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Sample records for carbamide

  1. HOME BLEACHING TECHNIQUE USING CARBAMIDE PEROXIDE

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    Rahmi Alma Farah Adang

    2015-06-01

    Full Text Available There are two basic kinds of tooth whitening agents. The first is over the counter materials and the other is material used by the dentist or under dentist control. Home bleaching is a technique using 10% carbamide peroxide on a tray applied by patient under dentist supervision. This paper is a review of the effect of 10% carbamide peroxide home bleaching technique. It is revealed that this method is simple, safe, economic, and has short chairside time.

  2. OPTICAL PROPERTIES OF CARBAMIDE AQUEOUS SOLUTIONS

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    E. V. Avramenko

    2016-03-01

    Full Text Available Subject of Research. The paper presents the results of measurements of refractometric properties (refractive index n, its temperature factor dn/dt and the ultraviolet spectral absorption in carbonic acid diamide aqueous solutions (carbamide depending on solid residue mass fraction md = 0-50 % and on temperaturet = 10-70 °C.Method of Research. Laboratory methods ofliquid-phase medium refractometry and ultraviolet spectrophotometry were applied for the research. We carried out computational modeling of electronic states spectrum for the carbonic acid diamide molecule and theoretical calculation of the fundamental electronic absorption of the molecule in the ultraviolet wavelenght region.Main Results. We have established that the solution concentration md has a nonlinear character and may be represented by the quadratic polynomial with the error Δn= ± 0,0005. We have shown the refractive indexdependence on temperature n(t changes in linear fashion att = 10-70 °C.At that, the inclination of lines n(t increases at the increase of md; so, the temperature factor dn/dt may be approximated by the quadratic polynomial. Transmission spectra of solutions in the spectral region λ= 225-760 nm have no special features except for the sharp edge in the short-wavelength region; the fundamental electronic absorptionis responsible for it. We have established that dispersion dependences of the refraction index n(λ;md in aqueous solutions of carbamide at λ= 360-760 nm and at md = 0-50 % may be calculated with the satisfactory error without additional adjustable parameters from the ultraviolet absorption data in terms of the one-dimentional oscillator Lorentz model.PracticalRelevance. Representedmeasurements of carbonic acid diamide aqueous solutions optical properties may be applied for the adjustment and calibration of commercial refractometers at processing lines of the AdBlue reagent manufacture for the selective catalytic reduction (SCR of motor transport

  3. The dysprosium nitrate-carbamide-water and the holmium nitrate-carbamide-water systems at 30 deg C

    International Nuclear Information System (INIS)

    Dysprosium nitrate-carbamide-water(1) and holmium nitrate-carbamide-water(2) systems are studied at 30 deg C by the solubility method. In both systems formed are incongruently soluble compounds of Dy(NO3)3x3CON2H4, Ho(NO3)3x3CON2H4 composition and congruently soluble ones of Dy(NO3)3x4CON2H4, Ho(NO3)3x4CON2H4 composition. Presented are solubility diagrams of the systems

  4. Comparing the Effect of Different Bleaching Regims of Carbamide Peroxide on Microhardness of Z250 Composite

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    B Esmaeili

    2015-11-01

    Full Text Available Introduction: Bleaching products with oxidizing mechanism can exert side effects on the restorative materials existing in the oral cavity. Since bleaching agents are applied in different concentrations, the present study aimed to compare the effect of different bleaching regims of carbamide peroxide on microhardness of Z250 microhybride composite. Methods: In this in vitro study , 32 specimens of micro hybride composite (Z250 were made which were randomly divided into 4 subgroups (n=8: G1: bleached with10% carbamide peroxide 4 hours a day for 2 weeks G2: bleached with 16%carbamide peroxide 3 hours a day for 2 weeks G3: bleached with 22%carbamide peroxide 1hour a day for 2 weeks G4: the control subgroup stored in distilled water at 37◦c for 2 weeks. Microhardness of specimens was measured before and after bleaching using Vickers hardness testing machine. Moreover, the study data were analyzed statistically applying Anova and t-test (&alpha= 0.05. Results: This study findings revealed that using bleaching agent significantly decreased the  microhardness of composite resin in the bleaching groups compared to the control group, though the concentration of carbamide peroxide produced no significant effect on the microhardness value. (p>0.13 Conclusion: Bleaching therapy can cause a reduction in microhardness of Z250 composite and different concentrations of carbamide peroxide can reduce microhardness of Z250 to the same value.

  5. Effect of Surface Polishing on Mercury Release from Dental Amalgam After Treatment 16% Carbamide Peroxide Gel

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    Z. Khamverdi

    2011-03-01

    Full Text Available Objectives: This study evaluated the effect of surface polishing on mercury release from dental amalgam after treatment with 16% carbamide peroxide gel.Materials and Methods: Ninety-six samples from two different amalgam brands were prepared in truncated cone-shaped PVC polymer molds with an external surface area of 195 mm². Half of the specimens were polished with green and red rubber, a brush and tin oxide paste at low speed. Samples were treated with 16% carbamide peroxide gel intubes containing 3 mL of carbamide peroxide gel and 0.1 mL of distilled water for 14 and 28 hours. Subsequently, carbamide peroxide gel on the sample surfaces was rinsed away with 7.0 mL of distilled water until the volume of each tube increased to 10 mL. Themercury level of each solution was measured using the VAV–440 mercury analyzer system.Considering the surface area of each amalgam disc, mercury amounts were calculated in μg ⁄mm². Data were analyzed using two-way ANOVA.Results: There were significant differences between the mean levels of mercury release from polished vs. unpolished amalgam surfaces after treatment with 16% carbamide peroxide.Increasing the storage time from 14 to 28 hours did not result in significant changes in the amount of mercury release. There was no significant interaction effect between amalgam surface polish and storage time statistically.Conclusion: Polished amalgam restorations release less mercury after treatment with carbamide peroxide bleaching gel in comparison with unpolished amalgam restorations.

  6. Effect of Surface Polishing on Mercury Release from Dental Amalgam After Treatment 16% Carbamide Peroxide Gel

    OpenAIRE

    Z. Khamverdi; Masoum, T.; Sh. Kasraei; Azarsina, M.

    2011-01-01

    Objectives: This study evaluated the effect of surface polishing on mercury release from dental amalgam after treatment with 16% carbamide peroxide gel. Materials and Methods: Ninety-six samples from two different amalgam brands were prepared in truncated cone-shaped PVC polymer molds with an external surface area of 195 mm2. Half of the specimens were polished with green and red rubber, a brush and tin oxide paste at low speed. Samples were treated with 16% carbamide peroxide gel in tubes co...

  7. Evaluation of remineralization capacity of casein phosphopeptide-amorphous calcium phosphate on the carbamide peroxide treated enamel

    OpenAIRE

    Penumatsa, Narendra Varma; Kaminedi, Raja Rajeswari; Baroudi, Kusai; Barakath, Ola

    2015-01-01

    Objective: The aim of this study was to evaluate the potential of casein phosphopeptide-amorphous calcium phosphate (CPP-ACP) in remineralizing the bleached enamel surface using micro-hardness. Materials and Methods: Thirty human enamel slabs were randomly divided into three groups (n = 10). Groups A and B were exposed to 20% carbamide peroxide and 35% carbamide peroxide gel, respectively. After the exposure to the bleaching agent, the slabs were kept in artificial saliva for 1-week. Group C ...

  8. Temperature Effect on Hydroxyapatite Preparation by Co-precipitation Method under Carbamide Influence

    OpenAIRE

    Luo Jing; Chen Juan; Li Wenzhao; Huang Zhiliang; Chen Changlian

    2015-01-01

    Hydroxyapatite crystal was prepared by homogeneous co-precipitation method using a mixture of Calcium nitrate and diammonium phosphate as raw materials and carbamide as the buffering agent. To analyzed the influence of temperature on hydroxyapatite crystal morphology, the phase composition, crystal morphology and growth orientation were characterized by X-ray diffraction, scanning electron microscope and infrared spectrum respectively. The results show that when the reaction temperature incre...

  9. THE EFFECT OF THE APPLICATION OF 20% CARBAMIDE PEROXIDE ON THE GLASS IONOMER CEMENT TYPE II SURFACE HARDNESS

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    Ali Noerdin

    2015-06-01

    Full Text Available In dental bleaching, carbamide peroxide is usually used at concentration of 10%, 15%, to 20%. The result of our previous study showed that the application of 10% and 15% carbamide peroxide bleaching agent has increased the surface hardness of glass ionomer cement. The purpose of this study was to observe the effect of 20% carbamide peroxide bleaching to glass ionomer surface hardness. Twenty specimens of glass ionomer type II after exposed to 20% carbamide peroxide were divided into two application time groups: 4 and 8 hours per day. Glass ionomer cement surface hardness was measured by Vickers Microhardness Tester series HMV-2 with a weight of 0,025 Hv for 20 seconds. The measurement was conducted at before/no application, after a week, and after 2 weeks of application in both groups. It can be concluded that the application of 20% carbamide peroxide bleaching agent could increase the surface hardness of glass ionomer cement after 1 week and 2 weeks application period.

  10. Effect of chemical activation of 10% carbamide peroxide gel in tooth bleaching.

    Science.gov (United States)

    Batista, Graziela Ribeiro; Arantes, Paula Tamiao; Attin, Thomas; Wiegand, Annette; Torres, Carlos Rocha

    2013-01-01

    This study aimed to evaluate the efficacy of chemical agents to increase the bleaching effectiveness of 10% carbamide peroxide. Two hundred and ninety enamel-dentin discs were prepared from bovine incisors. The color measurement was performed by a spectrophotometer using the CIE L*a*b*system. The groups were divided according to the bleaching treatment: negative control group (NC): without bleaching; positive control group (PC): bleached with 10% carbamide peroxide gel without any chemical activator; Manganese gluconate (MG); Manganese chloride (MC); Ferrous gluconate (FG); Ferric chloride (FC); and Ferrous sulphate (FS). Three different concentrations (MG, MC, FG, FC: 0.01, 0.02 and 0.03% w/w; FS: 0.001, 0.002 and 0.003% w/w) for each agent were tested. The bleaching gel was applied on the specimens for 8 h, after which they were immersed in artificial saliva for 16 h, during 14 days. Color assessments were made after 7 and 14 days. The data were analyzed by repeated measures analysis of variance and Tukey's test (5%). Generally, the test groups were unable to increase the bleaching effect (ΔE) significantly compared to the PC group. Only for ΔL, significant higher values compared to the PC group could be seen after 7 days in groups MG (0.02%), and FS (0.002 and 0.003%). The NC group showed significantly lower values than all tested groups. It was concluded that for home bleaching procedures, the addition of chemical activators did not produce a bleaching result significantly higher than the use of 10% carbamide peroxide without activation, and that the concentration of chemical activators used did not significantly influence the effectiveness of treatment. PMID:23390623

  11. Evaluation of human dental loss caused by carbamide peroxide bleacher compared with phosphoric acid conditioning - radioactive method

    International Nuclear Information System (INIS)

    The radiometric method was applied to the evaluation of dental loss caused by carbamide peroxide when it is applied on the surface layers of enamel and dentin tissues. Also the dental loss caused by the etching with 37% phosphoric acid procedure used in aesthetic restoration was assessed for comparison with those results obtained. The tooth samples irradiated with a P standard in a thermal neutron flux of the nuclear reactor were placed in contact with 10% carbamide peroxide or with 37% phosphoric acid solution. The radioactivity of 32 P transferred from the radioactive teeth to the bleaching gel or to etching acid was measured using a Geiger Muller detector to calculate the mass of P removed in this treatment and losses were calculated after obtaining their P concentrations. Results obtained indicated that enamel and dentin exposed to carbamide peroxide bleaching agent lose phosphorus. The extent of enamel loss was smaller than that obtained for dentin. In the case of acid etching, there was no difference between the results obtained for enamel and dentin loss. Also the dentin loss obtained after a treatment of 30 applications of 10% carbamide peroxide was the same magnitude of that one application of 37% phosphoric acid. (author)

  12. The effect of space holder content and decomposition methods in fabrication of aluminum foams by powder metallurgy method using carbamide space holder

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    Amirah, A. H.; Nurulakmal, M. S.; Anasyida, A. S.

    2016-07-01

    The effect of space holder amount and decomposition methods on the morphology, density and porosity and compressive properties of aluminum foams were investigated. Aluminum foam was fabricated by powder metallurgy method using spherical carbamide as space holder using three different decomposition method of carbamide includes; dissolution process, normal sintering process and two step sintering process. Aluminum foam with 60 wt.% carbamide has the lowest density and exhibited the highest porosity for all the decomposition. The results indicated that Al foams produced by dissolution method have the highest compressive properties with acceptable density and porosity value.

  13. On thermal decomposition of carbamide compounds of terbium, dysprosium, holmium, erbium and yttrium propionates

    International Nuclear Information System (INIS)

    Carbamide compounds of REE propionates of the composition of M(C3H5O2)3CO(NH2)2x2H2O, where M is Tb, Dy, Ho, Er, or Y, have been obtained for the first time. Their individuality has been confirmed by chemical and X-ray phase analyses. The composition of the intermediate products obtained upon thermal decomposition of these compounds have been determined by thermography, thermogravimetry, infrared spectroscopy, chemical and X-ray phase analyses. The scheme of thermolysis has been confirmed on the basis of experimental data. Oxides of the corresponding metals are formed at 480 deg C with a small amount of CO2 which evaporates completely at 700 deg C

  14. Dermal penetration of radio-labeled topical repellents cyclohexamethylene carbamide and n-butylsulfonimido cyclohexamethylene. Special study Aug 1974--Feb 1975

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    Snodgrass, H.L. Jr; Weeks, M.H.

    1975-11-19

    The percutaneous absorption of radio-labeled topical insect repellents cyclohexamethylene carbamide and n-butylsulfonimidocyclohexamethyelen was determined following application to the intact skin of rabbits. Urine excretion of cyclohexamethylene carbamide was 64.9 percent of applied dose after seven days. n-Butylsulfonimidocyclohexamethylene excreted in the urine was 48.4 percent of applied dose after seven days. Only trace quantities of labeled repellents were found in tissue specimens of rabbits monitored seven days after topical application. (GRA)

  15. Spectrophotometric assessment of the effects of 10% carbamide peroxide on enamel translucency

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    Glauco Fioranelli Vieira

    2008-03-01

    Full Text Available Tooth shade results from the interaction between enamel color, enamel translucency and dentine color. A change in any of these parameters will change a tooth’s color. The objective of this study was to evaluate the changes occurring in enamel translucency during a tooth whitening process. Fourteen human tooth enamel fragments, with a mean thickness of 0.96 mm (± 0.3 mm, were subjected to a bleaching agent (10% carbamide peroxide 8 hours per day for 28 days. The enamel fragment translucency was measured by a computer controlled spectrophotometer before and after the bleaching agent applications in accordance with ANSI Z80.3-1986 - American National Standard for Ophthalmics - nonprescription sunglasses and fashion eyewear-requirements. The measurements were statistically compared by the Mann-Whitney non-parametric test. A decrease was observed in the translucency of all specimens and, consequently, there was a decrease in transmittance values for all samples. It was observed that the bleaching procedure significantly changes the enamel translucency, making it more opaque.

  16. Ion release from a composite resin after exposure to different 10% carbamide peroxide bleaching agents

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    Renata Plá Rizzolo Bueno

    2012-06-01

    Full Text Available OBJECTIVE: This in vitro study evaluated the influence of two 10% carbamide peroxide bleaching agents - a commercial product (Opalescence PF; Ultradent Products, Inc. and a bleaching agent prepared in a compounding pharmacy - on the chemical degradation of a light-activated composite resin by determining its release of ions before and after exposure to the agents. MATERIAL AND METHODS: Thirty composite resin (Filtek Z250; 3M/ESPE samples were divided into three groups: group I (exposed to Opalescence PF commercial bleaching agent, group II (exposed to a compounded bleaching agent and group III (control - Milli-Q water. After 14 days of exposure, with a protocol of 8 h of daily exposure to the bleaching agents and 16 h of immersion in Milli-Q water, the analysis of ion release was carried out using a HP 8453 spectrophotometer. The values were analyzed statistically by ANOVA, Tukey's test and the paired t-tests. The significance level was set at 5%. RESULTS: After 14 days of the experiment, statistically significant difference was found between group II and groups I and III, with greater ion release from the composite resin in group II. CONCLUSIONS: The compounded bleaching agent had a more aggressive effect on the composite resin after 14 days of exposure than the commercial product and the control (no bleaching.

  17. At-home vital bleaching: a comparison of hydrogen peroxide and carbamide peroxide treatments.

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    Berga-Caballero, Amparo; Forner-Navarro, Leopoldo; Amengual-Lorenzo, José

    2006-01-01

    Tray bleaching of vital teeth performed at home by the patient under the dentist s supervision, whether alone or in combination with any of the in-office techniques, provides an interesting alternative to other methods employed in this type of dental treatment. This bleaching procedure applies low-concentration peroxides to the enamel by means of a custom-made mouth tray specifically designed for this purpose. The aim of this study is to examine and compare two commercially-available bleaching products, at equivalent concentrations, for use in this technique: VivaStyle (Vivadent) and FKD (Kin); the former is a 10% carbamide peroxide and the latter a 3.5% hydrogen peroxide formulation. It examines the parameters that must be monitored during the application of this type of procedure and presents 6 cases (3 treated with one of the above-mentioned products and the other 3 with the other), establishing the bleaching power of the products and the appearance and intensity of post-operatory hypersensitivity. The results obtained show that both products are effective for the purpose for which they were designed. In general, dental hypersensitivity was minimal. PMID:16388304

  18. Effects of different concentrations of carbamide peroxide and bleaching periods on the roughness of dental ceramics

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    Sérgio Augusto Morey Ourique

    2011-10-01

    Full Text Available The wide use of dental bleaching treatment has brought concern about the possible effects of hydrogen peroxide on dental tissue and restorative materials. The objective of this study was to evaluate in vitro the effect of nightguard bleaching on the surface roughness of dental ceramics after different periods of bleaching treatment. Fifteen specimens of 5 × 3 × 1 mm were created with three dental ceramics following the manufacturers' instructions: IPS Classic (Ivoclar-Vivadent; IPS d.Sign (Ivoclar-Vivadent; and VMK-95 (Vita. A profilometer was used to evaluate baseline surface roughness (Ra values of all ceramics by five parallel measurements with five 0.25 mm cut off (Λc at 0.1 mm/s. Afterwards, all specimens were submitted to 6-h daily bleaching treatments with 10% or 16% carbamide peroxide (Whiteness- FGM for 21 days, while control groups from each ceramic system were stored in artificial saliva. The surface roughness of all groups was evaluated after 18 h, 42 h, 84 h, and 126 h of bleaching treatment. The surface roughness of each specimen (n = 5 was based on the mean value of five parallel measurements in each time and all data were submitted to two-way repeated measures ANOVA and Tukey's post-hoc test (α = 0.05. No significant differences in ceramic surface roughness were observed between untreated and bleached ceramic surfaces, regardless of bleaching intervals or bleaching treatments. This study provided evidence that at-home bleaching systems do not cause detrimental effects on surface roughness of dental ceramics.

  19. Synthesis and structures of new uranyl malonate complexes with carbamide derivatives

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    Serezhkina, L. B., E-mail: Lserezh@samsu.ru [Samara State University (Russian Federation); Grigor’ev, M. S. [Russian Academy of Sciences, Frumkin Institute of Physical Chemistry and Electrochemistry (Russian Federation); Medvedkov, Ya. A.; Serezhkin, V. N. [Samara State University (Russian Federation)

    2015-09-15

    Crystals of new malonate-containing uranyl complexes [UO{sub 2}(C{sub 3}H{sub 2}O{sub 4})(Imon)(H{sub 2}O)] (I) and [UO{sub 2}(C{sub 3}H{sub 2}O4)(Meur){sub 3}] (II), where Imon is imidazolidin-2-one (ethylenecarbamide) and Meur is methyl-carbamide, have been synthesized and studied by X-ray diffraction. Both compounds crystallize in the monoclinic system with the following unit-cell parameters (at 100 K): a = 11.1147(10) Å, b = 6.9900(6) Å, c = 14.4934(12) Å, β = 92.042(2)°, V = 1125.30(17) Å{sup 3}, sp. gr. P2{sub 1}/n, Z = 4, R{sub 1} = 0.0398 (I); a = 16.6613(5) Å, b = 9.5635(3) Å, c = 22.9773(6) Å, β = 103.669(2)°, V = 3557.51(18) Å{sup 3}, sp. gr. C2/c, Z = 8, R{sub 1} = 0.0207 (II). The crystals are composed of electroneutral chains [UO{sub 2}(C{sub 3}H{sub 2}O{sub 4})(Imon)(H{sub 2}O)] and mononuclear groups [UO{sub 2}(C{sub 3}H{sub 2}O{sub 4})(Meur){sub 3}] as the structural units belonging to the crystal-chemical groups AT{sup 11}M{sub 2}{sup 1} and AB{sup 01}M{sub 3}{sup 1} (A =UO{sub 2}{sup 2+}, T{sup 11} and B{sup 01} = C{sub 3}H{sub 2}, M{sup 1} = Imon, H{sub 2}O, or Meur), respectively, of uranyl complexes. The packing modes of the uranyl-containing complexes were analyzed by the method of molecular Voronoi—Dirichlet polyhedra.

  20. EFFECTIVITY OF TWO BLEACHING AGENT OF 10% CARBAMIDE PEROXIDE WITH AND WITHOUT POTASSIUM NITRATE-FLUORIDE (CLINICAL STUDY

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    Ayus Lusiyanti

    2015-06-01

    Full Text Available Tooth bleaching has become a popular treatment for esthetic improvement in dentistry. There are several 10% carbamide peroxide bleaching agents that are available in Indonesia which contained potassium nitrate-fluoride or without potassium nitrate-fluoride. However, there was no clinical report about these products in Indonesia. This study was conducted to compare the effectiveness of two bleaching and sensitivity of tooth and gingiva. Sixty-four participants were divided into 2 groups. The first group was treated with bleaching agent that contained potassium nitrate-fluoride (Opalescence PF, Ultradent. Bleaching treatment was done for 6-8 hours per night over a 2 week-period. Evaluations were performed at the baseline and at 3, 7, 14 day afterwards. Color change was measured using a value-ordered Vita classic shade guide; tooth and gingival sensitivity were examine using Electric Pulp Tester, Gingival Index and patient log. The results showed that there were no statistical differences in degree of color change between the two products. The mean color change after 2 weeks was 7-8 tabs lighter than baseline. Also there was no statistical difference in tooth and gingival sensitivity between the products. It can be concluded that 10% carbamide peroxide containing potassium nitrate-fluoride has the same effectiveness compared to other agent without potassium nitrate-fluoride for tooth color change and tooth and gingival sensitivity.

  1. Effect of 16% Carbamide Peroxide Bleaching Gel on Enamel and Dentin Surface Micromorphology and Roughness of Uremic Patients: An Atomic Force Microscopic Study

    OpenAIRE

    Mahmoud, Salah Hasab; Elembaby, Abeer El Sayed; Zaher, Ahmed Ragheb; Grawish, Mohammed El-Awady; Elsabaa, Heba M; El-Negoly, Salwa Abd El-Raof; Sobh, Mohamed Abdel Kader

    2010-01-01

    Objectives: To investigate the effect of 16% carbamide peroxide bleaching gel on surface micromorphology and roughness of enamel and root dentin of uremic patients receiving hemodialysis using atomic force microscopy (AFM). Methods: A total of 20 sound molars were collected from healthy individuals (n=10) and uremic patients (n=10). The roots were separated from their crowns at the cemento-enamel junction. Dental slabs (3 mm x 2 mm x 2 mm) were obtained from the buccal surface for enamel slab...

  2. Crystal structure of the binary complex of cobalt and zinc chlorides with carbamide [Co(OCN2H4)5(H2O)][ZnCl4

    International Nuclear Information System (INIS)

    Mixed single crystals of [Co(OCN2H4)5(H2O)][ZnCl4] were grown by the isothermal evaporation of an aqueous solution. The crystal structure of this complex was established by X-ray diffraction (R = 0.052 based on 7003 reflections). The crystals consist of [Co(OCN2H4)5(H2O)]2+ cations containing Co atoms in an octahedral coordination and [ZnCl4]2-] anions containing Zn atoms in a tetrahedral coordination. The carbamide molecules are involved in both intramolecular and interionic hydrogen bonds. The H2O molecule forms hydrogen bonds with the anions.

  3. Effects of 15% carbamide peroxide and 40% hydrogen peroxide on the microhardness and color change of composite resins.

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    Sedighe Sadat Hashemi Kamangar

    2014-04-01

    Full Text Available The aim of this study was to determine the effects of 40% hydrogen peroxide and 15% carbamide peroxide on microhardness and color change of a silorane-based composite resin in comparison with two methacrylate-based composites.Fifty-four disc-shaped specimens (A3 shade were fabricated of Filtek P90 (P90, Filtek Z350XT Enamel (Z350 and Filtek Z250 (Z250 (3MESPE (n=18. The samples of each composite were randomly divided into three subgroups of 6. The control subgroups were immersed in distilled water; the test groups were exposed to Opalescence Boost (OB once; and Opalescence PF (OP (Ultradent for two weeks. Vickers microhardness testing and a spectrophotometric analysis of the color of samples were performed before and after each intervention.The baseline microhardness of P90 was significantly lower than that of the other two composites (P=0.001, but no difference was found between Z250 and Z350 in this respect (P=0.293. Bleaching treatments significantly decreased the microhardness of Z250 and Z350 (P 0.05. No significant difference was detected between the two types of bleaching (P>0.05. After bleaching with OB, ΔE value was measured to be 3.12(1.97, 3.31(1.84 and 3.7(2.11 for P90, Z250 and Z350, respectively. These values were 5.98(2.42, 4.66(2.85 and 4.90(2.78 after bleaching with OP with no significant difference.Bleaching decreased the microhardness of methacrylate-based but not silorane-based composites. Although no significant differences were found in ΔE of composites, ΔE of all groups did not remain in the clinically acceptable range after bleaching except for P90 after bleaching with 40% H2O2 (ΔE < 3.3.

  4. Micromorphology and microhardness of enamel after treatment with home-use bleaching agents containing 10% carbamide peroxide and 7.5% hydrogen peroxide

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    Robson Tetsuo Sasaki

    2009-12-01

    Full Text Available OBJECTIVE: The purpose of this study was to assess the effect of home-use bleaching agents containing 10% carbamide peroxide and 7.5% hydrogen peroxide on enamel microhardness and surface micromorphology. MATERIAL AND METHODS: Enamel slabs (n=10 received the bleaching agents for 1 h/day and remained in artificial saliva solution for 23 h/day, during a total period of 21 days. Control group was composed of enamel slabs that were not subjected to treatment with the agents and were maintained in artificial saliva solution. Microhardness tests were performed before treatment application, 21 days of treatment and 14 days after the end of treatment. Scanning electron microscopy analyses were performed after 14 days after the end of bleaching treatment by 3 calibrated observers who attributed scores. RESULTS: The Tukey's test (α=0.05 showed no significant differences in microhardness values among bleaching agents, at 21 days of treatment and a significant increase in microhardness for different agents after 14 days from the end of treatment. Fisher's exact test showed differences in micromorphology of enamel between control and experimental groups (p=0.0342. CONCLUSIONS: Bleaching agents containing 10% carbamide peroxide and 7.5% hydrogen peroxide may change surface micromorphology of enamel, although no changes in microhardness were observed.

  5. Murine T cell activation is regulated by surfen (bis-2-methyl-4-amino-quinolyl-6-carbamide)

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    Warford, Jordan, E-mail: jordan.warford@dal.ca [Department of Pathology, Dalhousie University, Tupper Building, 5850 College Street, Halifax, Nova Scotia B3H 4R2 (Canada); Doucette, Carolyn D., E-mail: carolyn.doucette@dal.ca [Department of Microbiology and Immunology, Dalhousie University, Tupper Building, 5850 College Street, Halifax, Nova Scotia B3H 4R2 (Canada); Hoskin, David W., E-mail: d.w.hoskin@dal.ca [Department of Pathology, Dalhousie University, Tupper Building, 5850 College Street, Halifax, Nova Scotia B3H 4R2 (Canada); Department of Microbiology and Immunology, Dalhousie University, Tupper Building, 5850 College Street, Halifax, Nova Scotia B3H 4R2 (Canada); Easton, Alexander S., E-mail: alexander.easton@dal.ca [Department of Pathology, Dalhousie University, Tupper Building, 5850 College Street, Halifax, Nova Scotia B3H 4R2 (Canada); Department of Microbiology and Immunology, Dalhousie University, Tupper Building, 5850 College Street, Halifax, Nova Scotia B3H 4R2 (Canada); Department of Surgery (Neurosurgery), Dalhousie University, Tupper Building, 5850 College Street, Halifax, Nova Scotia B3H 4R2 (Canada)

    2014-01-10

    Highlights: •Surfen is the first inhibitor of glycosaminoglycan function to be studied in murine T cells. •Surfen reduces T cell proliferation stimulated in vitro and in vivo. •Surfen reduces CD25 expression in T cells activated in vivo but not in vitro. •Surfen increases T cell proliferation when T cell receptor activation is bypassed. •Surfen’s effects are blocked by co-administration of heparin sulfate. -- Abstract: Surfen (bis-2-methyl-4-amino-quinolyl-6-carbamide) binds to glycosaminoglycans (GAGs) and has been shown to influence their function, and the function of proteoglycans (complexes of GAGs linked to a core protein). T cells synthesize, secrete and express GAGs and proteoglycans which are involved in several aspects of T cell function. However, there are as yet no studies on the effect of GAG-binding agents such as surfen on T cell function. In this study, surfen was found to influence murine T cell activation. Doses between 2.5 and 20 μM produced a graduated reduction in the proliferation of T cells activated with anti-CD3/CD28 antibody-coated T cell expander beads. Surfen (20 mg/kg) was also administered to mice treated with anti-CD3 antibody to activate T cells in vivo. Lymphocytes from surfen-treated mice also showed reduced proliferation and lymph node cell counts were reduced. Surfen reduced labeling with a cell viability marker (7-ADD) but to a much lower extent than its effect on proliferation. Surfen also reduced CD25 (the α-subunit of the interleukin (IL)-2 receptor) expression with no effect on CD69 expression in T cells treated in vivo but not in vitro. When receptor activation was bypassed by treating T cells in vitro with phorbyl myristate acetate (10 ng/ml) and ionomycin (100 ng/ml), surfen treatment either increased proliferation (10 μM) or had no effect (2.5, 5 and 20 μM). In vitro treatment of T cells with surfen had no effect on IL-2 or interferon-γ synthesis and did not alter proliferation of the IL-2 dependent cell

  6. Crystal structure of a complex of cadmium iodide with carbamide, CdI2 · 2CO(NH2)2

    International Nuclear Information System (INIS)

    Structure of CdI2 · 2CO(NH2)2 complex was determined by x-ray diffraction analysis. Crystals are monoclinic, a = 24.213(8), b 17.626(2), c = 7.823(1) A, β = 98.87(2) Deg, Z = 12, sp. gr. C2/c. The structure contains two types of cadmium atoms: Cd(1) atom with tetragonal coordination occupies the common position in crystal and enters the composition of [CdI3]∞- chain anion; Cd(2) located on 2 axis has an octahedral coordination by carbamide molecules. So the composition of crystals may be presented by the formula [Cd(OCN2H4)6][CdI3]2

  7. Shear bond strength after dentin bleaching with 10% carbamide peroxide agents Resistência ao cisalhamento da dentina após clareamento com peróxido de carbamida a 10%

    OpenAIRE

    Roberta Tarkany Basting; Patrícia Moreira de Freitas; Luiz André Freire Pimenta; Mônica Campos Serra

    2004-01-01

    This in vitro study evaluated the shear bond strength (SBS) of dentin treated with two 10% carbamide peroxide bleaching agents 15 days after bleaching and storage in artificial saliva. Dentin fragments were randomly divided into 3 groups (n = 20) for the treatment with the two different bleaching agents (Rembrandt 10% or Opalescence 10%) or with a placebo agent, applied to the tooth surface for 8 hours a day. During the remaining time, the specimens were stored in artificial saliva. After 42 ...

  8. An in vitro study to evaluate the effect of two ethanol-based and two acetone-based dental bonding agents on the bond strength of composite to enamel treated with 10% carbamide peroxide

    Directory of Open Access Journals (Sweden)

    Deepa Basavaraj Benni

    2014-01-01

    Full Text Available Background and Objective: Carbamide peroxide bleaching has been implicated in adversely affecting the bond strength of composite to enamel. The objective of this in vitro study was to evaluate the effect of ethanol-based (Clearfil S 3 bond, Kuraray, Adper Single bond 2, 3M ESPE dental products and acetone-based (Prime and Bond NT, Dentsply, One Step, Bisco bonding agents on the shear bond strength of composite to enamel treated with 10% carbamide peroxide bleaching agent. Materials and Methods: A total of 120 extracted human noncarious permanent incisors were randomly divided into two groups (control and experimental. Experimental group specimens were subjected to a bleaching regimen with a 10% carbamide peroxide bleaching system (Opalescence; Ultradent Products Inc, South Jordan, USA. Composite resin cylinders were bonded to the specimens using four bonding agents and shear bond strength was determined with universal testing machine. Results: There was no statistically significant difference in the shear bond strength between control and experimental groups with both ethanol-based (Clearfil S 3 Bond and Adper Single Bond 2 and acetone-based bonding agent (Prime and Bond NT and One Step. Interpretation and Conclusion: The adverse effect of bleaching on bonding composite to enamel can be reduced or eliminated by using either ethanol- or acetone-based bonding agent. Clinical Significances: Immediate bonding following bleaching procedure can be done using ethanol- or acetone-based bonding agent without compromising bond strength.

  9. Evaluation and comparison of bond strength to 10% carbamide peroxide bleached enamel following the application of 10% and 25% sodium ascorbate and alpha-tocopherol solutions: An in vitro study

    Science.gov (United States)

    Thapa, Asha; Vivekananda, Pai AR; Thomas, Manuel S

    2013-01-01

    Aim: To evaluate and compare composite bond strength to carbamide peroxide bleached enamel following the application of 10% and 25% sodium ascorbate and alpha-tocopherol solutions. Materials and Methods: Sixty premolars were divided into six groups. Groups I and VI served as unbleached and bleached controls respectively. Groups II, III, IV and V served as the experimental groups and were subjected to 10% carbamide peroxide bleaching followed by 10 min application of 10% and 25% sodium ascorbate and 10% and 25% alpha-tocopherol solutions, respectively. Following composite bonding, shear bond strength was determined and the results were analyzed using ANOVA and Tukey highest significant difference test. Results: Only Group IV showed significantly lower bond strength when compared to Group I (unbleached control). When compared to Group VI (bleached control), except Group IV, groups II, III and V showed significantly higher bond strength. However, there was no statistically significant difference between the experimental groups corresponding to 10% and 25% and similar concentrations of sodium ascorbate and alpha-tocopherol solutions. Conclusion: Following 10% carbamide peroxide bleaching, except 10% alpha tocopherol, 10 min application of 10% and 25% sodium ascorbate and 25% alpha-tocopherol solutions significantly improves the shear bond strength of composite resin to enamel. PMID:23716960

  10. Evaluation and comparison of bond strength to 10% carbamide peroxide bleached enamel following the application of 10% and 25% sodium ascorbate and alpha-tocopherol solutions: An in vitro study

    Directory of Open Access Journals (Sweden)

    Asha Thapa

    2013-01-01

    Full Text Available Aim: To evaluate and compare composite bond strength to carbamide peroxide bleached enamel following the application of 10% and 25% sodium ascorbate and alpha-tocopherol solutions. Materials and Methods: Sixty premolars were divided into six groups. Groups I and VI served as unbleached and bleached controls respectively. Groups II, III, IV and V served as the experimental groups and were subjected to 10% carbamide peroxide bleaching followed by 10 min application of 10% and 25% sodium ascorbate and 10% and 25% alpha-tocopherol solutions, respectively. Following composite bonding, shear bond strength was determined and the results were analyzed using ANOVA and Tukey highest significant difference test. Results: Only Group IV showed significantly lower bond strength when compared to Group I (unbleached control. When compared to Group VI (bleached control, except Group IV, groups II, III and V showed significantly higher bond strength. However, there was no statistically significant difference between the experimental groups corresponding to 10% and 25% and similar concentrations of sodium ascorbate and alpha-tocopherol solutions. Conclusion: Following 10% carbamide peroxide bleaching, except 10% alpha tocopherol, 10 min application of 10% and 25% sodium ascorbate and 25% alpha-tocopherol solutions significantly improves the shear bond strength of composite resin to enamel.

  11. Influence of carbamide peroxide-based bleaching agents on the bond strength of resin-enamel/dentin interfaces Influência de agentes clareadores à base de peróxido de carbamida na resistência de união entre resina-esmalte/dentina

    OpenAIRE

    Vanessa Cavalli; Ricardo Marins Carvalho; Marcelo Giannini

    2005-01-01

    In this bond strength study, a bleaching agent containing 10% carbamide peroxide was applied over composite-teeth bonded interfaces of two adhesive systems applied to enamel and dentin. Sixteen human third molars were used for bonding procedures. Single Bond (SB) and Clearfil SE Bond (CB) were applied to enamel and dentin according to the manufacturers' instructions. A resin composite cube-like structure was incrementally built on the bonded surfaces. The restored teeth were sectioned into 0....

  12. In vitro evaluation of human dental enamel surface roughness bleached with 35% carbamide peroxide and submitted to abrasive dentifrice brushing Avaliação in vitro da rugosidade superficial do esmalte dental humano clareado com peróxido de carbamida a 35% e submetido à escovação com dentifrícios abrasivos

    OpenAIRE

    Claudia Cia Worschech; José Augusto Rodrigues; Luis Roberto Marcondes Martins; Gláucia Maria Bovi Ambrosano

    2003-01-01

    The aim of this in vitro study was to evaluate the surface roughness of human enamel bleached with 35% carbamide peroxide at different times and submitted to different superficial cleaning treatments: G1 - not brushed; G2 - brushed with fluoride abrasive dentifrice; G3 - brushed with a non-fluoride abrasive dentifrice; G4 - brushed without dentifrice. Sixty fragments of human molar teeth with 4 x 4 mm were obtained using a diamond disc. The specimens were polished with sandpaper and abrasive ...

  13. Shear bond strength after dentin bleaching with 10% carbamide peroxide agents Resistência ao cisalhamento da dentina após clareamento com peróxido de carbamida a 10%

    Directory of Open Access Journals (Sweden)

    Roberta Tarkany Basting

    2004-06-01

    Full Text Available This in vitro study evaluated the shear bond strength (SBS of dentin treated with two 10% carbamide peroxide bleaching agents 15 days after bleaching and storage in artificial saliva. Dentin fragments were randomly divided into 3 groups (n = 20 for the treatment with the two different bleaching agents (Rembrandt 10% or Opalescence 10% or with a placebo agent, applied to the tooth surface for 8 hours a day. During the remaining time, the specimens were stored in artificial saliva. After 42 days, the fragments were stored in artificial saliva for 14 days. Another group (n = 20 was exposed to distilled and deionized water for 56 days. An adhesive system and microhybrid composite resin were used to prepare specimens for the SBS test. SBS tests were performed and the fractured surfaces were visually examined using a stereoscope at 30 X magnification. The analysis of variance (ANOVA and SIDAK tests showed higher SBS values for dentin treated with Opalescence 10% than for dentin treated with Rembrandt 10% or placebo. Groups treated with Rembrandt 10%, Opalescence 10% or placebo did not differ from the group treated with distilled and deionized water. Ten percent carbamide peroxide agents or a placebo agent caused no differences in SBS of dentin after 15 days of storage in artificial saliva.Este estudo in vitro avaliou a resistência ao cisalhamento da dentina submetida ao tratamento com dois agentes clareadores contendo peróxido de carbamida a 10% depois de 15 dias de clareamento e armazenagem em saliva artificial. Fragmentos de dentina foram aleatoriamente distribuídos em 3 grupos (n = 20 para receber o tratamento com dois diferentes agentes clareadores (Rembrandt a 10% ou Opalescence a 10% ou com um agente placebo, aplicados na superfície dental por 8 horas diárias. No restante do tempo, os espécimens permaneceram imersos em saliva artificial. Após o tratamento por 42 dias, os fragmentos foram armazenados em saliva artificial por 14 dias. Outro

  14. DIELECTRIC RESEARCH OF POLYISOPRENE MODIFIED BY CARBAMIDE

    OpenAIRE

    Острогруд, А.Ю.

    2012-01-01

    Conducted dielectric research of polyisoprene modification by polyacrylamide in the frequency range 1-100 kHz have shown the existence of increase or decrease in molecular mobility groups of atoms and cross-site segments of the mesh polyisoprene through the displacement of existing relaxation processes in the direction of high or low frequencies at various contents of polyacrylamide.

  15. Influence of carbamide peroxide-based bleaching agents on the bond strength of resin-enamel/dentin interfaces Influência de agentes clareadores à base de peróxido de carbamida na resistência de união entre resina-esmalte/dentina

    Directory of Open Access Journals (Sweden)

    Vanessa Cavalli

    2005-03-01

    Full Text Available In this bond strength study, a bleaching agent containing 10% carbamide peroxide was applied over composite-teeth bonded interfaces of two adhesive systems applied to enamel and dentin. Sixteen human third molars were used for bonding procedures. Single Bond (SB and Clearfil SE Bond (CB were applied to enamel and dentin according to the manufacturers' instructions. A resin composite cube-like structure was incrementally built on the bonded surfaces. The restored teeth were sectioned into 0.7 mm thick slices that were trimmed at enamel or dentin bonded interfaces to an hourglass shape with a cross-sectional area of approximately 0.5 mm². Specimens were assigned to 8 groups (n = 10 according to the following factors under study: dental substrate (enamel and dentin; adhesive system (SB and CB and treatment (10% carbamide peroxide and not bleached/control. The bleaching gel (Opalescence was applied at the bonded interfaces for 6 hours during 14 days and after daily treatment specimens were stored in artificial saliva. Unbleached specimens were stored in artificial saliva for 14 days. Specimens were tested for tension and the data were analyzed by three-way ANOVA and Tukey's test (p Este estudo avaliou a resistência de união de dois sistemas adesivos ao esmalte e à dentina após a aplicação de agente clareador sobre a união compósito-dente. Dezesseis terceiros molares humanos foram usados nos procedimentos restauradores. Single Bond (SB e Clearfil SE Bond (CB foram aplicados no esmalte e na dentina de acordo com as instruções dos fabricantes. Um bloco de compósito foi construído nas superfícies tratadas com os adesivos. Os dentes restaurados foram seccionados em fatias com espessura de 0,7 mm, que receberam constrição na interface de união num formato de ampulheta, com área de secção transversal de ± 0,5 mm². Os espécimes foram distribuídos em 8 grupos (n = 10 de acordo com os fatores em estudo: substrato dental (esmalte e

  16. In vitro evaluation of human dental enamel surface roughness bleached with 35% carbamide peroxide and submitted to abrasive dentifrice brushing Avaliação in vitro da rugosidade superficial do esmalte dental humano clareado com peróxido de carbamida a 35% e submetido à escovação com dentifrícios abrasivos

    Directory of Open Access Journals (Sweden)

    Claudia Cia Worschech

    2003-12-01

    Full Text Available The aim of this in vitro study was to evaluate the surface roughness of human enamel bleached with 35% carbamide peroxide at different times and submitted to different superficial cleaning treatments: G1 - not brushed; G2 - brushed with fluoride abrasive dentifrice; G3 - brushed with a non-fluoride abrasive dentifrice; G4 - brushed without dentifrice. Sixty fragments of human molar teeth with 4 x 4 mm were obtained using a diamond disc. The specimens were polished with sandpaper and abrasive pastes. A perfilometer was used to measure roughness average (Ra values of the initial surface roughness and at each 7-day-interval after the beginning of treatment. The bleaching was performed on the surface of the fragments for 1 hour a week, and the surface cleaning treatment for 3 minutes daily. The samples were stored in individual receptacles with artificial saliva. Analysis of variance and the Tukey test revealed significant differences in surface roughness values for G2 and G3, which showed an increase in roughness over time; G1 and G4 showed no significant roughness differences. The bleaching with 35% carbamide peroxide did not alter the enamel surface roughness, but when the bleaching treatment was performed combined with brushing with abrasive dentifrices, there was a significant increase in roughness values.O propósito deste estudo in vitro foi avaliar em diferentes tempos a rugosidade superficial do esmalte dental humano clareado com peróxido de carbamida a 35% e submetido a diferentes tratamentos superficiais de limpeza: G1 - não escovado; G2 - escovado com dentifrício fluoretado abrasivo; G3 - escovado com dentifrício não fluoretado abrasivo; G4 - escovado sem dentifrício. Sessenta fragmentos de molares humanos com 4 x 4 mm foram obtidos através do seccionamento com discos diamantados. Os espécimes foram polidos com lixas e pastas abrasivas. Um perfilômetro foi utilizado para determinar os valores da média de dureza Ra ("roughness

  17. Influência do agente clareador peróxido de carbamida a 10% na resistência mecânica da colagem de braquetes ortodônticos Influence of 10% carbamide peroxide gel on the shear bond strength of orthodontic brackets

    Directory of Open Access Journals (Sweden)

    Edgard Norões R. da Matta

    2005-04-01

    Full Text Available O propósito deste estudo in vitro foi determinar a influência do agente clareador peróxido de carbamida a 10% na resistência mecânica da colagem de braquetes ortodônticos. Foram estudados três grupos denominados G1 (não submetido ao clareamento, G2 (com clareamento e colagem realizada 1 semana após e G3 (com clareamento e colagem realizada 24h após. O teste de cisalhamento foi conduzido na máquina de ensaios mecânicos Emic, com a velocidade de deformação de 0,5 mm/min.A resitência ao cisalhamento em relação à área de colagem foi calculada para cada dente e expressa em MPa. Os resultados mostraram aumento estatisticamente significante (pThe purpose of this in vitro study was to determine the influence of 10% carbamide peroxide gel on the shear bond strength of orthodontic brackets. Three group were studied: G1 (without bleaching, G2 (bleaching and bonding after 1 week and G3 (bleaching and bonding after 24h. The shear test was conduced in a Emic testing machine with a crosshead speed of 0,5 mm/min. The shear bond strength was calculated for each tooth and expressed in MPa. The results show enhance statistical significant (p<0,001 on the shear bond strength after bleaching and encreased with the time interval between bleaching and bonding, significantily.

  18. Preparation of mechanically activated starch acetate of ester-film material for carbamide controlled release and its film performance%尿素缓释膜材料--机械活化醋酸酯淀粉的制备及其膜性能

    Institute of Scientific and Technical Information of China (English)

    陈渊; 杨家添; 韦庆敏; 何军; 黄祖强; 欧诗德; 张秀姣

    2014-01-01

    In order to improve the properties of starch-based films for carbamide controlled release, the mechanically ac-tivated starch acetate (MASA) was synthesized from mechanically activated cassava starch (MAS). The biodegradable mechani-cally activated starch acetate polyvinyl alcohol(MASA/PVA) films were produced. Fourier transform infrared spectrogram (FT-IR), scanning electron microscopy (SEM) and differential scanning calorimetry (DSC), the microstructure, particle shape and thermal property of MASA were studied. And the film performances were compared with those made of starch acetate (SA) with variacs degrees of substitution(DS). The results revealed that the microstructure and particle shape changed greatly and thermal property of MASA increased. The properties of MASA/PVA were better than those of SA/PVA. The tensile strength of the MA-SA/PVA with MASA ( DS = 0. 2 ) was 3. 23 MPa, the breaking elongation was 206. 68% before soaking in water, the absorption of water was 115. 96% after 24 h, and the rate of biodegradation was 36. 46% in the soil after 20 d. The to-tal urea stripping rate of MASA /PVA coated urea reached 45. 69% after 9 times leaching, 18. 12 percent and 51. 49 per-cent lower than urea and coated that with SA/PVA, respec-tively. Coating film made of MASA/PVA had remarkable controlling effects on urea nitrogen release.%为了有效提高淀粉基质尿素缓释膜的性能,对机械活化1.0 h的木薯淀粉( MAS)进行酯化改性,制备了机械活化醋酸酯淀粉(MASA)、机械活化醋酸酯淀粉/聚乙烯醇的生物降解塑料膜(MASA/PVA)及MASA/PVA包膜尿素。用傅立叶红外光谱仪(FTIR)、扫描电镜(SEM)、差示扫描量热仪(DSC)分别对MASA的结构、形貌、热稳定性等进行测试,并与用不同取代度制备的原木薯醋酸酯淀粉/聚乙烯醇生物降解塑料膜( SA/PVA)进行比较。结果表明,机械活化淀粉经酯化改性后,结构和形貌都有很大的改变,热性能提高;MASA/PVA的性

  19. Testing keratolytic effect of carbamide in various vehicles

    OpenAIRE

    Toskić-Radojičić Marija

    2002-01-01

    Background. Urea is a natural protein degradation product widely used in keratolytic preparations due to its property to promote fibrinogen decomposition and to act as a proteolytic agent dissolving and denaturing proteins. Preparations containing 20% or 40% urea in commercial ambiphylic bases are widely used to produce keratolysis. At such high concentration urea recrystallization occurs and is separated over the preparation mass, particularly if the urea content is 40%. This was the initial...

  20. Testing keratolytic effect of carbamide in various vehicles

    Directory of Open Access Journals (Sweden)

    Toskić-Radojičić Marija

    2002-01-01

    Full Text Available Background. Urea is a natural protein degradation product widely used in keratolytic preparations due to its property to promote fibrinogen decomposition and to act as a proteolytic agent dissolving and denaturing proteins. Preparations containing 20% or 40% urea in commercial ambiphylic bases are widely used to produce keratolysis. At such high concentration urea recrystallization occurs and is separated over the preparation mass, particularly if the urea content is 40%. This was the initial reason to look for a new preparation formulation that would not have the above-mentioned technological inadequacy. Considering urea's water solubility and its high content in the preparations, the most convenient form, in which recrystallisation would not occur, was gel. The aim of this work was to experimentally estimate the influence of the vehicle upon the proteolytic effect of urea on keratin in the human hair model. Methods. Hair geometrical properties, the change in longitudinal mass, and the change of disruptive force and disruptive hair elongation were measured. Results. The effect of 20% and 40% urea was estimated in three various vehicles, of which two were of organic hydrogel type, and one was an ambiphylic base of mixed type - Basiscreme. Conclusion. Keratin proteolysis effects of urea incorporated into various bases, as measured by human hair disruption forces, depended upon the base; preparations containing 20% and 40% urea in Basiscreme (ambiphylic base had no desired proteolytic effect upon keratin fibers; proteolysis was best expressed bay urea preparations in 3.5% NaCMC gel, and proteolytic effect of these preparations was best expressed in the first hour.

  1. Effect of carbamide peroxide-based bleaching agents containing fluoride or calcium on tensile strength of human enamel Efeito de agentes clareadores à base de peróxido de carbamida contendo fluoreto e cálcio na resistência à tração do esmalte humano

    Directory of Open Access Journals (Sweden)

    Marcelo Giannini

    2006-04-01

    Full Text Available OBJECTIVE: The aim of this study was to evaluate the effects of carbamide peroxide-based bleaching agents (CPG containing fluoride (CF or calcium (CCa on the ultimate tensile strength of enamel (UTS. METHOD: A "cube-like" resin composite structure was built-up on the occlusal surface of twenty-two sound third molars to facilitate specimen preparation for the micro-tensile test. The restored teeth were serially sectioned in buccal-lingual direction in slices with approximate 0.7 mm thickness. Each slice was trimmed with a fine diamond bur to reduce the buccal, internal slope enamel of the cusps to a dumb-bell shape with a cross-sectional area at the "neck" of less than 0.5 mm². The samples were randomly divided into 12 groups (n=11. The control groups were not submitted to the bleaching regimen. Specimens were treated with 10% CPG gel or with 10% CPG formulations containing CF (0.2% and 0.5% or CCa (0.05% and 0.2%. Bleached groups received the application of the 10% CPGs for 6 hours/day at 37º C, during 14 consecutive days and were stored in artificial saliva (AS or 100% relative humidity (RH among each application. After bleaching, specimens were tested with the microtensile method at 0.5 mm/min. Data were analyzed by two-way ANOVA and Tukey test (5%. RESULTS: No significant difference was observed between groups stored in AS or RH. Specimens treated with CF or CCa presented similar UTS as unbleached control groups. CONCLUSION: Either 10% CPG formulations containing CF or CCa can preserve the UTS after bleaching regimen.OBJETIVO: O propósito deste estudo foi avaliar os efeitos de agents clareadores à base de peróxido de carbamida (CPG contendo fluoreto (CF e cálcio (CCa na resistência à tração do esmalte (UTS. MÉTODO: Um bloco de resina composta foi confeccionada na superfície oclusal de vinte e dois terceiros molars hígidos para facilitar a preparação dos espécimes para o teste de micro-tração. Os dentes restaurados foram

  2. Fracture resistance and failure pattern of teeth submitted to internal bleaching with 37% carbamide peroxide, with application of different restorative procedures Resistência à fratura e padrão de falha de dentes submetidos ao clareamento interno com peróxido de carbamida a 37%, com aplicação de diferentes procedimentos restauradores

    Directory of Open Access Journals (Sweden)

    Gerson Bonfante

    2006-08-01

    Full Text Available OBJECTIVE: This study investigated the compressive fracture strength and failure pattern in premolars submitted to endodontic treatment and internal bleaching with 37% carbamide peroxide for 21 days, with application of different restorative procedures. MATERIAL AND METHODS: Six groups were employed (n = 10: 1 non-bleached teeth and pulp chamber sealed with IRM; 2 bleached teeth and pulp chamber sealed with IRM; 3 bleached teeth and pulp chamber filled with light cured composite resin; 4 bleached teeth, root canals prepared at 10mm, filling of the root canal and pulp chamber with IRM; 5 bleached teeth, root canals prepared at 10mm, luting of prefabricated metallic post with zinc phosphate and pulp chamber sealed with composite resin; 6 bleached teeth, root canals prepared at 10mm, luting of glass fiber post with resin cement and pulp chamber sealed with composite resin. After 24-hour storage in distilled water, the specimens were submitted to compressive fracture strength testing in a universal testing machine. RESULTS: The following values were found: Group 1 - 56.23kgf; Group 2 - 48.96kgf; Group 3 - 53.99kgf; Group 4 - 45.72kgf; Group 5 - 54.22kgf; Group 6 - 60.12kgf. The analysis of variance did not reveal statistically significant difference between groups (pOBJETIVO: O objetivo do estudo foi investigar a resistência à fratura sob compressão e padrão de falha de pré-molares tratados endodonticamente e clareados internamente por 21 dias com peróxido de carbamida a 37%, aplicando-se diferentes procedimentos restauradores. MATERIAL E MÉTODOS: O objetivo deste estudo foi investigar a resistência à fratura sob compressão e padrão de falha de pré-molares unirradiculares tratados endodonticamente e clareados internamente com peróxido de carbamida a 37%. Foram constituídos 6 grupos (n = 10: 1 dentes sem clareamento e câmara pulpar vedada com IRM; 2 dentes clareados e câmara pulpar vedada com IRM; 3 dentes clareados e câmara pulpar

  3. Influence of bioactive materials used on the dentin surface whitened with carbamide peroxide 16%

    Directory of Open Access Journals (Sweden)

    Helena Burlamaqui Pinheiro

    2010-06-01

    Full Text Available This study investigated the influence of bioactive materials on the dentin surface whitened. MATERIAL AND METHODS: Three bovine teeth were shaped into three dentin wafers. Each wafer was then sectioned, into six dentin slices. One slice from each tooth was distributed into one of 6 groups: 1.CG = control group (distilled water; 2.WT = whitening treatment; 3.WT + MI Paste Plus, applied once a day; 4.WT + Relief ACP30, applied once a day for 30 mintes; 5.WT + Relief ACP60, applied once a day for 60 minutes; 6.WT + Biosilicate®, applied once a week. All groups were treated over 14 days. RESULTS: CG presented all dentinal tubules occluded by smear layer; WT group was observed all dentinal tubules opened. In the groups 3, 4 and 6, tubules were occluded. Group 5, dentinal tubules were completely occluded by mineral deposits. CONCLUSION: The use of bioactive materials immediately after whitening treatment can reduce or even avoid the demineralization effect of whitening and avoid exposing dentinal tubules.

  4. Study on the Carbamide in Washing Powder%碳酰胺在洗衣粉中的研究及应用

    Institute of Scientific and Technical Information of China (English)

    郭俊华

    2016-01-01

    分析了碳酰胺的功能用途,并通过实验测试,解决了由于洗衣粉所含的碳酸钠及部分原料对皮肤的刺激损害问题,提高了产品的抗冻效果和增溶、去污能力,使洗涤产品具有洗涤、去污、护肤的功能。%The function of carbamideis is introduced. The skin irritation as a result of sodium carbonate and other material in washing powder is decreased, and the freeze resistance and soil-releasing is increased.

  5. Structural analysis and reactivity of unusual tetrahedral intermediates enabled by SmI2-mediated reduction of barbituric acids: vinylogous N-acyliminium additions to α-hydroxy-N-acyl-carbamides.

    Science.gov (United States)

    Szostak, Michal; Sautier, Brice; Procter, David J

    2014-03-01

    Structural characterisation and reactivity of new tetrahedral intermediates based on a highly modular barbituric acid scaffold, formed via chemoselective electron transfer using the SmI2-H2O reagent, are reported. Lewis acid promoted cleavage of bicyclic α-amino alcohols affords vinylogous N-acyliminium ions, which undergo selective (>95 : 5, 1,4 over 1,2) capture with a suite of diverse nucleophiles in a practical sequence to biologically active uracil derivatives. PMID:24463565

  6. Drug: D00023 [KEGG MEDICUS

    Lifescience Database Archive (English)

    Full Text Available D00023 Drug Urea ... (JP16/USP); Carbamide; Pastaron (TN) CH4N2O 60.0324 60.0553 D00023.gif Diuretic ... s 26 Epidermides 266 Emollients 2669 Others D00023 Urea ... (JP16/USP) Anatomical Therapeutic Chemical (ATC) c ... roducing osmotic diuresis B05BC02 Carbamide D00023 Urea ... (JP16/USP) D DERMATOLOGICALS D02 EMOLLIENTS AND PR ...

  7. Shear Bond Strength of Orthodontic Brackets to Tooth Enamel After Treatment With Different Tooth Bleaching Methods

    Science.gov (United States)

    Vahid Dastjerdi, Elahe; Khaloo, Negar; Mojahedi, Seyed Masoud; Azarsina, Mohadese

    2015-01-01

    Background: Bleaching treatments decrease shear bond strength between orthodontic brackets and teeth; although definite results have not been reported in this regard. Objectives: This study determined the effects of different bleaching protocols on the shear bond strength of orthodontic brackets to teeth. Materials and Methods: This experimental study was performed in Iran. Forty-eight extracted human premolars were randomly assigned into four groups. In the control group, no bleaching treatment was performed. In groups 2 - 4, the bleaching procedures were performed using carbamide peroxide 45%, carbamide peroxide 20% and diode laser, respectively. Two weeks later, brackets were bonded to teeth and thermocycled. The shear bond strengths of the brackets to the teeth were measured. Data was analyzed by one-way ANOVA and Dunnett post-hoc test. Results: Shear bond strength of the brackets to the teeth were 10.54 ± 1.51, 6.37 ± 0.92, 7.67 ± 1.01 and 7.49 ± 1.19 MPa, in groups 1 - 4, respectively. Significant differences were found between control group and all other groups (P laser significantly decreased shear bond strength of brackets to the teeth. 45% carbamide peroxide had a more significant effect on bond strength compared to 20% carbamide peroxide. The difference in bond strength was not significant between laser group and either carbamide peroxide groups. PMID:26734481

  8. Effects of In-Office and Home Bleaching Gels on the Surface Mercury Levels of Dental Amalgam

    OpenAIRE

    Oskoee, Parnian Alizadeh; Kahnamoui, Mahdi Abed; Oskoee, Siavash Savadi; Zadfattah, Firooz; Pournaghi-Azar, Fatemeh

    2010-01-01

    Objectives: The aim of this study was to evaluate the effect of different in-office and home bleaching gels on the surface mercury levels of dental amalgam. Methods: Sixty disk-shaped amalgam specimens (GS-80, SDI- Australia) were prepared and randomly divided into the following treatment groups: 1. Distilled water (control); 2. 15% home-bleach carbamide peroxide (Opalescence PF, Ultra dent, USA) applied for 6 h/day for 3 weeks; and 3. 35% in-office bleach carbamide peroxide (Opalescence Quic...

  9. Splitting a Substrate into Three Parts: Gold-Catalyzed Nitrogenation of Alkynes by C-C and C≡C Bond Cleavage.

    Science.gov (United States)

    Qin, Chong; Su, Yijin; Shen, Tao; Shi, Xiaodong; Jiao, Ning

    2016-01-01

    A gold-catalyzed nitrogenation of alkynes for the synthesis of carbamides and amino tetrazoles through C-C and C≡C bond cleavages is described. A diverse set of functionalized carbamide and amino tetrazole derivatives were selectively constructed under mild conditions. The chemoselectivity can be easily switched by the selection of the acid additives. The reaction is characterized by its broad substrate scope, direct construction of high value products, easy operation under air, and mild conditions at room temperature. This chemistry provides a way to transform alkynes by splitting the substrate into three parts. PMID:26494539

  10. Colour Change of Enamel after Application of Averrhoa bilimbi

    Directory of Open Access Journals (Sweden)

    Cut Fauziah

    2013-07-01

    Full Text Available Normal 0 false false false MicrosoftInternetExplorer4 Teeth discoloration is mainly treated with dental bleaching. Use of chemical bleaching has side effects, so it is important to find an alternative natural dental bleaching agent. Averrhoa bilimbi contains peroxide and oxalate acid that possess tooth whitening properties. Objective: To determine the change in color of dental enamel after the application of Averrhoa bilimbi and 10% carbamide peroxide. Methods: Samples were 20 post-extracted of the two tested materials premolars (10 specimens each for Averrhoa bilimbi and carbamide peroxide application. After the application, the specimens were incubated at 37ºC for 2 hours, washed and soaked in aquadest before further incubated for another 14 days. The colour changed was observed by 5 independent observers using shade guide. Results: Quantitative and qualitative analyzes were performed. Qualitatively, A3 color has changed into C1, A2, D2, B2 and B1 in the Averrhoa bilimbi group. A more significant color change in the 10% carbamide peroxide group (p=0.005 compared to Averrhoa bilimbi group (p=0.005 were observed. The difference of resulted enamel colour change was statistically significant (p=0.002. Conclusion: Averrhoa bilimbi had a good prospect as dental bleaching agent since its application effectively resulted in a slight enamel colour change although its whitening properties was still lower than 10% carbamide peroxide.DOI: 10.14693/jdi.v19i3.134

  11. The effect of elapsed time following bleaching on enamel bond strength of resin composite.

    Science.gov (United States)

    Cavalli, V; Reis, A F; Giannini, M; Ambrosano, G M

    2001-01-01

    Recent studies have concluded that carbamide peroxide bleaching agents significantly affect the bond strength of composite to bleached enamel. This study evaluated the effects of bleaching regimen with different carbamide peroxide concentrations and post-treatment times on composite bond strength to enamel. Two hundred and four flat buccal and lingual enamel surfaces obtained from erupted sound third molars were randomly divided into 17 groups (n = 12). Sixteen experimental groups comprised the evaluation of four carbamide peroxide home bleaching agents (Opalescence 10%-20% and Whiteness 10%-16%) and four time intervals after bleaching (one day, one, two and three weeks). Specimens of control group were not submitted to bleaching and were stored in artificial saliva at 37 degrees C for 10 days. The specimens of experimental groups were exposed to one daily application of carbamide peroxide for six hours for 10 consecutive days. After each daily treatment and post-bleaching, the specimens were stored in artificial saliva solution. Bonds were formed with Scotchbond MP and Z-100 composite resin, and shear bond test was carried out 24 hours after adhesive-composite application. Two-way ANOVA showed that the bond strengths were significantly different (p < 0.05). For the first two weeks post-bleaching, the bond strengths of resin to enamel were low. After a lapse of three weeks, the bond strength returned to that of the untreated control group. Increased concentration did not prolong the time needed prior to bonding. PMID:11699184

  12. New semisynthetic antimicrobial labdane-type diterpenoids derived from the resin "ladano" of Cistus creticus.

    Science.gov (United States)

    Kalpoutzakis, E; Aligiannis, N; Mitaku, S; Chinou, I; Harvala, C; Skaltsounis, A L

    2001-01-01

    The antimicrobial activity of fifteen semisynthetic labdane-type diterpenes derived from the two major natural compounds 3 and 4 of the resin "ladano" of Cistus creticus is reported. The chloroethyl carbamidic esters 15 and 20 showed the strongest antimicrobial activity against Gram(+), Gram(-) bacteria and pathogenic fungi. PMID:11302213

  13. Вивчення процесу мікрокапсулювання диоксиду титану карбамідоформальдегідними олігомерами

    OpenAIRE

    Маслош, Володимир Зіновійович; Островерхова, Інна Олександрівна; Маслош, Ольга Володимирівна

    2010-01-01

    The possibility of titanium dioxide microcapsulation by water-soluble urea-formaldehyde oligomer is studied. It is established that in process of microcapsulation occurs the carbamide sorption on titanium dioxide surface with subsequent formation of polymetileurea on titanium dioxide surface. Injection of polymetileurea to 30 % from weight titanium dioxide weight doesn't impact on properties of the received product.

  14. In vitro study on tooth enamel lesions related to whitening dentifrice

    Directory of Open Access Journals (Sweden)

    Danilo Barral de Araújo

    2011-01-01

    Full Text Available Background: The tooth whitening substances for extrinsic use that are available in Brazil contain hydrogen peroxide or carbamide peroxide. Several studies have attributed the appearance of lesions in the enamel morphology, including hypersensitivity, to these substances. Such lesions justify fluoride therapy and application of infrared lasers, among other procedures. However, there is no consensus among researchers regarding the relevance of the severity of lesions detected on the tooth surface. Objectives: The present study was carried out with an aim of evaluating in vitro the effects of the hydrogen peroxide, carbamide peroxide and sodium bicarbonate contained in dentifrice formulations, on human tooth enamel. Materials and Methods: After darkening process in laboratory, human premolars were brushed using dentifrice containing the two whitening substances (Rembrandt - carbamide peroxide and Mentadent - hydrogen peroxide and the abrasive product (Colgate - sodium bicarbonate. The degree of specimen staining before and after this procedure was determined using spectrophotometry. Scanning electron microscopy (SEM was used to obtain images, which were analyzed to show the nature of the lesions that appeared on the enamel surface. Results: The effectiveness of the whitening caused by hydrogen peroxide and carbamide peroxide and the abrasion caused by bicarbonate were confirmed, given that the treated test pieces returned to their original coloration. Based on SEM, evaluation of the enamel surfaces subjected to the test products showed that different types of morphologic lesions of varying severity appeared. Conclusions: Whitening dentifrice containing hydrogen peroxide and carbamide peroxide produced lesions on the enamel surface such that the greatest sequelae were associated with exposure to hydrogen peroxide.

  15. Evaluation of the bleached human enamel by Scanning Electron Microscopy

    DEFF Research Database (Denmark)

    Miranda, Carolina Baptista; Pagani, Clovis; Benetti, Ana Raquel;

    2005-01-01

    : 2h); G3- four 2-hour exposures to 35% carbamide peroxide (total exposure: 8h); G4- two applications of 35% hydrogen peroxide, which was light-activated with halogen lamp at 700mW/cm² during 7min and remained in contact with enamel for 20min (total exposure: 40min). All bleaching treatments adopted...... for SEM analysis performing gold sputter coating under vacuum and were examined using 15kV at 500x and 2000x magnification. Results: Morphological alterations on the enamel surface were similarly detected after bleaching with either 35% carbamide peroxide or 35% hydrogen peroxide. Surface porosities......Since bleaching has become a popular procedure, the effect of peroxides on dental hard tissues is of great interest in research. Purpose: The aim of this in vitro study was to perform a qualitative analysis of the human enamel after the application of in-office bleaching agents, using Scanning...

  16. Production and characterization of high porosity porous FeCrC alloys by the space holder leaching technique

    Institute of Scientific and Technical Information of China (English)

    Da-rong Tian; Yu-hua Pang; Liang Yu; Li Sun

    2016-01-01

    Spherical carbamide particles were employed to produce porous Fe–Cr–C alloy with high porosity and large aperture via the space-holder leaching technique. A series of porous samples were prepared by regulating the processing parameters, which included the car-bamide content and the compaction pressure. The pore characteristics and compression properties of the produced samples were investigated. The samples were characterized by scanning electron microscopy, image analysis, and compression tests. The results showed that the macro-porosity and the mean pore size were in the ranges 40.4%–82.4% and 0.6–1.5 mm, respectively. The compressive strength varied be-tween 25.38 MPa and 127.9 MPa, and was observed to decrease with increasing total porosity.

  17. Surfen, a small molecule antagonist of heparan sulfate

    OpenAIRE

    Schuksz, Manuela; Fuster, Mark M.; Brown, Jillian R.; Crawford, Brett E.; Ditto, David P.; Lawrence, Roger; Glass, Charles A; Wang, Lianchun; Tor, Yitzhak; Esko, Jeffrey D

    2008-01-01

    In a search for small molecule antagonists of heparan sulfate, we examined the activity of bis-2-methyl-4-amino-quinolyl-6-carbamide, also known as surfen. Fluorescence-based titrations indicated that surfen bound to glycosaminoglycans, and the extent of binding increased according to charge density in the order heparin > dermatan sulfate > heparan sulfate > chondroitin sulfate. All charged groups in heparin (N-sulfates, O-sulfates, and carboxyl groups) contributed to binding, consistent with...

  18. Peroxide bleaching agent effects on enamel surface microhardness, roughness and morphology Efeitos de agentes clareadores à base de peróxidos na microdureza, rugosidade e morfologia superficial do esmalte

    OpenAIRE

    Cristiane Franco Pinto; Rogério de Oliveira; Vanessa Cavalli; Marcelo Giannini

    2004-01-01

    The aim of this study was to evaluate the surface roughness, microhardness and morphology of human enamel exposed to six bleaching agents (at baseline and post-treatment). Human dental enamel samples were obtained from human third molars and randomly divided into seven groups (n = 11): control, Whiteness Perfect - 10% carbamide peroxide (10% CP), Colgate Platinum - 10% CP, Day White 2Z - 7.5% hydrogen peroxide (7.5% HP), Whiteness Super - 37% CP, Opalescence Quick - 35% CP and Whiteness HP - ...

  19. THE EFFECTS OF HOME BLEACHING ON THE HARDNESS OF AMALGAM FILLING

    OpenAIRE

    Andi Soufyan; Niti Matram

    2015-01-01

    Dental bleaching has been considered as a feasible approach for dental esthetic, and many dental bleaching products can be seen in the market. Therefore, the side effect of such dental product should be studied. This study was aimed to determine the effect of carbamide peroxide-containing home bleaching agent on the hardness of dental amalgam surface structure. Forty amalgam filling specimens were divided into 4 groups, which consist of 3 treatment groups and 1 controu group. Each group was e...

  20. The effect of different drinks on tooth color after home bleaching

    OpenAIRE

    Karadas, Muhammet; Seven, Nilgun

    2014-01-01

    Objective: This study evaluated the influence of coffee, tea, cola, and red wine staining on the color of teeth after home bleaching. Materials and Methods: A total of 45 samples were obtained from 45 sound maxillary central incisors. The home bleaching procedure was performed using 10% carbamide peroxide gel applied to the sample surface for a period of 6 h each day, for 14 days. After bleaching, baseline color measurements were taken, and the samples were immersed in four staining solutions...

  1. Effect of at-home bleaching with different thickeners and aging on physical properties of a nanocomposite

    OpenAIRE

    Gouveia, Thayla Hellen Nunes; Públio, Juliana do Carmo; Ambrosano, Glaucia Maria Bovi; Paulillo, Luís Alexandre Maffei Sartini; Aguiar, Flávio Henrique Baggio; Lima, Débora Alves Nunes Leite

    2016-01-01

    Objective: To evaluate the influence of 16% carbamide peroxide (CP) containing different thickeners on the physical characteristics of a nanocomposite resin submitted or not to accelerated artificial aging (AAA). Materials and Methods: One hundred samples were randomly distributed into two groups (n = 50) according to AAA. Each group was divided into 5 subgroups (n = 10) depending on the bleaching/thickener treatment: CP + carbopol, CP + natrosol, carbopol, natrosol, and no treatment (control...

  2. In vivo Spectrophotometric Assessment of the Tooth Whitening Effectiveness of Nite White 10% with Amorphous Calcium Phosphate, Potassium Nitrate and Fluoride, Over a 6-month Period

    OpenAIRE

    Grobler, Sias R; MAJEED, Abdul; Moola, Mohamad H; Rossouw, Roelof J; van Wyk Kotze, Theuns

    2011-01-01

    To clinically evaluate the effectiveness of Nite White 10% carbamide peroxide with amorphous calcium phosphate, potassium nitrate and fluoride over a 6-month follow-up period. Nite White was applied nightly for 14 days, according to the manufacturer’s instructions. The color of teeth 11 and 21 of twenty one subjects was measured with a spectrophotometer (L*; a*; b*). Subjects were instructed to take note of any tooth sensitivity and gingival irritation. For all three components (L*, a* and b*...

  3. Comparison of the bleaching efficacy of three different agents used for intracoronal bleaching of discolored primary teeth: An in vitro study

    Directory of Open Access Journals (Sweden)

    R Ganesh

    2013-01-01

    Full Text Available Everyone wants whiter teeth to make them feel younger and to provide beautiful smiles with the accompanying increase in self-esteem. Bleaching is an established, simple, cost-effective and conservative method for improving the color of the discolored teeth. Aim: The aim of this in vitro study was to compare the bleaching efficacy of 10% carbamide peroxide, 10% hydrogen peroxide and 2g sodium perborate as bleaching agents on the artificially discolored human primary maxillary central incisors. Materials and Methods: Forty extracted human primary central incisors with intact crowns were selected for the study. Pulpectomy was performed and each tooth was artificially stained with 2 ml of fresh human blood and centrifuged. --The teeth were randomly divided into four experimental groups of 10 teeth each and the baseline color evaluation was performed. 0.04 ml of the bleaching agent is syringed into the access cavity of the tooth and, in the control group, 0.04 ml of distilled water was syringed into the access cavity and it was sealed with IRM and placed at 37°C in an incubator throughout the experiment. The color of the bleached teeth was determined at 0, 7 and 14 days. The data obtained were analyzed using ANOVA and Turkey′s test. Results: There was statistical significance (P = 0.00 among the carbamide peroxide, sodium perborate, hydrogen peroxide and control groups after 7 and 14 days and a significance of P = 0.013 among the carbamide peroxide, sodium perborate and hydrogen peroxide after two bleaching sessions (day 14 was seen. Conclusions: The bleaching efficacy of 10% hydrogen peroxide gel was more effective than 10% carbamide peroxide and sodium perborate in bleaching the artificially discolored primary teeth.

  4. Influence of fluoride-containing adhesives and bleaching agents on enamel bond strength

    OpenAIRE

    Vanessa Cavalli; Priscila Cristiane Suzy Liporoni; Marcos Augusto do Rego; Sandrine Bittencourt Berger; Marcelo Giannini

    2012-01-01

    This study evaluated the influence of fluoride-containing carbamide peroxide (CP) bleaching agents and adhesive systems on bonded enamel interfaces that are part of the dynamic pH cycling and thermal cycling models. The buccal surfaces of 60 bovine incisors were restored with a composite resin and bonded with three- and two-step, etch-and-rinse, fluoride-containing adhesives, Optibond FL (FL) and Optibond Solo Plus (SP), respectively. Restored teeth were subjected to thermal cycling to age th...

  5. Preparation and Characterization of Nanocrystalline Hard Chromium Coatings Using Eco-Friendly Trivalent Chromium Bath

    OpenAIRE

    V. S. Protsenko; V. O Gordiienko; Danilov, F. I.; Kwon, S.C.

    2011-01-01

    A new aqueous sulfate trivalent chromium bath is described. The chromium bath contains formic acid and carbamide as complexing agents. Chromium was deposited at a temperature of 30÷40 oC and a cathode current density of 10÷25 A dm-2. The bath allows obtaining thick (up to several hundred micrometers) hard chromium coatings with nanocrystalline structure. The electrodeposition rate reaches 0.8÷0.9 µm min-1.

  6. Avaliação clínica da eficácia do clareamento dental pela técnica caseira utilizando moldeiras com e sem alívio

    OpenAIRE

    Fábio Herrmann Coelho-de-Souza; Celso Afonso Klein-Júnior; Leandro Azambuja Reichert; Renata Zago; Gabriela Figueiredo Braga; Michele Souza Pontes

    2010-01-01

    The aim of this study was to evaluate the clinical performance of 16% carbamide peroxide home vital bleaching, using trays constructed with or without reservoirs, and analyze the postoperative hypersensitivity. This was a randomized, double-blind and split-mouth study. Two examinators evaluated 11 and 21 teeth from eleven patients (Kappa 0,75). Right side of upper stone models received reservoirs before trays were constructed, left side didn't. Home bleaching was performed through two weeks, ...

  7. Electrochemical behavior of non-precious dental alloys in bleaching agents

    International Nuclear Information System (INIS)

    Corrosion behavior of dental alloys in artificial saliva containing different concentrations of hydrogen peroxide, carbamide peroxide and fluoride ions was studied using electrochemical technique. The alloys have been arranged according to its corrosion resistance in the hydrogen peroxide and carbamide peroxide as follows: wiron99 > wirolloy > wironit. Alloys suffer less corrosion rates in presence of carbamide peroxide than hydrogen peroxide. The effect of CH6N2O3 on the corrosion is less than the effect of H2O2 and this is due to the presence of centers rich by electrons such as nitrogen and oxygen in CH6N2O3. Nitrogen and oxygen adsorbed on the alloy surface forming protective layer isolate it relatively from the corrosive medium. The order of increasing resistivity of the alloys in fluoride solution is as follows: wironit > wiron99 > wirolloy. SEM for the three alloys in artificial saliva containing 0.015 M F- shows that wironit has less corrosion compared to the two other alloys and this agrees with the results obtained from potentiodynamic polarization curves and Nyquist impedance diagrams

  8. Effectiveness of home bleaching agents in discolored teeth and influence on enamel microhardness

    Directory of Open Access Journals (Sweden)

    Carina Sinclér Delfino

    2009-08-01

    Full Text Available OBJECTIVES: This study evaluated the effectiveness of different home bleaching agents on color alteration and their influence on surface and subsurface microhardness of discolored bovine enamel. MATERIAL AND METHODS: Forty-five fragments of bovine incisors were randomly allocated into 3 groups (n=15 according to the bleaching agent: 10% carbamide peroxide gel (CP10, 16% carbamide peroxide gel (CP16 and 6.5%-hydrogen-peroxide-based strip (HP6.5. Before bleaching treatment, initial values of Knoop surface microhardness and color (CIEL*a*b* were obtained and the fragments were artificially stained in hemolyzed rat blood. Then, bleaching treatments were performed over a 21-day period. Color changes (ΔE were assessed at 7, 14 and 21 days, and final surface microhardness reading was done after 21 days. Thereafter, the fragments were bisected to obtain subsurface microhardness. Data were subjected to ANOVA and Tukey's tests (α=5%. RESULTS: Color changes produced by CP16 were similar to those of CP10, and the color changes produced by these materials were significantly superior to those produced by HP6.5. Color changes at 21 days were superior to 7 days and similar to 14 days. The time did not influence color changes for CP16, which showed similarity between the 14- and 21-day results. No statistically significant differences were found among the home bleaching agents for surface and subsurface microhardness. CONCLUSIONS: Microhardness of bovine enamel was not affected by the bleaching agents. The 16% carbamide peroxide gel was the most effective for bleaching the stained substrate.

  9. Effect of casein phosphopeptide-amorphous calcium phosphate on the flexural strength of enamel-dentin complex following extracoronal bleaching

    Directory of Open Access Journals (Sweden)

    Diatri Nari Ratih

    2015-03-01

    Full Text Available Background: Bleaching can affect the mechanical properties of enamel-dentin complex, such as flexural strength. Casein phosphopeptide-amorphus calcium phosphate (CPP-ACP is often used following bleaching treatment to reduce hypersensitivity and to increase demineralization of tooth. Purpose: The purpose of the study was to investigate the effect of CPP-ACP on the flexural strength of enamel-dentin complex following extracoronal bleaching. Methods: Forty-eight enamel-dentin plates (size 8 x 2 x 3 mm were randomly assigned into 6 groups, each consisted of 8 samples. Group 1, no bleaching and immersed in artificial saliva. Group 2, no bleaching, CPP-ACP application only. Group 3, bleaching using 15% carbamide peroxide. Group 4, similar to group 3, except application of CPP-ACP for the times between bleaching. Group 5, bleaching with 40% hydrogen peroxide. Group 6, similar to group 5, except application of CPP-ACP for the times between bleaching. Flexural strength of each enamel-dentin plate was tested by threepoint bending test using universal testing machine. Results: The results showed that 15% carbamide peroxide and 40% hydrogen peroxide significantly reduced flexural strength of enamel-dentin (216.25±26.44 MPa and 206.67±32.07 MPa respectively. Conversely, application of CPP-ACP following both bleachings increased flexural strength (266.75± 28.27MPa and 254.58±36.59 MPa respectively. A two-way Anova revealed that extracoronal bleaching agents significantly reduced flexural strength (p<0.05. Conclusion: Extracoronal bleaching agents reduce flexural strength, whereas application of CPP-ACP following bleaching either with 15% carbamide peroxide or 40% hydrogen peroxide can increase the flexural strength of enamel-dentin complex.

  10. 硅钙包裹尿素对温室大棚菜地土壤养分的影响%Effect of Si-Ca Coated Urea on Vegetable Soil Nutrient in the Greenhouse

    Institute of Scientific and Technical Information of China (English)

    戚新革; 王曰鑫; 吴迪

    2014-01-01

    通过不同用量硅钙包裹尿素与普通尿素对土壤养分的对比试验,研究了硅钙包裹尿素对温室大棚西葫芦菜地土壤养分的影响。试验结果表明:相同施肥条件下,硅钙包裹尿素处理的土壤速效钾、有效硅、水溶性钙和镁、有机质含量高于普通尿素处理,且随着硅钙包裹尿素施入量的增加而提高,最高值出现在施入量为0.224 kg/m2时;硅钙包裹尿素处理的速效磷含量优于普通尿素处理,其含量随硅钙包裹尿素施入量增加而降低;硅钙包裹肥对碱解氮起到了缓释效果,在生长后期含量较高,且随施肥量增加而提高。%The effect of different amount of Si-Ca coated carbamide fertilizer and carbamide on soil fertility were stud-ied with contrast Experiment. The results showed that under the same fertilization conditions, the contents of available potassium, available silicon, water soluble calcium and magnesium, organic matter were higher in wrapped fertilizer treatment than those in the carbamide treatment. These indice increased with the enhancing of fertilizer. The maximum vaule appeared in the application of 0.224 kg/m2 coated fertilizer. The wrapped fertilizer increased with the enhancing of fertilizer that caused by slow-releasing on available nitrogen.

  11. Effect of postoperative bleaching on microleakage of etch-and-rinse and self-etch adhesives

    Directory of Open Access Journals (Sweden)

    Vajihesadat Mortazavi

    2011-01-01

    Full Text Available Background: Bleaching the discoloured teeth may affect the tooth/composite interface. The aim of this in vitro experimental study was to evaluate the effect of vital tooth bleaching on microleakage of existent class V composite resin restorations bonded with three dental bonding agents. Methods : Class V cavities were prepared on buccal surfaces of 72 intact, extracted human anterior teeth with gingival margins in dentin and occlusal margins in enamel, and randomly divided into 3 groups. Cavities in the three groups were treated with Scotch bond Multi-Purpose, a total etch system and Prompt L-Pop and iBond, two self-etch adhesives. All teeth were restored with Z250 resin composite material and thermo-cycled. Each group was equally divided into the control and the bleached subgroups (n = 12. The bleached subgroups were bleached with 15% carbamide peroxide gel for 8 hours a day for 15 days. Microleakage scores were evaluated on the incisal and cervical walls. Data were analyzed using Kruskal-Wallis, Mann-Whitney and Bonferroni post-hoc tests (α = 0.05. Results: Bleaching with carbamide peroxide gel significantly increased the microleakage of composite restorations in Prompt L-Pop group at dentinal walls (P = 0.001. Bleaching had no effect on microleakage of restorations in the Scotch bond Multi-Purpose and iBond groups. Conclusion: Vital tooth bleaching with carbamide peroxide gel has an adverse effect on marginal seal of dentinal walls of existent composite resin restorations bonded with prompt L-Pop self-etch adhesive.

  12. Fluorescent properties of low-molecular-weight fractions from chernozem humic acids

    Science.gov (United States)

    Trubetskoi, O. A.; Demin, D. V.; Trubetskaya, O. E.

    2013-10-01

    The polyacrylamide gel electrophoresis of chernozem humic acids (HAs) followed by ultraviolet detection (λ = 312 nm) has revealed a new highly fluorescent fraction that has the highest electrophoretic mobility and the lowest nominal molecular weight (NMW). The preparative isolation of the fraction has been performed using the multiple microfiltration of the same HA sample in a 7 M carbamide solution on a membrane with a nominal pore size of 5 kDa. Thirty ultrafiltrates with NMW 5 kDa. Fluorescence maximums at and below 490 nm have been noted only in the first four ultrafiltrates. All the ultrafiltrates have been combined into the fraction with NMW extracted soil HAs.

  13. Mercury release of amalgams with various silver contents after exposure to bleaching agent

    OpenAIRE

    Bahari, Mahmoud; Alizadeh Oskoee, Parnian; Savadi Oskoee, Siavash; Pouralibaba, Firoz; Morsali Ahari, Ali

    2016-01-01

    Background. Since it is possible for carbamide peroxide (CP) bleaching agent to contact old amalgam restorations, the present in vitro study evaluated the amount of dissolved mercury released from amalgam restorations with various percent-ages of silver content subsequent to the use of 15% CP. Methods. Thirty ANA 2000 amalgam disks with 43.1% silver content and thirty ANA 70 amalgam disks with 69.3% silver content were prepared. In each group, 15 samples were randomly placed in glass tubes co...

  14. Synthesis of indium tin oxide nanorods by a facile process with ethylene glycol as solvent

    International Nuclear Information System (INIS)

    Indium tin oxide nanorods with cubic bixbyite crystalline structure were synthesized by a facilely heating process using InCl3.4H2O, SnCl4.5H2O, carbamide, polyisobutylene bis-succinimide, and ethylene glycol as precursors. The length of the obtained nanorods ranges from 80 nm to 500 nm, with the short dimension ranging from 50 nm to 100 nm. The electrical conductivity of the nanorods is higher than those reported in previous works due to less grain boundaries. The nanorods show strong absorption in the ultraviolet region while very weak absorption in the visible range due to its relative wide bandgap.

  15. Effect of bleaching on the shear bond strength of the enamel

    Directory of Open Access Journals (Sweden)

    Thiago Arruda

    2008-01-01

    Full Text Available Objective: To evaluate the effect of dental bleaching on the shear bond strength of enamel. Methods: Fifty molars were selected and divided into five groups (n=10; G1-without bleaching (control; G2-bleached with 10% carbamide peroxide and restored 24h later; G3-bleached with 10% carbamide peroxide and restored seven days later; G4-bleached with 35% hydrogen peroxide and restored a 35% and restored 24h later; G5-bleached with 35% hydrogen peroxide and restored a 35% and restored seven days later. During the 24h and 7-day intervals the test specimens remained stored in artificial saliva, after which the restorative procedures were performed on the enamel. Results: The microshear bond strength test indicated the following results in MPa (ANOVA and Tukey post-hoc: G1-43.15 a (±5.19; G2-31.34 ab (± 4.41; G3-36.66 ab (± 3.11; G4-22.87 c (±3.76 and G5-35.67 ab (± 4.64. Conclusion: Groups G1, G2, G3 and G5 showed no statistical difference and Group G4 (bleached with 35% hydrogen peroxide and restored 24h later showed diminished bond strength between the bleached enamel and resin composite.

  16. THE EFFECTS OF HOME BLEACHING ON THE HARDNESS OF AMALGAM FILLING

    Directory of Open Access Journals (Sweden)

    Andi Soufyan

    2015-06-01

    Full Text Available Dental bleaching has been considered as a feasible approach for dental esthetic, and many dental bleaching products can be seen in the market. Therefore, the side effect of such dental product should be studied. This study was aimed to determine the effect of carbamide peroxide-containing home bleaching agent on the hardness of dental amalgam surface structure. Forty amalgam filling specimens were divided into 4 groups, which consist of 3 treatment groups and 1 controu group. Each group was exposed to the bleaching agent daily for 2, 4 and 8 hours within 7 days. The Vickers Microhardness Tester, with loads 98.07 mN for 20 seconds, was used to measure the hardness of amalgam surface. It was revealed that, there was a significant difference between the treatment and the control group on 8 hours period. It was concluded that there was a decrease in hardness of dental amalgam surface after having a contact with carbamide peroxide bleaching agent.

  17. X-ray diffraction study of uranyl sulfate complexes with acetamide

    International Nuclear Information System (INIS)

    X-ray diffraction study of UO2SO4xLx2H2O (1), UO2SO4x2Lx2H2O (2) and UO2SO4x3LxH2O (3) (L-acetamide) complexes, which crystals were prepared by slow evaporation at room temperature uranyl sulfate and acetamide aqueous solutions with a definite molar ratio, is carried out. The lattice parameters for (1) are: a=17.520; b=6.917; c=8.759 A; β=104.40 deg sp.gr. s2/mC2 or Cm; for (2): a=7.248; b=9.451; c=10.623 A; α=109.15; β=107.79; γ=74.55 deg; sp.gr. P1-bar; for (3): a=8.494; b=10.170; c=10.606 A; α=118.81; β=102.92; γ=90.10 deg; sp.gr. P1-bar. Peculiarities of crystal-structure transformations in acetamide and carbamide uranyl sulfate complexes with change of UO2SO4:L ratio (L-acetamide or carbamide) are discussed

  18. Susceptibility of Enamel Treated with Bleaching Agents to Mineral Loss after Cariogenic Challenge

    Directory of Open Access Journals (Sweden)

    Hüseyin Tezel

    2011-01-01

    Full Text Available Objectives. Controversial reports exist whether bleaching agents cause a susceptibility to demineralization. The aim of this study was to compare the calcium loss of enamel treated with different bleaching agents and activation methods. Method and Materials. The specimens obtained from human premolars were treated in accordance with manufacturer protocols; 10% carbamide peroxide, 38% hydrogen peroxide light-activated, 38% hydrogen peroxide laser-activated, and no treatment (control. After cariogenic challenge calcium concentrations were determined by Inductively Coupled Plasma Mass Spectrometry. Results. No differences were found between the calcium loss of the laser-activated group and 10% carbamide peroxide group (>0.05. However, the differences between laser-activated and control groups were statistically significant (0.05. On the other hand, the light-activated group showed a significantly higher calcium loss compared with the other groups (<0.05. Conclusions. The results show that bleaching agents may cause calcium loss but it seems to be a negligible quantity for clinical aspects.

  19. Erosion and abrasion on dental structures undergoing at-home bleaching

    Directory of Open Access Journals (Sweden)

    Tarquinio SBC

    2011-07-01

    Full Text Available Flávio Fernando Demarco1, Sônia Saeger Meireles2, Hugo Ramalho Sarmento1, Raquel Venâncio Fernandes Dantas1, Tatiana Botero3, Sandra Beatriz Chaves Tarquinio11Graduate Program in Dentistry, School of Dentistry, Federal University of Pelotas, Brazil; 2Department of Operative Dentistry, Federal University of Paraíba, Brazil; 3Cariology, Restorative Science, and Endodontics Department, School of Dentistry, University of Michigan, MI, USAAbstract: This review investigates erosion and abrasion in dental structures undergoing at-home bleaching. Dental erosion is a multifactorial condition that may be idiopathic or caused by a known acid source. Some bleaching agents have a pH lower than the critical level, which can cause changes in the enamel mineral content. Investigations have shown that at-home tooth bleaching with low concentrations of hydrogen or carbamide peroxide have no significant damaging effects on enamel and dentin surface properties. Most studies where erosion was observed were in vitro. Even though the treatment may cause side effects like sensitivity and gingival irritation, these usually disappear at the end of treatment. Considering the literature reviewed, we conclude that tooth bleaching agents based on hydrogen or carbamide peroxide have no clinically significant influence on enamel/dentin mineral loss caused by erosion or abrasion. Furthermore, the treatment is tolerable and safe, and any adverse effects can be easily reversed and controlled.Keywords: peroxide, tooth bleaching, enamel, dentin, erosion, abrasion

  20. 3种浓度过氧化脲漂白剂对牙科陶瓷表面粗糙度的影响%Effects of three different concentrations of bleaching gels on the surface roughness of dental porcelain

    Institute of Scientific and Technical Information of China (English)

    刘金萍; 谢瑜侠

    2012-01-01

    目的 评估3种浓度过氧化脲漂白剂对牙科陶瓷表面粗糙度的影响.方法 80个瓷块按随机数字表法分成4组.A、B、C组所有瓷块进行为期3周,每天8h的漂白,A组漂白剂为质量分数10%的过氧化脲,B组为质量分数15%的过氧化脲,C组为质量分数20%的过氧化脲;D组为空白对照组,浸泡于人工唾液里.表面粗糙度仪测量所有样本初始时和漂白1d、2d、3d、1周、2周、3周后的瓷块表面粗糙度,并进行统计学分析.结果 A、B、C、D 4组瓷块的初始表面粗糙度分别为(0.073±0.003)μm、(0.073±0.002)μm、(0.072±0,003)μm、(0.074±0.003)μm,3周后的粗糙度分别为(0.073±0.004)μm、(0.073±0.005)μm、(0.074±0.006)μm、(0.074±0.005)μm.7个时间点,4组组间和组内表面粗糙度差异均无统计学意义(P>0.05).结论 3种浓度过氧化脲漂白剂对牙科陶瓷表面无明显不良影响.%Objective To assess effects of three different concentrations of carbamide peroxide on the surface roughness of dental porcelain. Methods Surface roughness of 80 ceramic blocks were measured by a surface roughness tester, and then were randomly divided into four groups; group A were bleached with 10% carbamide peroxide eight hours per day; group B were bleached with 15% carbamide peroxide eight hours per day; group C were bleached with 20% carbamide peroxide eight hours per day; group D were soaked in artificial saliva as a blank control group. The first three groups were bleached for 3 weeks. Ceramic blocks surface roughness were measured at time points of 1 d,2d,3d, 1 w, 2 w, 3 w. Results There were no significant difference (P >0.05) of ceramic blocks surface roughness among the four groups. Conclusion Bleaching with 10% , 15% or 20% carbamide peroxide for three weeks have no obvious adverse effects on dental porcelain surface.

  1. Bleaching in vital teeth: a literary review

    Directory of Open Access Journals (Sweden)

    Felipe Fagundes Soares

    2008-01-01

    Full Text Available Tooth bleaching technique has presented a significant evolution, promoting higher satisfaction and comfort to the patients. Therefore, the aim of this study was to present the bleaching agents and the techniques, discussing advantages and disadvantages of each one, and the effect of these agents in the oral environment. The main agents used in the bleaching technique are the hydrogen peroxide and the carbamide peroxide, promoting the bleaching effect through oxidation of organic compounds. The application of these agents can be made at home or at a doctor office. During treatment, it may occur some adverse effects, such as tooth sensibility, increasing of dental porosity, and some interactions with the restorative material. However, these adverse effects can be eliminated or controlled when the treatment is executed under professional orientation. When the bleaching technique is well indicated and correctly conducted, it is associated with significantly positive results.

  2. Synthesis of fungicide bis-(8-guanidino-octyl)amine acetate and its intermediates and bioactivity%双胍辛醋酸盐杀菌剂及其两种中间体的合成与生物活性

    Institute of Scientific and Technical Information of China (English)

    邹曲辉; 于世涛; 刘福胜; 解从霞

    2003-01-01

    O-methylisourea acetate was synthesized by two procedures from the main raw materials including carbamide, dimethyl sulfate, acetic acid and concentrated sulfuric acid. Its content reaches 98 % and the total yield attains to 70%. 1, 17-Diamino-9-azaheptadecane was first synthesized by two procedures using sebcic acid, 1,8-octanediamine, sodium azide and concentrated sulfuric acid as the main raw materials. Its content reaches 98% and the total yield is 65%. The structure of both were confirmed by FT-IR, 1H NMR and their available analysis method was established. Fungicide bis-(8-guanidino-octyl )amine acetate was synthesized from these two intermediates and its structure was confirmed by FT-IR and 1HNMR. Fungicidal activity test showed that it is a kind of broad-spectrum fungicide with notably effect.

  3. Comparative study of the effects of two bleaching agents on oral microbiota.

    Science.gov (United States)

    Alkmin, Yara Tardelli; Sartorelli, Renata; Flório, Flávia Martão; Basting, Roberta Tarkany

    2005-01-01

    This study evaluated the in vivo effects of bleaching agents containing 10% carbamide peroxide (Platinum/Colgate) or 7.5% hydrogen peroxide (Day White 2Z/Discus Dental) on mutans Streptococcus during dental bleaching. The products were applied on 30 volunteers who needed dental bleaching. In each volunteer, one of the two bleaching agents was used on both dental arches one hour a day for three weeks. Analysis of the bacterial counts was made by collecting saliva before (baseline values), during (7 and 21 days) bleaching treatments and 14 days posttreatment. The Friedman non-parametric analysis (alpha=0.05) found no differences in microorganism counts at different times for each group for both agents (p>0.05). The Mann Whitney nonparametric test (alpha=0.05) showed no differences in micro-organism counts for both agents (p>0.05). Different bleaching agents did not change the oral cavity mutans Streptococcus counts. PMID:16130860

  4. Experimental investigation of the input section structure elements of the paste-cooled channel of a reusable pulsed MHD generator

    International Nuclear Information System (INIS)

    The results of experimental study on thermal stability of the input section structure elements of the paste-cooled channel of the MHD multi-action pulse generator are presented. The test rocket fuel engine with addition of powder-like aluminium was used as a gas generator. The engine nozzle with a critical cross section of a rectangular shape is accomplished from upper paste-cooled walls. Two paste-coolants: the melting one on the basis of carbamide and sublimation one on the basis of ammonium oxalate are tested. The fire tests confirmed the efficiency of copper walls by cooling through the paste-like coolants of two types by multiple thermal loadings. It is proved that the gas generator is a comfortable instrument for working off the MHD channel design on thermal stability through multicycle operation

  5. Cation Tuning toward the Inference of the Gelation Behavior of Supramolecular Gels

    Science.gov (United States)

    Xue, Peng; Wu, Huiqiong; Wang, Xiaojuan; He, Ting; Shen, Rujuan; Yue, Fan; Wang, Jide; Zhang, Yi

    2016-01-01

    We serendipitously discovered that the tripeptide Asp–Phe–Phe trifluoroacetic acid salt (hereafter abbreviated as β-AspFF) formed a reversible thermotropic gel in chloroform solution (at temperatures higher than the boiling point of chloroform), and a stable gel in toluene solution (at equal to or lower than the room temperature). Experimental results indicate that doping metal ions into β-AspFF toluene gels can trigger morphological variations in the gel skeleton, thereby increasing gel volume and inducing the collapse of organogels. Investigation on the cation-tuned gelation behavior of β-AspFF can be used to elucidate heating-induced gel collapse (of normal gel) or reverse thermotropic gelation as well as select carbamide and acetamide as activators of β-AspFF gels in chloroform solution at room temperature. PMID:27138527

  6. Cation Tuning toward the Inference of the Gelation Behavior of Supramolecular Gels.

    Science.gov (United States)

    Xue, Peng; Wu, Huiqiong; Wang, Xiaojuan; He, Ting; Shen, Rujuan; Yue, Fan; Wang, Jide; Zhang, Yi

    2016-01-01

    We serendipitously discovered that the tripeptide Asp-Phe-Phe trifluoroacetic acid salt (hereafter abbreviated as β-AspFF) formed a reversible thermotropic gel in chloroform solution (at temperatures higher than the boiling point of chloroform), and a stable gel in toluene solution (at equal to or lower than the room temperature). Experimental results indicate that doping metal ions into β-AspFF toluene gels can trigger morphological variations in the gel skeleton, thereby increasing gel volume and inducing the collapse of organogels. Investigation on the cation-tuned gelation behavior of β-AspFF can be used to elucidate heating-induced gel collapse (of normal gel) or reverse thermotropic gelation as well as select carbamide and acetamide as activators of β-AspFF gels in chloroform solution at room temperature. PMID:27138527

  7. Cation Tuning toward the Inference of the Gelation Behavior of Supramolecular Gels

    Science.gov (United States)

    Xue, Peng; Wu, Huiqiong; Wang, Xiaojuan; He, Ting; Shen, Rujuan; Yue, Fan; Wang, Jide; Zhang, Yi

    2016-05-01

    We serendipitously discovered that the tripeptide Asp–Phe–Phe trifluoroacetic acid salt (hereafter abbreviated as β-AspFF) formed a reversible thermotropic gel in chloroform solution (at temperatures higher than the boiling point of chloroform), and a stable gel in toluene solution (at equal to or lower than the room temperature). Experimental results indicate that doping metal ions into β-AspFF toluene gels can trigger morphological variations in the gel skeleton, thereby increasing gel volume and inducing the collapse of organogels. Investigation on the cation-tuned gelation behavior of β-AspFF can be used to elucidate heating-induced gel collapse (of normal gel) or reverse thermotropic gelation as well as select carbamide and acetamide as activators of β-AspFF gels in chloroform solution at room temperature.

  8. [Effect of tricarboxylic acid cycle intermediates on nitric oxide system during acute hypoxia].

    Science.gov (United States)

    Kurhaliuk, N M

    2002-01-01

    Effects Crebs Cycle of exogenous intermediates sodium succinate (50 mg/kg) and sodium alpha-ketoglutarate (200 mg/kg) on processes of mitochondrial ADP-stimulated respiration (using as substrates of oxidation 0.35 mM succinate, 1 mM alpha-ketoglutarate), production of nitric oxide under NO2-, NO3-, as well as carbamide, putrescyne content and processes of lipid peroxidation in the rats liver under acute hypoxia (7% O2 in N2, 30 min) have been studied. It was shown, that the exogenous sodium alpha-ketoglutarate increases nitric oxide content, aminotransferase activation, inhibition of succinatedehydrogenase simultaneously more than exogenous sodium succinate. It correlates with decreasing of processes lipid peroxidation in liver. PMID:14964867

  9. Synthesis and Characterization of Nickel Nanorods Transferred from Hydrotherally Decomposed Rod-like NiS

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    Powders of hexagonal-structured single-crystalline nickel sulfide nanorods have been synthesized in cetyltrimethyl ammonium bromide (CTAB)/water/hexane/n-pentanol quaternary microemulsion under hydrothermal conditions by using the reaction of carbamide and carbon disulfide as a sulfide source. Single-crystalline nickel nanorods have been synthesized via thermal decomposition by using single-crystalline nickel sulfide nanorods as precursor. The influence of different reaction parameters on the morphology of the products has been investigated. The structure, morphology and magnetic properties of the products were characterized by X-ray diffraction (XRD), transmission electron microscope (TEM), thermogravimetric analysis-differential scanning calorimeter (TGA-DSC) and vibrating sample magnetometer (VSM). The results of magnetic measurements showed that the specific saturation magnetization (σs) and coercivity values (Hc) of nickel nanorods were 37.5 emu/g and 68.5 Oe, respectively.

  10. A review of the kinetics of oxidation and reduction of sale-free reagents in the U/Pu separation process

    International Nuclear Information System (INIS)

    Background: Recently, the most reductant widely used to partition plutonium from uranium in the Purex solvent extraction purification process have been salt-free reagents. Purpose: In order to determine the utility of sale-free reagents in the Purex solvent extraction process. Methods: The report is a review of the applications of sale-free reagents in the U/Pu separation process, such as hydroxylamine derivative, U(IV), aldehyde derivative, hydrazine, hydroxyl carbamide, derivative, hydroxamic acid and so on. Results: In this review, we have investigated and summarized the previous works covering the thermodynamics and dynamics behaviors to offer references for the future R and D works on the capability of salt-free reagents in the PUREX process and to indicate its applications. Conclusions: Acetohydroxamic acid and hydroxysemicarbazide have the capability of stripping trace amount plutonium of uranium in the future industrialization. (authors)

  11. 基于环境友好的可替代煤及石油中有机碳源的CO2合成利用途径与技术探析%Utilization and Technology Exploration of Organic Carbon Source CO2 in Environmental Friendly and Replaceable Coal and Oil

    Institute of Scientific and Technical Information of China (English)

    沈发治

    2012-01-01

    The ways and technology of synthesis of alcghol, ether, ester, amine ester, lactone, polyester, carbamide and diamond based on CO2 were explored. Using CO2 as potential organic carbon resources not only solves environmental problem, but also eases shortage of resources.%对以CO2为原料合成醇、醚、酯、胺酯、内酯、聚酯、尿素及金钢石等物质的途径与技术进行了探析,指出二氧化碳作为潜在的有机碳资源,充分利用,变废为宝,不仅解决了环境问题,也能缓解资源短缺.

  12. Preparation and characterization of porous magnesium materials

    Institute of Scientific and Technical Information of China (English)

    LIU Xi-qin; LIU Zi-li; ZHANG Xiao-hong; FENG Jun-dong; YU Ta-xi

    2006-01-01

    The proper spacer material and the preparation technology for biological compatible porous magnesium materials were explored by the powder metallurgy method, and microstructures, porosity and mechanical properties of sintered porous magnesium were investigated. The results show that compared with spacer materials of NH4CO3, NH3Cl and carbamide, NH4CO3 is the best one for preparation of sintered porous magnesium, and the worst one is NH3Cl. The isolated blind pores are formed mainly by the particle interval of the magnesium powders. Adding spacer material favors the formation of open pores, while has little contribution to the formation of blind pores. The overall porosity and porosity of open pore of the sintered porous magnesium increase with the increase of added spacer material, while decrease with the increase of the molding stress. The mechanical properties of sintered porous magnesium increase with decreasing addition of spacer material and increasing molding stress.

  13. Comparação da superfície do esmalte antes e após clareamento com dois diferentes agentes: estudo clínico

    Directory of Open Access Journals (Sweden)

    Virgínia Teichmann Espina

    2008-01-01

    Full Text Available The purpose of this study was to compare of enamel surface before and after bleaching with two different agents. Twenty subjects were selected and divided in two groups: Group 1- treated with the night guard vital bleaching using 10% carbamide peroxide (Whiteness Perfect and Group 2- treated with the in-offi ce technique using 35% hydrogen peroxide (Whiteness HP. Epoxi resin replicas obtained from the maxillary central incisors, before, immediately after and thirty days after the bleaching procedure. All replicas were photography in scanning electron microscopy and examined for one expert and blind examiner taken in scores: 1- surface without alteration 2- surface with alteration. This study demonstrated that bleaching treatment using both agents causes effect on namel surface, but these are partially reverted in thirty days.

  14. Influence of bleaching agents on the microhardness of nanoparticle resin composite

    Directory of Open Access Journals (Sweden)

    Vanderlei Salvador Bagnato

    2009-01-01

    Full Text Available Objective: To assess the effect of bleaching agents on the microhardness of nanoparticle resin composite. Methods: Twenty-eight cylindrical test specimens (8x1mm of FiltekTM Supreme XT resin (3M/ESPE were prepared and divided into 5 groups. The initial Vickers microhardness was measured (load of 50 grams force for 30 seconds on the top surface of the test specimens. The groupswere treated and divided as follows: G1 – artificial saliva (21 days - control; G2 - 7% hydrogen peroxide gel applied for 4h/day, for 14 days; G3 - 10% carbamide peroxide for 4h/day, for 14 days: G4 – 35% hydrogen peroxide gel applied in three sessions of 30 minutes each, with an interval of one week (21 days between the sessions; G5 - 35% carbamide peroxide, three sessions of 30 minutes each, with an interval of one week (21 days between the sessions. The top surfaces of the test specimens received treatment and were submitted to the Vickers microhardness test. Results: The results obtained were submitted to the Analysis of Variance at a fixed criterion, at a level of significance of p=0.05. No significant differences were observed among the treatments tested (p=0.42 when compared with G1. Significant differences (Tukey test were found when the initial microhardness values were compared with the values after experimental treatments (p<0.01. Conclusion: The application of bleaching agents did not alter the microhardness of resin composites. Therefore, there is no need to change restorations after bleaching.

  15. Molecular analysis of tooth enamel by Raman spectroscopy after treatment with bleaching agents at different concentrations

    International Nuclear Information System (INIS)

    The changes in the concentration of the v1 phosphate molecule of the surface of dentin enamel are treated and researched with bleaching agents of chemical activation to basis of hydrogen peroxide than 9,5% and 14% and carbamide peroxide than 38%, for a period of 28 days. Raman spectroscopy was used and 30 dental pieces extracted, of which, were to be free of blemishes and pigmentations, without possessing fractures of the enamel, decay nor any other type of defect. The Raman spectrum was obtained of each dental piece prior to the application of bleaching agents. The specimens were separated into three experimental groups according to the concentration of whitening. The concentration of the v1 phosphate molecule was measured in the tooth enamel to the second and fourth week of treatment. In addition, ANOVA was performed for respective measurements (p≤0.05). A reduction of the v1 phosphate molecule were observed during and after the bleaching process in the experimental groups that have used of hydrogen peroxide to 14% and carbamide peroxide 38%. In the group of hydrogen peroxide to 9,5% has remained unproven a significant reduction. Within the limitations of this study is concluded that the bleaching agent causes a loss of v1 phosphate. This loss has been greater in the whitening of higher concentration. In spite, that the possible effect remineralizing of the saliva on a teeth whitening process has been unevaluated, it is recommended using during and after the treatment, toothpastes, mouthwashes, chewing gums, dental floss, among others, that contain ACP to help to cushion the potential loss of phosphate from tooth enamel. (author)

  16. Effect of dental bleaching after bracket bonding and debonding using three different adhesive systems

    Directory of Open Access Journals (Sweden)

    Lucianna de Oliveira Gomes

    2013-04-01

    Full Text Available OBJECTIVE: To evaluate the influence of bonding and debonding of orthodontic brackets on dental in-home bleaching, taking into account three different adhesive systems. METHODS: Forty-four bovine incisors were divided into four groups according to the primer system used for orthodontic bracket bonding. Following the debonding of orthodontic brackets, the teeth were stored in staining solution for 96 hours. Then, teeth were whitened using 10% carbamide peroxide for two weeks at a 6-hour-a-day regime. Standardized digital photographs were taken at the following intervals: T0 (initial; T1 (after debonding; T2 (after pigmentation; T3, T4 and T5 representing 1, 7, and 14 days of bleaching. Repeatability and stability tests were carried out to check the method accuracy. Images were analyzed using Adobe Photoshop 7.0 software considering (L*a*b*color coordinate values and a modified color difference total (Δ;E'. RESULTS: The results of this study (ANOVA and Tukey; p < 0.01 demonstrated that after 7 days of bleaching, experimental groups showed significantly less teeth whitening compared to the control group. However, there were no significant color differences between the groups after 14 days, according to values of lightness (L*. CONCLUSIONS: Regardless of the adhesive primer system applied, bonding and debonding of orthodontic brackets alters the outcome of tooth whitening in the first 7 days of bleaching, however it has no influence on the whitening of the dental structure after 14 days of in-home dental bleaching with 10% carbamide peroxide.

  17. 一锅法合成5,6-二苯基-4-对甲苯基-3,4-二氢嘧啶-2-酮工艺研究%Study of synthesis technology of 5,6-diphenyl-4-p-tolyl-3,4-dihydropyrimidin-2 (1H)-ketone by one-pot method

    Institute of Scientific and Technical Information of China (English)

    闫杏丽; 陈天云

    2013-01-01

    In the presence of a catalyst,5,6-diphenyl-4-p-tolyl-3,4-dihydropyrimidin-2 (1H)-ketone were synthetized by acetophenone,p-methylbenzaldehyde and carbamide which were used as raw materials.The experimental results showed that when the molar ratio of acetophenone,p-methylbenzaldehyde and carbamide was 1 ∶ 1.15 ∶ 1.1,the reaction temperture was 80 ℃,the reaction time was 2.0 h,and the amount of substance of NaOC2H5 used as the catalyst is 0.001 mol,the product yield could reach 96%.The structure of the product was confirmed by FT-IR and 1HNMR.%文章以二苯乙酮、对甲基苯甲醛和尿素为原料,在催化剂的作用下合成了5,6-二苯基-4-对甲苯基-3,4-二氢嘧啶-2-酮.通过实验确定了反应的较佳工艺参数如下:二苯乙酮、对甲基苯甲醛、尿素的摩尔比为1∶1.15∶1.1,反应温度为80℃,反应时间为2.0h,催化剂选用NaOC2 H5,其用量为0.001 mol,在该工艺条件下,产物的收率达到了96%.采用FT-IR和1HNMR对目标化合物的结构进行了表征.

  18. Efficacy of casein phosphopeptide-amorphous calcium phosphate to prevent stain absorption on freshly bleached enamel: An in vitro study

    Directory of Open Access Journals (Sweden)

    Singh Raghuwar

    2010-01-01

    Full Text Available Background: Teeth when subjected to bleaching bring about the desiccation of the enamel, making it more susceptible to stain absorption. While subjecting the freshly bleached enamel surface to various surface treatments of Fluoride and Casein Phosphopeptide - Amorphous Calcium phosphate (CPP-ACP brought about the reduction in stain absorption, which is assessed in this study. Aims: The study aims to evaluate the tea stain absorption on freshly bleached enamel surface of extracted human teeth with varied surface treatment. The stain absorption was evaluated at the end of one hour and 24 hours post bleaching. Materials and Methods: Forty extracted human permanent maxillary central incisors were subjected to bleaching with 10% carbamide peroxide for eight days. They were divided into four groups of 10 each. Group I was control group. Group II was immersed in tea solution without surface treatment, while Group III and IV were immersed in tea solution with surface treatment of topical Fluoride and CPP-ACP respectively. Spectrophotometer was used for color analysis. Results: Surface treatment with CPP-ACP and topical fluoride on freshly beached enamel surface, significantly reduced the stain absorption. Conclusion: Remineralizing agents reduce stain absorption after tooth bleaching.

  19. Comparative clinical evaluation of two professional tooth-whitening products.

    Science.gov (United States)

    Kowitz, G M; Nathoo, S A; Wong, R

    1994-01-01

    A 2-week study was conducted to compare the tooth-whitening efficacy of two 10% carbamide peroxide products: Colgate Platinum Professional Toothwhitening System and Rembrandt Lighten Bleaching Gel. Fifty subjects were divided into two groups and assigned a product to use for 2 weeks. Change in tooth color was measured by reflectance spectroscopy at the initiation of study, at 1 week, and at 2 weeks into the study. Color change was calculated using the color-difference equation established by the Commission International de L'Eclairage. Results showed that Colgate Platinum was 62% more effective at tooth whitening after 1 week and 83% more effective after 2 weeks of treatment vs Rembrandt. At the termination of the study, the mean color difference (deltaE) for Colgate Platinum was 4.29 and 2.34 for Rembrandt. Statistical analysis demonstrated that the Colgate product is significantly superior at increasing tooth whiteness, increasing tooth lightness, reducing redness, and reducing yellowness. In this study, no adverse reactions were noted on clinical examination and none were reported by panelists with normal healthy dentition. PMID:8205580

  20. Can a bleaching toothpaste containing Blue Covarine demonstrate the same bleaching as conventional techniques? An in vitro, randomized and blinded study

    Directory of Open Access Journals (Sweden)

    Andréa Abi Rached DANTAS

    2015-12-01

    Full Text Available ABSTRACT Objective The purpose of this in vitro study was to compare the efficacy of a bleaching toothpaste containing Blue Covarine vs. conventional tooth bleaching techniques using peroxides (both in-office and at-home. Material and Methods Samples were randomly distributed into five experimental groups (n=15: C - Control; BC – Bleaching toothpaste containing Blue Covarine; WBC – Bleaching toothpaste without Blue Covarine; HP35 - In-office bleaching using 35% hydrogen peroxide; and CP10 – At-home bleaching with 10% carbamide peroxide. The dental bleaching efficacy was determined by the color difference (ΔE, luminosity (ΔL, green-red axis (Δa, and blue-yellow axis (Δb. The CIELab coordinates were recorded with reflectance spectroscopy at different times: T0 - baseline, T1 – immediately after bleaching, T2 - 7 days, T3 - 14 days, and T4 - 21 days after the end of treatments. Data were analyzed by a repeated measures mixed ANOVA and post hoc Bonferroni test, with a significance level of 5%. Results No significant differences were found between the treatment groups C, BC, and WBC. The groups HP35 and CP10 showed significantly higher whitening efficacy than groups C, BC, and WBC. Conclusions There were no significant differences in the whitening efficacy between a Blue Covarine containing toothpaste, a standard whitening toothpaste, and a control. Neither of the whitening toothpastes tested were as effective as in-office or at-home bleaching treatments.

  1. Effect of sodium ascorbate on the bond strength of silorane and methacrylate composites after vital bleaching

    Directory of Open Access Journals (Sweden)

    Eda Guler

    2013-07-01

    Full Text Available We investigated the effect of sodium ascorbate (SA on the microtensile bond strengths (MTBSs of different composites to bovine enamel after vital bleaching with hydrogen peroxide (HP or carbamide peroxide (CP. Thirty bovine incisors were randomly divided into five groups and treated with no bleaching application (control, 35% HP alone, 35% HP + 10% SA for 10 minutes (HP + SA, 16% CP alone, or 16% CP + 10% SA for 10 minutes (CP + SA. Specimens were restored with Silorane adhesive and Filtek Silorane composite (designated as S / group or with Clearfil SE bond and Filtek Supreme XT (designated as F / group. Composite build-up was created on the enamel. Sectioned specimens (n = 10 per group; 1 mm2; cross-sectional area were created and stressed in a universal testing machine at 1 mm/min crosshead speed. The application of 10% SA immediately after bleaching with 16% CP or 35% HP increased the enamel MTBS, regardless of the adhesive / composite resin used. The resulting MTBS values were similar to those of the control groups. Use of 16% CP and 35% HP alone decreased the enamel MTBS, regardless of the adhesive / composite resin used, with F / CP + SA = F / HP + SA = F / CP = S / CP + SA = S / HP + SA = S / C > S / CP = S / HP = F / CP = F / HP (p < 0.05. We concluded that the application of SA for 10 minutes immediately after vital bleaching increases the enamel BS for dimethacrylate- and silorane-based composites

  2. Evaluation of the bleached human enamel by Scanning Electron Microscopy Avaliação do esmalte dental humano submetido ao tratamento clareador por meio de Microscopia Eletrônica de Varredura

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    Carolina Baptista Miranda

    2005-06-01

    Full Text Available Since bleaching has become a popular procedure, the effect of peroxides on dental hard tissues is of great interest in research. Purpose: The aim of this in vitro study was to perform a qualitative analysis of the human enamel after the application of in-office bleaching agents, using Scanning Electron Microscopy (SEM. Materials and Methods: Twenty intact human third molars extracted for orthodontic reasons were randomly divided into four groups (n=5 treated as follows: G1- storage in artificial saliva (control group; G2- four 30-minute applications of 35% carbamide peroxide (total exposure: 2h; G3- four 2-hour exposures to 35% carbamide peroxide (total exposure: 8h; G4- two applications of 35% hydrogen peroxide, which was light-activated with halogen lamp at 700mW/cm² during 7min and remained in contact with enamel for 20min (total exposure: 40min. All bleaching treatments adopted in this study followed the application protocols advised by manufacturers. Evaluation of groups submitted to 35% carbamide peroxide was carried out after two time intervals (30 minutes and 2 hours per session, following the extreme situations recommended by the manufacturer. Specimens were prepared for SEM analysis performing gold sputter coating under vacuum and were examined using 15kV at 500x and 2000x magnification. Results: Morphological alterations on the enamel surface were similarly detected after bleaching with either 35% carbamide peroxide or 35% hydrogen peroxide. Surface porosities were characteristic of an erosive process that took place on human enamel. Depression areas, including the formation of craters, and exposure of enamel rods could also be detected. Conclusion: Bleaching effects on enamel morphology were randomly distributed throughout enamel surface and various degrees of enamel damage could be noticed. Clinical significance: In-office bleaching materials may adversely affect enamel morphology and therefore should be used with caution.Desde o

  3. The effect of light-activation sources on tooth bleaching

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    Kusai Baroudi

    2014-01-01

    Full Text Available Vital bleaching is one of the most requested cosmetic dental procedures asked by patients who seek a more pleasing smile. This procedure consists of carbamide or hydrogen peroxide gel applications that can be applied in-office or by the patient (at-home/overnight bleaching system. Some in-office treatments utilise whitening light with the objective of speeding up the whitening process. The objective of this article is to review and summarise the current literature with regard to the effect of light-activation sources on in-office tooth bleaching. A literature search was conducted using Medline, accessed via the National Library of Medicine Pub Med from 2003 to 2013 searching for articles relating to effectiveness of light activation sources on in-office tooth bleaching. This study found conflicting evidence on whether light truly improve tooth whitening. Other factors such as, type of stain, initial tooth colour and subject age which can influence tooth bleaching outcome were discussed. Conclusions: The use of light activator sources with in-office bleaching treatment of vital teeth did not increase the efficacy of bleaching or accelerate the bleaching.

  4. Physical-chemical characteristics of whitening toothpaste and evaluation of its effects on enamel roughness

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    Sérgio Paulo Hilgenberg

    2011-08-01

    Full Text Available This in vitro study evaluated the physical-chemical characteristics of whitening toothpastes and their effect on bovine enamel after application of a bleaching agent (16% carbamide peroxide. Physical-chemical analysis was made considering mass loss by desiccation, ash content and pH of the toothpastes. Thirty bovine dental enamel fragments were prepared for roughness measurements. The samples were subjected to bleaching treatments and simulated brushing: G1. Sorriso Dentes Brancos (Conventional toothpaste, G2. Close-UP Whitening (Whitening toothpaste, and G3. Sensodyne Branqueador (Whitening toothpaste. The average roughness (Ra was evaluated prior to the bleaching treatment and after brushing. The results revealed differences in the physical-chemical characteristics of the toothpastes (p < 0.0001. The final Ra had higher values (p < 0.05 following the procedures. The mean of the Ra did not show significant differences, considering toothpaste groups and bleaching treatment. Interaction (toothpaste and bleaching treatment showed significant difference (p < 0.0001. The whitening toothpastes showed differences in their physical-chemical properties. All toothpastes promoted changes to the enamel surface, probably by the use of a bleaching agent.

  5. In vitro evaluation of the chemical and morphological changes of the enamel surface using different bleaching techniques

    International Nuclear Information System (INIS)

    'In vitro' evaluation through MEV and EDS of the morphological and chemical changes, respectively, of the bovine enamel, submitted to different bleaching techniques. For the MEV evaluation eighteen apical thirds were pigmented and divided into two parts. One half of each sample was the control and the other half was bleached according to the protocol of each test group (n= 6). Group I - home bleaching with a 10% carbamide peroxide; group II bleaching with 35% hydrogen peroxide and LED; group III - bleaching with 35% hydrogen peroxide with diode laser bleaching. The same procedure was done with the eighteen samples which were analyzed through EDS and which had their buccal surface grinded and polished before the bleaching procedure in order to obtain more precise values of the fraction of calcium and phosphorus. The results showed no morphological changes among the analyzed control halves and the bleached halves. There was not a statistical significant difference about Ca and P values, among the control halves and the bleached halves regarding the chemical components (p< 0,05). (author)

  6. 葛林美腐植酸有机复合液肥对苦瓜产量和品质的影响%Effects of Greentech Humic Acid Organic Compound Fertilizer on the Yield and Quality of Momordica charantia

    Institute of Scientific and Technical Information of China (English)

    游勇; 张志元

    2011-01-01

    The field experiment and instrument analytical method was conducted to study the effects of the Greentech humic acid organic compound fertilizer on the yield and quality of Momordica charantia L.. The results showed that the yield of cucumber was increased drastically through applying Greentech humic acid organic compound fertilizer, the yield was 19.3%higher than the contrast, and 11.8% higher compared with the treatment of carbamide. The economic benefits increased RMB 8 340 per hectare.%采用田间试验和仪器分析方法,研究了葛林美腐植酸有机复合液肥对苦瓜(Momordica charantia L.)产量和品质的影响.结果表明,葛林美腐植酸有机复合液肥处理的产量显著高于不施肥和尿素处理,比不施肥增产19.3%,比尿素处理增产11.8%,每公顷增加经济效益8340元以上.

  7. USE OF NEUTRALIZED PHOSPHOGYPSUM AS MULTICOMPONENT FERTILIZER FOR RICE CROPS. MESSAGE II

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    Sheudghen A. H.

    2015-11-01

    Full Text Available The article shows a possibility of using neutralized phosphogypsum as multicomponent fertilizer for rice crops. In the system of rice fertilization replace of 150kg/ha of ammophos during main application with 40 kg/ha of carbamide and 4 tons/ha of phosphogypsum applied in spring provides the same content of available forms of nitrogen, phosphorus and potassium in soil and plants as with application of N120P80K60. Application of phosphogypsum in spring before sowing is less effective than application in autumn before plowing. When applicating phosphogypsum in spring 2013 with a rate of 4 t / ha the obtained yield was 0.57 t / ha or 8.98% higher than in the control, and in 2014 it was not different from that obtained with the application of solid mineral fertilizers with a rate of N120P80K60. With autumn application of phosphogypsum increase in yield in 2014 was 0.98 t / ha or 12.6%. Yield growth is the result of increasing the survival of plants, grain content in panicle and grain weight per plant. Use of neutralized phosphogypsum is economically feasible. Relative benefits of using phosphogypsum instead of phosphorus fertilizer (ammonium phosphate on rice crops in the Federal State Unitary Enterprise SRSF "Krasnoarmeyskiy" named after A.I.Maystrenko, Krasnoarmeyskiy district of Krasnodar region at the optimal rate amounted to 13139.7 rubles per 1 ha

  8. An overview of Gly-Oxide liquid in control and prevention of dental disease.

    Science.gov (United States)

    Stindt, D J; Quenette, L

    1989-09-01

    Removal of dental plaque is the generally accepted method of preventing and controlling periodontal disease. Several studies have identified bacterial plaque as the primary etiologic factor in periodontal disease. However, many individuals have difficulty in mechanically removing plaque or may have physical limitations that hinder their ability to effectively brush and floss. Consequently, in recent years, the search for an agent to remove or inhibit dental plaque has intensified. Numerous studies have been conducted to investigate the effectiveness of various agents in removing or inhibiting plaque. In its Technical Report No. 26, the Federation Dentair Internationale provides a comprehensive overview of the efficacy of antibiotics, antiseptics, chemical agents, irrigation, pastes, and slow release devices in plaque removal and inhibition. Addy has suggested that investigation of oxygenating mouthrinses as antiplaque agents deserves attention because of their potential ability to affect the anaerobes responsible for periodontal disease. The purpose of this article is to provide an overview of the role of one oxygenating agent, carbamide peroxide in glycerol solution, in the prevention and control of periodontal disease. PMID:2637067

  9. Can a bleaching toothpaste containing Blue Covarine demonstrate the same bleaching as conventional techniques? An in vitro, randomized and blinded study

    Science.gov (United States)

    DANTAS, Andréa Abi Rached; BORTOLATTO, Janaina Freitas; RONCOLATO, Ávery; MERCHAN, Hugo; FLOROS, Michael Christopher; KUGA, Milton Carlos; de OLIVEIRA, Osmir Batista

    2015-01-01

    ABSTRACT Objective The purpose of this in vitro study was to compare the efficacy of a bleaching toothpaste containing Blue Covarine vs. conventional tooth bleaching techniques using peroxides (both in-office and at-home). Material and Methods Samples were randomly distributed into five experimental groups (n=15): C - Control; BC – Bleaching toothpaste containing Blue Covarine; WBC – Bleaching toothpaste without Blue Covarine; HP35 - In-office bleaching using 35% hydrogen peroxide; and CP10 – At-home bleaching with 10% carbamide peroxide. The dental bleaching efficacy was determined by the color difference (ΔE), luminosity (ΔL), green-red axis (Δa), and blue-yellow axis (Δb). The CIELab coordinates were recorded with reflectance spectroscopy at different times: T0 - baseline, T1 – immediately after bleaching, T2 - 7 days, T3 - 14 days, and T4 - 21 days after the end of treatments. Data were analyzed by a repeated measures mixed ANOVA and post hoc Bonferroni test, with a significance level of 5%. Results No significant differences were found between the treatment groups C, BC, and WBC. The groups HP35 and CP10 showed significantly higher whitening efficacy than groups C, BC, and WBC. Conclusions There were no significant differences in the whitening efficacy between a Blue Covarine containing toothpaste, a standard whitening toothpaste, and a control. Neither of the whitening toothpastes tested were as effective as in-office or at-home bleaching treatments. PMID:26814462

  10. Penggunaan Karbamid Peroksida Sebagai Bahan Pemutih Gigi

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    Endang Suprastiwi

    2015-10-01

    Full Text Available Carbamide peroxide as a whitening agent for teeth is very popular because the use of this agent is easy and inexpensive. There are two kinds of concentrations, i.e. 10%-15% and 35%. The methods are home bleaching and in office bleaching. For home bleaching, the duration of whitening application is 2-6 weeks, each day for 8 hours, whilst for in office bleaching, two hour application will be required. Whitening efficacy might be increased up to 2-5 levels and the color may sustain for 1-3 years, and this treatment could be reapplied. There is an effect on pulp system, but the effect is reversible, i.e. sensitivity which could be treated with fluoridation or application of potassium nitrate. The side effects on gingiva include inflammation which is caused by the buffer and is only temporary. Bleaching is safe to be use and the result will be satisfying if proper procedure is followed.

  11. Effect of hydrazine and hydroxylaminophosphate on chrome plating from trivalent electrolytes

    Science.gov (United States)

    Survilienė, S.; Jasulaitienė, V.; Nivinskienė, O.; Češūnienė, A.

    2007-06-01

    The influence of hydrazine and hydroxylaminophosphate on solution chemistry and quality of chromium coatings deposited from Cr(III) formate-urea baths has been studied by FT-IR, XPS and AFM. The results have shown that hydrazine and hydroxylaminophosphate differently affect Cr plating. The morphology of Cr deposits obtained in the formate-urea electrolytes is a typical nodular structure with a less nodular and smoother fine-grained structure of Cr obtained in the presence of hydroxylaminophosphate. Hydrazine, in contrast, worsened the quality and lowered the hardness of the deposits. The current efficiency of chromium increases in the presence of both hydrazine and hydroxylaminophosphate. This may be related with the ability of these ligands to reduce the CrH content in the growing Cr deposit. The data obtained suggest that hydroxylaminophosphate improves the stability of the active [Cr(carbamide) n(H 2O) 6- n] 3 complexes providing good quality of the deposits and prolonged working lifetime in the formate-urea bath.

  12. Application of biological markers for the identification of oil-type pollutants in recent sediments: Alluvial formation of the Danube river, Oil refinery Pančevo

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    Rašović Aleksandar S.

    2002-01-01

    Full Text Available The purpose of this paper was to examine to which extent the abundance and distribution of certain biological markers may be used for the identification of oil-type pollutants in recent sediments and ground waters. The samples were taken from the area of the Oil Refinery Pančevo (alluvial formation of the Danube River. The organic matter of the investigated samples was isolated using an extraction method with chloroform. The group composition and usual biological markers were analyzed in the obtained extracts. n-Alkanes and acyclic isoprenoids, pristane and phytane were analyzed using gas chromatographie (GC analysis of saturated hydrocarbons. Polycyclic alkanes of the sterane and terpane type were analyzed using gas chromatography-mass spectrometry (GC-MS, i.e. by analyzing the carbamide non-adduct of the total alkane fraction (Single Ion Monitoring SIM-technique. The obtained results indicate that n-alkanes can be used for the identification of oil-type pollutants (for example, if the oil-pollutant is biodegraded or present in very low concentrations, and steranes and triterpanes can be used as very reliable indicators of oil-type pollution in recent sediments and ground waters.

  13. A conservative approach to esthetically treat stained arrested caries lesions.

    Science.gov (United States)

    Al-Angari, Sarah S; Hara, Anderson T

    2016-01-01

    Esthetic treatment of stained arrested caries lesions (ACLs) has mostly been done using invasive restorative techniques. The aim of this paper was to propose and report the efficacy of a conservative approach based on dental bleaching to esthetically treat these lesions, both experimentally (extracted teeth) and clinically. In a laboratory experiment, ten extracted human teeth with stained ACLs in either pit and fissure or smooth surface were selected and treated with 15% carbamide peroxide gel, 4 h per day, for a total of 6 days. The second part of the paper reports a clinical case of pit and fissure-stained ACLs in four posterior teeth, which were treated with 40% hydrogen peroxide in-office bleaching. Digital photographs were taken in both parts to document the efficacy of the treatment. The lesions showed noticeable increase in color lightness indicating the efficacy and suitability of the proposed approach. By using the conservative clinical technique presented, the esthetics of most stained ACLs could be improved, eliminating the need for invasive restorative treatments. PMID:27092359

  14. Mercury release of amalgams with various silver contents after exposure to bleaching agent.

    Science.gov (United States)

    Bahari, Mahmoud; Alizadeh Oskoee, Parnian; Savadi Oskoee, Siavash; Pouralibaba, Firoz; Morsali Ahari, Ali

    2016-01-01

    Background. Since it is possible for carbamide peroxide (CP) bleaching agent to contact old amalgam restorations, the present in vitro study evaluated the amount of dissolved mercury released from amalgam restorations with various percent-ages of silver content subsequent to the use of 15% CP. Methods. Thirty ANA 2000 amalgam disks with 43.1% silver content and thirty ANA 70 amalgam disks with 69.3% silver content were prepared. In each group, 15 samples were randomly placed in glass tubes containing 15% CP (as experimental groups) and the remaining 15 samples were placed in buffered phosphate solution (as control groups) with the same 3-mL volume for 48 hours. Subsequently, the amount of mercury dissolved in each test tube was measured using Mercury Analyzing System (Cold Vapor Atomic Absorption, MASLO, Shimadzu, Japan). Data was analyzed with two-way ANOVA and a post hoc Tukey test. (α = 0.05). Results. The amount of mercury released after exposure to CP was significantly higher than that released after exposure to buffered phosphate (P dental amalgam with a silver content of 43% was significantly higher than that released from dental amalgam with a silver content of 69% (P dental amalgam. PMID:27429729

  15. Esthetic rehabilitation with tooth bleaching, enamel microabrasion, and direct adhesive restorations.

    Science.gov (United States)

    Bezerra-Júnior, Douglas Machado; Silva, Luciana Mendonça; Martins, Leandro de Moura; Cohen-Carneiro, Flávia; Pontes, Danielson Guedes

    2016-01-01

    The aim of this case report is to report esthetic rehabilitation with combined tooth bleaching, enamel microabrasion, and anterior restoration replacement in a 26-year-old man. Clinical examination showed deficient restorations in the maxillary anterior teeth, significant discoloration of the maxillary left central incisor, and hypoplastic stains affecting the maxillary right lateral incisor. A radiograph of the left central incisor showed satisfactory endodontic treatment, allowing preparation for the walking bleach technique. For 3 weeks, 37% carbamide peroxide in the pulp chamber was renewed every week. In-office bleaching with 35% hydrogen peroxide was also performed on the maxillary teeth. After 21 days, all teeth had been bleached to shade A1. After bleaching was completed, enamel microabrasion of the maxillary right lateral incisor was conducted with 6% hydrochloric acid. In later sessions, microhybrid composite resin restorations were placed in all 4 maxillary incisors. A combination of dental bleaching techniques, enamel microabrasion, and resin restorations was a successful and conservative choice for reestablishing the natural appearance of discolored teeth, improving the self-esteem of the patient. PMID:26943091

  16. Influence of fluoride-containing adhesives and bleaching agents on enamel bond strength

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    Vanessa Cavalli

    2012-12-01

    Full Text Available This study evaluated the influence of fluoride-containing carbamide peroxide (CP bleaching agents and adhesive systems on bonded enamel interfaces that are part of the dynamic pH cycling and thermal cycling models. The buccal surfaces of 60 bovine incisors were restored with a composite resin and bonded with three- and two-step, etch-and-rinse, fluoride-containing adhesives, Optibond FL (FL and Optibond Solo Plus (SP, respectively. Restored teeth were subjected to thermal cycling to age the interface. Both SP and FL adhesive-restored teeth were bleached (n = 10 with 10% CP (CP and 10% CP + fluoride (CPF or were left unbleached (control. Bleaching was performed for 14 days simultaneously with pH cycling, which comprised of 14 h of remineralization, 2 h of demineralization and 8 h of bleaching. The control groups (FL and SP were stored in remineralizing solution during their bleaching periods and were also subjected to carious lesion formation. Parallelepiped-shaped samples were obtained from the bonded interface for microtensile bond strength (∝TBS testing. The enamel ∝TBS of the FL and SP groups (control, not bleached were higher (p FL + CPF = FL + CP and SP > SP + CPF = SP + CP. The groups subjected to treatment with the fluoride-containing bleaching agents exhibited similar ∝TBS compared to regular bleaching agents. Bleaching agents, regardless of whether they contained fluoride, decreased enamel bond strength.

  17. Influence of fluoride-containing adhesives and bleaching agents on enamel bond strength.

    Science.gov (United States)

    Cavalli, Vanessa; Liporoni, Priscila Cristiane Suzy; Rego, Marcos Augusto do; Berger, Sandrine Bittencourt; Giannini, Marcelo

    2012-01-01

    This study evaluated the influence of fluoride-containing carbamide peroxide (CP) bleaching agents and adhesive systems on bonded enamel interfaces that are part of the dynamic pH cycling and thermal cycling models. The buccal surfaces of 60 bovine incisors were restored with a composite resin and bonded with three- and two-step, etch-and-rinse, fluoride-containing adhesives, Optibond FL (FL) and Optibond Solo Plus (SP), respectively. Restored teeth were subjected to thermal cycling to age the interface. Both SP and FL adhesive-restored teeth were bleached (n = 10) with 10% CP (CP) and 10% CP + fluoride (CPF) or were left unbleached (control). Bleaching was performed for 14 days simultaneously with pH cycling, which comprised of 14 h of remineralization, 2 h of demineralization and 8 h of bleaching. The control groups (FL and SP) were stored in remineralizing solution during their bleaching periods and were also subjected to carious lesion formation. Parallelepiped-shaped samples were obtained from the bonded interface for microtensile bond strength (μTBS) testing. The enamel μTBS of the FL and SP groups (control, not bleached) were higher (p FL > FL + CPF = FL + CP and SP > SP + CPF = SP + CP). The groups subjected to treatment with the fluoride-containing bleaching agents exhibited similar μTBS compared to regular bleaching agents. Bleaching agents, regardless of whether they contained fluoride, decreased enamel bond strength. PMID:23184165

  18. Microhardness of demineralized enamel following home bleaching and laser-assisted in office bleaching

    Science.gov (United States)

    Ghanbarzadeh, Majid; Akbari, Majid; Hamzei, Haniye

    2015-01-01

    Background There is little data regarding the effect of tooth whitening on microhardness of white spot lesions. This study was conducted to investigate the effect of home-bleaching and laser-assisted in-office bleaching on microhardness of demineralized enamel. Material and Methods Forty bovine incisors were selected and immersed in a demineralizing solution for 12 weeks to induce white spot lesions. Enamel blocks were prepared and randomly assigned to two groups of 20 each. The first group underwent home bleaching with 15% carbamide peroxide which was applied for 8 hours a day over a period of 15 days. In the second group, in-office bleaching was performed by 40% hydrogen peroxide and powered by irradiation from an 810 nm gallium-aluminum-arsenide (GaAlAs) diode laser (CW, 2W). This process was performed for 3 sessions every seven days, in 15 days. The specimens were stored in Fusayama Meyer artificial saliva during the experiment. Surface microhardness was assessed before and after the bleaching therapies in both groups. Results Microhardness decreased significantly following both home bleaching and laser-assisted in-office bleaching (plaser-assisted in-office bleaching can result in a significant reduction in microhardness of white spot lesions. Therefore, it is suggested to take protective measures on bleached demineralized enamel. Key words:White spot lesion, bleaching, laser, microhardness, demineralized enamel, home bleaching, in-office bleaching. PMID:26330939

  19. In vitro evaluation of the chemical and morphological changes of the enamel surface using different bleaching techniques; Avaliacao in vitro das alteracoes quimica e morfologica da superficie do esmalte utilizando diferentes tecnicas de clareamento dental

    Energy Technology Data Exchange (ETDEWEB)

    Mattos, Alessandra de Siervi

    2003-07-01

    'In vitro' evaluation through MEV and EDS of the morphological and chemical changes, respectively, of the bovine enamel, submitted to different bleaching techniques. For the MEV evaluation eighteen apical thirds were pigmented and divided into two parts. One half of each sample was the control and the other half was bleached according to the protocol of each test group (n= 6). Group I - home bleaching with a 10% carbamide peroxide; group II bleaching with 35% hydrogen peroxide and LED; group III - bleaching with 35% hydrogen peroxide with diode laser bleaching. The same procedure was done with the eighteen samples which were analyzed through EDS and which had their buccal surface grinded and polished before the bleaching procedure in order to obtain more precise values of the fraction of calcium and phosphorus. The results showed no morphological changes among the analyzed control halves and the bleached halves. There was not a statistical significant difference about Ca and P values, among the control halves and the bleached halves regarding the chemical components (p< 0,05). (author)

  20. Effect of Bleaching and Thermocycling on Resin-Enamel Bond Strength

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    Horieh Moosavi

    2015-01-01

    Full Text Available The aim of this study was to evaluate the effect of bleaching and thermocycling on microshear bond strength of bonded resin composites to enamel. Enamel slices were prepared from ninety-six intact human premolars and resin composite cylinders were bonded by using Adper Single Bond 2 + Filtek Z350 or Filtek silorane adhesive and resin composite. Each essential group was randomly subdivided to two subgroups: control and bleaching. In bleaching group, 35% hydrogen peroxide was applied on samples. Thermocycling procedure was conducted between 5°C and 55°C, for 3.000 cycles on the half of each subgroup specimen. Then microshear bond strength was tested. Methacrylate-based resin composite had higher bond strength than silorane-based one. The meyhacrylate-based group without bleaching along with thermocycling showed the most bond strength, while bleaching with 35% carbamide peroxide on silorane-based group without thermocycling showed the least microshear bond strength. Bleaching caused a significant degradation on shear bond strength of silorane-based resin composites that bonded using self-etch adhesive resin systems.

  1. Mercury release of amalgams with various silver contents after exposure to bleaching agent

    Science.gov (United States)

    Bahari, Mahmoud; Alizadeh Oskoee, Parnian; Savadi Oskoee, Siavash; Pouralibaba, Firoz; Morsali Ahari, Ali

    2016-01-01

    Background. Since it is possible for carbamide peroxide (CP) bleaching agent to contact old amalgam restorations, the present in vitro study evaluated the amount of dissolved mercury released from amalgam restorations with various percent-ages of silver content subsequent to the use of 15% CP. Methods. Thirty ANA 2000 amalgam disks with 43.1% silver content and thirty ANA 70 amalgam disks with 69.3% silver content were prepared. In each group, 15 samples were randomly placed in glass tubes containing 15% CP (as experimental groups) and the remaining 15 samples were placed in buffered phosphate solution (as control groups) with the same 3-mL volume for 48 hours. Subsequently, the amount of mercury dissolved in each test tube was measured using Mercury Analyzing System (Cold Vapor Atomic Absorption, MASLO, Shimadzu, Japan). Data was analyzed with two-way ANOVA and a post hoc Tukey test. (α = 0.05). Results. The amount of mercury released after exposure to CP was significantly higher than that released after exposure to buffered phosphate (P < 0.001). In addition, the amount of mercury released from dental amalgam with a silver content of 43% was significantly higher than that released from dental amalgam with a silver content of 69% (P < 0.001). Conclusion. The amount of mercury release is inversely proportional to the silver content of dental amalgam. PMID:27429729

  2. Effect of Bleaching on Color Change and Surface Topography of Composite Restorations

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    Gunjan Pruthi

    2010-01-01

    Full Text Available This study was conducted to determine the effect of 15% carbamide peroxide bleaching agent on color change and surface topography of different composite veneering materials (Filtek Z350 (3M ESPE, Esthet X (Dentsply India, and Admira (Voco, Germany. Methods. 30 samples were fabricated for evaluation of color change using CIELAB color system and Gonioreflectometer (GK 311/M, ZEISS. 45 disc-shaped specimens were made for evaluation of surface topography after bleaching (Nupro White Gold; Dentsply using SEM. Statistical analysis. One way ANOVA and Multiple comparison tests were used to analyze the data. Statistical significance was declared if the P value was .05 or less. Results and conclusion. All the specimens showed significant discoloration (ΔE>3.3 after their immersion in solutions representing food and beverages. The total color change after bleaching as compared to baseline color was significant in Filtek Z350 (P=.000 and Esthet X (P=.002, while it was insignificant for Admira (P=.18. Esthet X showed maximum surface roughness followed by Admira and Filtek Z350. Bleaching was effective in reducing the discoloration to a clinically acceptable value in all the three groups (ΔE<3.3.

  3. Structural features of nanocrystalline holmium oxide prepared by the thermal decomposition of organic precursors

    International Nuclear Information System (INIS)

    Highlights: • Nanocrystalline C-Ho2O3 was prepared from Ho acetate at 600 and 700 °C. • Nanocrystalline C-Ho2O3 was prepared from urea-containing complex of Ho at 700 °C. • The bcc lattice parameter of C-Ho2O3 increases as the crystallite size decreases. - Abstract: Powders of nanostructured holmium oxide (C-Ho2O3) with the crystallite sizes ranging from 6 to 16 nm have been prepared in bulk from the thermal decomposition of holmium acetate and carbamide-containing complex of holmium as precursors at 600 and 700 °C. The powders obtained have been investigated by X-ray diffraction, TEM, thermogravimetry, IR- and Raman spectroscopy. A comparison has been drawn between these and powdered holmium oxide with micron-sized crystallites prepared from the thermal decomposition of holmium chloride. The bcc lattice parameter of the oxides has been found to increase when the crystallite size decreases. It has been noted that the surface of air-exposed powders of holmium oxides is covered by products formed due to the chemisorption of atmospheric CO2 and H2O molecules

  4. Structural features of nanocrystalline holmium oxide prepared by the thermal decomposition of organic precursors

    Energy Technology Data Exchange (ETDEWEB)

    Abdusalyamova, M.N.; Makhmudov, F.A.; Shairmardanov, E.N. [Institute of Chemistry of Tajik Academy of Science, Ajni Str. 299/2, 734063 Dushanbe (Tajikistan); Kovalev, I.D., E-mail: i2212@yandex.ru [Institute of Structural Macrokinetics and Materials Science of RAS, 142432 Chernogolovka, Moscow Region (Russian Federation); Fursikov, P.V., E-mail: fpv@icp.ac.ru [Institute of Problems of Chemical Physics of RAS, 142432 Chernogolovka, Moscow Region (Russian Federation); Khodos, I.I., E-mail: khodos@iptm.ru [Institute of Microelectronics Technology and High-Purity Materials of RAS, 142432 Chernogolovka, Moscow Region (Russian Federation); Shulga, Y.M., E-mail: shulga@icp.ac.ru [Institute of Problems of Chemical Physics of RAS, 142432 Chernogolovka, Moscow Region (Russian Federation)

    2014-07-15

    Highlights: • Nanocrystalline C-Ho{sub 2}O{sub 3} was prepared from Ho acetate at 600 and 700 °C. • Nanocrystalline C-Ho{sub 2}O{sub 3} was prepared from urea-containing complex of Ho at 700 °C. • The bcc lattice parameter of C-Ho{sub 2}O{sub 3} increases as the crystallite size decreases. - Abstract: Powders of nanostructured holmium oxide (C-Ho{sub 2}O{sub 3}) with the crystallite sizes ranging from 6 to 16 nm have been prepared in bulk from the thermal decomposition of holmium acetate and carbamide-containing complex of holmium as precursors at 600 and 700 °C. The powders obtained have been investigated by X-ray diffraction, TEM, thermogravimetry, IR- and Raman spectroscopy. A comparison has been drawn between these and powdered holmium oxide with micron-sized crystallites prepared from the thermal decomposition of holmium chloride. The bcc lattice parameter of the oxides has been found to increase when the crystallite size decreases. It has been noted that the surface of air-exposed powders of holmium oxides is covered by products formed due to the chemisorption of atmospheric CO{sub 2} and H{sub 2}O molecules.

  5. Effect of thickener agents on dental enamel microhardness submitted to at-home bleaching Efeito de agentes espessantes na microdureza do esmalte submetido ao clareamento dental caseiro

    Directory of Open Access Journals (Sweden)

    José Augusto Rodrigues

    2007-06-01

    Full Text Available Dental bleaching occurs due to an oxidation reaction between the bleaching agents and the macromolecules of pigments in the teeth. This reaction is unspecific and the peroxides can also affect the dental matrix causing mineral loss. On the other hand, recent studies have suggested that the thickener agent carbopol can also cause mineral loss. Thus, the objective of this study was to evaluate in vitro the effect of at-home dental bleaching on dental enamel microhardness after the use of bleaching agents with and without carbopol as a thickener agent. Bovine dental slabs with 3 x 3 x 3 mm were obtained, sequentially polished, and randomly divided into 4 groups according to the experimental treatment: G1: 2% carbopol; G2: 10% carbamide peroxide with carbopol; G3: carbowax; G4: 10% carbamide peroxide with poloxamer. Bleaching was performed daily for 4 weeks, immersed in artificial saliva. Enamel microhardness values were obtained before the treatment (T0 and 7 (T1, 14 (T2, 21 (T3, 28 (T4, and 42 (T5 days after the beginning of the treatment. ANOVA and Tukey's test revealed statistically significant differences only for the factor Time (F = 5.48; p O clareamento dental ocorre devido a uma reação de oxidação entre o agente clareador e as macromoléculas de pigmentos presentes nos dentes. Esta reação é inespecífica e o peróxido pode agir na matriz dental causando perdas de mineral. Por outro lado, estudos recentes sugerem que o agente espessante carbopol também pode causar perda mineral. Assim, o objetivo deste trabalho foi avaliar in vitro o efeito do clareamento caseiro sobre a microdureza do esmalte após o uso de agentes clareadores com e sem carbopol como espessante. Fragmentos de esmalte bovino de 3 x 3 x 3 mm foram obtidos, polidos seqüencialmente e aleatoriamente divididos em 4 grupos de acordo com o tratamento experimental: G1: carbopol a 2%; G2: peróxido de carbamida a 10% com carbopol; G3: carbowax; G4: peróxido de carbamida a

  6. In-Vitro Effect of Casein Phosphopeptide Amorphous Calcium Phosphate on Enamel Susceptibility to Staining by Tea during Bleaching Treatment

    Science.gov (United States)

    Alaghemand, Homayoom; Hashemi Kamangar, Sedighe Sadat; Zarenegad, Nafiseh; Tabari, Negin; Khafri, Soraya

    2015-01-01

    Objectives: Bleached enamel is more susceptible to staining, and application of remineralizing agents may decrease enamel susceptibility to staining. This study sought to assess the effect of casein phosphopeptide amorphous calcium phosphate (CPP-ACP) on enamel susceptibility to staining during bleaching treatment. Materials and Methods: Forty central and lateral incisors and first premolar teeth were evaluated in four groups of 10. Group one specimens were subjected to in-office bleaching. Group two underwent in-office bleaching followed by surface treatment with CPP-ACP. Group three specimens received home bleaching and group four underwent home bleaching followed by CPP-ACP surface treatment. After each course of daily bleaching, specimens were immersed in tea solution. Home bleaching (15% carbamide peroxide) was performed for 14 days and in-office bleaching (40% hydrogen peroxide) was carried out in two sessions with an eight-day interval. The color of specimens was analyzed at baseline and post-intervention using Easy Shade Shade-Selection Device. Two-way ANOVA was used to evaluate the effects of bleaching type and surface treatment on color change. Then, the means were compared by Tukey’s HSD test (P=0.05). Results: The interaction effect of surface treatment and type of bleaching was not significant on any color parameter (P>0.05). Surface treatment had significant effects on ΔL (P=0.004). Type of bleaching had a significant effect on “b” parameter (P=0.00). The effect of bleaching type on ΔE was significant (P=0.00) but the effect of surface treatment was not (P=0.34). Conclusion: CPP-ACP had no significant effect on preventing enamel staining by tea during bleaching treatment.

  7. The effect of remin pro and MI paste plus on bleached enamel surface roughness.

    Directory of Open Access Journals (Sweden)

    Haleh Heshmat

    2014-04-01

    Full Text Available The growing demand for enhanced esthetic appearance has led to great developments in bleaching products. The exposure of hard tissues of the tooth to bleaching agents can affect the roughness of the enamel surface. The freshly bleached enamel surface exposed to various surface treatments such as fluoride and other remineralizing agents have been assessed in this study. The aim of this experimental study was to compare the effect of Casein Phosphopeptide-Amorphous Calcium Phosphate with Fluoride (MI Paste Plus and Remin Pro on the enamel surface roughness after bleaching.Thirty enamel samples of sound human permanent molars were prepared for this study. After initial roughness measurement with profilometer, the samples were exposed to 37% carbamide peroxide bleaching agent 20 minutes twice, and randomly divided into three groups of ten. In group 1, a CPP-ACPF containing paste (MI Paste Plus and in group 2, Remin Pro were applied to the teeth during a 15 day period for 5 minutes, twice a day. Samples of group 3 (control were immersed in artificial saliva for 15 days. The roughness of all samples were measured at the beginning, after bleaching and after the study intervention and statistically analyzed.The surface roughness significantly increased in all groups following bleaching, and then it showed a decrease after application of both Remin Pro and CPP-ACPF in comparison to using bleaching agent (P0.05.There was no difference between surface roughness of MI Paste Plus and Remin Pro groups. Also the surface roughness was decreased compared to the initial enamel surface roughness.

  8. High-efficiency tooth bleaching using non-thermal atmospheric pressure plasma with low concentration of hydrogen peroxide

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    Seoul Hee NAM

    2013-06-01

    Full Text Available Light-activated tooth bleaching with a high hydrogen peroxide (HP; H2O2 concentration has risks and the actual role of the light source is doubtful. The use of conventional light might result in an increase in the temperature and cause thermal damage to the health of the tooth tissue. Objective This study investigated the efficacy of tooth bleaching using non-thermal atmospheric pressure plasma (NAPP with 15% carbamide peroxide (CP; CH6N2O3 including 5.4% HP, as compared with conventional light sources. Material and Methods Forty human teeth were randomly divided into four groups: Group I (CP+NAPP, Group II (CP+plasma arc lamp; PAC, Group III (CP+diode laser, and Group IV (CP alone. Color changes (∆E of the tooth and tooth surface temperatures were measured. Data were evaluated by one-way analysis of variance (ANOVA and post-hoc Tukey's tests. Results Group I showed the highest bleaching efficacy, with a ∆E value of 1.92-, 2.61 and 2.97-fold greater than those of Groups II, III and IV, respectively (P<0.05. The tooth surface temperature was maintained around 37°C in Group I, but it reached 43°C in Groups II and III. Conclusions The NAPP has a greater capability for effective tooth bleaching than conventional light sources with a low concentration of HP without causing thermal damage. Tooth bleaching using NAPP can become a major technique for in-office bleaching in the near future.

  9. Comparative clinical study of the effectiveness of different dental bleaching methods - two year follow-up

    Directory of Open Access Journals (Sweden)

    Rafael Francisco Lia Mondelli

    2012-08-01

    Full Text Available This study evaluated color change, stability, and tooth sensitivity in patients submitted to different bleaching techniques. MATERIAL AND METHODS: In this study, 48 patients were divided into five groups. A half-mouth design was conducted to compare two in-office bleaching techniques (with and without light activation: G1: 35% hydrogen peroxide (HP (Lase Peroxide - DMC Equipments, São Carlos, SP, Brazil + hybrid light (HL (LED/Diode Laser, Whitening Lase II DMC Equipments, São Carlos, SP, Brazil; G2: 35% HP; G3: 38% HP (X-traBoost - Ultradent, South Jordan UT, USA + HL; G4: 38% HP; and G5: 15% carbamide peroxide (CP (Opalescence PF - Ultradent, South Jordan UT, USA. For G1 and G3, HP was applied on the enamel surface for 3 consecutive applications activated by HL. Each application included 3x3' HL activations with 1' between each interval; for G2 and G4, HP was applied 3x15' with 15' between intervals; and for G5, 15% CP was applied for 120'/10 days at home. A spectrophotometer was used to measure color change before the treatment and after 24 h, 1 week, 1, 6, 12, 18 and 24 months. A VAS questionnaire was used to evaluate tooth sensitivity before the treatment, immediately following treatment, 24 h after and finally 1 week after. RESULTS: Statistical analysis did not reveal any significant differences between in-office bleaching with or without HL activation related to effectiveness; nevertheless the time required was less with HL. Statistical differences were observed between the results after 24 h, 1 week and 1, 6, 12, 18 and 24 months (intergroup. Immediately, in-office bleaching increased tooth sensitivity. The groups activated with HL required less application time with gel. CONCLUSION: All techniques and bleaching agents used were effective and demonstrated similar behaviors.

  10. Effect of the nitrogen fertilizer type on the enzyme activity in the rhizosphere of calcic chernozem and soybean production

    Science.gov (United States)

    Emnova, E. E.; Daraban, O. V.; Bizgan, Ya. V.; Toma, S. I.; Vozian, V. I.; Iacobuta, M. D.

    2015-05-01

    Three varieties (Aura, Magie, and Indra) of soybean ( Glycine max [L.] Merr.) were grown in a small-plot experiment on a calcic chernozem with the application of two types of nitrogen fertilizers: ammonium nitrate (Nan) or carbamide (Nc). These fertilizers at the rate of 20 kg N/ha were applied before sowing together with potassium phosphate (60 kg P2O5/ha). The microbial nitrification capacity and the activity of enzymes related to the nitrogen cycle (urease and nitrate reductase) were measured in the rhizosphere (0-20 cm) at the stage of soybean flowering. It was determined that the biological (enzyme) activity of the calcic chernozem in the soybean rhizosphere was more intense on the plots with the Nan fertilizer than on the plots with the Nc fertilizer. The urease activity depended on the type of nitrogen fertilizer (Nan or Nc) under the conditions of soil water deficiency. In the soil under the Aura variety, the urease activity was significantly lower in the treatments with Nc application, and this was accompanied by a decrease in the crop yield. The nitrification capacity of the calcic chernozem was generally low; in the case of the Nc fertilizer, it was significantly lower than in the case of the Nan fertilizer. The nitrate reductase activity of the soil was also lower in the case of the Nc fertilizer. Each of the three soybean varieties had its own response to changes in the nitrogen nutrition aimed at improving the soybean tolerance to fluctuations in the soil water content during the growing season.

  11. Surface discoloration of composite resins: Effects of staining and bleaching

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    Claudio Poggio

    2012-01-01

    Full Text Available Background: The purpose of this in vitro study was to evaluate surface discoloration of three microhybrid composite resins (Esthet·X HD, Clearfil AP-X, Gradia Direct and five nanohybrid composite resins (Ceram·X, GC Kalore, G-aenial, Grandio, GrandioSO, after staining and bleaching procedures. Materials and Methods: The composite resins were polymerized with a curing light (Celalux II, Voco, Cuxhaven, Germany into 160 silicon molds (6,4 mm in diameter and 2 mm in thickness to obtain identical specimens. Twenty samples for each composite resin were prepared. The specimens were polished using an automated polishing machine with the sequence of 600-, 800-, 1000-grit abrasive paper under water irrigation. The specimens were immersed in tea and distilled water: the specimens were dipped for 20 min, once a day (every 24 h, for 14 days into the drinks. The specimens were then bleached with carbamide peroxide at 17% (Perfect Bleach-Voco. The color of specimens was measured with a spectrophotometer according to the CIE LFNx01aFNx01bFNx01 system after light-polymerization of composite resin specimens, after 7 days, after 14 days, and after bleaching. The color difference h index (DE abFNx01 between each measurement was calculated. Statistical analysis was made using analysis of variance (ANOVA. Results: All specimens showed a significant increase in staining with a similar trend and no significant differences between microhybrid and nanohybrid composite resins. After whitening procedures, materials tested showed both significant and unsignificant differences of the h index. Conclusions: Microhybrid and nanohybrid composite resins had similar in vitro surface discoloration in tea. After bleaching, discoloration was removed from some composite resins tested.

  12. Effect of at-home bleaching with different thickeners and aging on physical properties of a nanocomposite

    Science.gov (United States)

    Gouveia, Thayla Hellen Nunes; Públio, Juliana do Carmo; Ambrosano, Glaucia Maria Bovi; Paulillo, Luís Alexandre Maffei Sartini; Aguiar, Flávio Henrique Baggio; Lima, Débora Alves Nunes Leite

    2016-01-01

    Objective: To evaluate the influence of 16% carbamide peroxide (CP) containing different thickeners on the physical characteristics of a nanocomposite resin submitted or not to accelerated artificial aging (AAA). Materials and Methods: One hundred samples were randomly distributed into two groups (n = 50) according to AAA. Each group was divided into 5 subgroups (n = 10) depending on the bleaching/thickener treatment: CP + carbopol, CP + natrosol, carbopol, natrosol, and no treatment (control). The physical properties tested were color (ΔE), gloss (GU), mean roughness (Ra), and Knoop microhardness (KHN). The resin surface was performed with atomic force microscopy (AFM). Statistical Analysis: The color (variable Δ E) was assessed with two-way analysis of variance (ANOVA) and additionally with Tukey's and Dunnett's tests, the roughness values were submitted to Kruskal–Wallis, Dunn's, and Mann–Whitney's tests. Data on gloss and KHN were submitted to two-way ANOVA and Tukey's test (α = 0.05). Results: Among the physical properties evaluated, CP + carbopol promoted a reduction in composite microhardness only, thus differing statistically from the controls. As for CP + natrosol, such a change was not observed. The aging process reduced all the physical properties, thus differing statistically from the nonaging group. CP + carbopol increased the roughness and decreased the gloss of aged resins, whereas natrosol reduced gloss only, which differed statistically from the controls. Conclusions: AFM showed evidence of the loss of organic matrix and exposure to load particles in the aged samples. Therefore, the replacement of carbopol with natrosol provided maintenance of the composite microhardness following bleaching. The aging process reduced the physical properties evaluated, and some changes were enhanced by the application of bleaching. PMID:27011745

  13. Nanotribological and Nanomechanical Properties Changes of Tooth After Bleaching and Remineralization in Wet Environment

    Science.gov (United States)

    Yu, Dandan; Gao, Shanshan; Min, Jie; Zhang, Qianqian; Gao, Shuai; Yu, Haiyang

    2015-12-01

    Teeth bleaching cases had increased with people's desire for oral aesthetic; however, bleached teeth would still undertake chewing actions and remineralizing process in saliva. Nanotribological and nanomechanical properties are proper displays for dental performance of bleached teeth. The purpose of the research was to reveal the effect of bleaching and remineralization on the nanotribological and nanomechanical properties of teeth in wet environment. The specimens were divided into four groups according to the bleaching products used: 12 % hydrogen peroxide (HP) (12HP group); 15 % carbamide peroxide (CP) (15CP group); 35 % CP (35CP group); and artificial saliva (control group). The nanotribological and nanomechanical property changes of tooth enamel after bleaching and remineralization were evaluated respectively by nanoscratch and nanoindentation tests in wet environment, imitating the wet oral environment. The morphology changes were evaluated by statistical parametric mapping (SPM) and scanning electron microscopy (SEM). After bleaching, 12HP group and 15CP group showed increased scratch depth with more pile ups on the scratch edges, decreased nanohardness, and corroded surface appearance. While the 35CP group showed an increase in nanoscratch depth, no change in nanohardness and surface appearance was observed. The control group showed no change in these measurements. After remineralization, the three bleaching groups showed decreased nanoscratch depth and no change of nanohardness compared with the bleached teeth. And the control group showed no changes in nanotribological and nanomechanical properties. The nanotribological and nanomechanical properties of the 12HP group and 15CP group were affected by bleaching, but the nanotribological properties recovered partly and the nanomechanical properties got no change after 1 week of remineralization. As for the 35CP group, the nanotribological properties were influenced and the nanomechanical properties were not

  14. High-level expression and characterization of the Bacillus subtilis subsp. subtilis str. BSP1 YwaD aminopeptidase in Pichia pastoris.

    Science.gov (United States)

    Tang, Wei; Li, Zhezhe; Li, Chunhua; Yu, Xianhong; Wang, Fei; Wan, Xin; Wang, Yaping; Ma, Lixin

    2016-06-01

    Aminopeptidases are widely used for creating protein hydrolysates and peptide sequencing. The ywaD gene from a new Bacillus isolate, named Bacillus subtilis subsp. subtilis str. BSP1, was cloned into the yeast expression vector pHBM905A and expressed and secreted by Pichia pastoris strain GS115. The deduced amino acid sequence of the aminopeptidase encoded by the ywaD gene shared up to 98% identity with aminopeptidases from B. subtilis strains 168 and zj016. The yield (3.81 g/l) and specific activity (788 U/mg) of recombinant YwaD in high-density fermentation were extremely high. And 829.83 mg of the purified enzyme (4089.72 U/mg) were harvested. YwaD was glycosylated, and its activity decreased after deglycosylation, which was similar to that of the aminopeptidase from B. subtilis strain zj016. YwaD was most active toward l-arginine-4-nitroanilide. Moreover, it exhibited high resistance to carbamide, which was not true for aminopeptidases from B. subtilis strains 168 and zj016, which could simplify the purification of YwaD. Moreover, the expression and parts of characterization of the aminopeptidase from B. subtilis strain 168 in Pichia pastoris were added as supplementary material. The sequence and other characteristics of YwaD were compared with those of aminopeptidases from B. subtilis strains 168 and zj016, and they will provide a solid foundation for further research on the influence of amino acid mutations on the function of aminopeptidases. PMID:26898926

  15. Mineral loss and color change of enamel after bleaching and staining solutions combination.

    Science.gov (United States)

    de Araújo, Larissa Sgarbosa Napoleão; dos Santos, Paulo Henrique; Anchieta, Rodolfo Bruniera; Catelan, Anderson; Fraga Briso, André Luiz; Fraga Zaze, Ana Carolina Soares; Sundfeld, Renato Herman

    2013-10-01

    Pigments of food and beverages could affect dental bleaching efficacy. The aim of this investigation was to evaluate color change and mineral loss of tooth enamel as well as the influence of staining solutions normally used by adolescent patients undergoing home bleaching. Initial hardness and baseline color were measured on enamel blocks. Specimens were divided into five groups (n=5): G1 (control) specimens were kept in artificial saliva throughout the experiment (3 weeks); G2 enamel was exposed to 10% carbamide peroxide for 6 h daily, and after this period, the teeth were cleaned and stored in artificial saliva until the next bleaching session; and G3, G4, and G5 received the same treatments as G2, but after bleaching, they were stored for 1 h in cola soft drink, melted chocolate, or red wine, respectively. Mineral loss was obtained by the percentage of hardness reduction, and color change was determined by the difference between the data obtained before and after treatments. Data were subjected to analysis of variance and Fisher's test (α=0.05). G3 and G5 showed higher mineral loss (92.96 ± 5.50 and 94.46 ± 1.00, respectively) compared to the other groups (p ≤ 0.05). G5 showed high-color change (9.34 ± 2.90), whereas G1 presented lower color change (2.22 ± 0.44) (p ≤ 0.05). Acidic drinks cause mineral loss of the enamel, which could modify the surface and reduce staining resistance after bleaching. PMID:24165745

  16. Aircraft measurements of polar organic tracer compounds in tropospheric particles (PM10) over central China

    Science.gov (United States)

    Fu, P. Q.; Kawamura, K.; Cheng, Y. F.; Hatakeyama, S.; Takami, A.; Li, H.; Wang, W.

    2014-04-01

    Atmospheric aerosol samples were collected by aircraft at low to middle altitudes (0.8-3.5 km a.g.l.) over central East to West China during summer 2003 and spring 2004. The samples were analyzed for polar organic compounds using a technique of solvent extraction/BSTFA derivatization/gas chromatography-mass spectrometry. Biogenic secondary organic aerosol (SOA) tracers from the oxidation of isoprene were found to be more abundant in summer (3.3-138 ng m-3, mean 39 ng m-3) than in spring (3.2-42 ng m-3, 15 ng m-3), while α/β-pinene and β-caryophyllene SOA tracers showed similar abundances between these two seasons. A strong positive correlation (R2 = 0.83) between levoglucosan and β-caryophyllinic acid was found in the spring samples vs. a weak correlation (R2 = 0.17) in the summer samples, implying substantial contributions from biomass burning to the β-caryophyllinic acid production in spring. Two organic nitrogen species (oxamic acid and carbamide) were detected in the aircraft aerosol samples, and their concentrations were comparable to those of biogenic SOA tracers. Most of the primary organic aerosol (POA) and SOA tracers were less abundant at higher altitudes, suggesting they are of ground surface origin, either being directly emitted from anthropogenic/natural sources on the ground surface, or rapidly formed through photooxidation of their precursors emitted from the ground surface and then diluted during uplifting into the troposphere. This study demonstrates that primary biological aerosols, biogenic SOA, and organic nitrogen species are important components of organic aerosols in the troposphere over central China during warm seasons.

  17. Over-the-counter whitening agents: a concise review

    Directory of Open Access Journals (Sweden)

    Flávio Fernando Demarco

    2009-06-01

    Full Text Available Tooth discoloration is commonly found in the dental clinic and tooth bleaching has been considered the preferred esthetic alternative, being more conservative, safe and with predictable results. Supervised home-use of 10% Carbamide Peroxide (CP bleaching with custom-trays is the most common bleaching procedure dispensed by dentists to their patients. The good results obtained with this technique stimulated the flourishing of new products and techniques. Over-the-counter (OTC bleaching products appeared as a low-cost alternative to bleach discolored teeth without dentist supervision. Different OTC products are available in supermarkets, drug stores or on the Internet, including rinses, paint-on brushes, toothpastes, chewing guns, dental floss, and whitening strips. There is lack of clinical evidence regarding the safety and effectiveness of these products, being most of the studies supported by the manufacturers'. Basically, toothpastes, chewing gums, and dental floss are removal agents of superficial stains. Rinses and paint-on brushes with low levels of hydrogen peroxide have some whitening effect, but without clinical relevance. Strips present similar esthetic results and side-effects, compared to bleaching with 10% CP using trays; however, the studies have financial support from the manufacturers and were based on short term evaluations. Legislation varies widely in different countries regarding OTC dental bleaching. Concerns have appeared due to the potential abusive use of these self-medication agents, especially in young patients, with potential harmful results. Dentists should be acquainted with this kind of products to be able to inform their patients. In conclusion, there is a need for independent clinical trials to provide sufficient evidence regarding the use of OTC bleaching products.

  18. The Influence of Post Bleaching Treatments in Stain Absorption and Microhardness

    Science.gov (United States)

    Moosavi, Horieh; Darvishzadeh, Fatemeh

    2016-01-01

    Objectives: This study investigated the effects of post bleaching treatments to prevent restaining and the change of enamel surface microhardness after dental bleaching in vitro. Methods: Sixty intact human incisor teeth were stained in tea solution and randomly assigned into four groups (n=15). Then samples were bleached for two weeks (8 hours daily) by 15% carbamide peroxide. Tooth color was determined both with a spectrophotometer and visually before bleaching (T1) and immediately after bleaching (T2). Next, it was applied in group 1 fluoride (Naf 2%) gel for 2 minutes, and in group 2 a fractional CO2 laser (10 mJ, 200 Hz, 10 s), and in group 3, nanohydroxyapatite gel for 2 minutes. The bleached teeth in group 4 remained untreated (control group). Then teeth placed in tea solution again. Color examinations were repeated after various post bleaching treatments (T3) and restaining with tea (T4) and color change values recorded. The microhardness was measured at the enamel surface of samples. Data was analyzed using ANOVA, Tukey HSD test and Dunnett T3 (α = 0.05). Results: Directly after bleaching (ΔE T3-T2), the treatment with nanohydroxyapatite showed significantly the least color lapse in colorimetric evaluation. In experimental groups, the color change between T3 and T4 stages (ΔE T4-T3) was significantly lower than control group (P laser and nanohydroxyapatite as post bleaching treatments are suggested for prevention of stain absorption and increasing the hardening of bleached enamel. PMID:27099635

  19. Synthesis, characterization and optical properties of sheet-like ZnO

    International Nuclear Information System (INIS)

    Highlights: → Sheet-like ZnO with regular hexagon shape was synthesized with a two-step method. → Sheet-like ZnO predecessor was synthesized at low temperature in open system. → The diameter and thickness of ZnO sheet can be controlled conveniently. → This low-cost and environmentally benign approach is controllable and reproducible. → Sheet-like ZnO may have potential application in optical and electrical devices. -- Abstract: Sheet-like ZnO with regular hexagon shape and uniform diameter has been successfully synthesized through a two-step method without any metal catalyst. First, the sheet-like ZnO precursor was synthesized in a weak alkaline carbamide environment with stirring in a constant temperature water-bath by the homogeneous precipitation method, then sheet-like ZnO was obtained by calcining at 600 oC for 2 h. The structures and optical properties of sheet-like ZnO have been characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), high-resolution transmission electron microscopy (HRTEM), photoluminescence (PL) and UV-vis-NIR spectrophotometer. The results reveal that the product is highly crystalline with hexagonal wurtzite phase and has appearance of hexagon at (0 0 0 1) plane. The HRTEM images confirm that the individual sheet-like ZnO is single crystal. The PL spectrum exhibits a narrow ultraviolet emission at 397 nm and a broad visible emission centering at 502 nm. The band gap of sheet-like ZnO is about 3.15 eV.

  20. Porous materials with gradient and biporous structure, methods of their production

    International Nuclear Information System (INIS)

    We have worked out the technology of production porous powder materials (PPMs) of bronze, nickel, corrosion resistant steel and titanium powders with gradient and (or) biporous structure: vibrating forming of metal powders (including in electromagnetic field); layer-by-layer forming of metal powders with pore-maker while different proportion of the latter in the layer; forming of powder polymer layer on the preliminary sintered metal PPM surface. We have worked out the technology of production biporous structure by the following methods: metal granules forming and sintering; forming and sintering of metal powder with granules (2-3 mm) and pores-forming powder (size of particles is 0,4-0,63 mm). The novelty is in creation of technological bases of pores sizes regulation from 5 mkm on one PPM surface to 120 mkm on the opposite PPM surface which thickness can be 2-6 mm. PPM porosity can be constant within 0,3-0,6 relative units. More effective are those PPM which pores sizes are changeable and also porosity (from 0,35 to 0,60) from one surface o the opposite one. Two-layer metal-polymer PPM have pores sizes of 20-40 mkm in polymer layer and porosity 0,4-0,5 and, correspondingly, in metal layer 80-100 mkm and 0,45-0,55. In biporous structures made of 2-3 mm metal granules the distance between granules is 300-600 mkm and in granules - 14-30 mkm. The integral porosity of such PPM is 0,55-0,70. The technology of forming and sintering metal powder with granules and pores-making powder (carbamide) enables to regulate the integral porosity within 0,7-0,8 and average pores sizes within 100-1000 mkm with average size of metal powder particles of 0,63-1,0 mm. (author)

  1. Comparison of the effect of hydrogel and solution forms of sodium ascorbate on orthodontic bracket-enamel shear bond strength immediately after bleaching: An in vitro study

    Directory of Open Access Journals (Sweden)

    Kimyai Soodabeh

    2010-01-01

    Full Text Available Aim: This study compared the effects of hydrogel and solution forms of sodium ascorbate (SA with two different application times on bracket bond strength subsequent to bleaching. Materials and Methods: A total of 72 sound premolars were randomly divided into six groups (n = 12: An unbleached control group (group one and five experimental groups of carbamide peroxide. Specimens in group two were bonded immediately after bleaching; specimens in groups three and four were bleached, then treated with SA solution for ten minutes and three hours, respectively, and then bonded. In groups five and six, SA hydrogel was used and the specimens were prepared similar to groups three and four, respectively. Following debonding, bond strengths were recorded in MPa. To evaluate the amount of resin left on the enamel surfaces, adhesive remnant index (ARI scores were used. Statistical Analysis: The bond strength data were analyzed with ANOVA and pairwise comparisons were made by Tukey test. The ARI data were subjected to Kruskal-Wallis test and two-by-two comparisons were made by the Mann-Whitney U test. Results: There were significant differences in bond strengths between the groups ( P < 0.0005. However, the differences between groups three, four, five and six were not significant. Furthermore, there were no significant differences between group one and groups four and six, whereas the differences between the other groups were significant ( P < 0.05. Regarding ARI, there were significant differences among the groups ( P = 0.004. Conclusion: Bleaching significantly decreased the bracket bond strength. Compromised bonding was reversed with a three-hour application of both forms of SA.

  2. 沙床栽培中施肥对忽地笑生长量及净光合速率的影响%Effect of fertilization in sand bed on growth and photosynthesis of Lycoris aurea

    Institute of Scientific and Technical Information of China (English)

    鲍淳松; 张鹏翀; 张海珍; 徐芸茜; 江燕

    2012-01-01

    以尿素和磷酸二氢钾在沙床上对忽地笑(Lycoris aurea)进行施肥试验,分析施肥对忽地笑叶生长量、净光合速率及鳞茎生物量的影响,并且就忽地笑净光合速率对光有效辐射的响应、净光合速率的日变化进行了探讨.结果表明:沙土栽培施肥未明显增加忽地笑叶生长量和鳞茎生物量,也未显著提高净光合速率;忽地笑为耐阳植物,其光响应有“单峰型”和“抛物线型”两种类型,净光合速率日变化为“单峰型”.%Carbamide and KH2PO4 were set for topdressing fertilization to study the fertilization effects on leaf growth, bulb biomass and the net photosynthetic rate (Pn) of Lycoris aurea. The light-response to photosynthesis and a diurnal change of Pn were also studied. Results showed that the fertilization couldn't increase the leaf growth, bulb biomass and Pn significantly. L. aurea showed light-tolerance with two types of the light-response curve, single-peak and parabola, and the diurnal change of Pn had a single peak. Finally a suggestion was given for the cultivation of L. aurea.

  3. The Effect of Aloe Vera, Pomegranate Peel, Grape Seed Extract, Green Tea, and Sodium Ascorbate as Antioxidants on the Shear Bond Strength of Composite Resin to Home-bleached Enamel

    Directory of Open Access Journals (Sweden)

    Farahnaz Sharafeddin

    2015-12-01

    Full Text Available Statement of the Problem: Immediate application of bonding agent to home- bleached enamel leads to significant reduction in the shear bond strength of composite resin due to the residual oxygen. Different antioxidant agents may overcome this problem. Purpose: This study aimed to assess the effect of different antioxidants on the shear bond strength of composite resin to home-bleached. Materials and Method: Sixty extracted intact human incisors were embedded in cylindrical acrylic resin blocks (2.5×1.5 cm, with the coronal portion left out of the block. After bleaching the labial enamel surface with 15% carbamide peroxide, they were randomly divided into 6 groups (n=10. Before performing composite resin restoration by using a cylindrical Teflon mold (5×2 mm, each group was treated with one of the following antioxidants: 10% sodium ascorbate solution, 10% pomegranate peel solution, 10% grape seed extract, 5% green tea extract, and aloe vera leaf gel. One group was left untreated as the control. The shear bond strength of samples was tested under a universal testing machine (ZwickRoell Z020. The shear bond strength data were analyzed by one-way ANOVA and post hoc Tukey tests (p< 0.05. Results: No significant difference existed between the control and experimental groups. Moreover, there was no statistically significant difference between the effects of different antioxidants on the shear bond strength of bleached enamel. Conclusion: Different antioxidants used in this study had the same effect on the shear bond strength of home-bleached enamel, and none of them caused a statistically significant increase in its value.

  4. 不同施肥水平对日光温室番茄产量和品质的影响%Effects of different fertilization levels on yield and quality of greenhouse tomato

    Institute of Scientific and Technical Information of China (English)

    贺会强; 陈凯利; 邹志荣; 李丽霞

    2012-01-01

    【目的】研究不同施肥水平对日光温室春茬番茄果实产量和品质的影响,为日光温室番茄的高产优质栽培确定合理的施肥指标。【方法】以"金棚一号"番茄为试材,以当地常规施肥为对照,设定3个不同的施肥水平(T1.每小区的施肥量为尿素711.1g、过磷酸钙1 511.1g、硫酸钾462.2g、牛粪46.67kg;T2.每小区的施肥量为尿素1 066.7g、过磷酸钙2 266.7g、硫酸钾693.3g、牛粪70.00kg;T3.每小区的施肥量尿素1 422.2g、过磷酸钙3 022.2g、硫酸钾924.3g、牛粪93.33kg,小区面积4.68m2)处理,测定番茄果实产量及果实中NO3--N、可溶性固形物、可溶性糖、有机酸、VC、番茄红素的含量。【结果】与对照相比,T1、T2、T3处理的番茄产量分别提高了11.5%,43.4%和25.5%,其中T2处理的单果质量、小区果数、产量均高于T1和T3处理。随着施肥量的增加,NO3--N、可溶性糖、可溶性固形物含量和糖酸比减小,番茄红素和有机酸含量呈上升趋势,VC含量呈先上升后下降趋势。【结论】综合考虑产量和品质因素,T2处理的施肥量最佳。推荐的施肥量为:每hm2施N 1 182.0kg、P2O5655.5kg、K2O835.5kg、牛粪168.75t,在此施肥条件下,番茄可得到较高的产量和较好的品质。%【Objective】 Under different fertilizer levels,the yield and quality of tomato in solar greenhouse in spring were explored,which can provide a theoretical evidence for the reasonable fertilization index to ensure the high quality and high yield of tomato in greenhouse cultivation.【Method】 With tomato "Jinpeng No.1" as experimental materials,taking local conventional fertilization as control treatment,setting 3 different fertilization levels(The fertilization amount T1 was carbamide 711.1 g,calcium superphosphate 1 511.1 g,potassium sulphate 462.2 g,cow dung 46.67 kg.The fertilization amount T2 was carbamide 1 066.7 g,calcium superphosphate 2 266.7 g,potassium sulphate

  5. Peroxide bleaching agent effects on enamel surface microhardness, roughness and morphology Efeitos de agentes clareadores à base de peróxidos na microdureza, rugosidade e morfologia superficial do esmalte

    Directory of Open Access Journals (Sweden)

    Cristiane Franco Pinto

    2004-12-01

    Full Text Available The aim of this study was to evaluate the surface roughness, microhardness and morphology of human enamel exposed to six bleaching agents (at baseline and post-treatment. Human dental enamel samples were obtained from human third molars and randomly divided into seven groups (n = 11: control, Whiteness Perfect - 10% carbamide peroxide (10% CP, Colgate Platinum - 10% CP, Day White 2Z - 7.5% hydrogen peroxide (7.5% HP, Whiteness Super - 37% CP, Opalescence Quick - 35% CP and Whiteness HP - 35% HP. Bleaching agents were applied according to manufacturers' instructions. The control group remained not treated and stored in artificial saliva. Microhardness testing was performed with a Knoop indentor and surface roughness was analyzed with a profilometer. Morphologic observations were carried out with scanning electron microscopy (SEM. Results were statistically analyzed by two-way analysis of variance and Tukey's test (5%, and revealed a significant decrease in microhardness values and a significant increase in surface roughness post-bleaching. Changes in enamel morphology after bleaching were observed under SEM. It was concluded that bleaching agents can alter the microhardness, roughness and morphology of dental enamel surface.O objetivo deste estudo foi avaliar a rugosidade, microdureza e morfologia superficial do esmalte dental humano tratado com seis agentes clareadores (antes e depois do tratamento. Amostras de esmalte dental humano foram obtidas de terceiros molares e aleatoriamente distribuídas em sete grupos (n = 11: controle, Whiteness Perfect - peróxido de carbamida a 10% (PC 10%, Colgate Platinum - PC 10%, Day White 2Z - peróxido de hidrogênio a 7,5% (PH 7,5%, Whiteness Super - PC 37%, Opalescence Quick - PC 35% e Whiteness HP - PH 35%. Os agentes clareadores foram aplicados de acordo com as instruções dos fabricantes. O grupo controle permaneceu sem tratamento e armazenado em saliva artificial. O teste de microdureza foi realizado

  6. Exogenous bleaching evaluation on dentin using chemical activated technique compared with diode laser technique

    International Nuclear Information System (INIS)

    This in vitro study compared the results of different exogenous bleaching proceedings on dentin after treatment of enamel surface. Thirty human canine were hewn preserving the vestibular half of the crown and 3 mm of root, showing a vestibular-lingual thickness average of 3,5 mm, measuring in the third middle of the crown. Ali teeth were maintained in wet chamber during the experiment. Digital photographs were taken of the dentin surface at 3 experimental times (LI: initial record, L0: immediate pos-bleaching record and L 15: 15 days after bleaching). The teeth were divided into 3 experimental groups of 10 teeth in each. The Control Group did not receive any kind of treatment. The Laser Group received 2 session of laser bleaching, with 3 applications each, using 35% hydrogen peroxide, activated by diode laser during 30 seconds, by scanning the enamel surface from incisal edge to the top of the crown, from mesial to distal portion of the crown and circularly, each movement during 10 seconds. The following parameters being adopted: wavelength of 808 nm, power of 1,5 W and optic fiber with 600 μm (core). The Peroxide Group received 28 daily applications, during 4 hours each application, using 16% carbamide peroxide. The bleaching records were analysed using a computer, through RGBK (red, green , blue and black). The K averages (K=100% for black and K=0% for white) of the records for Control Group were: LI=50,1 %, L0=50,3% and L 15=50,6%. For Laser Group the K averages were LI=48,5%, L0=50,0% and L 15=47,7%. And for the Peroxide Group were LI=50,5%, L0=35,9% and L 15=37,3%. The statistical analysis showed no significant difference of the K between the Control Group and the Laser Group, as to LI, L0 and L 15. Only Peroxide Group showed significant statistical difference between LI with L0 and L 15 (0,1%), and L0 in comparison with L 15 did not show any difference. (author)

  7. 腐烂柑橘与猪粪混合厌氧发酵产沼气试验研究%Study on Biogas Yield of Rotten Citrus Fruits Mixed with Swine Manure in Anaerobic Fermentation

    Institute of Scientific and Technical Information of China (English)

    赵红; 张衍林

    2011-01-01

    The secondary pH regulation were tested to reactivate the soured anaerobic system treating mixture of rotten citrus fruits and swine manure.Various indexes of biogas and effluent in anaerobic fermentation system were determined.The result showed that the soured anaerobic system treating rotten citrus fruits and swine manure mixture could be reactivated by secondary pH regulation with limewater and C: N regulation with carbamide.The best ratio for rotten citrus fruits and swine manure was 2:1 ,and the optimum inoculum rates was 30%, under which the gas production could last 30 days with TS gas yield of 480.69 mL · g-1.The average methane content of biogas was 51.5% ,and COD removal rate was 75.14%.%文章以腐烂柑橘果实和猪粪为原料,通过测定厌氧发酵过程中发酵液和沼气的各项指标,探讨二次调节pH值是否可启动橘类比高的厌氧发酵系统及在此条件下腐烂柑橘与猪粪混合厌氧发酵产沼气的最佳配比和最优接种率.研究表明:用石灰水调节pH值,尿素调节其C∶N,二次调节pH值可以重新启动橘粪比高的厌氧发酵系统.在二次调解pH值情况下,腐烂柑橘与猪粪混合厌氧发酵最佳配比为2∶1,接种率30%最为适宜.该组合条件下产气可维持30天,TS产气率为480.69 mL·g-1,平均甲烷含量为51.5%,COD去除率为75.14%.

  8. 桑叶褐斑病病原菌的生物学特性研究%Bilolgical Characteristics of Pathogenic Fungus Causing Brown Spot on Mulberry Leaves

    Institute of Scientific and Technical Information of China (English)

    吴庭观; 章一鸣; 叶政平; 何永宏; 张泽; 徐升胜; 洪逗

    2014-01-01

    Through cultivating pathogenic fungi of mulberry brown rot disease under 6 conditions such as different media, temperature, carbon source and nitrogen source after 6 days, research on the biological characteristics of pathogenic fungus causing brown spot on mulberry leaves was conducted .The results showed that nutrition , tem-perature and pH had significant influence on mycelial growth . It was found that the best medium for mycelial growth was oatmeal medium , the proper temperature was 20~30℃, the optimal temperature for mycelial growth was 25℃, the light had no obvious promotion effect on mycelial growth .It was also found that the optimal pH was 9 to 10 , the best carbon source and nitrogen source for mycelial grow are α-Galoctaose and Carbamide , and the mycelial could not survive above 55℃more than 10 min.%通过对桑叶褐斑病病原菌在不同种类培养基培养、不同氮源与碳源、不同温度等6种条件下培养6天后,测定菌落直径,观察菌丝颜色和菌落形态,分析了桑褐斑病病原菌的生物学特性。结果表明,在室内培养条件下,不同的营养成分、 pH值、温度、光照都对菌丝的生长有影响。病原菌菌丝生长的最适宜培养基是燕麦片培养基,适宜生长温度范围是20~30℃,最适生长温度为25℃,光照对菌丝生长无显著影响,最适pH值为9~10,最适碳源为α-乳糖,最适氮源为尿素,菌丝在55℃水浴10 min后则不能生长。

  9. Techno-economic analysis for the evaluation of three UCG synthesis gas end use approaches

    Science.gov (United States)

    Nakaten, Natalie; Kempka, Thomas; Burchart-Korol, Dorota; Krawczyk, Piotr; Kapusta, Krzysztof; Stańczyk, Krzysztof

    2016-04-01

    production, the UCG synthesis gas should have a calorific value of at least 7 MJ/Nm³. However, UCG feedstock production in view of the underlying geological and chemical boundary conditions can compete on the market. Kempka, T., Plötz, M.L., Hamann, J., Deowan, S.A., Azzam, R. (2010) Carbon dioxide utilisation for carbamide production by application of the coupled UCG-urea process. Energy Procedia 4: 2200-2205. Nakaten, N., Schlüter, R., Azzam, R., Kempka, T. (2014) Development of a techno-economic model for dynamic calculation of COE, energy demand and CO2 emissions of an integrated UCG-CCS process. Energy (in print). Doi 10.1016/j.energy.2014.01.014

  10. Enzymatic Properties of Polyphenol Oxidase from Kidney Bean Pods%菜豆豆荚多酚氧化酶的酶学特性研究

    Institute of Scientific and Technical Information of China (English)

    李雯妮; 赵秀文; 田维娜; 曹建康; 姜微波

    2011-01-01

    Objective: To explore enzymatic properties of polyphenol oxidase(PPO) from kidney bean pods(Phaseolus vulgaris L.cv.Shuangqing).Methods: The optimal pH,temperature,substrate specificity and inhibitors of PPO were evaluated by polyacrylamide gel electrophoresis(PAGE).Results: The optima pH for PPO activity was 6.0.The PPO was relatively stable at 30 ℃ and inactivated at 80 ℃.Catechol was the optimal substrate for the enzyme.Its activity was inhibited by ascorbic acid,β-mercaptoethanol,glycine or L-cysteine.Moreover,the PPO activity was inhibited completely by 1.0 mmol/L β-mercaptoethanol or ascorbic acid;however,it was activated by copper dichloride and carbamide.Conclusion: High temperature,high pH and β-mercaptoethanol or ascorbic acid can inhibit the activity of the PPO enzyme.%目的:了解菜豆豆荚多酚氧化酶(polyphenol Oxidase,PPO)的酶学特性。方法:采用聚丙烯酰氨凝胶电泳(polyacrylamide gel electrophoresis,PAGE)法对菜豆豆荚PPO的最适pH值、最适温度、底物专一性、激活剂及抑制剂进行研究。结果:菜豆豆荚PPO最适pH值为6.0;最适温度为30℃,且温度为30℃时,该酶具有较强的热稳定性,80℃可使其完全失活;该酶对不同酚类物质表现出不同的底物专一性,邻苯二酚为该酶的最适底物;抗坏血酸、L-半胱氨酸、β-巯基乙醇、甘氨酸均能抑制该酶的活性,而1.0mmol/Lβ-巯基乙醇或抗坏血酸可完全抑制其活性;氯化铜、尿素对该酶均有激活作用,其中氯化铜的激活作用明显。结论:高温、偏碱性环境、β-巯基乙醇或抗坏血酸处理均可有效抑制菜豆豆荚PPO活性。

  11. Effect of bleaching on the microhardness of tooth-colored restorative materials

    Directory of Open Access Journals (Sweden)

    Abdolrahim Davari

    2013-08-01

    Full Text Available   Background and Aims: Bleaching agents not only affect the tooth structure, but also may alter the properties of restorative materials. The aim of this in vitro study was to evaluate the effect of different bleaching regimens on the microhardness of four tooth-colored restorative materials.   Materials and Methods: Eighty specimens of four restorative materials (Microhybrid resin composite (Z250 (3M, ESPE, nanohybrid composite Z350 (3M, ESPE, packable composite P60 (3M, ESPE, and resin modified glass ionomer Vitremer (3M, ESPE were fabricated and were polished after 24 h with Soflex discs (3M,ESPE. Then the specimens were divided into two groups: In office bleach group, 40 specimens (10 of each restorative material were bleached with hydrogen peroxide 37.5% for 30 min in two sessions with 7 days interval. In home bleaching group, 40 specimens were bleached with carbamid peroxide 22%, 6 h a day for 14 days. Vickers microhardness test were done before and after bleaching (baseline. Finally data were evaluated using analysis of Variance.   Results: Two bleaching regimens were significantly decreased the microhardness values. In Z250 resin composite, the microhardness values before and after bleaching were 95.30 and 92.67 kg/mm2, respectively. for office bleaching (P=0.011 and 95.38 and 92.39 kg/mm2 for home bleaching (P<0.001. In Z350 resin composite, the microhardness values before and after bleaching were 98.29 and 92.41 kg/mm2, for office bleaching (P<0.001 and 97.35 and 93.44 kg/mm2 for home bleaching (P<0.001 respectively. In P60 resin composite, the microhardness values before and after bleaching were 103.10 and 96.16 kg/mm2, respectively. for office bleaching (P=0.045 and 102.61 and 98.16 kg/mm2 for home bleaching (P=0.001. In resin modified glass ionomer (Vitremer, the microhardness values before and after bleaching were 56.79 and 49.41 kg/mm2, respectively. for office bleaching (P=0.004 and 54.17 and 46.50 kg/mm2 for home bleaching (P

  12. Exogenous bleaching evaluation on dentin using chemical activated technique compared with diode laser technique; Avaliacao do clareamento exogeno sobre a dentina realizado pela tecnica por ativacao quimica comparada com a tecnica por ativacao pelo laser de diodo

    Energy Technology Data Exchange (ETDEWEB)

    Carvalho, Breno Carnevalli Franco de

    2003-07-01

    This in vitro study compared the results of different exogenous bleaching proceedings on dentin after treatment of enamel surface. Thirty human canine were hewn preserving the vestibular half of the crown and 3 mm of root, showing a vestibular-lingual thickness average of 3,5 mm, measuring in the third middle of the crown. Ali teeth were maintained in wet chamber during the experiment. Digital photographs were taken of the dentin surface at 3 experimental times (LI: initial record, L0: immediate pos-bleaching record and L 15: 15 days after bleaching). The teeth were divided into 3 experimental groups of 10 teeth in each. The Control Group did not receive any kind of treatment. The Laser Group received 2 session of laser bleaching, with 3 applications each, using 35% hydrogen peroxide, activated by diode laser during 30 seconds, by scanning the enamel surface from incisal edge to the top of the crown, from mesial to distal portion of the crown and circularly, each movement during 10 seconds. The following parameters being adopted: wavelength of 808 nm, power of 1,5 W and optic fiber with 600 {mu}m (core). The Peroxide Group received 28 daily applications, during 4 hours each application, using 16% carbamide peroxide. The bleaching records were analysed using a computer, through RGBK (red, green , blue and black). The K averages (K=100% for black and K=0% for white) of the records for Control Group were: LI=50,1 %, L0=50,3% and L 15=50,6%. For Laser Group the K averages were LI=48,5%, L0=50,0% and L 15=47,7%. And for the Peroxide Group were LI=50,5%, L0=35,9% and L 15=37,3%. The statistical analysis showed no significant difference of the K between the Control Group and the Laser Group, as to LI, L0 and L 15. Only Peroxide Group showed significant statistical difference between LI with L0 and L 15 (0,1%), and L0 in comparison with L 15 did not show any difference. (author)

  13. Effects of combination of superabsorbent polymers (SAP) with nitrogen fertilizer on growth and photosynthesis of pepper plants%保水剂与氮肥结合对辣椒生长及光合作用的影响

    Institute of Scientific and Technical Information of China (English)

    徐刚; 韩玉玲; 高文瑞; 李德翠; 韩冰; 孙艳军

    2012-01-01

    Pepper variety Chaoyue No. 5 was selected as material to study the effects of combination of superabsorbent polymers (SAP) with nitrogen fertilizer on growth and photosynthesis of pepper during flowering using SAP absorbing carbamide. The combination of SAP with nitrogen fertiliser significantly increased the height, stem diameter, fresh weight, dry weight and chlorophyll content of leaves, as well as the net photosynthetic rate (Pn), intercellular CO2 concentration (Ci) , stomatal conduct (Gs) and transpiration rate (Tr) , but decreased the stomata limitation (Ls) and water efficiency ( WUE) under the same nitrogen application condition. The growth, chlorophyll content, Pn, Ci, Gs and Tr of pepper with the treatment of SAP combining nitrogen of 0. 75 times as many as standard application level were significantly higher than those with the treatment of applying nitrogen at standard level. It indicated that using SAP to absorb urea increased the fertiliser use efficiency, and reduced the loss of fertilizer.%以辣椒品种超越5号为试验材料,采用保水剂吸收尿素溶液的方法,探讨了保水剂与氮肥结合对辣椒开花坐果期植株生长及光合特性的影响.结果表明:在相同的氮肥条件下,保水剂与氮肥结合提高了植株的株高、茎粗、干鲜重、叶绿素含量以及净光合速率(Pn)、胞间CO2浓度(Ci)、气孔导度(Gs)和蒸腾速率(Tr)等光合参数,降低了气孔限制值(Ls)和水分利用效率(WUE);同时保水剂+0.75倍标准氮肥用量处理的叶片生长量、叶绿素含量、Pn、Ci、Gs和Tr都显著高子1倍标准氮肥用量的处理,表明采用保水剂吸收尿素溶液的方式能够提高肥料利用率,降低肥料损失.

  14. 不同施肥处理对战骨生长特性和生物量的影响研究%Effects of Different Fertilization Treatments on Grow-th Characteristics and Medicinal Biomass of Premnafulva

    Institute of Scientific and Technical Information of China (English)

    韦霄; 史艳财; 陈宗游; 唐健民; 韦记青

    2014-01-01

    【目的】为提高战骨(Premnafulva )的产量与质量,研究基肥和追施化肥对战骨生长特性及生物量的影响,以期为战骨生产中的合理施肥提供理论依据。【方法】采用随机区组设计方法,在大田种植条件下研究了不同基肥(鸡粪、猪粪、牛粪、火土、鸡粪+猪粪、鸡粪+牛粪、鸡粪+火土、猪粪+牛粪、猪粪+火土、牛粪+火土)、追肥种类(磷肥、钾肥、尿素、复合肥)、追肥量(20g/株、40g/株、60g/株)和追肥次数(1次、2次、3次)对战骨生长特性和生物量的影响。【结果】4种单一基肥中,鸡粪处理后植株的基径、株高、冠幅、茎重和根重都较大;两种基肥混合处理的植株长势和生物量优于猪粪、牛粪和火土3种单一基肥处理;火土和猪粪处理的基径、株高、冠幅、茎重和根重值较大;追肥以复合肥效果最好;追加钾肥和磷肥处理的植株生长指标和生物量较差。【结论】基肥以火土+猪粪(1∶1);追肥以施用复合肥,施用量为40g/株,追肥3次,战骨的产量最高。%Objective]Effects of different fertilization treatments on growth characteristics and medicinal biomass of Premna fulva were discussed in order to provide a theory basis for ra-tional fertilization of Premna fulva production,and yield and quality improvment.[Methods]A field randomized block experiment was used to analyze effects of different basal fertilizer (chicken manure,pig manure,cattle manure,ash soil,chicken manure+pig manure,chicken manure+cattle manure,chicken manure+ash soil,pig manure+cattle manure,pig manure+ash soil and cattle manure+ash soil),different additional fertilization (phosphate fertilizer, potassium fertilizer,carbamide and compound fertilizer),volume (20g/plant,40g/plant,60g/plant)and times of fertilization (once,twice and three times)on Premnafulva growth index and yield.[Results]The ground

  15. Influence of post-bleaching time intervals on dentin bond strength Influência de tempos de espera pós-clareamento na resistência adesiva da dentina

    Directory of Open Access Journals (Sweden)

    Erica Cappelletto Nogueira Teixeira

    2004-03-01

    Full Text Available It has been reported that bond strength of resin to tooth structure can be reduced when the bonding procedure is carried out immediately after the bleaching treatment. This study evaluated the effect of bleaching of non-vital teeth bleaching on the shear bond strength (SBS of composite resin/bovine dentin interface and the influence of delaying the bonding procedures for different time intervals following internal bleaching. According to a randomized block design, composite resin cylinders (Z100/Single bond - 3M were bonded to the flattened dentin surface of two hundred and fifty-six teeth which had previously been subjected to four different treatments: SPH - sodium perborate + 30% hydrogen peroxide; SPW - sodium perborate + distilled water; CP - 37% carbamide peroxide; and CON - distilled water (control, each one followed by storage in artificial saliva for 0 (baseline, 7, 14, and 21 days after bleaching (n = 16. The bleaching agents in the pulp chambers were replaced every 7 days, over 4 weeks. The SBS test of the blocks was done using a universal testing machine. The ANOVA showed that there was no significant interaction between time and bleaching agents, and that the factor time was not statistically significant (p > 0.05. For the factor bleaching treatment, the Student's t-test showed that [CON = CP] > [SPW = SPH]. The bleaching of non-vital teeth affected the resin/dentin SBS values when sodium perborate mixed with 30% hydrogen peroxide or water was used, independently of the elapsed time following the bleaching treatment.Tem-se sugerido que a qualidade da adesão resina composta-dentina pode ser prejudicada quando restaurações são confeccionadas imediatamente após o tratamento clareador. Este estudo avaliou o efeito da postergação do procedimento adesivo após o clareamento interno realizado com diferentes agentes na resistência ao cisalhamento da interface compósito/dentina. De acordo com um delineamento aleatório em blocos

  16. 水溶性叶面肥对豇豆产量的影响%Effect of Water Soluble Foliar Fertilizer on Cowpea Yield

    Institute of Scientific and Technical Information of China (English)

    张慧亮; 许恩光; 王顺德

    2013-01-01

    To investigate the effects of foliar fertilizer on the yield of cowpea, eight different foliar fertilizers were sprayed in cowpea vegetative growth stage for 3 times. Results showed that the yield increased 67%by spraying 4.3%fulvic acid foliar fertilizer, increased 57% by spraying 8% fulvic acid+(N+P2O5+K2O), increased 48.2% by spraying major elements and trace elements[(N+P2O5+K2O≥23% 9∶6∶8)+(Fe+B+Z≥1%)], increased 43.2% by spraying 4%potassium humate+major elements+trace elements[(N+P2O5+K2O≥23% 9∶6∶8)+(Fe+B+Zn≥1%)], increased 40.8%by spraying 3% potassium humate+vitamin+carbamide urea+potassium sulfate≥7%; increased 39.5% by spraying major elements+tace elements[(N+P2O5+K2O≥35% 12∶10∶13)+(Fe+B+Zn≥0.6%)]; increased 33.7% by spraying 3%potassium humate+major elements and trace elements [(N+P2O5+K2O≥35% 12∶10∶13)+(Fe+B+Zn≥0.6%)];increased 15.9%by spraying 4%potassium humate. The most obvious of yield increase was fulvic acid, the effect of trace elements was better than that of major elements, potassium humate was the lowest, potassium humate+major elements+trace elements was less than major elements+trace elements.%使用8个不同配方叶面肥在豇豆营养生长阶段喷施3次,调查叶面肥对豇豆产量的影响。结果表明,与对照相比,喷施4.3%黄腐酸叶面肥处理增产67.0%;8%黄腐酸+氮磷钾增产57.1%;大量元素+微量元素[(N+P2O5+K2O≥23%9∶6∶8)+(F e+B+Z n≥1%)]的增产48.2%;4%腐植酸钾+大量元素+微量元素[(N+P2O5+K2O≥23%9∶6∶8)+(Fe+B+Zn≥1%)]增产43.2%(添加腐植酸钾不利于提高产量);3%腐植酸钾+维生素+尿素+硫酸钾≥7%增产40.8%;大量元素+微量元素[(N+P2O5+K2O≥35%12∶10∶13)+(F e+B+Z n≥0.6%)]增产39.5%;3%腐植酸钾+大量元素+微量元素[(N+P2O5+K2O≥35%12∶10∶13)+(F e+B+Z n≥0.6%)]增产33.7%;4%腐植酸钾增产15.9%。黄腐酸增产效果最明显,微量元素增产效果比大量元素明显,腐植酸

  17. Underground coal gasification with extended CO2 utilization as economic and carbon neutral approach to address energy and fertilizer supply shortages in Bangladesh

    Science.gov (United States)

    Nakaten, Natalie; Islam, Rafiqul; Kempka, Thomas

    2014-05-01

    injected in the scope of the scheduled EGR operation. Our techno-economic modeling results considering EGR reservoir simulations demonstrate that an economic and carbon neutral operation of UCG combined with fertilizer production and CCS is feasible. The suggested approach may provide a bridging technology to tackle fertilizer and power supply shortages in Bangladesh, and in addition support further production from depleting natural gas deposits. References Kempka, T., Plötz, M.L., Hamann, J., Deowan, S.A., Azzam, R. (2010) Carbon dioxide utilisation for carbamide production by application of the coupled UCG-urea process. Energy Procedia 4: 2200-2205. Nakaten, N., Schlüter, R., Azzam, R., Kempka, T. (2014) Development of a techno-economic model for dynamic calculation of COE, energy demand and CO2 emissions of an integrated UCG-CCS process. Energy (in print). Doi 10.1016/j.energy.2014.01.014

  18. 黄芪注射液对高通透性腹膜透析大鼠透析效能及腹膜结构的影响%Huangqi Injection's Effect on the Dialysis Efficiency and Structure of Peritoneal Dialysis Rat with High Permeable Perineum

    Institute of Scientific and Technical Information of China (English)

    刁金囡; 盛梅笑; 朱萱萱; 王宁皎; 朱长乐; 何伟明

    2011-01-01

    (Group D). Rats in Group B, C and D received intraperitoneal injection respectively with 4.25 % glucose icodextrin, Huangqi injection of low concentration, and Huangqi injection of high concentration (25m/1) for 10 days. The peritoneal function test was taken at day 11 through observing the level changes of D/ Purea of urea nitrogen, D/PCr of creatinine, D/DoGlu of glucose in peritoneal cavity for 0,30、60、90 and 120 mins , levels changes of Curea, CCr, UF and NetUF for 120 mins and the morphostructure changes of peritoneum. RESULTS ① the D/PCr levels of Group B,C and D at different time were higher than that of Group A;the D/DoGlu levels of Group B, C and D lower than that of Group A (P<0.05) ;the UF、NetUF levels of Group B were lower than that of Group A(P<0. 05) ;②D/Purea levels of Group C and D(60 mins) were lower than that of Group B(P<0.05) ;D/PCr levels of Group D after 60 and 90 mins were higher than those of Group B (p< 0.05) ;D/DoGlu level of Group D was lower than that of Group B(P< o. 05). ③ Group C and D showed significant difference in the levels of D/Purea、 D/PCr(30、60、90mins) and D/DoGlu(30、60min) (P<0.05) ;④ The level of Curea、 CCr、 UF and NetUF of Group D were higher than those of Group B (P<0.05) ;⑤ The condition of peritoneal incrassation and mesothelial cells dropping improved compared with that of Group B. CONCLUSION Peritoneal diailysis fluid of 4.25 % glucose can destroy the mesothelial cells, improve the permeability, and reduce ultrafiltration volume in the peritoneum. Huangqi injection of different concentration can protect the mesothelial level, improve the clearance of carbamide and creatinine and enhance the peritoneal dialysis efficacy, without increasing peritoneum's absorption of glucose. Besides, Huangqi dialysate of high concentration can promote peritoneum' s clearance of water and increase the dialysis hyperfiltration.