Semiha Özkan

Effect of different finishing techniques for restorative materials on surface roughness and bacterial adhesion

STATEMENT OF PROBLEM The formation of biofilm and bacterial accumulation on dental materials may lead to the development of gingival inflammation and secondary caries. PURPOSE The purpose of this study was to examine the effect of different surface finishing and polishing methods on surface roughness and the adhesion of S. mutans bacteria to 2 new-generation indirect composite resins, 1 direct composite resin, and 1 ceramic material. MATERIAL AND METHODS Forty specimens (10 x 10 x 2 mm) of each material, indirect composite resins (SR Adoro, Estenia), direct composite resin (Tetric), and a ceramic material (VITABLOCS Mark II), were fabricated. Specimens were divided into 4 groups (n=10) that were treated with 1 of the following 4 surface finishing techniques: diamond rotary cutting instrument, sandpaper discs (Sof-Lex), silicone-carbide rubber points (Shofu), or a felt wheel with diamond paste. Surface roughness was measured with a profilometer. Test specimens were covered with artificial saliva and mucin to produce pellicle. Bacterial suspension (10(9) CFU/ml) was then added to the pellicle-coated specimens, and bacterial adhesion was determined using a confocal laser microscope and image analyzing program. Data were analyzed with 2-way ANOVA, followed by Tukey HSD test, Pearson correlation, and regression analysis (alpha=.05). RESULTS The highest surface roughness values were recorded in SR Adoro and diamond rotary cutting instrument groups. The lowest vital S. mutans adhesion was seen in the ceramic group and in SR Adoro indirect composite resin (P<.05). CONCLUSIONS Bacterial adhesion to indirect composite resin materials differed from that to ceramic material after surface treatments. A positive correlation was observed between surface roughness and the vital S. mutans adhesion.

Synthesis, biological evaluation and 2D-QSAR analysis of benzoxazoles as antimicrobial agents.

A new series of 5(or 6)-nitro/amino-2-(substituted phenyl/benzyl)benzoxazole derivatives were synthesized and evaluated for antibacterial and antifungal activities against Staphylococcus aureus, Bacillus subtilis, Klebsiella pneumoniae, Pseudomonas aeruginosa, Escherichia coli, Candida albicans and their drug-resistant isolate. Microbiological results indicated that the synthesized compounds possessed a broad spectrum of activity against the tested microorganisms at MIC values between > 400 and 12.5 microg/ml. The results against B. subtilis, P. aeruginosa, drug-resistant B. subtilis, drug-resistant E. coli, and C. albicans isolate for these kinds of structures are quite encouraging. The 2D-QSAR analysis of a set of newly and previously synthesized benzoxazoles tested for growth inhibitory activity against B. subtilis ATCC 6633 was performed by using the multivariable regression analysis. The activity contributions for substituent effects of these compounds were determined from the correlation equation for predictions of the lead optimization.

Synthesis, antimicrobial activity, pharmacophore analysis of some new 2-(substitutedphenyl/benzyl)-5-[(2-benzofuryl)carboxamido]benzoxazoles.

The synthesis and antimicrobial activity of a new series of 2-(substitutedphenyl/benzyl)-5-[(2-benzofuryl)carboxamido]benzoxazole derivatives 3-12 were described. The in vitro antimicrobial activity of the compounds was determined against some Gram-positive, Gram-negative bacteria and fungi and their drug-resistant isolates in comparison with standard drugs. Antimicrobial results indicated that the synthesized compounds possessed a broad spectrum of activity with MIC values 500-15.625 microg/ml. In the series, the most active compound against Candida krusei and Candida albicans isolate is 8 with MIC value 31.25 microg/ml. However, it is one dilution less potent than the compared fluconazole. Some of the screened compounds exhibit significant activity, having MIC value as 31.25 microg/ml in Pseudomonas aeruginosa having same activity as Rifampicin. Furthermore, considering the worth of developing new antibacterial agents against drug-resistant P. aeruginosa the present study explores the structure-activity relationship analysis of 2-(substitutedphenyl/benzyl)-5-[(2-benzofuryl)carboxamido]benzoxazoles using 3D-common features pharmacophore hypotheses approach.

Alkaloid profile and antimicrobial activity of Lupinus angustifolius L. alkaloid extract

Purpose of the present study was to evaluate alkaloid profile of the aerial parts of Lupinus angustifolius growing in Turkey by capillary gas chromatography-mass spectrometry (GC-MS). Fifteen alkaloids were identified by capillary GC-MS. 13α-Hydroxylupanine (50.78%) and lupanine (23.55%) were determined as the main alkaloids in the aerial parts of L. angustifolius. Ammodendrine, isoangustifoline, tetrahydrorhombifoline, angustifoline, α-isolupanine, 5,6-dehydrolupanine, 11,12-dehydrolupanine, 13α-acetoxylupanine, 13α-isovaleroyloxylupanine, 13α-valeroyloxylupanine, 13α-tigloyloxylupanine, 13α-cis-cinnamoyloxylupanine and 13α-cis-cinnamoyloxy-17-oxolupanine were identified as the minor alkaloids of the plant. Furthermore, antibacterial and antifungal activities of L. angustifolius alkaloid extract were tested against standard strains of the following bacteria; Escherichia coli, Pseudomonas aeruginosa, Bacillus subtilis and Staphylococcus aureus as well as the fungi; Candida albicans and C. krusei. The alkaloid extract showed significant activity on B. subtilis, S. aureus and P. aeruginosa while it was weakly active on E. coli. On the other hand, the extract possessed moderate activity against C. albicans and C. krusei.

Synthesis and antimicrobial activity of new 1,2,4-triazole and 1,3,4-thiadiazole derivatives

In this study, new 3-[(1(2H)-phthalazinone-2-yl(methyl/ethyl]-4-aryl-1,2,4-triazole-5-thione and 2-[[1(2H)-phthalazinone-2-yl]methyl/ethyl]-5-arylamino-1,3,4-thiadiazole derivatives were synthesized. Antimicrobial properties of the title compounds were investigated against two Gram (+) bacteria (S. aureus, B. subtilis), two Gram ( − ) bacteria (P. aeruginosa, E. coli) and two yeast-like fungi (C. albicans and C. parapsilosis) using the broth microdilution method. Generally the compounds were found to be active against B. subtilis and the fungi. Derivatives carrying a 1,3,4-thiadiazole ring generally showed higher antimicrobial activity against B. subtilis and the fungi when compared to other synthesized compounds.

Slime production and proteinase activity of Candida species isolated from blood samples and the comparison of these activities with minimum inhibitory concentration values of antifungal agents.

Slime and proteinase activity of 54 strains consisting of 19 Candida parapsilosis and 35 C. albicans strains isolated from blood samples were investigated in this study. Ketoconazole, amphothericin B, and fluconazole susceptibility of Candida species were compared with slime production and proteinase activity of these species. For both Candida species, no correlation was detected between the slime activity and minimum inhibitory concentration (MIC) values of the three antifungal agents. For both Candida species no correlation was detected between the proteinase activity and the MIC values of amphothericin B, and fluconazole however, statistically significant difference, was determined between the proteinase activity and MIC values of ketoconazole (p = 0.007). Slime production was determined by using modified Christensen macrotube method and proteinase activity was measured by the method of Staib. Antifungal susceptibility was determined through the guidelines of National Committee for Laboratory Standards (NCCLS M27-A).

PVA/PAA-Based Antibacterial Wound Dressing Material with Aloe Vera

The incorporation of drugs into the dressings make these dressings antimicrobial and help in control of infection around the wound. The wound dressing materials based on PVA/PAA, ciprofloxacin HCl, and aloe vera have been designed and developed so that the wound undergoes proper healing and scar formation is minimal. These wound dressing materials are produced using the electrospinning method. The wound dressing materials are characterized using the FT-IR, DSC, DTA, TGA, and SEM techniques. The wound dressing materials are tested for microbial activity tests and drug release experiments. Controlled ciprofloxacin HCl release is observed.

Gentamicin Release from Photopolymerized PEG Diacrylate and pHEMA Hydrogel Discs and Their In Vitro Antimicrobial Activities

Hydrogels based on poly(ethylene glycol)-diacrylate (PEG-DA) and 2-hydroxyethyl methacrylate (HEMA) were polymerized with cross-linking agent ethylene glycol diacrylate (EGDMA) under mild photoinitiating conditions. PEG-DA and HEMA concentrations of disks with 1 ± 0.3 mm thickness were 30% and 50% w/w and 40% and 60% w/w, respectively. Gentamicin sulphate was incorporated into the hydrogel during photopolymerization and its release kinetics were tested by spectrophotometric method at 255 nm wavelength in phosphate buffer (pH 7.4) and citrate buffer (pH 2.2). The drug release in citrate buffer was faster compared with to phosphate buffer. The release of drug from 40% HEMA containing hydrogel showed Fickian diffusion mechanisms in phosphate buffer (pH 7.4). Antimicrobial efficiency of the samples was tested by agar diffusion method in two different bacterial cultures (Pseudomonas aeruginosa [ATCC 10145], Staphylococcus aureus [ATCC 25923]). Inhibition zone diameter (mm) surrounding each sample was measured after 24 hr incubation of drug loaded disks onto agar plates at 37°C. Inhibition zone formation also confirms that gentamicin sulphate preserves its antimicrobial activity after subjected to photopolymerization conditions.

Development of topical hydrogels of terbinafine hydrochloride and evaluation of their antifungal activity

Abstract The purpose of this study was to prepare hydrogels and microemulsion (ME)-based gel formulations containing 1% terbinafine hydrochloride (TER-HCL) and to evaluate the use of these formulations for the antifungal treatment of fungal infections. Three different hydrogel formulations were prepared using chitosan, Carbopol® 974 and Natrosol® 250 polymers. A pseudo-ternary phase diagram was constructed, and starting from ME formulation, a ME gel form containing 1% Carbopol 974 was prepared. We also examined the characteristic properties of the prepared hyrogels. The physical stability of hydrogels and the ME -based gels were evaluated after storage at different temperatures for a period of 3 months. The release of TER-HCL from the gels and the commercial product (Lamisil®) was carried out by using a standard dialysis membrane in phosphate buffer (pH 5.2) at 32 °C. The results of the in vitro release study showed that the Natrosol gel released the highest amount of drug, followed by Carbopol gel, chitosan gel, commercial product, and the microoemulsion-based gel in that order. In vitro examination of antifungal activity revealed that all the prepared and commercial products were effective against Candida parapsilosis, Penicillium, Aspergillus niger and Microsporum. These results indicate that the Natrosol®-based hydrogel is a good candidate for the topical delivery of TER-HCL.

Candida albicans and Pseudomonas aeruginosa adhesion on soft contact lenses

BackgroundIn this study it was aimed to determine the adherence of Pseudomonas and Candida to contact lens surfaces, and to determine the difference in adherence between five contact lens types. Biofilm-negative control strains were also used to emphasize the difference between biofilm-positive and biofilm-negative strains in adherence.MethodsFive different soft contact lenses were used to investigate the adherence of Pseudomonas aeruginosa and Candida albicans strains. P. aeruginosa ATCC 27853, P. aeruginosa ATCC 10145, C.albicans ATCC 10231 standard strains and C. albicans clinical isolate were included in the study. Slime formation was investigated by two methods; modified Christensen macrotube method, and a modified microtiter plate test. P. aeruginosa and C. albicans slime formation on soft contact lenses was studied in adherence and separation phases. Pseudomonas and Candida suspensions were serially diluted and inoculated to blood agar and sabouraud dextrose agar surfaces respectively. After overnight incubation, the colonies were counted. Sterile unworn contact lenses were used as negative controls, and bacterial and fungal culture suspensions were used as positive controls. The experiments were conducted in three parallel series.ResultsThe number of adherent Pseudomonas was as follows from high to low in polymacon, etafilcon A, hilafilcon, ocufilcon and lotrafilcon contact lenses respectively. However, the number of adherent yeast were determined higher in lotrafilcon and ocufilcon contact lenses, followed by hilafilcon, etafilcon A and polymacon contact lenses. Biofilm-negative Pseudomonas ATCC standard strain and Candida clinical isolate were used to confirm that the number of adherent cells were lower than the biofilm-positive ones.ConclusionsThis study demonstrates that in addition to the contact lens properties, the microorganisms themselves and their interactions with the lens material also play an important role in adherence.