05) by a stepwise selection method, resulting in a probabilistic model. The developed models were then validated with observed growth responses. S. aureus growth was observed only under aerobic storage at $10-15^{\circ}C$. At $10-15^{\circ}C$, NaCl and $NaNO_2$ did not inhibit S. aureus growth at less than 1.25% NaCl. Concentration dependency was observed for NaCl at more than 1.25%, but not for $NaNO_2$. The concordance percentage between observed and predicted growth data was approximately 93.86%. This result indicates that S. aureus growth can be inhibited in vacuum packaging and even aerobic storage below $10^{\circ}C$. Furthermore, $NaNO_2$ does not effectively inhibit S. aureus growth.

• Restorative Dentistry and Endodontics
• /
• v.30 no.5
• /
• pp.393-401
• /
• 2005

The purpose of this study was to compare the canal configuration after shaping by ProTaper rotary files and ProTaper hand files in resin simulated canals. Forty resin simulated canals with a curvature of J-shape and S-shape were divided into four groups by 10 blocks each Simulated root canals in resin block were prepared by ProTaper rotary files and ProTaper hand files using a crown-down pressureless technique All simulated canals were prepared up to size $\#25$ file at end-point of preparation. Pre- and post-instrumentation images were recorded with color scanner. Assessment of canal shape was completed with an image analysis program. Measurements were made at 0, 1, 2, 3, 4, 5, 6 and 7 mm from the apex. At each level, outer canal width, inner canal width, total canal width, and amount of transportation from original axis were recorded. Instrumentation time was recorded. The data were analyzed statistically using independent t-test. The result was that ProTaper hand files cause significantly less canal transportation from original axis of canal body and maintain original canal configuration better than ProTaper rotary files, however ProTaper hand files take more shaping time.

• Journal of the korean academy of Pediatric Dentistry
• /
• v.42 no.2
• /
• pp.151-157
• /
• 2015

The purpose of this study was to evaluate the effects of Photochemotherapy using a combination of erythrosine and standard halogen dental curing lights on the viability of Streptococcus mutans in the biofilm phase. To investigate the optimum treatment parameters, the researchers controlled the concentration of erythrosine, light irradiation time and the treatment time of erythrosine. The higher concentration of erythrosine (0, 10, 20, 40, 80 M) in the presence of light irradiation created greater effects in reducing the viability of S. mutans. The results showed a statistically significant difference among the antimicrobial effects in 20, 40, 80 M erythrosine. The higher irradiation time of light (0, 5, 15, 30, 60, 75s) in the presence of erythrosine showed greater effects in reducing the viability of S. mutans. There was statistically significant difference in 30, 60, 75 seconds. The higher treatment time of erythrosine (0, 1, 2.5, 5min) in the presence of erythrosine created greater effects on reduction of S. mutans viability. Statistically significant differences were found between 2.5 and 5 minutes of erythrosine treatment time. The results of this study showed that the photochemotherapy on S. mutans using erythrosine and the halogen dental curing lights conventionally used in dental clinics is effective in the condition of 20-40 M erythrosine concentration, irradiation time over 30 seconds, and erythrosine treatment time over 2.5 minutes.