Heat treatment following surface silanization in rebonded tribochemical silica-coated ceramic brackets: shear bond strength analysis

OBJECTIVE: This study aimed to evaluate the effects of heat treatment on the tribochemical silica coating and silane surface conditioning and the bond strength of rebonded alumina monocrystalline brackets. MATERIAL AND METHODS: Sixty alumina monocrystalline brackets were randomly divided according to adhesive base surface treatments (n=20): Gc, no treatment (control); Gt, tribochemical silica coating + silane application; Gh, as per Gt + post-heat treatment (air flux at 100ºC for 60 s). Brackets were bonded to the enamel premolars surface with a light-polymerized resin and stored in distilled water at 37ºC for 100 days. Additionally, half the specimens of each group were thermocycled (6,000 cycles between 5-55ºC) (TC). The specimens were submitted to the shear bond strength (SBS) test using a universal testing machine (1 mm/min). Failure mode was assessed using optical and scanning electron microscopy (SEM), together with the surface roughness (Ra) of the resin cement in the bracket using interference microscopy (IM). 2-way ANOVA and the Tukey test were used to compare the data (p>0.05). RESULTS: The strategies used to treat the bracket surface had an effect on the SBS results (p=0.0), but thermocycling did not (p=0.6974). Considering the SBS results (MPa), Gh-TC and Gc showed the highest values (27.59±6.4 and 27.18±2.9) and Gt-TC showed the lowest (8.45±6.7). For the Ra parameter, ANOVA revealed that the aging method had an effect (p=0.0157) but the surface treatments did not (p=0.458). For the thermocycled and non-thermocycled groups, Ra (µm) was 0.69±0.16 and 1.12±0.52, respectively. The most frequent failure mode exhibited was mixed failure involving the enamel-resin-bracket interfaces. CONCLUSION: Regardless of the aging method, Gh promoted similar SBS results to Gc, suggesting that rebonded ceramic brackets are a more effective strategy

JOURNAL OF PURE AND APPLIED MICROBIOLOGY

The antimicrobial activities of the extracts of ethyl acetate, chloroform, methanol, ethanol and acetone Silene laxa Boiss. & Kotschy and Silene caramanica Boiss. & Heldr were studied by disc diffusion method. These extracts were tested against seven bacteria and one fungus, which revealed various levels of antimicrobial activity. The ethanol extracts of Silene laxa leaves showed the best antibacterial activity against Pseudomonas aeruginosa, Enterobacter cloacae, Bacillus megaterium (15mm 30 mu l(-1)). The chloroform extracts of S. laxa branches displayed the best antibacterial activity against E. cloacae (16mm 30 mu l(-1)). The ethyl acetate extracts of S.laxa fruits showed the best antibacterial activity against B.megaterium and E.cloacae (15mm 30 mu l(-1)). The methanol extracts of S. laxa leaves showed the best antibacterial activity against Staphylococcus aureus (18 mm 30 mu l(-1)). The methanol extracts of S. laxa fruits showed the best antibacterial activity against B.megaterium (14mm 30 mu(-1))

Resistances of antibiotics and heavy metals in Enterobacteriaceae spp. isolated from gilis and intestines of Achanthobrama marmid (Heckel, 1843 from Sir Dam lake Turkey

PubMedID: 20112859A total of 94 bacteria, associated with wild Achanthobrama marmid (Heckel, 1843) in Sir Dam lake of Turkey identified. Subsequently, selected isolates were characterized and identified to the genus level. The 94 members of Enterobacteriaceae were isolated in the gills and intestines, and among the isolates, E. coli were represented at a rate of 55%, Shigella spp. at a rate of 21%, Salmonella spp. at a rate of 9%, Citrobacter spp. at a rate of 9%, Klebsiella spp. at a rate of 3% and Proteus spp., at a rate of 3%. A total of 94 bacteria resistant to antibiotics and heavy metals were isolated from total 47 of A. marmid samples and were investigated. Viable counts of antibiotic resistant bacteria isolated from gill and intestinal content samples showed high frequencies of resistance to Penicilline-G (KP) (68%), CZ (54%), FOX (48%), while the proportion of CRO (39%) and CTX (36%) resistance was low. In this research, heavy metal contamination in Sir Dam lake water samples and resistance frequency against heavy metals in isolated bacteria from gill and intestinal contents in A. marmid were investigated. Heavy metal contamination such as nickel (Ni), cadmium (Cd), copper (Cu) and chromium (Cr) determined diverse rate (except Mn) in water samples. The resistance frequency of the isolates was revealed different rate for the following heavy metals: Ni, Cd, Cu and Cr. When the concentration of heavy metals increased, the resistance against heavy metals in diverse genus of isolates in different rate decreased. © Triveni Enterprises, Lucknow (India)

Effects of sandblasting and silica coating on the bond strength of rebonded mechanically retentive ceramic brackets

Introduction: The aim of this study was to determine the bond strength of rebonded mechanically retentive ceramic brackets after treatment with 2 abrasive techniques. Methods: In addition to a group of new brackets, 3 groups were treated according to the following conditions of debonded ceramic bracket bases: sandblasting, sandblasting + silane, and silica coating + silane (15 in each group). Treated ceramic brackets were rebonded on premolars. The samples were stored in distilled deionized water for 24 hours at 37°C in an incubator and then thermocycled for 1000 times between 5°C and 55°C. Shear force was applied to the enamel-adhesive interface until debonding. Results: The highest bond strength values were in the silica coating + silane and the new bracket groups (12.7 and 12.0 MPa, respectively), followed by the sandblasting + silane group (10.5 MPa). The sandblasting group had a significantly lower bond strength value (4.5 MPa). No enamel fracture was noted in any sample tested. In the new bracket and the sandblasting + silane groups, 20% of the samples had adhesive remnant index scores of 2, and 80% had scores of 3. In the sandblasting group, all specimens debonded at the bracket-adhesive interface. The silica coating + silane group showed mixed failures. Conclusions: Sandblasting + silane and silica coating + silane applications on debonded ceramic bracket base can produce bond strengths comparable with new brackets. © 2008 American Association of Orthodontists

Porcelain refinishing with two different polishing systems after orthodontic debonding

PubMedID: 18298209Objective: To compare the effects of two polishing systems on the surface roughness of three types of porcelain after orthodontic debonding. Materials and Methods: A total of 90 porcelain discs were fabricated from feldspathic (n = 30), leucite-based (n = 30) or lithia disilicate-based (n = 30) ceramics. Ten samples in each group served as the control and received no surface treatment. The remaining 60 samples in three of the porcelain groups were bonded with lower incisor brackets and debonded using a testing machine in shear mode at a rate of 1 mm/minute crosshead speed. After debonding, the remaining adhesive resin was removed with a tungsten carbide bur. Then, two experimental subgroups (10 each) in each porcelain group were treated as follows: in the first subgroup, porcelain polishing wheel and polishing paste were applied, whereas in the second, polishing was performed using a series of Sof-Lex discs. The average surface roughness (Ra) of the all samples was evaluated using SPM/AFM (surface probe microscope/atomic force microscope). Data were statistically analyzed by analysis of variance for each porcelain material and polishing method. Results: The polishing techniques affected surface roughness significantly. There were significant differences between the groups; higher Ra values were obtained with the use of porcelain polishing wheel and polishing paste (P < .001). Conclusion: The application of Sof-Lex discs can produce smoother porcelain surfaces than porcelain polishing wheel and polishing paste. © 2008 by The EH Angle Education and Research Foundation, Inc

Heavy metal resistances of enterobacteriaceae from Aksu river (Turkey) polluted with different sources

In this study, the heavy metal contamination of Aksu river, which have urban, industrial and agricultural effluents and also resistance frequency against heavy metals, belonging to Enterobacteriaceae (representative of the human and animal commensal flora) (66 isolates) and Pseudomonas sp., (only one isolate) were investigated. The samples were taken from five different sample stations settled on Aksu river and its brooks. The level of heavy metals, namely nickel, cadmium, copper and chromate, in water samples were measured by using a Perkin-Elmer 3110 atomic absorption spectrophoto-meter. Resistance frequency of the isolates was analyzed by agar dilution method. The highest resistances against all concentrations of all metals were found out Klebsiella sp. strains. Highest ratio of heavy metal resistance in the isolates was determined in 1 mM nickel (97 %), copper (88 %), cadmium (61 %) and chromate (25 %) concentration, respectively. No resistant bacteria was observed at 7 mM Cu and Cd and 5 mM Ni and Cr concentrations. These results suggest that releasing of urban and industrial wastewater into running surface waters without treatment processess increases the bacterial resistance against heavy metals. Therefore, the infectious diseases and heavy metal resistance are spreaded on large areas

Determination of microbial quality and plasmid-mediated multidrug resistant bacteria in fountain drinking water sources in Turkey

PubMedID: 23741812The bacterial contamination as the total aerobic bacteria, coliform and fecal coliform numbers were determined and analyzed for temperature, pH, conductivity and dissolved oxygen in seasonally collected water samples from fifteen different stations placed in Adana-Tufanbeyli road line during March 2008-January 2009. In addition, antibiotic resistance profiles of isolates were examined against frequently used antibiotics, and analyzed plasmid DNAof multiple antibiotic resistant (MAR) isolates. Total aerobic bacteria in fountain water samples was determined as 3×103 CFU ml-1 and total and fecal coliforms were determined 460 MPN/100 ml. Results obtained from biochemical analysis showed that 121 of the isolates were Proteus vulgaris, 69 Escherichia coii, 51 Pseudomonas aeruginosa and 28 Citrobacter spp. According to these results, the existence of Vibrio parahaemolyticus in stations 2 and 10, and Streptococcus faecalis in stations 11 and 15 respectively were confirmed. Clostridium perfringens was not detected in water samples. A total of 273 isolates were tested for antimicrobial susceptibility by agar disc diffusion methods. A total of sixteen antibiotics were used for determination of antibiotic resistance of isolates. Resistance to bacitracin, vancomycine, cephalothin and ampicillin was detected in 77,77,63 and 50%, respectively. Multiple antibiotic resistance (MAR) value ? 0.25 was determined in 68.4%of identified 273 isolates and meaning of this percentage were resistant to four and more antibiotics. Plasmid DNA was isolated from 22 isolates with multiple antibiotic resistance index ranged from 0.3 to 0.6 taken randomly by agarose-gel electrophoresis, some of them contain a high-molecular weight plasmid DNA. Highlight of our study that the appearance of potential antibiotic resistances in fountain drinking water requires increased surveillance for risk assessment and prevention strategies to protect public health. © Triveni Enterprises

The effect of certain operating parameters on the grinding efficiency in grinding the Kokaksu bauxite in a stirred mill and comparison of the grinding efficiency with that of the bond mill [Karistirmali bi·lyali degi·rmende kokaksu boksi·ti·ni·n ögütülmesi·nde bazi çalişma parametreleri·ni·n ögütme veri·mi·ne etki·si· ve bond degi·rmeni· i·le ögütme veri·mli·li·kleri·ni·n karşilaştirilmasi]

This paper presents grindability of the Kokaksu (Zonguldak) bauxite crushed below -3.35 mm in a stirred mill. It was established that the operating parameters of the stirred mill such as the ball size, stirring time and the stirring speed have a considerable effect on the fineness of the product and these parameters are directly related to energy consumption. For grinding in a unit time, increasing the ball size yielded finer products and also increased the energy consumption. It was determined from the balls of various diameters tested that the optimal ball size for the feeding size was 6.5 mm. On the other hand, an increase in stirring time and stirring speed both yielded finer products and increased the energy consumption. To conclude, the yield of finer products by means of the stirred mill was established to be directly related to the energy consumed per unit time. In the last stage, the bauxite sample was ground in a conventional Bond mill and the grinding efficiency was compared with that of the stirred mill. It was established that the stirred mill is more advantageous in grinding fine particles (140 µm) in terms of energy consumption. However, for both size groups, the stirred mill was established to be advantageous in terms of grinding time. The stirred mill yielded products of a few micrometers in a few minutes

Prediction of metallurgical coke strength from the petrographic composition of coal blends

Turkey, especially Zonguldak on the West Coast of Black Sea region, has large reserves of bituminous coal that can be used either directly or in blends with other coals for metallurgical coke production. It is possible to predict the coking properties of these coals by petrographic analysis. In this study, semi- and non-coking coals were blended with coking bituminous coals in varying proportions and an estimation was made as to their stability factors through petrographic techniques. It was established that semi- and non-coking bituminous coals could be used in the production of metallurgical coke.ZKU-AFP-97-111-003-05The authors would like to express their gratitude to Zonguldak Karaelmas University Scientific Research Fund (ZKU-AFP-97-111-003-05) for their financial assistance at the project level and to Assoc. Prof. Dr. Sait Kizgut for measurements of petrographic analyses