• The Journal of Advanced Prosthodontics
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• v.6 no.2
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• pp.88-95
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• 2014

PURPOSE. The purpose of this study is to evaluate if pre-treatment with desensitizers have a negative effect on microtensile bond strength before cementing a restoration using recently introduced self-adhesive resin cement to dentin. MATERIALS AND METHODS. Thirty-five human molars' occlusal surfaces were ground to expose dentin; and were randomly grouped as (n=5); 1) Gluma-(Glutaraldehyde/HEMA) 2) Aqua-Prep F-(Fluoride), 3) Bisblock-(Oxalate), 4) Cervitec Plus-(Clorhexidine), 5) Smart protect-(Triclosan), 6) Nd:YAG laser, 7) No treatment (control). After applying the selected agent, RelyX U200 self-adhesive resin cement was used to bond composite resin blocks to dentin. All groups were subjected to thermocycling for 1000 cycles between $5-55^{\circ}C$. Each bonded specimen was sectioned to microbars ($6mm{\times}1mm{\times}1mm$) (n=20). Specimens were submitted to microtensile bond strength test at a crosshead speed of 0.5 mm/min. Kolmogorov-Smirnov, Levene's test, Kruskal-Wallis One-way Analysis of Variance, and Conover's nonparametric statistical analysis were used (P<.05). RESULTS. Gluma, Smart Protect and Nd:YAG laser treatments showed comparable microtensile bond strengths compared with the control group (P>.05). The microtensile bond strengths of Aqua-Prep F, and Cervitec Plus were similar to each other but significantly lower than the control group (P<.05). Bisblock showed the lowest microtensile bond strength among all groups (P<.001). Most groups showed adhesive failure. CONCLUSION. Within the limitation of this study, it is not recommended to use Aqua-prep F, Cervitec Plus and Bisblock on dentin when used with a self-adhesive resin cement due to the decrease they cause in bond strength. Beside, pre-treatment of dentin with Gluma, Smart protect, and Nd:YAG laser do not have a negative effect.

• Journal of the korean academy of Pediatric Dentistry
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• v.31 no.4
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• pp.605-616
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• 2004

Subinhibitory concentrations (sub-MICs) refer to concentrations below minimum inhibitory concentrations (MICs). The antimicrobial agents may be present at relatively high concentration, at least higher than bacterial MIC and thereafter be deserted off a surface and function at sub-MICs, perhaps by interfering with bacterial metabolism. Consequently, the aim of this study was to determine the effects of growth, in the presence of sub-MICs of antimicrobial agents, on the cell surface properties and virulence factors of mutans streptococci and to investigate the efficacy of a chemical approach in vitro. Streptococcus mutans Ingbritt and Streptococcus sobrinus 6715-7 were used. Eight antimicrobial agents (Sanguinaria extract;SG, Chlorhexidine digluconate;CHX, Fluoride;F, Propolis;PP, Hydrogen peroxide;HP, Triclosan;TC, Sodium dodecyl sulfate;SDS Cetylpyridinium chloride; CC) were diluted serially in broth to determine MICs and to compare the growth rate, acid production, hydrophobicity, adhesion activity to saliva coated hydroxyapatite, glucan synthesis and cellular aggregation of experiment groups (in the presence of sub-MICs) with those of control (in the absence of antimicrobial agents). Sub-MICs of antimicrobial agents affected the growth of cells, hydrophobicity, and adhesion of bacteria to saliva coated hydroxyapatite and glucan synthesis. They also resulted in a significant reduction in pH after 12 hours (p<0.05). By cells pretreated with proteinase K, either the aggregation induced by antimicrobial agents was completely inhibited or the aggregation titers were markedly increased. According to the results of the present study, each antimicrobial agent at sub-MICs could affect similar as its known action mechanism and could continually inhibit cariogenic bacteria at such concentrations. Thus, the use of these antimicrobial agents would be one of the effective methods to prevent dental caries.

• Journal of Environmental Science International
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• v.18 no.3
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• pp.245-254
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• 2009

In recent years, environmental pollution by phannaceuticals and personal care products (PPCPs) in the aquatic environment is of great concern worldwide. Recent studies have been reported to occur in a variety of environmental organisms such as surface, drinking and ground water, soils, sediments and hospitals. The purpose of this study was to evaluate the occurrence and environmental behavior of fourteen human PPCPs in surface waters of Mankyung River in South Korea. We were conducted to field survey for water quality and PPCPs analysis at November, 2006. PPCPs were analyzed by liquid chromatograph coupled with a tandem mass spectrometer (HPLC-MS/MS). The concentration of COD was measured to be 2.37$\sim$19.71 mg/L, which was belong to 4$\sim$5 grade in water quality criteria of lake. Station 2 that there is no pollution in upper stream, was appeared to lower concentration. The concentration of TN and TP, that is cause matter of eutrophication, were found to be 7.78$\sim$35.42 mg/L and 0.08$\sim$0.95 mg/L, respectively, which were exceeding 5 grade in Lake water quality criteria. The 11 kind of PPCPs compounds except levofloxacin and triclosan were detected to Mankyung river. PPCPs concentrations of STP(Sewer Treatment Plant) effluents and aquatic environment in Mankyung river have been detected in the range from dozens of ng/L to hundreds of ${\mu}g/L$ that by order of atenolol, carbamazepine, propranolol, Ibuprofen, erythromycin, ifenprodil, clarithromycin, mefenamic acid, fluconazole, indomethacin, disopyramide. PPCPs concentration of Station 1 and 5, which was influenced by Jeonju STP and Wanju STP, was detected high values. Station 2 that there is no pollution, showed lower values. Station 3 which joined Gosan stream and Jeonju stream and station 4 which influenced by stock wastewater was detected to low values.

• Applied Chemistry for Engineering
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• v.30 no.3
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• pp.303-307
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• 2019

Sophorolipid is a biological surfactant of the glycolipid structure produced by Candida bombicola, which generally exists as a mixture of acidic and lactonic forms. In this study, we investigated physico-chemical properties, antibacterial activities, and cytotoxicity of the sophorolipid containing more than 96% of the lactonic form, produced by the gene regulation of production strains and application of a metabolic engineering technique. The lactonic sophorolipid showed a weak acidity in the range of pH 3.2~4.6 when diluted in water at the concentrations from 1 to 0.001 wt%. The $pK_a$ value of the lactonic sophorolipid was estimated to be around 4.3 from the acid-base titration curve. The critical micelle concentration (CMC) of the lactonic sophorolipid was $10^{-2}wt%$, at which the surface tension of aqueous solution was reduced to 36 mN/m. The lactonic sophorolipid showed the minimum inhibitory concentrations (MIC) of $1{\times}10^{-3}$ and $5{\times}10^{-3}g/mL$ against Propionibacterium acnes and Corynebacterium xerosis, respectively. The MTT (3-(4,5-Dimethylthiazol-2-yl)-2,5-Diphenyltetrazolium Bromide] assay showed that cytotoxicity of the lactonic sophorolipid was ten times lower than that of triclosan.

• Journal of Life Science
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• v.31 no.3
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• pp.330-337
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• 2021

This study was conducted to investigate the potential of Stewartia koreana as oral healthcare materials. The antibacterial activity of ethanol extracts from leaves and branches of S. koreana against oral bacteria was confirmed. The leaf and branch extracts (1 mg/disc) showed antibacterial activity against P. gingivalis only among several tested oral bacteria. The leaf extracts showed higher antibacterial activity, with values similar to those of chlorhexidine, which was used as a positive control. The MIC of the leaf extract against P. gingivalis was 0.4 mg/ml and showed bacteriostatic action. The inhibitory effects of the extract on biofilm formation and on gene expression related to biofilm formation by P. gingivalis were determined by biofilm biomass staining, scanning electron microscopy (SEM), and qRT-PCR analysis. The biofilm production rate and cell growth of P. gingivalis in the cultures treated with 0.2-2.0 mg/ml of S. koreana leaf extracts were significantly decreased in a concentration-dependent manner. The inhibitory effect on the formation of P. gingivalis biofilms at concentrations of 1 mg/ml was confirmed by SEM. The qRT-PCR analysis showed concentration-dependent suppression of the fimA and fimB gene expression associated with fimbriae formation in the cultures treated with 0.2-2.0 mg/ml S. koreana leaf extract. These results support the conclusion that S. koreana leaf extracts can be used as oral healthcare materials derived from natural materials, as demonstrated by the antibacterial action and inhibition of biofilm formation of P. gingivalis.