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Sample records for carbamide

  1. Systems of erbium chloride- carbamide- water and erbium nitrate- carbamide- water at 30 deg C

    International Nuclear Information System (INIS)

    Ajtimbetov, K.; Sulajmankulov, K.S.; Batyuk, A.G.; Ismailov, M.

    1975-01-01

    The systems erbium chloride - carbamide - water and erbium nitrate - carbamide - water were studied by solubility method at 30 deg C. In the system erbium chloride - carbamide - water three compounds were detected: ErClsub(3).6CO(NHsub(2))sub(2), ErClsub(3).4CO(NHsub(2))sub(2), ErClsub(3).2CO(NHsub(2))sub2.6Hsub(2)O. In the system erbium nitrate -carbamide - water two new compounds were found: Er(NOsub(3))sub(3).4CO(NHsub(2))sub2, Er(NOsub(3) )sub(3)

  2. REMINERALIZATION POTENTIAL OF A CARBAMIDE BLEACHING AGENT

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    Marinova-Takorova Borislavova Mirela

    2016-03-01

    Full Text Available Background: Bleaching has gradually became a popular procedure for people searching for aesthetic improvement. The aim of this in vitro study was to investigate the effect of bleaching with 45% carbamide peroxide on the level of mineralization of enamel, using laser fluorescence. Materials and methods: Sixty extracted human teeth were treated with 45% carbamid peroxide (Opalescence, Ultradent, 4 consecutive days for one hour each day. The effect of the bleaching agent on the level of mineralization of enamel was measured with DIAGNO dent pen. The statistical method we use was descriptive analysis. Results: The average values, measured before the applications of the carbamid peroxide were 6.33. On the first day they were 5.41, on the second 5.38, on the third 5.11 and 5.35 on the forth. Conclusion: There was observed a slight remineralization effect due to the incorporated Ca2+ and F- ions in the bleaching agent that we have used.

  3. 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

  4. Estimation of effect of inorganic salts on state of melts and carbamide solutions

    International Nuclear Information System (INIS)

    Dymnikov, N.S.; Yakunin, N.A.; Baranov, A.V.; Moryganov, A.P.

    1995-01-01

    The character of coordination in the systems carbamide-LiCl and carbamide-CaCl 2 has been shown on the basis of IR spectroscopy data. Interrelation between complexing in the melt carbamide-inorganic salt and thermal resistance of amide compound has been ascertained. 3 refs.; 3 figs

  5. The gadolinium nitrate-carbamide-water and the ytterbium nitrate-carbamide-water systems at 30 deg C

    International Nuclear Information System (INIS)

    Khudajbergenova, N.; Sulajmankulov, K.

    1980-01-01

    Gadolinium nitrate-carbamide-water(1) and ytterbium nitrate-carbamide-water(2) systems are studied at 30 deg C by the solubility method. Two new compounds are formed in the system(1). One of them is incongruent Gd(NO 3 ) 3 x3CON 2 H 4 and Gd(NO 3 ) 3 x4CON 2 H 4 is congruently soluble. Incongruent compound of Yb(NO 3 ) 3 xCON 2 H 4 composition and congruently soluble Yb(NO 3 ) 3 x4CON 2 H 4 are also formed in the system(2). Presented are solubility isotherms of the systems [ru

  6. Effect of acetamide, carbamide and thiocarbamide on sodium tetraborate solubility

    Energy Technology Data Exchange (ETDEWEB)

    Sadetdinov, Sh V

    1985-07-01

    By the methods of solubility and refractometry it is ascertained that sodium tetraborate-acetamide (carbamide, thiocarbamide)-water systems are of a simple eutonic type. Amides reduce salt solubility. Lyotropic effect on conversion to mole concentrations grows from acetamide to thiocarbamide by the absolute value.

  7. Effect of acetamide, carbamide and thiocarbamide on sodium tetraborate solubility

    International Nuclear Information System (INIS)

    Sadetdinov, Sh.V.

    1985-01-01

    By the methods of solubility and refractometry it is ascertained that sodium tetraborate-acetamide (carbamide, thiocarbamide)-water systems are of a simple eutonic type. Amides reduce salt solubility. Lyotropic effect on conversion to mole concentrations grows from acetamide to thiocarbamide by the absolute value

  8. Effect of various factors on the quality of products of deparaffinization with crystalline carbamide

    Energy Technology Data Exchange (ETDEWEB)

    Dorodnova, V.S.; Martynenko, A.G.; Matrirosov, R.A.; Tarelkin, L.P.

    1981-01-01

    The refining of Stavropol and Romashkin crude into liquid paraffin and diesel fuel was studied at a commercial carbamide deparaffinization installation. From a solidification temp. of 35/sup 0/ and below, the product of diesel fuel from Romashkin crude is ensured by introducing carbamide 80 at the complex formation stage and 1% MeOH in the crude. Here the solid phase in the suspension makes up 21%, while the capacity of paraffin in the complex is 0.135g/g. The temp. of the separated paraffin is about 25/sup 0/ during its selection from a potential up to 65%. Increasing the amount of MeOH to 2.0% while decreasing the carbamide consumption to 60% in the crude leads to an increased paraffin capacity in the complex of 0.215 g/g, which makes possible the production of diesel fuel from a solidification temp. of 44/sup 0/. For the production of diesel fuel from Stavropol crude from solidification temps. of 35/sup 0/ and below with a 1% MeOH consumption, it is necessary to add twice as much carbamide (150%) at the complex formation stage as compared with Romashkin crude. The solid phase content in the suspension is 34%. Analogous results were obtained for 2.0% MeOH consumption.

  9. Study of factors that influence complex-formation of n-alkanes with crystal carbamide

    Energy Technology Data Exchange (ETDEWEB)

    Dorodnova, V.S.; Korzhov, Yu.A.; Martynenko, A.G.

    1982-01-01

    Studies effect of temperature, solid phase content in the suspension and amount of MeOH on extent of n-alkane extraction during carbamide deparaffinization. A most thorough extraction of n-alkanes is achieved with a graduated temperature regimen of complex-formation.

  10. Effects of 35% Carbamide Peroxide Gel on Surface Roughness and Hardness of Composite Resins

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    F. Sharafeddin

    2010-03-01

    Full Text Available Objective: Bleaching agents may not be safe for dental materials. The purpose of this invitro study was to evaluate the effects of Opalescent Quick "in-office bleaching gel" containing 35% carbamide peroxide on the surface roughness and hardness of microfilled(Heliomolar and hybride (Spectrum TPH composite resins.Materials and Methods: Twenty specimens of Spectrum TPH composite resins and twenty Heliomolar composite resins were fabricated using a metallic ring (6.5 mm diameter and 2.5 mm thickness and light cured, then their surfaces were polished. Specimens of each composite resin were divided into two equal groups. Ten specimens of each type of composite were stored in water at 37°C as the control groups and 35% carbamide peroxide gel (Opalescence Quick as the other group for 30 minutes a week for 3 weeks. Then the specimens were subject to roughness and hardness tests.Results: This study revealed that using 35% carbamide peroxide bleaching gels had no significant effect on the surface roughness of Spectrum TPH "hybrid" and Heliomolar "microfilled" composite resins. The surface hardness of Spectrum TPH composite treated with the subject gel significantly increased compared to heliomolar, which had no significant change after treatment with this bleaching gel.Conclusion: If tooth color matching of the composite had been satisfactory after office bleaching with 35% carbamide peroxide gel, this material would have been acceptable because it has no adverse effect on Heliomolar and Spectrum TPH composite resins.

  11. Effect of protective coating on marginal integrity of nanohybrid composite during bleaching with carbamide peroxide: A microleakage study

    OpenAIRE

    A Ashok Kumar; V P Hariharavel; Ashwin Narayanan; S Murali

    2015-01-01

    Aim: The aim of the study was to evaluate the microleakage on the marginal integrity of nanohybrid composite during bleaching with carbamide peroxide after applying a protective coating of G-Coat plus (GC, Japan). Materials and Methods: Class V cavities were prepared and restored with nanohybrid composite restoration in 60 freshly extracted noncarious premolars extracted for orthodontic reasons. Then they were divided into 3 groups. Group 1 - bleaching with carbamide peroxide without G co...

  12. Shear bond strength after dentin bleaching with 10% carbamide peroxide agents

    OpenAIRE

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

    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 ...

  13. Effects of 35% Carbamide Peroxide Gel on Surface Roughness and Hardness of Composite Resins

    OpenAIRE

    Sharafeddin, F.; Jamalipour, GR.

    2010-01-01

    Objective: Bleaching agents may not be safe for dental materials. The purpose of this in-vitro study was to evaluate the effects of Opalescent Quick ?in-office bleaching gel? containing 35% carbamide peroxide on the surface roughness and hardness of microfilled (Heliomolar) and hybride (Spectrum TPH) composite resins. Materials and Methods: Twenty specimens of Spectrum TPH composite resins and twenty Heliomolar composite resins were fabricated using a metallic ring (6.5 mm diameter and 2.5 mm...

  14. A clinical assessment of the effects of 10% carbamide peroxide gel on human pulp tissue.

    Science.gov (United States)

    Anderson, D G; Chiego, D J; Glickman, G N; McCauley, L K

    1999-04-01

    Bleaching vital teeth with 10% carbamide peroxide gel is a routine procedure in which there has been no evidence of associated permanent pulpal damage. Synthesis of the enzyme heme oxygenase-1 (HO-1) is increased after exposure of eukaryotic cells to conditions of oxidative stress (including H2O2) as a defense against the damaging effects of free radicals. Dental pulps were evaluated for HO-1 (aka Heat Shock Protein 32) presence in teeth treated with 10% carbamide peroxide. Seventeen intact first premolars scheduled for orthodontic extraction were bleached for 4 h immediately preceding extraction. Fourteen additional premolars from the same individuals were not bleached. All 31 teeth were extracted, fixed, demineralized, frozen, sectioned, and immunostained with anti-HO-1 antibody using a standard ABC protocol. There was no significant difference in the presence of HO-1 between total bleached versus total unbleached teeth using the Fisher's Exact Test (p pulp proper may have the potential to respond to oxidative stress by increasing the synthesis of HO-1 (HSP32). This could represent a component of an initial defensive response by specific cells in strategic locations in the pulp that precedes classical inflammatory pathways.

  15. High-performance supercapacitors using flexible and freestanding MnOx/carbamide carbon nanofibers

    Science.gov (United States)

    Samuel, Edmund; Jo, Hong Seok; Joshi, Bhavana; Park, Hyun Goo; Kim, Yong Il; An, Seongpil; Swihart, Mark T.; Yun, Je Moon; Kim, Kwang Ho; Yoon, Sam S.

    2017-11-01

    We demonstrate the fabrication of a MnOx/carbamide carbon nanofiber (CCNF) composite consisting of MnO particles embedded in CCNFs as a highly flexible and freestanding electrode material for supercapacitors. A sacrificial polymer component, polymethylmethacrylate, included in the precursor solution, pyrolyzes during heating, resulting in pores in the fibers, some of which are filled by the MnO nanocrystals. Carbamide is added to control the size of the MnOx particles as well as to increase the carbon content of the composite and hence its conductivity. The X-ray diffraction and Raman spectra of the composite show that the MnO particles formed have low crystallinity. Transmission electron microscopy confirms that the MnO particles are distributed very uniformly over the CCNFs. Symmetric supercapacitors constructed using electrodes of this composite exhibit specific capacitances of 498 F•g-1 at a scan rate of 10 mV•s-1 and 271 F•g-1 at a current density of 1 A•g-1. They also exhibit excellent long-term cycling performance, retaining 93% of their initial capacity after 5000 cycles of galvanostatic charging/discharging.

  16. Synthesis and X-ray diffraction study of new uranyl malonate and oxalate complexes with carbamide

    International Nuclear Information System (INIS)

    Medvedkov, Ya. A.; Serezhkina, L. B.; Grigor’ev, M. S.; Serezhkin, V. N.

    2016-01-01

    Two new malonate-containing uranyl complexes with carbamide of the formulas [UO 2 (C 3 H 2 O 4 )(Urea) 2 ] (I) and [UO 2 (C 3 H 2 O 4 )(Urea) 3 ] (II), where Urea is carbamide, and one uranyl oxalate complex of the formula [UO 2 (C 2 O 4 )(Urea) 3 ] (III) were synthesized, and their crystals were studied by X-ray diffraction. The main structural units in crystals I are the electroneutral chains [UO 2 (C 3 H 2 O 4 )(Urea) 2 ] ∞ belonging to the crystal-chemical group AT 11 M 2 1 (A = UO 2 2+ , T 11 = C 3 H 2 O 4 2- , M 1 = Urea) of uranyl complexes. Crystals II and III are composed of the molecular complexes [UO 2 (L)(Urea) 3 ], where L = C 3 H 2 O 4 2- or C 2 O 4 2- , belonging to the crystal-chemical group AB 01 M 3 1 (A = UO 2 2+ , B 01 = C 3 H 2 O 4 2- or C 2 O 4 2- , M 1 = Urea). The characteristic features of the packing of the uranium-containing complexes are discussed in terms of molecular Voronoi–Dirichlet polyhedra. The effect of the Urea: U ratio on the structure of uranium-containing structural units is considered.

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

    International Nuclear Information System (INIS)

    Adachi, Eduardo Makoto; Yousseff, Michel Nicolau; Saiki, Mitiko

    2002-01-01

    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)

  18. Utilisation of the energy-independent underground gasification-uvea process for carbamide production; Einsatz des energieautarken Untertagevergasungs-Urea-Prozesses zur Carbamid-Herstellung

    Energy Technology Data Exchange (ETDEWEB)

    Nakaten, Natalie; Kempka, Thomas [Helmholtz Zentrum Potsdam, Deutsches GeoForschungszentrum (GFZ) Potsdam (Germany); Schlueter, Ralph [DMT GmbH und Co. KG, Essen (Germany). Abt. Geologie und Bohrlochvermessungen; Hamann, Joerg [EPC Industrial Engineering Deutschland GmbH, Alzenau (Germany); Islam, Rafiqul [Dhaka Univ. (Bangladesh). Dept. of Applied Chemistry and Chemical Engineering; Azzam, Rafig [RWTH Aachen (Germany). Lehrstuhl fuer Ingenieur- und Hydrogeologie

    2011-08-15

    The worldwide coal resources have an energy supply potential of several hundred years. However, great depths, thin seams and tectonic faults may greatly restrict the utilisation of the coal seams by means of conventional conveyor technologies. With the aim of production of a conveyable synthesis gas underground coal gasification (UCG) offers an environmentally friendly and economically viable possibility of utilisation of previously inaccessible coal deposits. The high-calorific UCG synthesis gas can be used, for example, for the generation of electricity in an integrated gas and steam turbine process (GaS) as well as the production of chemical starting materials. One possibility of product recovery from the UCG synthesis gas is the production of the fertiliser carbamide (CH{sub 6}N{sub 2}O{sub 2}). The aim of this study is the development of a utilisation concept for coal deposits on the basis of a combined and energy-independent UCG-GaS-urea process. To check the utilisation concept based on an independent electricity supply an economic feasibility study for a selected investigation area in the north of Bangladesh was carried out with consideration of the economic viability and potential of the UCG-GaS-urea process. (orig.)

  19. Effect of a 16% Carbamide Peroxide Bleaching Gel on Enamel Staining Susceptibility

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    M. Ghavamnasiri

    2005-03-01

    Full Text Available Statement of Problem: Due to the growing popularity of vital bleaching by CarbamidePeroxide it is imperative to understand the effect of such agents on enamel and dentine.Purpose: The purpose of this study was to evaluate the effect of a 16% carbamide peroxide bleaching gel; Vivastyle on enamel staining susceptibility.Materials and Methods: Thirty bovine specimens were selected and randomly divided into two groups of fifteen. The experimental group was subjected to Vivastyle gel and then was immersed in coffee, for half an hour daily for three weeks. The control group was only immersed in coffee. The teeth were evaluated by colorimeter readings to measure L*, a*, b* of each tooth. Total color differences between two colors (ΔE were calculated using the following formula: ΔE= [(ΔL* 2 + (Δa* 2+ (Δb* 2].ΔE1 represent color difference after bleaching; ΔE2: bleached and immersed in coffee,and ΔE3 immersed in coffee.Results: Mean color difference were: 9.478, 13.808, and 7.230 for ΔE1, ΔE2, and ΔE3 respectively. Paired comparison by Duncan test showed that there was a significant difference between ΔE1 and ΔE2 (P0.000. t-test showed that there was no significant difference between ΔE3 and ΔE1. (P=0.08, however, ΔE3 had significant difference with ΔE2 (P0.000.Conclusion: After vital bleaching, the enamel staining susceptibility is significantly increased.

  20. Synthesis and X-ray diffraction study of new uranyl malonate and oxalate complexes with carbamide

    Energy Technology Data Exchange (ETDEWEB)

    Medvedkov, Ya. A.; 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); Serezhkin, V. N. [Samara State University (Russian Federation)

    2016-05-15

    Two new malonate-containing uranyl complexes with carbamide of the formulas [UO{sub 2}(C{sub 3}H{sub 2}O{sub 4})(Urea){sub 2}] (I) and [UO{sub 2}(C{sub 3}H{sub 2}O{sub 4})(Urea){sub 3}] (II), where Urea is carbamide, and one uranyl oxalate complex of the formula [UO{sub 2}(C{sub 2}O{sub 4})(Urea){sub 3}] (III) were synthesized, and their crystals were studied by X-ray diffraction. The main structural units in crystals I are the electroneutral chains [UO{sub 2}(C{sub 3}H{sub 2}O{sub 4})(Urea){sub 2}]{sub ∞} belonging to the crystal-chemical group AT{sup 11}M{sub 2}{sup 1} (A = UO{sub 2}{sup 2+}, T{sup 11} = C{sub 3}H{sub 2}O{sub 4}{sup 2-}, M{sup 1} = Urea) of uranyl complexes. Crystals II and III are composed of the molecular complexes [UO{sub 2}(L)(Urea){sub 3}], where L = C{sub 3}H{sub 2}O{sub 4}{sup 2-} or C{sub 2}O{sub 4}{sup 2-}, belonging to the crystal-chemical group AB{sup 01}M{sub 3}{sup 1} (A = UO{sub 2}{sup 2+}, B{sup 01} = C{sub 3}H{sub 2}O{sub 4}{sup 2-} or C{sub 2}O{sub 4}{sup 2-}, M{sup 1} = Urea). The characteristic features of the packing of the uranium-containing complexes are discussed in terms of molecular Voronoi–Dirichlet polyhedra. The effect of the Urea: U ratio on the structure of uranium-containing structural units is considered.

  1. Effect of protective coating on marginal integrity of nanohybrid composite during bleaching with carbamide peroxide: A microleakage study.

    Science.gov (United States)

    Kumar, A Ashok; Hariharavel, V P; Narayanan, Ashwin; Murali, S

    2015-01-01

    The aim of the study was to evaluate the microleakage on the marginal integrity of nanohybrid composite during bleaching with carbamide peroxide after applying a protective coating of G-Coat plus (GC, Japan). Class V cavities were prepared and restored with nanohybrid composite restoration in 60 freshly extracted noncarious premolars extracted for orthodontic reasons. Then they were divided into 3 groups. Group 1 - bleaching with carbamide peroxide without G coat plus (n = 20), Group 2 - bleaching with carbamide peroxide with G-Coat plus (n = 20), Group 3 - without bleaching procedure (n = 20) (control group). In Group 2, G coat plus was applied over the restorative surface and margins. Then all teeth in Groups 1 and 2 were taken and mounted in dental stone. Bleaching trays were custom fabricated over the cast with the help of a heated vacuum-forming machine. 10% carbamide peroxide (opalescence PF) was applied over the tooth, and the bleaching process was done for about 2 weeks. Then all samples underwent thermocycling and were then immersed in the 2% methylene blue solution for 24 h and observed under a stereomicroscope to evaluate the amount of dye penetration. Data were compared using Kruskal-Wallis test and Mann-Whitney test using SPSS Inc.; Chicago, IL, USA, Version 17.0. Mann-Whitney test shows that the difference in microleakage between Group 1-Group 2 and Group 2-Group 3 is statistically significant (P < 0.05). Significant reduction in microleakage was seen in Group 2 when compared to other groups.

  2. Obtaining low-congealing oils and paraffins by carbamide deparaffinization method

    Energy Technology Data Exchange (ETDEWEB)

    Kalambet, I A; Dorodnova, V S

    1982-07-01

    Ethane cooling is required to obtain oils with congealing points lower than 15-20/sup 0/C. Thus a process of carbamide deparaffinization that would be relatively simple and would not require special cooling equipment was deemed desirable. Filtrates were selected from an oil separating device after basic solid paraffins had been removed. They were subjected to hydropurification with an alumimum-cobalt-molybdenum catalyst at 4 MPa pressure, 320/sup 0/C, feed of 1.5c/sup -1/ and hydrogen-containing gas compressed to 500 m/sup 3//m/sup 3/. Results showed that the initial mixed hydrocarbon filtrate was deparaffinized under these conditions to produce an oil that congealed on the average at temperatures 2-3/sup 0/ lower than controls. A benzine fraction at 80-120/sup 0/C was used as the solvent and methanol served as the activator. Using distillates from Stavropol crude oil, it was possible to obtain oils.

  3. 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.

  4. Effect of Hydrogen and Carbamide Peroxide in Bleaching, Enamel Morphology, and Mineral Composition: In vitro Study.

    Science.gov (United States)

    Llena, Carmen; Esteve, Irene; Forner, Leopoldo

    2017-07-01

    The aim of the study was to evaluate the bleaching effect, morphological changes, and variations in calcium (Ca) and phosphate (P) in the enamel with hydrogen peroxide (HP) and carbamide peroxide (CP) after the use of different application regimens. Four groups of five teeth were randomly assigned, according to the treatment protocol: HP 37.5% applied for 30 or 60 minutes (HP30, HP60), CP 16% applied for 14 or 28 hours (CP14, CP28). Changes in dental color were evaluated, according to the following formula: ΔE = [(L a -L b ) 2 +(a a -a b ) 2 + (b a -b b ) 2 ] 1/2 . Enamel morphology and Ca and P compositions were evaluated by confocal laser scanning microscope and environmental scanning electron microscopy. ΔE HP30 was significantly greater than CP14 (10.37 ± 2.65/8.56 ± 1.40), but not between HP60 and CP28. HP60 shows greater morphological changes than HP30. No morphological changes were observed in the groups treated with CP. The reduction in Ca and P was significantly greater in HP60 than in CP28 (p tooth color; HP produced morphological changes and Ca and P a gradual decrease, while CP produced no morphological changes, and the decrease in mineral component was smaller. CP 16% applied during 2 weeks could be equally effective and safer for tooth whitening than to administer two treatment sessions with HP 37.5%.

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

    Directory of Open Access Journals (Sweden)

    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.

  6. [Effect of carbamide peroxide bleaching agents on micro-leakage of composite resin interface in vitro].

    Science.gov (United States)

    Wang, Xiao-ling; Xu, Juan; Zhao, Xin-yi; He, Hui-ming

    2011-01-01

    To evaluate the effect of carbamide peroxide (CP) bleaching agents at different concentrations and with different carriers on the micro-leakage of composite resin interface. Class V cavity (2 mm in diameter and 2 mm in depth) preparations were made at the enamelo-cemental junction on the buccal and lingual surfaces of 35 extracted human premolars. The cavities were filled with hybrid composite resin. The teeth were stored for 24 h in distilled water at 37 degrees celsius; before thermocyling for 500 times between 5 and 55 degrees celsius;. The teeth were then randomly assigned into 7 groups, and in groups 1-6, the bleaching gels containing 10% or 20% of CP were applied on the buccal and lingual surface of the teeth for two weeks (6-8 h/day, 37 degrees celsius;, 100% relative humidity) using Carbopol, PVP or Poloxamer as the thickening carriers, respectively. The seventh group served as the control without bleaching treatment. Nail polish was applied to the surface of the tooth, and all the teeth were immersed in ammoniacal silver nitrate solution followed by developing solution. The teeth were finally sectioned through the midline of the restoration and observed under stereomicroscope. SEM micrographs were also made to observe the interface. With the same bleaching agent, the micro-leakage in the gingival wall was slightly greater than in the occlusive wall, but the difference was not significant. Only 20% CP with Poloxamer as the thickening agent significantly increased the leakage of dentine-resin composite interface, and 10% and 20% CP with Carbopol or PVP as the thickening agents and 10% CP with Poloxamer produced minimal effects on filling the micro-leakage. Thickening carriers and the concentration of CP (20% or below) have no significant effect on micro-leakage of composite resin.

  7. Study of the composition of impurities in paraffins, which have been removed at different stages of the carbamide deparaffinization process

    Energy Technology Data Exchange (ETDEWEB)

    Dorodnova, V.S.; Martirosov, R.A.; Martynenko, A.G.; Pereverzev, A.N.

    1980-01-01

    Results of the study on the composition of impurities in paraffin raw material, which has been removed from different stages of a deparaffinization unit are presented. It is shown that by using the method of chromatographic partitioning of paraffins during rinsing of the system basically monocyclic aromatics are removed, and the content of polycyclic aromatics and resins shows practically no change. A separation temperature of the system of 93-95/sup 0/ is recommended as optimum for existing G-64 commercial units. The content of residual paraffin in this case in the carbamide is about 1%.

  8. Role of fluoridated carbamide peroxide whitening gel in the remineralization of demineralized enamel: An in vitro study.

    Science.gov (United States)

    Bollineni, Swetha; Janga, Ravi Kumar; Venugopal, L; Reddy, Indukuri Ravikishore; Babu, P Ravisekhar; Kumar, Sunil S

    2014-05-01

    The use of self-administered carbamide peroxide bleaching gels has become increasingly popular for whitening of discolored vital teeth. Studies have reported that its use may induce increased levels of sensitivity and surface roughness of the tooth due to demineralization. This study evaluates the effect of fluoride addition to the bleaching agent - its remineralizing capacity and alterations in the whitening properties. Twenty-four extracted lower third molar teeth, with the pretreatment shade determined, were taken up in the study. Each tooth was sectioned into four and labeled as groups A, B, C, and D. The tooth quadrants in group A-C were demineralized; groups A and B were treated with 10% carbamide peroxide gel (group-A without fluoride and group-B with 0.463% fluoride addition) (no further treatment was carried out for group c) group-D remained as the control. The post-treatment shade was determined. The tooth samples were sectioned (approximately 200 μm) for evaluation under a light microscope. The depth of demineralization was analyzed at five different equidistant points. Statistical analysis was carried out with t-tests, accepting ≤0.05 as significant. Addition of fluoride caused remineralization of demineralized enamel. The tooth whitening system showed that the remineralization properties did not affect the whitening properties.

  9. 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.

  10. A Clinical Study of the Effectiveness of Two Different 10% Carbamide Peroxide Bleaching Products: A 6-Month Followup

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    S. R. Grobler

    2011-01-01

    Full Text Available The purpose of this study was to evaluate the efficacy of two different 10% carbamide peroxide bleaching products just after treatment and after a 6-month follow-up period. Methods. Two 10% carbamide peroxide products (Opalescence PF and Nite White ACP were applied nightly for 14 days, according to the manufacturers' instructions. The color of teeth 11 and 21 of thirty-four subjects having A2 or darker teeth were measured with a spectrophotometer (L∗;a∗;b∗ before treatment, just after treatment (14 days and after 6 months. Results and Conclusions. Both products produced significant whitening of teeth with total color change (ΔEab∗ of approximately 5.20 units. There was a significant improvement in all 3 color coordinates (L*,a*, and b∗ for up to 6 months postbleaching (P<.05. Nite White showed a higher degree of relapse (27% than Opalescence (18% over the 6-month period. It is suggested that rebleaching after 6 months is not necessary.

  11. Effect of 38% carbamide peroxide on the microleakage of silorane-based versus methacrylate-based composite restorations

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    Sedighe Sadat Hashemi Kamangar

    2014-08-01

    Full Text Available Objectives This study aimed to assess the effect of 38% carbamide peroxide on the microleakage of class V cavities restored with either a silorane-based composite or two methacrylate-based composites. Materials and Methods A total of 96 class V cavities were prepared on the buccal surface of extracted human teeth with both enamel and dentin margins and were randomly assigned into three groups of Filtek P90 (3M-ESPE + P90 system adhesive (3M-ESPE(group A, Filtek Z250 (3M-ESPE + Adper Prompt L-Pop (3M-ESPE(group B and Filtek Z350XT (3M-ESPE + Adper Prompt L-Pop (group C. Half of the teeth were randomly underwent bleaching (38% carbamide peroxide, Day White, Discus Dental, applying for 15 min, twice a day for 14 day while the remaining half (control were not bleached. Dye penetration was measured following immersion in basic fuchsine. Data were statistically analyzed using Kruskal-Wallis and Mann-Whitney U tests at a level of 0.05. Results No significant differences were found between composites in the control groups in enamel (p = 0.171 or dentin (p = 0.094 margins. After bleaching, microleakage of Z250 (in enamel [p = 0.867] or dentin [p = 0.590] margins and Z350 (in enamel [p = 0.445] or dentin [p = 0.591] margins did not change significantly, but the microleakage of P90 significantly increased in both enamel (p = 0.042 and dentin (p = 0.002 margins. Conclusions No significant differences were noted between the bleached and control subgroups of two methacrylate-based composites in enamel or dentin margins. Microleakage of silorane-based composite significantly increased after bleaching.

  12. Carbamide peroxide gel stability under different temperature conditions: is manipulated formulation an option?

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    Camila de Martini Bonesi

    2011-12-01

    Full Text Available Nowadays the use of gel containing carbamide peroxide (CP prepared in Pharmacy is a normal practice in the population. However, the quality of this product is questionable concerning its stability. The aim of this study is was to synthesize and to analyze this drug alone or associated to Carbopol gel through analytical methodology compatible with the routine of the Pharmacies. The reaction between urea and hydrogen peroxide was carried out at different resting times: 24 hours (CP 24 powder and 48 hours (CP48 powder after the mixture. Both products were associated with Carbopol 940® gel 1.5% (G generating G24 and G48 samples. The stability of powders (CP24 e CP48 and the formulations (G24 and G48 were evaluated as a function of time (15, 40 and 45 days and thermal variation (refrigeration: 8 °C±1; thermal shock 32 °C±1 /8 °C±1; stove: 32 °C±1, using a standard titration method. As a result, only under refrigeration the CP24 and CP48 contents remained stable during the period of 45 days. An interesting finding was that G24 and G48 presented greater stability for at least 45-days under refrigeration and thermal shock conditions, and up to 30 days under stove conditions. The results for the G24 and G48 were slightly higher than those obtained for the control. Therefore, we were able to conclude that association with Carbopol 940® Gel 1.5 % provided greater CP stability and that manipulated formulations containing CP may be viable for use in a period of 45 days under refrigeration conditions. The titration proved to be an effective technique for the analysis of CP with or without Carbopol 940® gel 1.5%.Atualmente, a utilização de gel contendo peróxido de carbamida manipulado em Farmácia é uma prática comum na população. No entanto, a qualidade deste produto é questionada, sobretudo no que se refere à estabilidade deste fármaco. O objetivo deste trabalho consiste na avaliação da viabilidade de sintetizar e analisar

  13. Effect of fluoride-treated enamel on indirect cytotoxicity of a 16% carbamide peroxide bleaching gel to pulp cells.

    Science.gov (United States)

    Soares, Diana Gabriela; Ribeiro, Ana Paula Dias; Lima, Adriano Fonseca; Sacono, Nancy Tomoko; Hebling, Josimeri; de Souza Costa, Carlos Alberto

    2013-01-01

    The aim of this study was to evaluate the possibility of fluoride solutions applied to enamel to protect pulp cells against the trans-enamel and transdentinal cytotoxicity of a 16% carbamide peroxide (CP) bleaching gel. The CP gel was applied to enamel/dentin discs adapted to aicial pulp chambers (8 h/day) during 1, 7 or 14 days, followed by fluoride (0.05% or 0.2%) application for 1 min. The extracts (culture medium in contact with dentin) were applied to MDPC-23 cells for 1 h, and cell metabolism (MTT assay), alkaline phosphatase (ALP) activity and cell membrane damage (flow cytometry) were analyzed. Knoop microhardness of enamel was also evaluated. Data were analyzed statistically by ANOVA and Kruskal-Wallis tests (α=0.05). For the MTT assay and ALP activity, significant reductions between the control and the bleached groups were observed (p0.05), regardless of fluoride application or treatment days. Flow cytometry analysis demonstrated 30% of cell membrane damage in all bleached groups. After 14 days of treatment, the fluoride-treated enamel presented significantly higher microhardness values than the bleached-only group (pfluoride solutions, the treated enamel surface did not prevent the toxic effects caused by the 16% CP gel to odontoblast-like cells.

  14. Investigation of 16% carbamide-peroxide on the structure and properties and effect return enamel staining teeth whitening after their

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    Matvijenko Vladimir

    2015-01-01

    Full Text Available The most tooth whitening is a procedure that removes stains and various discolorations of tooth surface. Discoloration of teeth may be endogenous and exogenous nature. The aim of this study was to investigate the impact of bleaching combined with daily use of drinks that cause tooth discoloration. Evaluated the changes in surface structure of enamel, and changes in hardness after bleaching. Were 20 extracted teeth. The teeth are marked with longitudinal lines halves (medial vestibular and distal surfaces. Tretitana mesial half of the 16% carbamide peroxide, a distal was left as control. NDT device HL-400DL, duroskopskom method of enamel hardness was measured before treatment, after treatment and after remineralization. Olympus inverted microscope GX41 enamel structures were observed in the treated and control half of the tooth. After bleaching there is a difference compared to the untreated surface, that surface is bleached a few shades lighter, but after the use of coffee and soft drinks teeth back to the original dark color. Enamel microhardness after the treatment is somewhat small but not significant. With a magnification of 2000x and see the structural changes in enamel. Tooth whitening, but that the remineralization and the abstinence from prebojenih beverages and tobacco.

  15. Microhardness and Roughness of Enamel Bleached with 10% Carbamide Peroxide and Brushed with Different Toothpastes: An In Situ Study

    Science.gov (United States)

    Melo, Carolina França de Medeiros; Manfroi, Fernanda Borguetti; Spohr, Ana Maria

    2014-01-01

    Background: This in situ study evaluated the roughness and microhardness of enamel bleached with 10% carbamide peroxide (PC10) and brushed with different toothpastes. Materials and Methods: Two groups of volunteers received PC10 and placebo agents for 21 days in two phases in a crossover 2 × 3 study. Fragments of human enamel were distributed among intraoral removable appliances (IRA). Nine fragments, divided into three triplets, were used in each IRA, and these were brushed with toothpastes R (Colgate), W (Colgate Total 12 Whiteness Gel) or BS (Colgate Whitening Oxygen Bubbles Fluoride). Treatments agents were applied for 8 h overnight. After brushing, the volunteers used the IRA for about 16 h/day. After a washout period, new IRAs were distributed and the volunteers were crossed over to the alternate agent for 21 days. Roughness and microhardness were measured before and after each phase. Results: According to the paired Student’s t-test, roughness of enamel increased and microhardness decreased (P Enamel microhardness and surface roughness are altered when PC10 bleaching is associated with tooth brushing using toothpastes BS, R, and W. PMID:25214727

  16. 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.

  17. Efficacy and safety of over-the-counter whitening strips as compared to home-whitening with 10 % carbamide peroxide gel--systematic review of RCTs and metanalysis.

    Science.gov (United States)

    Serraglio, Carla Regina; Zanella, Luana; Dalla-Vecchia, Karine Battestin; Rodrigues-Junior, Sinval Adalberto

    2016-01-01

    The study aims to compare the efficacy and safety of over-the-counter whitestrips with the American Dental Association (ADA)-recommended home-whitening using the 10 % carbamide peroxide gel. Randomized controlled trials (RCTs) comparing the clinical efficacy and safety of the whitestrips with the 10 % carbamide peroxide (10 % CP) gel applied on tray for tooth whitening in adults were searched at PubMed and Cochrane Central Register of Controlled Trials databases and selected up to October 2014. Efficacy of the whitening techniques was assessed through ∆E, ∆L, and ∆b parameters, while side effects were analyzed as dichotomous variables. Data was extracted independently by two reviewers. Metanalysis was performed using random- and fixed-effect models (RevMan 5.3). Eight studies were included in the metanalysis. The metanalysis revealed no significant difference between the intervention groups for tooth-whitening efficacy measured as ΔE (mean difference [MD]-0.53; 95 % CI [-1.72;0.66]; Z = 0.88; p = 0.38) and ΔL (MD-0.22; 95 % CI [-0.81;0.36]; z = 0.75; p = 0.45); reduction of yellowing was higher with the whitestrips (MD-0.47; 95 % CI [-0.89; -0.06]; Z = 2.25; p = 0.02). Tooth sensitivity (risk ratio [RR] 1.17; 95 % CI [0.81-1.69]; Z = 0.81; p = 0.42) and gingival sensitivity (RR 0.76; 95 % CI [0.53-1.10]; Z = 1.44; p = 0.15) were similar, regardless of the whitening method used. The observed gingival irritation was higher when the 10 % CP gel was applied on tray (RR 0.43; 95 % CI [0.20-0.93]; Z = 2.14; p = 0.03). The quality of evidence generated was rated very low for all outcomes. There is no sound evidence to support the use of the whitening strips in detriment of the ADA-recommended technique based on the 10 % carbamide peroxide gel applied on tray. To the moment, there is no sound evidence in dental literature to suggest that the ADA-recommended whitening technique based on 10 % carbamide peroxide gel could be substituted by the whitening strips. The

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

    Energy Technology Data Exchange (ETDEWEB)

    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

  19. Evaluation of human dental loss caused by carbamide peroxide bleacher compared with phosphoric acid conditioning - radioactive method; Avaliacao da perda dental humana com o uso do clareador peroxido de carbamida comparado ao condicionamento com acido fosforico - metodo radiometrico

    Energy Technology Data Exchange (ETDEWEB)

    Adachi, Eduardo Makoto; Yousseff, Michel Nicolau [Sao Paulo Univ., SP (Brazil). Faculdade de Odontologia. Dept. de Dentistica; Saiki, Mitiko [Instituto de Pesquisas Energeticas e Nucleares (IPEN), Sao Paulo, SP (Brazil). Lab. de Analise por Ativacao Neutronica

    2002-07-01

    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 {sup 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)

  20. Effect of In-Office Carbamide Peroxide-Based Tooth Bleaching System on Wear Resistance of Silorane-Based and Methacrylate-Based Dental Composites

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    Masoumeh Hasani Tabatabaei

    2016-04-01

    Full Text Available Objectives: Several studies have assessed the characteristics and properties of silorane-based composites and adhesive systems. Considering the extensive application of tooth-whitening agents, possible deteriorative effects of tooth bleaching agents on these restorative materials must be studied. The aim of this study was to evaluate the effect of an in-office carbamide peroxide-based tooth bleaching agent on the wear resistance of a silorane-based and a conventional microhybrid dimethyl methacrylate-based dental composite with two different application times.  Materials and Methods: Thirty cylindrical specimens were made of Z250 and P90 dental composite resins (n=15 for each composite. Samples made of each composite were divided into three groups (n=5 for immersion in an in-office bleaching agent (Opalescence® Quick 45% for either three or eight hours or saline solution (control. Wear tests were conducted after bleaching using a pin-on disk apparatus under the load of 40N at a constant sliding speed of 0.5 ms-1 for a sliding distance of 300 m. The samples were weighed before and after the wear test. Repeated measures ANOVA was used to statistically analyze the obtained data (α=0.05.Results: There was a significant decrease in the weight of samples after the wear test (P<0.001. However, no significant difference was found among groups in the mean weight of samples before and after the wear test (P>0.05. Conclusion: Bleaching for three or eight hours using 45% carbamide peroxide had no deteriorative effect on the wear resistance of Z250 and P90 composites.

  1. 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

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    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.

  2. Effects of conditioners on microshear bond strength to enamel after carbamide peroxide bleaching and/or casein phosphopeptide-amorphous calcium phosphate (CPP-ACP) treatment.

    Science.gov (United States)

    Adebayo, O A; Burrow, M F; Tyas, M J

    2007-11-01

    To evaluate (a) the enamel microshear bond strength (MSBS) of a universal adhesive and (b) the effects of conditioning with a self-etching primer adhesive with/without prior bleaching and/or casein phosphopeptide-amorphous calcium phosphate (CPP-ACP) application. Thirty-five molars were cut into four sections, assigned randomly to four groups (no treatment; 16% carbamide peroxide bleaching; CPP-ACP-containing paste (Tooth Mousse, TM); bleaching and TM) and treated accordingly. Specimens were divided into two for bonding with either a self-etching primer (Clearfil SE Bond, CSE) or a total-etch adhesive (Single Bond, SB). Specimens for CSE bonding were subdivided for one of four preconditioning treatments (no conditioning; 30-40% phosphoric acid (PA); 15% EDTA; 20% polyacrylic acid conditioner (Cavity conditioner, CC) and treated. The adhesives were applied and resin composite bonded to the enamel using microtubes (internal diameter 0.75mm). Bonds were stressed in shear until failure, mean MSBS calculated and data analysed using ANOVA with Tukey's HSD test (alpha=0.05). The modes of bond failure were assessed and classified. Two-way ANOVA revealed significant differences between treatments (Padhesive system on treated enamel may significantly improve bond strengths.

  3. Comparison of efficacy of tray-delivered carbamide and hydrogen peroxide for at-home bleaching: a systematic review and meta-analysis.

    Science.gov (United States)

    Luque-Martinez, Issis; Reis, Alessandra; Schroeder, Marcos; Muñoz, Miguel Angel; Loguercio, Alessandro D; Masterson, Danielle; Maia, Lucianne C

    2016-09-01

    The aim of the study was to compare the color change produced by tray-delivered carbamide peroxide [CP] versus hydrogen peroxide products [HP] for at-home bleaching through a systematic review and meta-analysis. MEDLINE via PubMeb, Scopus, Web of Science, Latin American and Caribbean Health Sciences Literature database (LILACS), Brazilian Library in Dentistry (BBO), and Cochrane Library and Grey literature were searched without restrictions. The abstracts of the International Association for Dental Research (IADR) and unpublished and ongoing trial registries were also searched. Dissertations and theses were explored using the ProQuest Dissertations and Periodicos Capes Theses databases. We included randomized clinical trials that compared tray-delivered CP versus HP for at-home dental bleaching. The color change in shade guide units (SGU) and ΔE were the primary outcomes, and tooth sensitivity and gingival irritation were the secondary outcomes. The risk of bias tool of the Cochrane Collaboration was used for quality assessment. After duplicate removal, 1379 articles were identified. However, only eight studies were considered to be at "low" risk of bias in the key domains of the risk bias tool and they were included in the analysis. For ΔE, the standardized mean difference was -0.45 (95 % CI -0.69 to -0.21), which favored tray-delivered CP products (p whitening efficacy than HP-based products in terms of ΔE, but they were similar in terms of ΔSGU. Both whitening systems demonstrated equal level of gingival irritation and tooth sensitivity. Tray-delivered CP gels have a slightly better whitening efficacy than HP-based products in terms of ΔE. This should be interpreted with caution as the data of ΔSGU did not show statistical difference between the products.

  4. 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

  5. Specific concentration evaluation of 16% carbamide peroxide compounded at dispensing pharmacies Avaliação da concentração específica do peróxido de carbamida a 16% produzido em farmácias de manipulação

    Directory of Open Access Journals (Sweden)

    Juliana Maria Habith Martin

    2007-12-01

    Full Text Available The aim of this work was to evaluate the concentration of carbamide peroxide compounded at different dispensing pharmacies. Immediate concentration analysis was made of bleaching gels dispensed by specialized pharmacies, and of a commercially available gel (control group (n = 20. The carbamide peroxide concentration was determined by titration and the results were analyzed statistically by the Kruskal-Wallis test. The commercial bleaching agent (control group and one of the gels from the pharmacies presented the best mean concentration values, close to 16%. In conclusion, the concentration of the manipulated and industrialized carbamide peroxide gels presented concentration values differing from 16%.O objetivo deste trabalho foi avaliar a concentração do peróxido de carbamida manipulado em diferentes farmácias de manipulação. Foram utilizados géis clareadores manipulados em farmácias especializadas e um industrializado (grupo controle (n = 20 com análise de concentração imediata. A concentração do peróxido de carbamida foi obtida por titulometria e os resultados foram submetidos a análise estatística pelo teste de Kruskal-Wallis. Como resultado, o agente clareador (controle e um dos produtos manipulados em farmácia apresentaram as melhores médias de concentração, próximas a 16%. Pode-se concluir que a concentração do peróxido de carbamida manipulado e dos industrializados apresentaram valores de concentração diferentes de 16%.

  6. Using ketones in the process of carbamide deparafinization with crystalline carbamides

    Energy Technology Data Exchange (ETDEWEB)

    Dorodnova, V.S.; Martirosov, R.A.; Martynenko, A.G.; Pereverzev, A.N.

    1983-01-01

    The use of MEK as an activator solvent in complex formation improves the filtering properties of the solid phase of the complex and the isolated paraffin contains a smaller volume of impurities (8.8 percent) than with the use of methanol.

  7. 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

  8. 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

  9. 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.

  10. 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

  11. 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

  12. Investigation of 16% carbamide-peroxide on the structure and properties and effect return enamel staining teeth whitening after their

    OpenAIRE

    Matvijenko Vladimir; Živković M.; Videnović G.; Kostić-Šubarić Lj.; Živković D.; Perić D.; Jovanović R.

    2015-01-01

    The most tooth whitening is a procedure that removes stains and various discolorations of tooth surface. Discoloration of teeth may be endogenous and exogenous nature. The aim of this study was to investigate the impact of bleaching combined with daily use of drinks that cause tooth discoloration. Evaluated the changes in surface structure of enamel, and changes in hardness after bleaching. Were 20 extracted teeth. The teeth are marked with longitudinal lines halves (medial vestibular and dis...

  13. A study of organic binding of incorporated tritium by means of the organic components of human urine

    International Nuclear Information System (INIS)

    Szilagyi, M.

    1976-01-01

    The change in tritium activity of metabolytic fractions of urine of persons working in the production of tritium labelled compounds was studied. The radioactivity of the separated fractions was measured during a 20 day period. A carbamide fraction proved to be the most sensitive to incorporative cases owing to its organic component fractioned together with the carbamide. (K.A.)

  14. Color Recovery Effect of Different Bleaching Systems on a ...

    African Journals Online (AJOL)

    2017-12-05

    Dec 5, 2017 ... KEYWORDS: Composite resin, discoloration, home bleaching, laser activated bleaching, office ... hexametaphosphate, which protect the teeth surface from .... exposure, saliva and other fluids diluting the staining .... Penetration of the pulp ... dentin permeability of carbamide peroxide and hydrogen peroxide.

  15. A Scanning Electron Microscopic Study

    African Journals Online (AJOL)

    2018-06-11

    Jun 11, 2018 ... 2018 Nigerian Journal of Clinical Practice | Published by Wolters Kluwer ‑ Medknow ... evaluate and compare the effect of different concentrations of carbamide .... Cements such as resin, glass ionomer, resin‑modified.

  16. Effect of four different opalescence tooth-whitening products on enamel microhardness.

    Science.gov (United States)

    Majeed, A; Grobler, S R; Moola, M H; Rossouw, R J; van Kotze, T J W

    2008-06-01

    The purpose was to evaluate the effect of various Opalescence tooth-whitening products on enamel. Enamel blocks were exposed to Opalescence PF 10% Carbamide Peroxide (n = 10), Opalescence PF 20% Carbamide Peroxide (n = 10), Opalescence Trèswhite Supreme 10% Hydrogen Peroxide (n = 10) and Opalescence Quick PF 45% Carbamide Peroxide (n = 10) according to the manufacturer's instructions. The control group was enamel blocks (n = 10) kept in artificial saliva. The values were obtained before exposure and after the 14-days treatment period. Enamel blocks were kept in saliva between treatments. Indent marks on enamel blocks were examined using the scanning electron microscope for treatment effects. All four different Opalescence products damaged enamel. The most damage was done when treated for a long period (112 hours). SEM images also showed damage to enamel by all 4 products. Opalescence with 10% and with 20% Carbamide Peroxide showed the highest damage, which also differed significantly (p enamel. Higher damage was done by the 10% carbamide peroxide and 20% carbamide peroxide products because of the much longer exposure period (112 hours in comparison to 7 hours).

  17. Scanning Electron Microscopy and Energy-Dispersive X-Ray Microanalysis of Set CEM Cement after Application of Different Bleaching Agents.

    Science.gov (United States)

    Samiei, Mohammad; Janani, Maryam; Vahdati, Amin; Alemzadeh, Yalda; Bahari, Mahmoud

    2017-01-01

    The present study evaluated the element distribution in completely set calcium-enriched mixture (CEM) cement after application of 35% carbamide peroxide, 40% hydrogen peroxide and sodium perborate as commercial bleaching agents using an energy-dispersive x-ray microanalysis (EDX) system. The surface structure was also observed using the scanning electron microscope (SEM). Twenty completely set CEM cement samples, measuring 4×4 mm 2 , were prepared in the present in vitro study and randomly divided into 4 groups based on the preparation technique as follows: the control group; 35% carbamide peroxide group in contact for 30-60 min for 4 times; 40% hydrogen peroxide group with contact time of 15-20 min for 3 times; and sodium perborate group, where the powder and liquid were mixed and placed on CEM cement surface 4 times. Data were analyzed at a significance level of 0.05 through the one Way ANOVA and Tukey's post hoc tests. EDX showed similar element distribution of oxygen, sodium, calcium and carbon in CEM cement with the use of carbamide peroxide and hydroxide peroxide; however, the distribution of silicon was different ( P structure. Sodium perborate was similar to control group due to its weak oxidizing properties. Globular structures and numerous woodpecker holes were observed on the even surface on the carbamide peroxide group. The mean elemental distribution of completely set CEM cement was different when exposed to sodium perborate, carbamide peroxide and hydrogen peroxide.

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

    Science.gov (United States)

    de Araújo, Danilo Barral; Silva, Luciana Rodrigues; Campos, Elisângela de Jesus; Correia de Araújo, Roberto Paulo

    2011-01-01

    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. 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. 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. 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. 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.

  19. 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

    2015-11-01

    Bleaching treatments decrease shear bond strength between orthodontic brackets and teeth; although definite results have not been reported in this regard. This study determined the effects of different bleaching protocols on the shear bond strength of orthodontic brackets to teeth. 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. 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 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.

  20. Study of the efectiveness of the mixed solvents for radically removing thiophenes from benzene and toluene by extractive rectification

    Energy Technology Data Exchange (ETDEWEB)

    Miroshnicenko, A.A.; Fedosyuk, A.A.

    1981-01-01

    A study has been made of the selectivity of solvents under the conditions of liquid-liquid equilibrium in the systems which include thiophene, benzene, toluene, the polar solvent and n-decane. The presence of the latter has maintained the heterogeneity of the mixtures being studied. The systems under consideration were drawn up in volumetric ratios. Equilibrium was studied in thermostat units. The equilibrium phases were analyzed by a special method, while the coefficient of the relative distribution of the components with respect to selectivity was calculated by the known relations. The investigations of the systems with different solvents have shown that there are functionally selective classes of extractants in which selectivity is determined by free unsubstituted functional groups of a solvent. The growth of the selectivity of solvents according to the following classes has been observed: aprotic ones with a keto group < protic ones with a hydroxyl < < unsubstituted amides of acids < sulphones < sulphoxides. To study the liquid-vapor equilibrium, use was made of the most selective extractants (including DMSO, Pyrrolidone-2, carbamide, ethylene carbamide, and NMP) which were revealed earlier in extraction investigations. Since the most selective representative of acid amides, namely, ethylene carbamide and carbamide, are solids, they were studied in mixtures with the less selective liquid solvents of NMP and pyrrolidone-2. NMP-ethylene-carbamide-water and pyrrolidone-2-ethylene carbamida-water are the most selective mixed solvents, and preference is given to the latter one.

  1. Preparation and characterization of porous Mg-Zn-Ca alloy by space holder technique

    Science.gov (United States)

    Annur, D.; Lestari, Franciska P.; Erryani, A.; Sijabat, Fernando A.; G. P. Astawa, I. N.; Kartika, I.

    2018-04-01

    Magnesium had been recently researched as a future biodegradable implant material. In the recent study, porous Mg-Zn-Ca alloys were developed using space holder technique in powder metallurgy process. Carbamide (10-20%wt) was added into Mg-6Zn-1Ca (in wt%) alloy system as a space holder to create porous structure material. Sintering process was done in a tube furnace under Argon atmosphere in 610 °C for 5 hours. Porous structure of the resulted alloy was examined using Scanning Electron Microscope (SEM), while the phase formation was characterized by X-ray diffraction analysis (XRD). Further, mechanical properties of porous Mg-Zn-Ca alloy was examined through compression testing. Microstructure characterization showed higher content of Carbamide in the alloy would give different type of pores. However, compression test showed that mechanical properties of Mg-Zn-Ca alloy would decrease significantly when higher content of carbamide was added.

  2. Calcium release rates from tooth enamel treated with dentifrices containing whitening agents and abrasives.

    Science.gov (United States)

    Araujo, Danilo Barral; Silva, Luciana Rodrigues; de Araujo, Roberto Paulo Correia

    2010-01-01

    Tooth whitening agents containing hydrogen peroxide and carbamide peroxide are used frequently in esthetic dental procedures. However, lesions on the enamel surface have been attributed to the action of these products. Using conventional procedures for separating and isolating biological structures, powdered enamel was obtained and treated with hydrogen peroxide, carbamide peroxide, and sodium bicarbonate, ingredients typically found in dentifrices. The enamel was exposed to different pH levels, and atomic emission spectrometry was used to determine calcium release rates. As the pH level increased, the rate of calcium release from enamel treated with dentifrices containing whitening agents decreased. Carbamide peroxide produced the lowest amount of decalcification, while sodium bicarbonate produced the highest release rates at all pH levels.

  3. The release of vitamin C from chewing gum and its effects on supragingival calculus formation.

    Science.gov (United States)

    Lingström, Peter; Fure, Solveig; Dinitzen, Bettina; Fritzne, Christina; Klefbom, Carin; Birkhed, Dowen

    2005-02-01

    The aims of this study were to evaluate (i): whether vitamin C in chewing gum, alone or in combination with carbamide, influences calculus formation, and (ii) whether carbamide affects the release, stability and uptake of vitamin C in a chewing gum. In two test series (Series I and II), 30 subjects, all calculus formers, participated. They were instructed to chew on five (Series I) or 10 (Series II) pieces of gum per day for a period of 3 months. The chewing gums were: vitamin C (60 mg, Series I), non-vitamin C (Series I) and vitamin C + carbamide (30 mg + 30 mg, Series II). In both series, no gum was used as a negative control. Calculus formation was scored on three lingual sites on the six anterior mandibular teeth according to the Volpe-Manhold index. The effect on plaque and gingivitis was also determined. A significant reduction in the total calculus score was observed after the use of vitamin C (33%) and vitamin C + carbamide (12%) gums compared with no gum use; this reduction was most pronounced in the heavy calculus formers. A reduced amount of visible plaque was also observed after use of vitamin C and non-vitamin C gum, but only the vitamin C gum reduced the number of bleeding sites (37%). In a separate study, the release, stability and uptake of vitamin C were evaluated using the iodine titration method in both saliva and urine after exposure to the following gums: vitamin C + carbamide (30 mg + 30 mg) and vitamin C (30 mg). There was no indication that carbamide affected the release, stability or uptake of vitamin C when used in a chewing gum.

  4. JMBR - SEPTEMBER 2013.cdr

    African Journals Online (AJOL)

    FinePrint

    treating discoloured non-vital teeth as a majority of the population may be unable to afford the alternative treatments like ceramic veneers and crowns. The aim of this study was to compare the efficacy and safety of 35% carbamide peroxide and sodium perborate as intracoronal bleaching agents; with a view to encouraging ...

  5. Bleaching of the discolored traumatized tooth

    DEFF Research Database (Denmark)

    Dahl, Jon E.; Kopperud, Siemen E.; Pallesen, Ulla

    2018-01-01

    This chapter focuses on the treatment of discolored traumatized teeth, most of them being non-vital and subsequently, endodontically treated. Tooth bleaching based upon hydrogen peroxide as the active agent, applied directly or produced in a chemical reaction from sodium perborate or carbamide pe...

  6. Effect of various bleaching treatments on shear bond strength of different universal adhesives and application modes

    Science.gov (United States)

    2018-01-01

    Objectives The aim of this in vitro study was to evaluate the bond strength of 2 universal adhesives used in different application modes to bleached enamel. Materials and Methods Extracted 160 sound human incisors were used for the study. Teeth were divided into 4 treatment groups: No treatment, 35% hydrogen peroxide, 16% carbamid peroxide, 7.5% carbamid peroxide. After bleaching treatments, groups were divided into subgroups according to the adhesive systems used and application modes (n = 10): 1) Single Bond Universal, etch and rinse mode; 2) Single Bond Universal, self-etch mode; 3) Gluma Universal, etch and rinse mode; 4) Gluma Universal, self-etch mode. After adhesive procedures nanohybrid composite resin cylinders were bonded to the enamel surfaces. All specimens were subjected to shear bond strength (SBS) test after thermocycling. Data were analyzed using a 3-way analysis of variance (ANOVA) and Tukey post hoc test. Results No significant difference were found among bleaching groups (35% hydrogen peroxide, 16% carbamid peroxide, 7.5% carbamid peroxide, and no treatment groups) in the mean SBS values. There was also no difference in SBS values between Single Bond Universal and Gluma Universal at same application modes, whereas self-etch mode showed significantly lower SBS values than etch and rinse mode (p adhesives was enhanced with the etch and rinse mode application to bleached enamel and non-bleached enamel. PMID:29765900

  7. 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

  8. Nitrogen-containing superlow-carbon austenitic steel 02Kh25N22AM2

    Science.gov (United States)

    Fe'ldgandler, É. G.; Svistunova, T. V.; Savkina, L. Ya.; Lapshina, O. B.

    1996-02-01

    At present the equipment for manufacturing carbamide mineral fertilizers is produced from domestic steel 03Kh17N14M3 having "carbamide quality." Imported equipment also used in the industry is produced from steel of the 25-22-2 (Cr -Ni-Mo) type shipped by various firms, namely, 2RE69 (Sandvik, Sweden), 254SFER (Avesta, Sweden), 2522LCN (VDM, Germany), DM 1.4466 (Germany), and X2CrNiMo 25-22-2 (Dalmine, Italy). The imported steels are used because in some units steel 03Khl7Nl4M3 does not provide the requisite corrosion resistance in an intensified process of carbamide manufacturing. We currently possess domestic high-alloyed steel for producing new and repairing imported equipment operating under the severe conditions of carbamide synthesis. The present paper concerns the structure, mechanical properties, and corrosion resistance of industrially produced steel 02Kh25N22AM2 (ChS-108) and the recommended range of its application.

  9. 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.

  10. The effect of two in-office and home bleaching gels on microhardness of composite resin

    Directory of Open Access Journals (Sweden)

    Alizadeh Oskoee P.

    2007-07-01

    Full Text Available Background and Aim: Bleaching products as chemical materials can exert side effects on soft and hard tissues and existing restorative materials with oxidizing mechanism. The aim of this study was to evaluate the effect of 15% and 35% carbamide peroxide gels as home and in-office bleaching agents respectively, on microhardness and surface topography of composite resin.Materials and Methods: In this in vitro study, a total of 75 disc shaped specimens were prepared from Z100  composite resin (3M and randomly divided into three groups with following treatment designs: group 1, 370C distilled water, group 2, 15% carbamide peroxide, 6 hours/day for 3 weeks, group 3, 35% carbamide peroxide 30 minutes/week for 3 weeks. The microhardness (Vickers hardness of samples was measured using Shimadzu set on three different points of each sample. 8 samples of each group were selected randomly to be assessed by scanning electron microscopy (SEM for probable changes in surface topography. Data were analyzed using one way ANOVA and Duncan tests with p<0.05 as the level of significance. Results: 15% carbamide peroxide group had the maximum amount of microhardness (84.59±1.87 and 35% carbamide peroxide group had the minimum (76. 14±1.77. Only the difference between home bleaching and control group was not statistically significant (P=0.24. The SEM assessing revealed no changes in surface topography.Conclusion: Based on the results of this study, in-office bleaching may decrease the microhardness of composite resin.

  11. Investigation of uranyl phosphite interaction with some amides

    International Nuclear Information System (INIS)

    Avduevskaya, K.A.; Ragulina, N.B.; Rozanov, I.A.; Mukhajlov, Yu.N.; Kanishcheva, A.S.; Grevtseva, T.G.

    1981-01-01

    Uranyl (amide) phosphitocomplexes of [UO 2 HPO 3 H 2 OAA]xH 2 O, [UO 2 HPO 3 (AA) 2 ], [UO 2 HPO 3 H 2 O DMC], [UO 2 HPO 3 H 2 ODMFA], [UO 2 HPO 3 DAMA] and UO 2 HPO 3 x2FAxH 2 O compositions, where AA-acetamide; DMC-N, N-dimetyl carbamide, DMFA-dimetyl formamide; DAMA-diamide of malonic acid; FA-formamide, are separated, identified and investigated. Derivatives of mono substituted uranyl phosphite of UO 2 (H 2 PO 3 ) 2 x2FA and [UO 2 (H 2 PO 3 ) 2 H 2 O]x2TMC composition (where TMC-tetramethyl carbamide), are synthesized. Structures of complexes with DAMA, TMC, DMFA and acid dimethyl-ammonium diphosphitouranylate-(CH 3 ] 2 NH 2 x[UO 2 (HPO 3 ) 3 (H 2 PO 3 )] are investigated [ru

  12. Radioactive ion exchanger fixation

    International Nuclear Information System (INIS)

    Pokonova, Yu.P.; Ivshina, O.A.; Il'ina, O.V.

    1993-01-01

    Properties of some binding agents for fixing radioactive cationites and anionites, namels cement, bitumen, carbamide and polyether resins are analyzed. It is shown that localization of ionites in carbamide resin is not very effective, the same is true of cementing process owing to considerable washing out of cesium-137 (∼ 1.1 x 10 -1 cm) and low water resistance (the samples are destructed when, storage conditions vary). Products of ionite localization in polyether feature a lower washing out (3x10 -2 - 4x10 -2 cm) and a better water resistance (water absorption rate is approximattely 1.5 x 10 -4 cm/day)/ Polyethers despite their high cost, are preferable for processing and transportation of small amounts of the ionites (up to 100 m 3 /year)

  13. 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

    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......: 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...... 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...

  14. 3.7. Technical and economic aspects of the application of cement concretes obtained from local minerals

    International Nuclear Information System (INIS)

    Saidov, D.Kh.

    2011-01-01

    This article is devoted to technical and economic aspects of the application of cement concretes obtained from local minerals. The following composite materials obtained from local raw materials were considered: mineral (cement, lime), inorganic (phosphates, sodium silicate), organic (phenol formaldehyde, epoxide, urea-formaldehyde, carbamide, acryl, organosilicon, furfural aniline). It was concluded that from technical and economical points of view the most effective materials were: mineral composite materials, crude shale oils and ligno sulphonates.

  15. A method for producing liquid paraffin

    Energy Technology Data Exchange (ETDEWEB)

    Dorodnova, V.S.; Martynenko, A.G.; Pereverzev, A.N.

    1983-01-01

    In the known method (Sp) for producing liquid paraffins (ZhP) through processing an oil fraction by crystalline carbamide in the presence of a solvent with subsequent removal of the formed complex (Km) of KA with the liquid paraffins from the deparaffinized product, staged washing and decomposition of the complex with isolation of the liquid paraffins, in order to increase the output of liquid paraffin and to improve its quality, beta,beta'-dichlorethyl ether (khloreks) in a mixture with methylethyl ketone (MEK) or methylisobutyl ketone in a ratio of 1 is used as the solvent, the processing by the crystalline carbamide is conducted with the addition of 180 to 260 percent solvent to raw material (Sr) and the washing of the composition is conducted by a solvent in the first stage and by methylethyl ketone or methylisobutyl ketone in the second stage. The crystalline carbamide for the complex formation is taken in a conversion of 60 to 70 percent for the raw material for observing the raw material to solvent ratio of from 1 to 1.8 to 2.6 to 0.6 to 0.6. The temperature in the zone of formation of the complex is maintained at 5 to 35 degrees. The presence of beta,beta'-dichlorethyl ether, which has high selectivity relative to aromatic hydrocarbons (ArU) and to resinous compounds provides for a sharp reduction in the adsorption of the undesired components on the surface of the granules of the complex and the crystalline carbamide and to a reduction in the portion of the alkylaromatic hydrocarbons (UV) extracted into the complex, which leads to a substantial improvement in the quality of the obtained liquid paraffins.

  16. Efficacy of Mouthwashes Containing Hydrogen Peroxide on Tooth Whitening

    OpenAIRE

    Karadas, Muhammet; Hatipoglu, Omer

    2015-01-01

    The aim of this study was to analyze the efficacy of mouthwashes containing hydrogen peroxide compared with 10% carbamide peroxide (CP) gel. Fifty enamel-dentin samples were obtained from bovine incisors and then stained in a tea solution. The stained samples were randomly divided into five groups according to the whitening product applied (n = 10): AS: no whitening (negative control), with the samples stored in artificial saliva; CR: Crest 3D White mouthwash; LS: Listerine Whitening mouthwas...

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

    OpenAIRE

    Pruthi, Gunjan; Jain, Veena; Kandpal, H. C.; Mathur, Vijay Prakash; Shah, Naseem

    2010-01-01

    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; Den...

  18. The potential of dental-protective chewing gum in oral health interventions.

    Science.gov (United States)

    Ly, Kiet A; Milgrom, Peter; Rothen, Marilynn

    2008-05-01

    The authors provide an overview of chewing gum as a delivery vehicle for dental-protective agents, highlighting xylitol and its potential application in caries-prevention programs for children. The authors reviewed selected clinical investigations and previous reviews associated with chewing gum containing substances such as calcium, bicarbonate, carbamide, chlorhexidine, fluoride and xylitol and their effects on reducing caries. They searched the MEDLINE database by using the key words "dental caries," "oral health," "calcium," "bicarbonate," "carbamide," "chlorhexidine," "fluoride" and "xylitol." Chewing gum is being used as a delivery vehicle for substances such as calcium, bicarbonate, carbamide, chlorhexidine, fluoride and xylitol to improve oral health and reduce caries. These substances exhibit properties that are protective of the oral environment and mediate common oral diseases. The debate for advocating xylitol use in caries prevention is advancing; however, chewing gum use by young schoolchildren in the United States is hindered by choking hazard concerns and lack of specific xylitol dosing recommendations. The use of chewing gum containing dental-protective substances, particularly xylitol, in caries-prevention programs can reduce the tooth decay epidemic. Chewing gum use by children in the school setting should be reconsidered.

  19. The effect of bleaching agents on the microhardness of dental aesthetic restorative materials.

    Science.gov (United States)

    Türker, S B; Biskin, T

    2002-07-01

    This study investigated the effects of three home bleaching agents on the microhardness of various dental aesthetic restorative materials. The restorative materials were: feldspatic porcelain, microfilled composite resin and light-cured modified glass-ionomer cement and the bleaching agents Nite-White (16% carbamide peroxide), Opalescence (10% carbamide peroxide and carbapol jel) and Rembrandt (10% carbamide peroxide jel). A total of 90 restorative material samples were prepared 1 cm diameter and 6 mm thick and kept in distilled water for 24 h before commencing bleaching which was carried out for 8 h day-1 for 4 weeks. Microhardness measurements were then made using a Tukon tester. Statistically significant differences with respect to unbleached controls were found only for the feldspatic porcelain and microfilled composite resins (P light cured modified glass-ionomer cement. For the composite resin, whereas Nite-White increased its microhardness, the other bleaching agents decreased it. There were no significant differences between the bleaching agents for any of the restorative materials.

  20. [Effect of casein phosphopeptide-amorphouscalcium phosphate (CPP-ACP) treatment on the shear bond strength of orthodontic brackets after tooth bleaching].

    Science.gov (United States)

    Lu, Jing; Ding, Xiao-jun; Yu, Xiao-ping; Gong, Yi-ming

    2015-10-01

    To evaluate the effect of casein phosphopeptide-amorphouscalcium phosphate (CPP-ACP) treatment on the shear bond strength of orthodontic brackets after tooth bleaching. One hundred extracted human premolars were randomly divided and treated according to 5 groups (n=20) : (1) no treatment; (2) 10% carbamide peroxide bleaching; (3) 38% hydrogen peroxide bleaching; (4)10% carbamide peroxide bleaching and CPP-ACP paste; (5)38% hydrogen peroxide bleaching and CPP-ACP paste. In all groups, the brackets were bonded using a conventional acid-etch and bond system (Transbond XT, 3M Unitek, Monrovia, Calif). The shear bond strength adhesive remnant index (ARI) of the brackets were determined and the data was analyzed by ANOVA and Bonferroni test using SPSS13.0 software package. The use of 10% carbamide peroxide and 38% hydrogen peroxide bleaching significantly decreased the shear bond strength of orthodontic brackets when compared with untreated group (P0.05). The ARI did not show any significant difference before and after CPP-ACP treatment. After tooth bleaching, CPP-ACP treatment have little influence on the shear bond strength of orthodontic brackets.

  1. Influence of tooth bleaching on dental enamel microhardness: a systematic review and meta-analysis.

    Science.gov (United States)

    Zanolla, J; Marques, Abc; da Costa, D C; de Souza, A S; Coutinho, M

    2017-09-01

    Several studies have investigated the effect of bleaching on dental tissues. The evaluation of the effect of home bleaching with 10% carbamide peroxide is important for assessing alterations in enamel microhardness that may affect dental health in terms of resistance to masticatory forces. This meta-analysis was performed in order to determine scientific evidence regarding the effects of home vital bleaching with 10% carbamide peroxide gel on the microhardness of human dental enamel. A systematic electronic literature search was conducted in the PubMed and Web of Science databases using search terms. Two independent researchers evaluated the information and methodological quality of the studies. Inclusion and exclusion criteria were established for article selection; further, only studies published in English were selected. Thirteen studies that met all of the inclusion and exclusion criteria were selected and underwent statistical analysis. The results of this meta-analysis showed no significant changes in enamel microhardness when using the 10% carbamide peroxide bleaching gel over periods of 7, 14 and 21 days. © 2016 Australian Dental Association.

  2. AC electrokinetic drug delivery in dentistry using an interdigitated electrode assembly powered by inductive coupling.

    Science.gov (United States)

    Ivanoff, Chris S; Wu, Jie Jayne; Mirzajani, Hadi; Cheng, Cheng; Yuan, Quan; Kevorkyan, Stepan; Gaydarova, Radostina; Tomlekova, Desislava

    2016-10-01

    AC electrokinetics (ACEK) has been shown to deliver certain drugs into human teeth more effectively than diffusion. However, using electrical wires to power intraoral ACEK devices poses risks to patients. The study demonstrates a novel interdigitated electrode arrays (IDE) assembly powered by inductive coupling to induce ACEK effects at appropriate frequencies to motivate drugs wirelessly. A signal generator produces the modulating signal, which multiplies with the carrier signal to produce the amplitude modulated (AM) signal. The AM signal goes through the inductive link to appear on the secondary coil, then rectified and filtered to dispose of its carrier signal, and the positive half of the modulating signal appears on the load. After characterizing the device, the device is validated under light microscopy by motivating carboxylate-modified microspheres, tetracycline, acetaminophen, benzocaine, lidocaine and carbamide peroxide particles with induced ACEK effects. The assembly is finally tested in a common dental bleaching application. After applying 35 % carbamide peroxide to human teeth topically or with the IDE at 1200 Hz, 5 Vpp for 20 min, spectrophotometric analysis showed that compared to diffusion, the IDE enhanced whitening in specular optic and specular optic excluded modes by 215 % and 194 % respectively. Carbamide peroxide absorbance by the ACEK group was two times greater than diffusion as measured by colorimetric oxidation-reduction and UV-Vis spectroscopy at 550 nm. The device motivates drugs of variable molecular weight and structure wirelessly. Wireless transport of drugs to intraoral targets under ACEK effects may potentially improve the efficacy and safety of drug delivery in dentistry.

  3. Characterization of the porous structures of the green body and sintered biomedical titanium scaffolds with micro-computed tomography

    Energy Technology Data Exchange (ETDEWEB)

    Arifvianto, B., E-mail: b.arifvianto@tudelft.nl; Leeflang, M.A.; Zhou, J.

    2016-11-15

    The present research was aimed at gaining an understanding of the porous structure changes from the green body through water leaching and sintering to titanium scaffolds. Micro-computed tomography (micro-CT) was performed to generate 3D models of titanium scaffold preforms containing carbamide space-holding particles and sintered scaffolds containing macro- and micro-pores. The porosity values and structural parameters were determined by means of image analysis. The result showed that the porosity values, macro-pore sizes, connectivity densities and specific surface areas of the titanium scaffolds sintered at 1200 °C for 3 h did not significantly deviate from those of the green structures with various volume fractions of the space holder. Titanium scaffolds with a maximum specific surface area could be produced with an addition of 60–65 vol% carbamide particles to the matrix powder. The connectivity of pores inside the scaffold increased with rising volume fraction of the space holder. The shrinkage of the scaffolds prepared with > 50 vol% carbamide space holder, occurring during sintering, was caused by the reductions of macro-pore sizes and micro-pore sizes as well as the thickness of struts. In conclusion, the final porous structural characteristics of titanium scaffolds could be estimated from those of the green body. - Highlights: •Porous structures of green body and sintered titanium scaffolds was studied. •Porous structures of both samples were quantitatively characterized with micro-CT. •Porous structures of scaffolds could be controlled from the green body. •Shrinkage mechanisms of titanium scaffolds during sintering was established.

  4. Influence of Bleaching Agents on Color and Translucency of Aged Resin Composites.

    Science.gov (United States)

    Lago, Maristela; Mozzaquatro, Lisandra R; Rodrigues, Camila; Kaizer, Marina R; Mallmann, André; Jacques, Letícia B

    2017-09-01

    Evaluate the influence of two bleaching agents (16% carbamide peroxide-CP and 35% hydrogen peroxide-HP) on color and translucency of one resin composite (Filtek Z350 XT) in two opacities (enamel and dentin) previously aged in deionized water or red wine. Sixty specimens of each material were divided in two groups (n = 30): aged in water or red wine for 14 days. Then the specimens were divided in three subgroups (n = 10): control/no treatment, treated with 16% carbamide peroxide (Mix Night), treated with 35% hydrogen peroxide (Mix One). Color readings were performed 24 hours after polishing (baseline); after the 14 days of aging; and after bleaching treatment. Color coordinates CIE L*a*b* were measured using a spectrophotometer (SP60 X-Rite). Color change (CIEDE2000) and translucency parameter were calculated. Data were analyzed with repeated measures two-way ANOVA, and Student-Newman-Keuls tests (5%). Bleaching decreased color change in stained resin composites (aged in red wine), whereas increased it in non-stained enamel resin composites (aged in water). CP had better bleaching results with stained resin composites than HP. Translucency of non-stained dentin resin composite decreased with aging, but did not change with bleaching. For stained resin composites, aging caused reduced translucency, whereas bleaching increased it. Effective bleaching of discolored resin composites aged in an acidic and alcoholic media rich in staining agents was achieved, improving color and translucency. Carbamide peroxide showed better performance than hydrogen peroxide for the bleaching of stained resin composites. (J Esthet Restor Dent 29:368-377, 2017). © 2016 Wiley Periodicals, Inc.

  5. Effect of two in-office whitening agents on the enamel surface in vivo: a morphological and non-contact profilometric study.

    Science.gov (United States)

    Cadenaro, Milena; Breschi, Lorenzo; Nucci, Cesare; Antoniolli, Francesca; Visintini, Erika; Prati, Carlo; Matis, Bruce A; Di Lenarda, Roberto

    2008-01-01

    This study evaluated the morphological effects produced in vivo by two in-office bleaching agents on enamel surface roughness using a noncontact profilometric analysis of epoxy replicas. The null hypothesis tested was that there would be no difference in the micromorphology of the enamel surface during or after bleaching with two different bleaching agents. Eighteen subjects were selected and randomly assigned to two treatment groups (n=9). The tooth whitening materials tested were 38% hydrogen peroxide (HP) (Opalescence Xtra Boost) and 35% carbamide peroxide (CP) (Rembrandt Quik Start). The bleaching agents were applied in accordance with manufacturer protocols. The treatments were repeated four times at one-week intervals. High precision impressions of the upper right incisor were taken at baseline as the control (CTRL) and after each bleaching treatment (T0: first application, T1: second application at one week, T2: third application at two weeks and T3: fourth application at three weeks). Epoxy resin replicas were poured from impressions, and the surface roughness was analyzed by means of a non-contact profilometer (Talysurf CLI 1000). Epoxy replicas were then observed using SEM. All data were statistically analyzed using ANOVA and differences were determined with a t-test. No significant differences in surface roughness were found on enamel replicas using either 38% hydrogen peroxide or 35% carbamide peroxide in vivo. This in vivo study supports the null hypothesis that two in-office bleaching agents, with either a high concentration of hydrogen or carbamide peroxide, do not alter enamel surface roughness, even after multiple applications.

  6. Therapeutic effectiveness of a new enzymatic bleaching dentifrice.

    Science.gov (United States)

    Forner, Leopaldo; Amengual, José; Liena, Carmen; Riutord, Pere

    2012-01-01

    Research into bleaching focuses on new products in order to minimize undesirable effects. This study evaluated the bleaching effectiveness of a new enzymatic-activated dentifrice. A total of 20 volunteers were bleached with a dentifrice containing 5% lactoperoxidase and 3% carbamide peroxide applied three times a day for two minutes over 21 days. Color was recorded before and after the treatment using a spectrophotometer. CIELAB differences were calculated before and after treatment using the paired t test (P whitening teeth. Enzymatic dental bleaching is able to increase the efficiency of low concentration peroxides, reducing the potential risk of peroxides on oral tissues.

  7. Comparison of Radicular Peroxide Leakage from four Commonly used Bleaching agents following Intracoronal Bleaching in Endodontically treated teeth - An In Vitro Study.

    Science.gov (United States)

    Madhu, Ks; Hegde, Swaroop; Mathew, Sylvia; Lata, DA; Bhandi, Shilpa H; N, Shruthi

    2013-08-01

    Non vital bleaching is simple, conservative procedure for esthetic correction of discolored endodontically treated teeth. The aim of this study was to determine and compare the amount of peroxide leakage from four different bleaching agents i.e superoxol, sodium perborate, combination of superoxol & sodium perborate and carbamide peroxide during intracoronal bleaching, as the safe and effective bleaching is the need of the hour. 50 extracted maxillary centrals were selected for the study. Following standardized protocol access, cleaning and shaping by step back technique and obturation was done using guttapercha and AH plus sealer. Access was sealed with Cavit G and outer root surface was coated with wax and nail varnish. The teeth were separated into crown and root and the root portion was placed in plastic tube containing distilled water for 7days.After incubation, 3mm of gutta-percha was removed below CEJ and 2mm glass ionomer cement base was placed. Grouped into five categories based on the bleaching agent placed in pulp chamber as -group1 (control)-distilled water, group 2-sodium perborate with distilled water , group 3- 30% hydrogen peroxide ,group 4-mixture of sodium perborate and 30% hydrogen peroxide and group 5-10% carbamide peroxide gel. Peroxide leakage was measured after 24hrs using ferrothiocyanate method and optical density using spectrophotometer. Statistical analysis of the data was conducted using ANOVA and multiple comparisons within the groups was done using BONFERRONI method (Post-Hoc tests). The results showed highest peroxide penetration from 30% hydrogen peroxide followed by mixture of sodium perborate with 30% hydrogen peroxide, mixture of sodium perborate with distilled water and least penetration from 10% carbamide peroxide gel. The results were statistically significant. Radicular peroxide leakage in 10% carbamide peroxide was significantly lower than the other tested bleaching agents making it a very safe alternative for intracoronal

  8. Study of sintering on Mg-Zn-Ca alloy system

    Science.gov (United States)

    Annur, Dhyah; Lestari, Franciska P.; Erryani, Aprilia; Kartika, Ika

    2018-05-01

    Magnesium and its alloy have gained a lot of interest to be used in biomedical application due to its biodegradable and biocompatible properties. In this study, sintering process in powder metallurgy was chosen to fabricatenonporous Mg-6Zn-1Ca (in wt%) alloy and porous Mg-6Zn-1Ca-10 Carbamide alloy. For creating porous alloy, carbamide (CO(NH2)2 was added to alloy system as the space holder to create porous structure material. Effect of the space holder addition and sintering temperature on porosity, phase formation, mechanical properties, and corrosion properties was observed. Sintering process was done in a tube furnace under Argon atmosphere in for 5 hours. The heat treatment was done in two steps; heated up at 250 °C for 4 hours to decompose spacer particle, followed by heated up at 580 °C or 630 °C for 5 hours. The porous structure of the resulted alloys was examined using Scanning Electron Microscope (SEM), while the phase formation was characterized by X-ray diffraction (XRD) analysis. Mechanical properties were examined using compression testing. From this study, increasing sintering temperature up to 630 °C reduced the mechanical properties of Mg-Zn-Ca alloy.

  9. Clinical and Spectrophotometric Evaluation of LED and Laser Activated Teeth Bleaching.

    Science.gov (United States)

    Lo Giudice, R; Pantaleo, G; Lizio, A; Romeo, U; Castiello, G; Spagnuolo, G; Giudice, G Lo

    2016-01-01

    Auxiliary power sources (LED and laser) are used in in-office teeth bleaching techniques to accelerate the redox reaction of the whitening gel to increase ease of use, to improve comfort and safety, and to decrease the procedure time. The aim this study is to evaluate the efficiency of the teeth whitening procedures performed with hydrogen peroxide and carbamide peroxide, LED or Laser activated. 18 patients, affected by exogenous dyschromia, were treated with a bleaching agent composed by 35% hydrogen peroxide and 10% carbamide peroxide. They were divided into two groups: in the first group the bleaching agent was activated by a LED lamp; in the second group it was activated by a Laser diode lamp. Both groups were subjected to 3 bleaching cycle of 15' each. The chromatic evaluations were performed before and after one week from the treatment, using a chromatic scale and a spectrophotometer. The mean value of pre, post bleaching and follow-up were analyzed using a T-test, with results statistically significant for Pbleaching effectiveness. All patients treated with laser activation complained an increase in dental sensitivity. The use of laser-activating systems did not improve the efficacy of bleaching.

  10. 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

  11. Does the Use of a "Walking Bleaching" Technique Increase Bone Resorption Markers?

    Science.gov (United States)

    Bersezio, C; Vildósola, P; Sáez, M; Sánchez, F; Vernal, R; Oliveira, O B; Jorquera, G; Basualdo, J; Loguercio, A; Fernández, E

    This randomized clinical trial evaluated the effect of 35% hydrogen peroxide in comparison with 37% carbamide peroxide in a nonvital bleaching technique of "walking bleaching" (four sessions of treatment) on periodontal markers: nuclear factor kappa B-ligand (RANK-L-process of root resorption marker) and interleukin 1β (IL-1β-inflammatory response marker). Fifty volunteers presenting with discoloration of nonvital teeth and endodontic treatment in good condition participated. Fifty teeth were randomly divided into two study groups according to bleaching gel: HP = 35% hydrogen peroxide (n=25) and 37% carbamide peroxide (n=25). Nonvital bleaching was performed with a walking bleaching technique consisting of four sessions of bleach application. Gingival crevicular fluid samples were taken in order to quantify the RANK-L and IL-1β levels by enzyme-linked immunosorbent assay. Samples were obtained from six periodontal sites for each bleached tooth: three vestibular and three palatine (mesial, middle, and distal) at seven time periods: baseline, after each of the four sessions of nonvital bleaching, at one week, and at one month after nonvital bleaching. Tooth color variations were analyzed in each session by VITA Bleachedguide 3D-MASTER (ΔSGU). Significant increments in the RANK-L and IL-1β levels were detected in each evaluated time compared with baseline ( pbleaching therapies ( pbleaching induced a significant increment in the RANK-L and IL-1β levels in periodontal tissues around bleached, nonvital teeth.

  12. Effects of hydrogen peroxide bleaching strip gels on dental restorative materials in vitro: surface microhardness and surface morphology.

    Science.gov (United States)

    Duschner, Heinz; Götz, Hermann; White, Donald J; Kozak, Kathleen M; Zoladz, James R

    2004-01-01

    This study examined the effects of peroxide tooth bleaching, including Crest Whitestrips hydrogen peroxide gel treatments, on the surface hardness and morphology of common dental restorative treatments. American Dental Association (ADA) recommended dental restorative materials, including amalgam, dental gold, porcelain, glass ionomer, and composites, were prepared according to manufacturers' instructions. A cycling treatment methodology was employed which alternated ex vivo human salivary exposures with bleaching treatments under conditions of controlled temperature and durations of treatment. Bleaching treatments included commercial Crest Whitestrips bleaching gels, which utilize hydrogen peroxide as the in situ bleaching source, and several commercial carbamide peroxide bleaching gels. Control treatments included placebo gels and an untreated group. Crest Whitestrips bleaching included treatment exposures simulating recommended clinical exposures (14 hours), along with excess bleaching simulating exposure to five times suggested Crest Whitestrips use. At the conclusion of treatments, surface microhardness measures and surface morphological assessments with standard and variable pressure (VP-) SEMs were conducted to assess the effects of bleaching exposure on the surface morphology and structural integrity of the restoratives. Surface microhardness and SEM measures revealed no significant deleterious effects on the restoration surfaces from Whitestrips gels. These results confirm that tooth bleaching from the selected commercial hydrogen peroxide or carbamide peroxide bleaching systems does not produce changes in surface morphology or microhardness of common dental restorative materials. These results support the clinical safety of the selected commercial bleaching systems to the oral environment, matching results obtained from long-term use of these ingredients applied in dental offices and available in commercial formulations.

  13. Separate whitening effects on enamel and dentin after fourteen days.

    Science.gov (United States)

    Kugel, Gerard; Petkevis, Jason; Gurgan, Sevil; Doherty, Eileen

    2007-01-01

    The purpose of this study was to investigate the mechanism of action of a bleaching agent, as it relates to enamel and dentin. Twenty-six extracted human molar teeth were sectioned at the cemento-enamel junction and were randomly assigned to two groups. L*a*b* readings were taken with a spectrophotometer: on buccal surfaces of the crown, at enamel and dentin. The teeth were exposed to carbamide peroxide or placebo gel and L*a*b* scores were again recorded to determine color changes. Treatments were compared using ancova test with baseline color as the covariate. Relative to placebo, buccal surfaces exhibited the greatest Deltab* and DeltaL* color change. On buccal surfaces, the adjusted mean (SE) treatment differences were -7.8 (1.00) for Deltab* and 5.7 (0.97) for DeltaL, with groups differing significantly (p enamel surfaces, treatment differences were -3.6 (0.61) for Deltab* and 4.6 (0.80) for DeltaL* (p tooth crowns exposed to carbamide peroxide 15% was because of the color change in enamel. As compared to enamel, dentin was less affected after 14 days.

  14. 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.

  15. Shear bond strength of self-etching adhesive systems with different pH values to bleached and/or CPP-ACP-treated enamel.

    Science.gov (United States)

    Oskoee, Siavash Savadi; Bahari, Mahmoud; Kimyai, Soodabeh; Navimipour, Elmira Jafari; Firouzmandi, Maryam

    2012-08-01

    To compare shear bond strengths of three different self-etching adhesive systems of different pH values to enamel bleached with carbamide peroxide, treated with casein phosphopeptide-amorphous calcium phosphate (CPP-ACP), or treated with CPP-ACP subsequent to bleaching with carbamide peroxide. Thirty-six human third molars were cut into 4 sections and randomly assigned to 4 groups (n = 36): group I: no treatment; group II: bleaching; group III: CPP-ACP; group IV: bleaching and CPP-ACP. After surface treatments, the samples of each group were further divided into three subgroups (n = 12) based on the adhesive used. The adhesives Clearfil SE Bond (CSE), AdhesE (ADE), and Adper SE Plus (ADP) were applied, and resin composite cylinders with a diameter of 2 mm and a height of 4 mm were bonded to the enamel. Then the specimens were subjected to shear bond strength testing. Two-way ANOVA and a post-hoc Tukey's test were used for statistical analysis (α = 0.05). There were significant differences between the adhesive systems (p system showed the highest bond strength, and the bleaching procedure reduced bond strengths (p = 0.001). Furthermore, there were no significant differences in shear bond strength values between the control and CPP groups. However, the differences between other groups were statistically significant (p material dependent.

  16. Smile restoration through use of enamel microabrasion associated with tooth bleaching.

    Science.gov (United States)

    Sundfeld, Renato Herman; Rahal, Vanessa; de Alexandre, Rodrigo Sversut; Briso, André Luiz Fraga; Sundfeld Neto, Daniel

    2011-01-01

    Enamel microabrasion can eliminate enamel irregularities and discoloration defects, improving the appearance of teeth. This article presents the latest treatment protocol of enamel microabrasion to remove stains on the enamel surface. It has been verified that teeth submitted to microabrasion acquire a yellowish color because of the thinness of the remaining enamel, revealing the color of dentinal tissue to a greater degree. In these clinical conditions, correction of the color pattern of these teeth can be obtained with a considerable margin of clinical success using products containing carbamide peroxide in custom trays. Thus, patients can benefit from combined enamel microabrasion/tooth bleaching therapy, which yields attractive cosmetic results. Esthetics plays an important role in contemporary dentistry, especially because the media emphasizes beauty and health. Currently, in many countries, a smile is considered beautiful if it imitates a natural appearance, with clear, well-aligned teeth and defined anatomical shapes. Enamel microabrasion is one technique that can be used to correct discolored enamel. This technique has been elucidated and strongly advocated by Croll and Cavanaugh since 1986, and by other investigators who suggested mechanical removal of enamel stains using acidic substances in conjunction with abrasive agents. Enamel microabrasion is indicated to remove intrinsic stains of any color and of hard texture, and is contraindicated for extrinsic stains, dentinal stains, for patients with deficient labial seals, and in cases where there is no possibility to place a rubber dam adequately during the microabrasion procedure. It should be emphasized that enamel microabrasion causes a microreduction on the enamel surface, and, in some cases, teeth submitted to microabrasion may appear a darker or yellowish color because the thin remaining enamel surface can reveal some of the dentinal tissue color. In these situations, according to Haywood and Heymann

  17. BLEACHING IN VITAL TEETH: A LITERARY REVIEW

    Directory of Open Access Journals (Sweden)

    Felipe Fagundes Soares

    2007-12-01

    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.

  18. Cleaning of paraffins and their microbiological transformation

    Energy Technology Data Exchange (ETDEWEB)

    Shakarashvili, T S; Bekauri, N G; Chubinidze, N G; Dididze, A V

    1982-01-01

    This paper provides a perfected technique for processing liquid C/sub 11/-C/sub 20/ alkanes extracted from Georgian oil (from the Samgori field). Utilizing this base, a biomass was derived with the aid of the Candida Guillermondy culture. The method for cleaning the paraffin complex with carbamide was simplified during the deparaffinization process of diesel fuel (fraction 200-300/sup 0/C) by application of a washing agent -petr. ether with a boiling temp. of 40-70/sup 0/C. The derived alkanes contained up to 0.2% of aromatic hydrocarbons. This eliminated the rather expensive and labor-intensive step in the dewaxing process -- adsorption chromatography. It was demonstrated that under optimal conditions the amount of cultured product was higher in n-alkanes from Samgori oil than from the petroleum utilized at the Akhmet biochemical plant.

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

    International Nuclear Information System (INIS)

    Li Sa; Ouyang Yinggen; Gao Yaobin

    2012-01-01

    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)

  20. Rapid analysis of fertilizers by the direct-reading thermometric method.

    Science.gov (United States)

    Sajó, I; Sipos, B

    1972-05-01

    The authors have developed rapid methods for the determination of the main components of fertilizers, namely phosphate, potassium and nitrogen fixed in various forms. In the absence of magnesium ions phosphate is precipitated with magnesia mixture; in the presence of magnesium ions ammonium phosphomolybdate is precipitated and the excess of molybdate is reacted with hydrogen peroxide. Potassium is determined by precipitation with silico-fluoride. For nitrogen fixed as ammonium salts the ammonium ions are condensed in a basic solution with formalin to hexamethylenetetramine; for nitrogen fixed as carbamide the latter is decomposed with sodium nitrite; for nitrogen fixed as nitrate the latter is reduced with titanium(III). In each case the temperature change of the test solution is measured. Practically all essential components of fertilizers may be determined by direct-reading thermometry; with this method and special apparatus the time of analysis is reduced to at most about 15 min for any determination.

  1. Masking of Enamel Fluorosis Discolorations and Tooth Misalignment With a Combination of At-Home Whitening, Resin Infiltration, and Direct Composite Restorations.

    Science.gov (United States)

    Perdigão, J; Lam, V Q; Burseth, B G; Real, C

    This clinical report illustrates a conservative technique to mask enamel discolorations in maxillary anterior teeth caused by hypomineralization associated with enamel fluorosis and subsequent direct resin composite to improve the anterior esthetics. The treatment consisted of at-home whitening with 10% carbamide peroxide gel with potassium nitrate and sodium fluoride in a custom-fitted tray to mask the brown-stained areas, followed by resin infiltration to mask the white spot areas. An existing resin composite restoration in the maxillary right central incisor was subsequently replaced after completion of the whitening and resin infiltration procedures, whereas the two misaligned and rotated maxillary lateral incisors were built up with direct resin composite restorations to provide the illusion of adequate arch alignment, as the patient was unable to use orthodontic therapy.

  2. Micro-structural integrity of dental enamel subjected to two tooth whitening regimes.

    Science.gov (United States)

    Tanaka, Reina; Shibata, Yo; Manabe, Atsufumi; Miyazaki, Takashi

    2010-04-01

    Colour modification of tooth enamel has proven successful, but it is unclear how various bleaching applications affect micro-structural integrity of the whitened enamel. To investigate the internal structural integrity of human intact tooth enamel with the application of two commonly used whitening regimes (in-office power bleaching with 35% hydrogen peroxide and home bleaching with 10% carbamide peroxide), evaluations were performed on teeth of identical colour classification. After the bleaching applications, the enamel mineral density was quantified and visualised with micro-computed tomography. The micro-structural differences between the whitened tooth enamel samples were distinctive, though the colour parameter changes within the samples were equivalent. Home bleaching achieved colour modification by demineralisation, whereas in-office bleaching depended on redistribution of the minerals after treatment and subsequent enhanced mineralisation.

  3. City sewer collectors biocorrosion

    Science.gov (United States)

    Ksiażek, Mariusz

    2014-12-01

    This paper presents the biocorrosion of city sewer collectors impregnated with special polymer sulphur binders, polymerized sulphur, which is applied as the industrial waste material. The city sewer collectors are settled with a colony of soil bacteria which have corrosive effects on its structure. Chemoautotrophic nitrifying bacteria utilize the residues of halites (carbamide) which migrate in the city sewer collectors, due to the damaged dampproofing of the roadway and produce nitrogen salts. Chemoorganotrophic bacteria utilize the traces of organic substrates and produce a number of organic acids (formic, acetic, propionic, citric, oxalic and other). The activity of microorganisms so enables the origination of primary and secondary salts which affect physical properties of concretes in city sewer collectors unfavourably.

  4. Application of quantitative light-induced fluorescence to determine the depth of demineralization of dental fluorosis in enamel microabrasion: a case report

    Directory of Open Access Journals (Sweden)

    Tae-Young Park

    2016-08-01

    Full Text Available Enamel microabrasion has become accepted as a conservative, nonrestorative method of removing intrinsic and superficial dysmineralization defects from dental fluorosis, restoring esthetics with minimal loss of enamel. However, it can be difficult to determine if restoration is necessary in dental fluorosis, because the lesion depth is often not easily recognized. This case report presents a method for analysis of enamel hypoplasia that uses quantitative light-induced fluorescence (QLF followed by a combination of enamel microabrasion with carbamide peroxide home bleaching. We describe the utility of QLF when selecting a conservative treatment plan and confirming treatment efficacy. In this case, the treatment plan was based on QLF analysis, and the selected combination treatment of microabrasion and bleaching had good results.

  5. 2-Ureido-1,3-thiazol-3-ium dihydrogen phosphate

    Directory of Open Access Journals (Sweden)

    Kateryna Gubina

    2011-07-01

    Full Text Available The title compound, C4H6N3OS+·H2PO4−, (I, was obtained as a result of hydrolysis of [(1,3-thiazol-2-ylaminocarbonyl]phosphoramidic acid, (II, in water. X-ray analysis has shown that the N—P bond in (II breaks, leading to the formation of the substituted carbamide (I. This compound exists as an internal salt. The unit cell consists of a urea cation and an anion of H2PO4−. Protonation of the N atom of the heterocyclic ring was confirmed by the location of the H atom in a difference Fourier map. The molecules of substituted urea are connected by O...O hydrogen bonds into unlimited planes. In turn, those planes are connected to each other via N—H...O hydrogen bonds with molecules of phosphoric acid, forming a three-dimensional polymer.

  6. Optimizing the Esthetics of peg-shaped teeth

    Directory of Open Access Journals (Sweden)

    Fabia Danielle Sales da Cunha Medeiros e Silva

    2008-01-01

    Full Text Available In modern esthetic dentistry, recontouring peg-shaped teeth present the option of a technique for obtaining a harmonious smile. In thiscontext, the advancement of direct dental materials, such as resin composites and adhesive systems, allows this procedure to be performedsimply and efficiently, when compared with other available techniques. Thus, the aim of this report is to present a clinical case with an esthetic solution in peg-shaped lateral incisors (12 and 22. Initially, it was opted first to perform dental bleaching with a home bleaching gel (16% carbamide peroxide associated with an acetate mold duly made for this purpose. The peg-shaped teeth were recontoured with a microhybrid resin composite (shade EA1 and DA1 with the aid of a platinum guide in silicone, obtained after diagnostic waxing on the plaster model. It was concluded that the association of esthetic procedures is of the utmost importance for obtaining good looking, aligned and harmonious teeth.

  7. Conditions for saccharification and fermentation of manioc mash

    Energy Technology Data Exchange (ETDEWEB)

    Nguen, D.C.; Velikaya, E.I.

    1972-01-01

    Saccharification time of manioc starch, proportion of enzyme preparations added (obtained from Aspergillus oryzae and Aspergillus awamori) and the effect of a nitrogenous medium on fermentation were studied. Extension of saccharification time led to inactivation of the enzymes which adversely affected fermentation. In 5 minutes saccharification with Aspergillus oryzae of material pureed by boiling, the alcohol yield was 38.71/ton of starch higher than when a 60-minute saccharification period was used. Saccharification with a combination of the 2 moulds produced a higher alcohol yield than when only Aspergillus oryzae was used. A high glucoamylase content in the mash gave a high alcohol yield. Nitrogenous substances must be added to the manioc mash to provide for the nutrition of the yeast cells; carbamide proved most efficient.

  8. Effect of in-office bleaching agents on physical properties of dental composite resins.

    Science.gov (United States)

    Mourouzis, Petros; Koulaouzidou, Elisabeth A; Helvatjoglu-Antoniades, Maria

    2013-04-01

    The physical properties of dental restorative materials have a crucial effect on the longevity of restorations and moreover on the esthetic demands of patients, but they may be compromised by bleaching treatments. The purpose of this study was to evaluate the effects of in-office bleaching agents on the physical properties of three composite resin restorative materials. The bleaching agents used were hydrogen peroxide and carbamide peroxide at high concentrations. Specimens of each material were prepared, cured, and polished. Measurements of color difference, microhardness, and surface roughness were recorded before and after bleaching and data were examined statistically by analysis of variance (ANOVA) and Tukey HSD post-hoc test at P composite resin altered after the bleaching procedure (P composite resins tested (P > .05). The silorane-based composite resin tested showed some color alteration after bleaching procedures. The bleaching procedure did not alter the microhardness and the surface roughness of all composite resins tested.

  9. Petroleum product deparaffination process

    Energy Technology Data Exchange (ETDEWEB)

    Martynenko, A.G.; Dorodnova, V.S.; Korzhov, Yu.A.

    1980-12-23

    In the process for deparaffination of petroleum products (NP) by treatment of them with carbamide (KA) in the presence of an activator (AK) and solvent with subsequent separation of the forming paraffin-carbamide complex (PKC) the NP is mixed with the AK at a temperature of 5-40/sup 0/ in an NP:AK ratio of 1:0.01-0.03 with subsequent addition of portions of KA at a temperature of 5-20/sup 0/. The advantages of the process in comparison with the known one consists in the fact that the process of complex formation is realized practically without an induction period, and paraffin yield is increased by 27% on the potential with a simultaneous decrease in reagent consumption: KA by 20% and MeOH by 35%. Example -- 100 g of diesel fuel (a 200-360/sup 0/ fraction) is mixed with MeOH (1.3% on the feedstock), which in the obtained mixture is found in a liquid droplet state. To the mixture 40 g KA is added (2/3 of the total amount of KA to be added). The complex formation temperature is held at 35/sup 0/. To the PKC practically forming at once 260 g of solvent (an 85-120/sup 0/ gasoline fraction) and then 20 g KA are added. The temperature is held at 20/sup 0/. The forming suspension of the complex is distinguished by uniformity and the absence of coarse conglomerates. The paraffin yield amounts to 11.8% on the feedstock or 74% on the potential. The melting point of the paraffin is 22/sup 0/. In the described deparaffination scheme according to the proposed process complex formation is carried out in two steps; in a third step the suspension of KA and centrifuged paraffin is separated; the KA is returned to the complex formation reactor, and the centrifuged paraffin --- for solvent regeneration.

  10. The effect of n-alkane selection depth on the quality of denormalizate

    Energy Technology Data Exchange (ETDEWEB)

    Dorodnova, V.S.; Bayburskaya, E.L.; Martynenko, A.G.

    1982-01-01

    The effect of n-alkane selection depth from crude diesel fuel on the quality of denormalization on a carbamide deparaffination G-64 device at the Gorknefteorgsintez Production Association. Diesel fuel with o.c. 210/sup 0/, c.c. 315/sup 0/, 828 kg/m/sup 3/ density, -25, n/sup 20/ D 1.4620, aniline point 66.9/sup 0/ and n-alkane content 14.7% was used. The regime of the stage of complex formation was maximal approximation of industrial conditions: ratio Cr: ben. 1:2.6 mass. no, complex formation 25/sup 0/, length of contact 30 min, levels of washing, 2; methanol, 2.0% in Cr. Changing the quantity of carbamide aided the various extraction depths of n-alkanes from the Cr. Following distillation of the solution the following parameters were examined: refraction, density, aniline point, diesel index; Obtained: the dependencies for changes in these indicators depending on the depth of the selection of n-alkanes from the potential or from their content in the denormalizate; as well as the dependence of the component composition of paraffins on the degree of their extraction from the Cr. To simultaneously obtain paraffins and diesel fuel of export quality with a diesel index no lower than 55, it is necessary to guarantee up to 50% (no higher) of paraffin selection from the potential Cr containing 14.7% n-alkanes; the sediment content of n-alkanes in the denormalizate must be found at the 7.4% level.

  11. Evaluation of the Efficacy and Color Stability of Two Different At-Home Bleaching Systems on Teeth of Different Shades: A Randomized Controlled Clinical Trial.

    Science.gov (United States)

    Aka, Betül; Celik, Esra Uzer

    2017-09-01

    This randomized controlled clinical trial compared the bleaching efficacy of two different at-home bleaching systems on teeth of different shades and their color stability after a 6-month follow-up. Ninety-two patients (777 teeth) were randomly divided into three groups: (a) negative control, (b) patients treated with a custom-made tray containing 10% carbamide peroxide (10% CP/PF) (Opalescence PF), and (c) patients treated with a pre-loaded tray containing 6% hydrogen peroxide (6% HP/Go) (Opalescence Go). Teeth in all groups were divided into three sub-groups according to the VITA Classic Shade Guide: light (A1-C1), medium dark (C2-B3), and dark (A3.5-C4). Bleaching systems were performed in accordance with manufacturers' instructions for 14 days. The color values were measured at the baseline, 10 days and 14 days of bleaching, 2 weeks, and 6 months after bleaching. Three-way ANOVA and Mann-Whitney U tests were used for statistical analysis (α = 0.05). Irrespective of original shade, both bleaching groups showed significantly higher ΔE* values than the control groups, and the ΔE* values were significantly higher in the 10% CP/PF groups than those in the 6% HP/Go groups (p bleaching systems, the dark teeth showed higher ΔE* values than the light teeth (p bleaching agents produced a bleaching effect, but 10% CP/PF was more effective. A pre-loaded tray system may be used for dental bleaching, but it is still less effective than conventional a 10% carbamide peroxide system, irrespective of the initial shade. (J Esthet Restor Dent 29:325-338, 2017). © 2017 Wiley Periodicals, Inc.

  12. Tooth sensitivity with a desensitizing-containing at-home bleaching gel-a randomized triple-blind clinical trial.

    Science.gov (United States)

    Maran, Bianca Medeiros; Vochikovski, Laína; de Andrade Hortkoff, Diego Rafael; Stanislawczuk, Rodrigo; Loguercio, Alessandro D; Reis, Alessandra

    2018-05-01

    Desensitizing agents are usually included in the composition of bleaching agents to reduce bleaching-induced tooth sensitivity (TS). This randomized clinical trial (RCT) evaluated the risk and intensity of TS and color change after at-home bleaching with a desensitizing-containing (3% potassium nitrate and 0.2% sodium fluoride) and desensitizing-free 10% carbamide peroxide (CP) gel (Whiteness Perfect, FGM). A triple-blind, within-person RCT was conducted on 60 caries-free adult patients. Each participant used the gel in a bleaching tray for 3 h daily for 21 days in both the upper and lower dental arches. The absolute risk and intensity of TS were assessed daily through the 0-10 VAS and NRS scale for 21 days. Color change was recorded using shade guides (Vita Classical and Vita Bleachedguide) and the Easyshade spectrophotometer at baseline, weekly and 30 days after the end of the bleaching. The risk and intensity of TS were evaluated by the McNemar and Wilcoxon Signed Rank tests, respectively. Color change (ΔSGU and ΔE) were evaluated by the Mann-Whitney test and a paired t-test, respectively (α = 0.05). No difference in the TS and color change was observed (p > 0.05). The incorporation of potassium nitrate and sodium fluoride in 10% carbamide peroxide at-home bleaching gel tested in this study did not reduce the TS and did not affect color change (RBR-4M6YR2). Copyright © 2018 Elsevier Ltd. All rights reserved.

  13. Effect of various tooth-whitening products on enamel microhardness.

    Science.gov (United States)

    Grobler, S R; Majeed, A; Moola, M H

    2009-11-01

    The purpose of this in vitro study was to evaluate the effect of various tooth-whitening products containing carbamide peroxide (CP) or hydrogen peroxide (HP), on enamel microhardness. Enamel blocks were exposed to: Nite White ACP 10% CP (Group 2, n=10); Yotuel Patient 10% CP (Group 3, n=10); Opalescence PF 10% CP (Group 4, n=10); Opalescence PF 20% CP (Group 5, n=10); Opalescence Treswhite Supreme 10% HP (Group 6, n=10); Yotuel 10 Minutes 30% CP (Group 7, n=10); Opalescence Quick 45% CP (Group 8, n=10), Yotuel Special 35% HP (Group 9, n=10), Opalescence Boost 38% HP (Group 10, n=10) according to the instructions of the manufacturers. The control (Group 1, n=10) was enamel blocks kept in artificial saliva at 37 degrees C without any treatment. The microhardness values were obtained before exposure and after a 14-day treatment period. Specimens were kept in artificial saliva at 37 degrees C between treatments. Data were analysed using Kruskal-Wallis one-way ANOVA and Tukey-Kramer Multiple Comparison Test. Indent marks on the enamel blocks were also examined under the Scanning Electron Microscope. All whitening products decreased enamel microhardness except group 10 but only Groups 2, 3, 4, 5 and 7 showed significant decrease in enamel microhardness as compared to the control group (p enamel. All products tested in this study decreased enamel microhardness except Opalescence Boost 38% HP. The products containing carbamide peroxide were more damaging to enamel because of the longer application times. Nite White ACP 10% CP showed the highest reduction in enamel microhardness as compared to other products tested.

  14. In-Vitro Comparative Study of In-office and Home Bleaching Agents on Surface Micro-morphology of Enamel.

    Science.gov (United States)

    Fatima, Nazish

    2016-01-01

    To evaluate the effect of home-use bleaching agent containing 16% Carbamide Peroxide (CP) and in-office bleaching agent with 38% Hydrogen Peroxide (HP) on surface micro-morphology of enamel. An experimental study. The discs were prepared at Material Engineering Department of NED University of Engineering and Technology, Karachi, and surface morphology was analyzed at Centralized Science Laboratory of Karachi University, Pakistan. Duration of study was one year from January to December 2012. Forty five sound human third molar crowns, extracted for periodontal reason, were included in the study. Longitudinal sections were made using diamond disks (0.2 mm) under water lubrication to obtain enamel slabs measuring (3 mm x 3 mm). The slabs were embedded in polystyrene resin by using 2.0 cm diameter PVC molds, leaving the outer enamel surface uncovered by the resin. Ninety dental enamel slabs were prepared. The slabs were then randomly divided into 3 groups. Each group contained thirty specimens (n=30). Group 1 was kept in artificial saliva at 37°C in incubator (Memart, Germany) during whole experiment. Group 2 was treated with power whitening gel (White Smile 2011, Germany). Group 3 was treated with tooth whitening pen (White Smile 2011, Germany). The most central region or the region that was most representative of the entire surface area was used. The SEM (Jeol-Japan-JSM6380A, JAPAN) micrographs were examined to determine the type of surface presented. The enamel changes were classified as no or mild alteration, moderate alteration and severe altered surface. Regarding micro-morphology, the enamel surface of control groups showed smooth surface in general with some scattered clear scratches due to the polishing procedure. The specimens bleached in group 2 and group 3, represented areas of mild erosion. Bleaching with 38% Hydrogen Peroxide (HP) and 16% Carbamide Peroxide (CP) resulted in mild changes in surface micro-morphology of enamel.

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

    International Nuclear Information System (INIS)

    Duran Sedo, Randall; Obando Rosabal, Sofia; Saenz Bonilla, Paola; Soto Aguilar, Calendy; Vasquez Rodriguez, Amaya

    2014-01-01

    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) [es

  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. 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.

  18. Effect of bleaching on microhardness of esthetic restorative materials.

    Science.gov (United States)

    Malkondu, Özlem; Yurdagüven, Haktan; Say, Esra Can; Kazazoğlu, Ender; Soyman, Mübin

    2011-01-01

    This study evaluated the effect of a high-concentration carbamide peroxide–containing home bleaching system (Opalescence PF) and a hydrogen peroxide–containing over-the-counter bleaching system (Treswhite Supreme) on the microhardness of two nanocomposites (Filtek Supreme XT and Premise) and leucite-reinforced glass ceramic (Empress Esthetic), glass ceramic (Empress 2 layering), and feldspathic porcelain (Matchmaker MC). A total of 100 specimens, 20 of each kind of the restorative materials, 2 mm in thickness and 10 mm in diameter, were fabricated. Then the specimens were polished with SiC paper and 1 μm alumina polishing paste. After polishing, porcelain specimens were glazed in accordance with the manufacturer's instructions. Each type of restorative material was then randomly divided into two groups (n=10), and the specimens were treated with either Opalescence PF or Treswhite Supreme. The microhardness of the specimens before bleaching (baseline) and after bleaching was determined using a digital microhardness tester. Data were analyzed using the Mann-Whitney U-test and the Wilcoxon test. Opalescence PF significantly influenced the hardness of all the restorative materials. Statistically significant decreases with respect to before bleaching were found for Premise (p=0.005), Empress Esthetic (p=0.003), Empress 2 layering (p=0.005), and Matchmaker-MC (p=0.003), whereas a statistically significant increase was observed in Filtek Supreme XT (p=0.028). The difference in the microhardness values between before and after bleaching using Treswhite Supreme was statistically significant only for Premise (p=0.022). High-concentration carbamide peroxide–containing home bleaching may affect the microhardness of restorative materials.

  19. Effect of Different Anti-Oxidants on Shear Bond Strength of Composite Resins to Bleached Human Enamel

    Science.gov (United States)

    Saladi, Hari Krishna; Bollu, Indira Priyadarshini; Burla, Devipriya; Ballullaya, Srinidhi Vishnu; Devalla, Srihari; Maroli, Sohani; Jayaprakash, Thumu

    2015-01-01

    Introduction The bond strength of the composite to the bleached enamel plays a very important role in the success and longevity of an aesthetic restoration. Aim The aim of this study was to compare and evaluate the effect of Aloe Vera with 10% Sodium Ascorbate on the Shear bond strength of composite resin to bleached human enamel. Materials and Methods Fifty freshly extracted human maxillary central incisors were selected and divided into 5 groups. Group I and V are unbleached and bleached controls groups respectively. Group II, III, IV served as experimental groups. The labial surfaces of groups II, III, IV, V were treated with 35% Carbamide Peroxide for 30mins. Group II specimens were subjected to delayed composite bonding. Group III and IV specimens were subjected to application of 10% Sodium Ascorbate and leaf extract of Aloe Vera following the Carbamide Peroxide bleaching respectively. Specimens were subjected to shear bond strength using universal testing machine and the results were statistically analysed using ANOVA test. Tukey (HSD) Honest Significant Difference test was used to comparatively analyse statistical differences between the groups. A p-value <0.05 is taken as statistically significant. Results The mean shear bond strength values of Group V showed significantly lower bond strengths than Groups I, II, III, IV (p-value <0.05). There was no statistically significant difference between the shear bond strength values of groups I, II, III, IV. Conclusion Treatment of the bleached enamel surface with Aloe Vera and 10% Sodium Ascorbate provided consistently better bond strength. Aloe Vera may be used as an alternative to 10% Sodium Ascorbate. PMID:26674656

  20. In Vitro Comparative Study of Two Different Bleaching Agents on Micro-hardness Dental Enamel.

    Science.gov (United States)

    Fatima, Nazish; Ali Abidi, Syed Yawar; Meo, Ashraf Ali

    2016-02-01

    To evaluate the effect of home-use bleaching agent containing 16% Carbamide Peroxide (CP) and in-office bleaching agent containing 38% Hydrogen Peroxide (HP) on enamel micro-hardness. An in vitroexperimental study. Department of Operative Dentistry and Science of Dental Materials at Dr. Ishrat-ul-Ebad Khan Institute of Oral Health Sciences, Dow University of Health Sciences and Material Engineering Department of NED University of Engineering and Technology, Karachi, from July to December 2014. Atotal of 90 enamel slabs from 45 sound human 3rd molar were randomly divided into 3 groups. Each group contained 30 specimens (n=30). Group 1 was kept in artificial saliva at 37°C in incubator during the whole experiment. However, Groups 2 and 3 were treated with power whitening gel and tooth whitening pen respectively. After bleaching session, specimens were thoroughly rinsed with deionized water again for 10 seconds and then stored in artificial saliva at 37°C in incubator. Artificial saliva was changed after every 2 days. The Vickers hardness tester (Wolpert 402 MVD, Germany) was adjusted to a load of 0.1 kg (100 gm) and dwell time of 5 seconds. Three Vickers were performed on each specimen using a hardness tester according to the ISO 6507-3:1998 specification. Micro-hardness measurements were performed before and after bleaching at day 1, 7 and 14. In the control group, the baseline micro-hardness was 181.1 ±9.3 which was reduced after the storage on day 1, 7 and 14 (p = 0.104). In Group 2, baseline micro-hardness was 180.4 ±10.1 which was reduced to 179.79 ±10.0 units after day 1. Whereas, on day 7 and 14, the values of micro-hardness were 179.8 ±10 and 179.7 ±10.29, respectively (p=0.091). Furthermore, the baseline micro-hardness in Group 3 was 174.0 ±22.9 units which was reduced to 173 ±23 on day 1, 170 ±30 on day 7 and 173 ±23 on day 14 (p = 0.256). The statistically insignificant difference was found among micro-hardness values of different bleaching

  1. In-Vitro Comparative Study of In-office and Home Bleaching Agents on Surface Micro-morphology of Enamel

    International Nuclear Information System (INIS)

    Fatima, N.

    2016-01-01

    Objective: To evaluate the effect of home-use bleaching agent containing 16 percent Carbamide Peroxide (CP) and in-office bleaching agent with 38 percentage Hydrogen Peroxide (HP) on surface micro-morphology of enamel. Study Design: An experimental study. Place and Duration of Study: The discs were prepared at Material Engineering Department of NED University of Engineering and Technology, Karachi, and surface morphology was analyzed at Centralized Science Laboratory of Karachi University, Pakistan. Duration of study was one year from January to December 2012. Methodology: Forty five sound human third molar crowns, extracted for periodontal reason, were included in the study. Longitudinal sections were made using diamond disks (0.2 mm) under water lubrication to obtain enamel slabs measuring (3 mm x 3 mm). The slabs were embedded in polystyrene resin by using 2.0 cm diameter PVC molds, leaving the outer enamel surface uncovered by the resin. Ninety dental enamel slabs were prepared. The slabs were then randomly divided into 3 groups. Each group contained thirty specimens (n=30). Group 1 was kept in artificial saliva at 37 degree C in incubator (Memart, Germany) during whole experiment. Group 2 was treated with power whitening gel (White Smile 2011, Germany). Group 3 was treated with tooth whitening pen (White Smile 2011, Germany). The most central region or the region that was most representative of the entire surface area was used. The SEM (Jeol-Japan-JSM6380A, JAPAN) micrographs were examined to determine the type of surface presented. The enamel changes were classified as no or mild alteration, moderate alteration and severe altered surface. Results: Regarding micro-morphology, the enamel surface of control groups showed smooth surface in general with some scattered clear scratches due to the polishing procedure. The specimens bleached in group 2 and group 3, represented areas of mild erosion. Conclusion: Bleaching with 38 percentage Hydrogen Peroxide (HP) and

  2. In Vitro Comparative Study of Two Different Bleaching Agents on Micro-hardness Dental Enamel

    International Nuclear Information System (INIS)

    Fatima, N.; Abidi, S. Y. A.; Meo, A. A.

    2016-01-01

    Objective: To evaluate the effect of home-use bleaching agent containing 16 percentage Carbamide Peroxide (CP) and in-office bleaching agent containing 38 percentage Hydrogen Peroxide (HP) on enamel micro-hardness. Study Design: An in vitro experimental study. Place and Duration of Study: Department of Operative Dentistry and Science of Dental Materials at Dr. Ishrat-ul-Ebad Khan Institute of Oral Health Sciences, Dow University of Health Sciences and Material Engineering Department of NED University of Engineering and Technology, Karachi, from July to December 2014. Methodology: A total of 90 enamel slabs from 45 sound human 3rd molar were randomly divided into 3 groups. Each group contained 30 specimens (n=30). Group 1 was kept in artificial saliva at 37 Degree C in incubator during the whole experiment. However, Groups 2 and 3 were treated with power whitening gel and tooth whitening pen respectively. After bleaching session, specimens were thoroughly rinsed with deionized water again for 10 seconds and then stored in artificial saliva at 37 Degree C in incubator. Artificial saliva was changed after every 2 days. The Vickers hardness tester (Wolpert 402 MVD, Germany) was adjusted to a load of 0.1 kg (100 gm) and dwell time of 5 seconds. Three Vickers were performed on each specimen using a hardness tester according to the ISO 6507-3:1998 specification. Micro-hardness measurements were performed before and after bleaching at day 1, 7 and 14. Results: In the control group, the baseline micro-hardness was 181.1 ± 9.3 which was reduced after the storage on day 1, 7 and 14 (p = 0.104). In Group 2, baseline micro-hardness was 180.4 ±10.1 which was reduced to 179.79 ± 10.0 units after day 1. Whereas, on day 7 and 14, the values of micro-hardness were 179.8 ±10 and 179.7 ±10.29, respectively (p=0.091). Furthermore, the baseline micro-hardness in Group 3 was 174.0 ±22.9 units which was reduced to 173 ± 23 on day 1, 170 ±30 on day 7 and 173 ± 23 on day 14 (p = 0

  3. Bleaching agent action on color stability, surface roughness and microhardness of composites submitted to accelerated artificial aging.

    Science.gov (United States)

    Rattacaso, Raphael Mendes Bezerra; da Fonseca Roberti Garcia, Lucas; Aguilar, Fabiano Gamero; Consani, Simonides; de Carvalho Panzeri Pires-de-Souza, Fernanda

    2011-04-01

    The purpose of this study was to evaluate the bleaching agent action on color stability, surface roughness and microhardness of composites (Charisma, Filtek Supreme and Heliomolar - A2) submitted to accelerated artificial aging (AAA). A Teflon matrix (12 x 2 mm) was used to fabricate 18 specimens (n=6) which, after polishing (Sof-Lex), were submitted to initial color reading (ΔE), Knoop microhardness (KHN) (50 g/15 s load) and roughness (R(a)) (cut-off 0.25 mm) tests. Afterwards, the samples were submitted to AAA for 384 hours and new color, microhardness and roughness readings were performed. After this, the samples were submitted to daily application (4 weeks) of 16% Carbamide Peroxide (NiteWhite ACP) for 8 hours and kept in artificial saliva for 16 hours. New color, microhardness and roughness readings were made at the end of the cycle, and 15 days after bleaching. Comparison of the ΔE means (2-way ANOVA, Bonferroni, P<.05) indicated clinically unacceptable color alteration for all composites after AAA, but without significant difference. Statistically significant increase in the KHN values after AAA was observed, but without significant alterations 15 days after bleaching. For R(a) there was no statistically significant difference after AAA and 15 days after bleaching. The alterations promoted by the bleaching agent and AAA are material dependent.

  4. The safety of peroxide-containing at-home tooth whiteners.

    Science.gov (United States)

    Li, Yiming

    2003-04-01

    Scientific data from research conducted during the past decade have demonstrated the safety of the dentist-dispensed at-home whiteners containing 10% carbamide peroxide. There has been no evidence of systemic adverse effects associated with the proper use of these whitening systems. Most commonly observed local adverse effects are mild-to-moderate tooth sensitivity and/or gingival irritation, which usually do not prevent the patient from completing the whitening treatment. The sensitivity and irritation are transient in most cases, and they dissipate when the patient discontinues the use of the whitener. There is no evidence of any long-term consequences that have resulted from tooth sensitivity and/or gingival irritation. However, potential adverse effects may occur from inappropriate applications, abuses, or the use of inappropriate products. The risks of using at-home whiteners without a dentist's involvement, or using formulations with a higher peroxide content than recommended, are yet to be determined. To maximize benefits while minimizing potential risks, the author advises using at-home tooth whiteners under the supervision of a dental professional.

  5. Effect of Home Bleaching on the Translucency of CAD/CAM Systems.

    Science.gov (United States)

    Karci, Muhammet; Demir, Necla

    2017-11-10

    To evaluate the effect of a home bleaching agent (Opalescence PF) on the translucency of CAD/CAM ceramic systems. The 28 sintered ceramic specimens (IPS Empress CAD and IPS e.max CAD; 15 mm long, 10 mm wide, 1 mm thick) were divided into two subgroups as control and bleaching groups (n = 7). Carbamide peroxide (CP), 16%, home bleaching agent was applied onto the surface of each specimen for 6 hours per day for 7 days. A spectrophotometer (VITA Easyshade Advance) was used to measure the CIE L * a * b * coordinates and the reflectance value (Y) of the specimens on white and black backgrounds. The translucency parameter (TP), contrast ratio (CR), and opalescence parameter (OP) of the specimens were calculated. The data were statistically analyzed using Kolmogorov-Smirnov, one-way ANOVA, Tukey's test, and Pearson's correlation. Statistically significant differences in the TP values after 16% CP bleaching treatment were observed (p ˂ 0.05); however, no significant differences were found in the OP and CR values after the surface treatment (p ˃ 0.05). According to our study, patients who have all-ceramic restorations in their mouths should be careful when using home bleaching agents, because whitening agents can affect the translucency of all-ceramic restorations such as e.max CAD and Empress CAD. © 2017 by the American College of Prosthodontists.

  6. Preparation of Titanium nitride nanomaterials for electrode and application in energy storage

    Science.gov (United States)

    Tang, Shun; Cheng, Qi; Zhao, Jinxing; Liang, Jiyuan; Liu, Chang; Lan, Qian; Cao, Yuan-Cheng; Liu, Jiyan

    The Titanium nitride was made by the carbamide and titanic chloride precursors. XRD results indicate that the precursor ratio N:Ti 3:1 leads to higher crystallinity. SEM and EDX demonstrated that Ti and N elements were distributed uniformly with the ratio of 1:1. The TiN used as the electrode material for supercapacitor was also studied. The specific capacities were changed from 407 F.g-1 to 385 F.g-1, 364 F.g-1 and 312 F.g-1, when the current densities were changed from 1 A.g-1 to 2 A.g-1, 5 A.g-1 and 10 A.g-1, respectively. Chronopotentiometry tests showed high coulombic efficiency. Cycling performance of the TiN electrode was evaluated by CV at a scanning rate of 50 mV.s-1 for 20,000 cycles and there was about 9.8% loss. These results indicate that TiN is a promising electrode material for the supercapacitors.

  7. Preparation of Titanium nitride nanomaterials for electrode and application in energy storage

    Directory of Open Access Journals (Sweden)

    Shun Tang

    Full Text Available The Titanium nitride was made by the carbamide and titanic chloride precursors. XRD results indicate that the precursor ratio N:Ti 3:1 leads to higher crystallinity. SEM and EDX demonstrated that Ti and N elements were distributed uniformly with the ratio of 1:1. The TiN used as the electrode material for supercapacitor was also studied. The specific capacities were changed from 407 F.g−1 to 385 F.g−1, 364 F.g−1 and 312 F.g−1, when the current densities were changed from 1 A.g−1 to 2 A.g−1, 5 A.g−1 and 10 A.g−1, respectively. Chronopotentiometry tests showed high coulombic efficiency. Cycling performance of the TiN electrode was evaluated by CV at a scanning rate of 50 mV.s−1 for 20,000 cycles and there was about 9.8% loss. These results indicate that TiN is a promising electrode material for the supercapacitors. Keywords: Energy storage, Nanomaterials, Anode, Titanium nitride, Supercapacitors

  8. Effects of in-office bleaching on human enamel and dentin. Morphological and mineral changes.

    Science.gov (United States)

    Llena, Carmen; Esteve, Irene; Forner, Leopoldo

    2018-05-01

    The effects of HP-based products upon dental enamel and dentin are inconclusive. To evaluate changes in micromorphology and composition of calcium (Ca) and phosphate (P) in enamel and dentin after the application of 37.5% hydrogen peroxide (HP) and 35% carbamide peroxide (CP) METHODS: Crowns of 20 human teeth were divided in two halves. One half was used as control specimen and the other as experimental specimen. The control specimens were kept in artificial saliva, and the experimental specimens were divided into four groups (n=5 each): group 1 (enamel HP for 45min); group 2 (dentin HP for 45min); group 3 (enamel CP for 90min); and group 4 (dentin CP for 90min). The morphological changes were evaluated using confocal laser scanning microscopy (CLSM), while the changes in the composition of Ca and P were assessed using environmental scanning electron microscopy combined with a microanalysis system (ESEM+EDX). The results within each group and between groups were compared using the Wilcoxon test and Mann-Whitney U-test, respectively (p0.05). When bleaching products with a neutral pH are used in clinical practice, both, the concentration and the application time should be taken into account in order to avoid possible structural and mineral changes in enamel and dentin. Copyright © 2018 Elsevier GmbH. All rights reserved.

  9. Justification of the Production Process of Pressed Wood and Study of its Properties

    Science.gov (United States)

    Polilov, A. N.; Dornyak, O. R.; Shamaev, V. A.; Rumachik, M. M.

    2018-05-01

    Results of a numerical analysis of the stress-strain state of wood during its pressing in different symmetry directions of the anisotropic material are presented. It is shown that the anisotropy of mechanical properties of wood is an important factor determining both the structural characteristics of the porous system and its strength. A mathematical modeling of the process of pressing wood as a three-phase anisotropic rheologically complex capillary-porous system allows one to predict parameters of the resulting wood composite. The compressed wood obtained by the production modes developed has a tensile strength eight times greater than that of the natural one, which is comparable to the strength of the St3 steel, but its specific strength is higher than that of the St45 steel. Compression and impregnation of softwood species with an aqueous solution of carbamide allows one to harden them. This kind of treatment endows the wood with enhanced strength characteristics comparable to the characteristics of the St3 steel. The special features of tensile tests used to estimate the elastic modulus and strength characteristics of such materials are considered. Data obtained by different testing methods are correlated, and characteristics of the strengthened wood and some brends of steel are compared.

  10. The use of stock with various contents of n-alkanes in G-64 installations

    Energy Technology Data Exchange (ETDEWEB)

    Dorodnova, V.S.; Martirosov, R.A.; Martynenko, A.G.; Okhrimenko, N.V.; Pereverzev, A.N.

    1979-01-01

    The industrial savings indicators of installations for the carbide separation of paraffin decrease with a processing of the fraction of diesel fuel from west Siberian petroleum with a content of 10 to 12% of n-paraffins. Presentation is made of the results of the calculations of the indicators of the operation of the G-64 installation for fractions of diesel fuel, with a boiling temperature of 200 to 320/sup 0/ and containing 30% (for Stavoropolsk), 20% (for Ukhtinsk) and 15% (for Romashkin oils) occurrence of n-paraffins. It is shown that for the processing of the required amount of paraffin at the G-64 installation, it is expedient to use the stock with an occurrence of 18% to 24% of n-paraffins. With this, besides paraffin, a significant amount of denormalizers are obtained which can be drawn into the composition of cold and export diesel fuels. The use in the capacity of the stock of diesel fraction of low and average paraffin bearing oil with a ratio of carbamide to the stock of 0.4 to 0.5 (mass.) insures the production of two commercial products -- liquid paraffins and diesel fuels.

  11. Accounting for measurement reliability to improve the quality of inference in dental microhardness research: a worked example.

    Science.gov (United States)

    Sever, Ivan; Klaric, Eva; Tarle, Zrinka

    2016-07-01

    Dental microhardness experiments are influenced by unobserved factors related to the varying tooth characteristics that affect measurement reproducibility. This paper explores the appropriate analytical tools for modeling different sources of unobserved variability to reduce the biases encountered and increase the validity of microhardness studies. The enamel microhardness of human third molars was measured by Vickers diamond. The effects of five bleaching agents-10, 16, and 30 % carbamide peroxide, and 25 and 38 % hydrogen peroxide-were examined, as well as the effect of artificial saliva and amorphous calcium phosphate. To account for both between- and within-tooth heterogeneity in evaluating treatment effects, the statistical analysis was performed in the mixed-effects framework, which also included the appropriate weighting procedure to adjust for confounding. The results were compared to those of the standard ANOVA model usually applied. The weighted mixed-effects model produced the parameter estimates of different magnitude and significance than the standard ANOVA model. The results of the former model were more intuitive, with more precise estimates and better fit. Confounding could seriously bias the study outcomes, highlighting the need for more robust statistical procedures in dental research that account for the measurement reliability. The presented framework is more flexible and informative than existing analytical techniques and may improve the quality of inference in dental research. Reported results could be misleading if underlying heterogeneity of microhardness measurements is not taken into account. The confidence in treatment outcomes could be increased by applying the framework presented.

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

    Science.gov (United States)

    Baroudi, Kusai; Hassan, Nadia Aly

    2014-01-01

    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. PMID:25298598

  13. Effect of a New Bleaching Gel on Tooth Whitening.

    Science.gov (United States)

    Barry, T N; Bailey, C W; Ashcraft-Olmscheid, D; Vandewalle, K S

    The purpose of this study was to compare the whitening efficacy of a novel bleaching agent containing a unique tribarrel hydremide-peroxide gel (KöR) with a traditional bleaching system of hydrogen peroxide or carbamide peroxide (Opalescence). Bovine incisors were mounted into a custom resin, arch-shaped mounting device. Four groups of 10 teeth were created using mounting devices containing five teeth each. The in-office and home bleaching gels of KöR and Opalescence were applied to the teeth alone and in trays to simulate a combination of in-office and home bleaching or home bleaching only. Spectrophotometer readings of L* a* b* were performed at baseline, the end of active bleaching (immediate), and three and six months postbleaching. Immediately postbleaching, the use of Opalescence gel resulted in greater change in ΔE* and Δb* (less yellow) for combined and home bleaching techniques compared with KöR. After six months, Opalescence had significantly greater ΔE* and Δb* compared with KöR for home bleaching only. There was no significant difference in ΔL* between Opalescence and KöR at any time period with either technique.

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

    Science.gov (United States)

    Moosavi, Horieh; Darvishzadeh, Fatemeh

    2016-01-01

    This study investigated the effects of post bleaching treatments to prevent restaining and the change of enamel surface microhardness after dental bleaching in vitro. 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). 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 bleaching treatments are suggested for prevention of stain absorption and increasing the hardening of bleached enamel.

  15. Effect of different bleaching strategies on microhardness of a silorane-based composite resin.

    Science.gov (United States)

    Bahari, Mahmoud; Savadi Oskoee, Siavash; Mohammadi, Narmin; Ebrahimi Chaharom, Mohammad Esmaeel; Godrati, Mostafa; Savadi Oskoee, Ayda

    2016-01-01

    Background. Dentists' awareness of the effects of bleaching agents on the surface and mechanical properties of restorative materials is of utmost importance. Therefore, this in vitro study was undertaken to investigate the effects of different bleaching strategies on the microhardness of a silorane-based composite resin. Methods. Eighty samples of a silorane-based composite resin (measuring 4 mm in diameter and 2 mm in thickness) were prepared within acrylic molds. The samples were polished and randomly assigned to 4 groups (n=20). Group 1 (controls) were stored in distilled water for 2 weeks. The samples in group 2 underwent a bleaching procedure with 15% carbamide peroxide for two weeks two hours daily. The samples in group 3 were bleached with 35% hydrogen peroxide twice 5 days apart for 30 minutes each time. The samples in group 4 underwent a bleaching procedure with light-activated 35% hydrogen peroxide under LED light once for 40 minutes. Then the microhardness of the samples was determined using Vickers method. Data were analyzed with one-way ANOVA and post hoc Tukey tests (P bleaching agents significantly decreased microhardness compared to the control group (P 0.05). Conclusion. Bleaching agents decreased microhardness of silorane-based composite resin restorations, the magnitude of which depending on the bleaching strategy used.

  16. 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)

  17. Efficacy of Mouthwashes Containing Hydrogen Peroxide on Tooth Whitening

    Directory of Open Access Journals (Sweden)

    Muhammet Karadas

    2015-01-01

    Full Text Available The aim of this study was to analyze the efficacy of mouthwashes containing hydrogen peroxide compared with 10% carbamide peroxide (CP gel. Fifty enamel-dentin samples were obtained from bovine incisors and then stained in a tea solution. The stained samples were randomly divided into five groups according to the whitening product applied (n=10: AS: no whitening (negative control, with the samples stored in artificial saliva; CR: Crest 3D White mouthwash; LS: Listerine Whitening mouthwash; SC: Scope White mouthwash; and OP group: 10% CP Opalescence PF (positive control. Color measurements were carried out with a spectrophotometer before staining, after staining, and on the 7th, 28th, and 56th day of the whitening period. The data were analyzed using two-way analysis of variance followed by a Tukey post hoc test. The color change (ΔE was significantly greater in all the groups compared to that of the AS group. After 56 days, no significant differences were found among the mouthwash products with respect to color change (P>0.05. The whiteness of the teeth treated with the mouthwashes increased significantly over time. Nevertheless, the color change achieved with the mouthwashes was significantly lower than that achieved with the 10% CP at-home bleaching gel.

  18. 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.

  19. A comparative study of different bleaching agents on the morphology of human enamel: an in vitro SEM study.

    Science.gov (United States)

    Uthappa, Roshan; Suprith, M L; Bhandary, Shreetha; Dash, Sumit

    2012-11-01

    The purpose of the study was to compare two different commercial bleaching agents, Opalescence with Colgate Platinum, and 30% phosphoric acid used as aggressive agent on the morphology of human enamel. Ten freshly extracted, noncarious, human maxillary central incisors extracted for periodontal reasons were used in this study. The labial surface of the disinfected teeth were polished using a polishing paste with the help of rubber cup and a slow speed handpiece. Each tooth was sectioned at cement-enamel junction and the crown was separated into four specimens, all taken from labial surface. Group 1 was treated with Colgate Platinum for 7 hours, group 2 with Opalescence for 7 hours, group 3 was treated with 30% phosphoric acid for 30 seconds and group 4 was untreated and used as control. After the treatment period, the specimens were washed with normal saline and stored in sterile bottle and sealed. Photomicrographs obtained from the scanning electron microscopy (SEM) after surface treatments were examined for no alteration, slight alteration, moderate alteration and severe alterations. The specimens treated with commercial bleaching agents revealed no enamel surface morphologic alterations compared to control group. The specimen treated with phosphoric acid showed severe alterations. Ten percent carbamide peroxide evaluated in this study does not etch tooth enamel or alter enamel surface morphology as do conventional etching techniques. Carbamine peroxide is a safe and effective tooth whitening agent even when used for extended period of time. The enamel surface remains smooth which reduces caries due to plaque collection.

  20. Effect of tray-based and trayless tooth whitening systems on microhardness of enamel surface and subsurface.

    Science.gov (United States)

    Teixeira, Erica C N; Ritter, André V; Thompson, Jeffrey Y; Leonard, Ralph H; Swift, Edward J

    2004-12-01

    To evaluate the effect of tray-based and trayless tooth whitening systems on surface and subsurface microhardness of human enamel. Enamel slabs were obtained from recently extracted human third molars. Specimens were randomly assigned to six groups according to tooth whitening treatment (n = 10): 6.0% hydrogen peroxide (HP) (Crest Whitestrips), 6.5% HP (Crest Professional Whitestrips), 7.5% HP (Day White Excel 3), 9.5% HP (Day White Excel 3), 10% carbamide peroxide (Opalescence), and a control group (untreated). Specimens were treated for 14 days following manufacturers' recommended protocols, and were immersed in artificial saliva between treatments. Enamel surface Knoop microhardness (KHN) was measured immediately before treatment, and at days 1, 7, and 14 of treatment. After treatment, subsurface microhardness was measured at depths of 50-500 microm. Data were analyzed for statistical significance using analysis of variance. Differences in microhardness for treated vs. untreated enamel surface were not statistically significant at any time interval. For 6.5% and 9.5% HP, there was a decrease in surface microhardness values during treatment, but at the end of treatment the microhardness values were not statistically different from the baseline values. For the enamel subsurface values, no differences were observed between treated vs. untreated specimens at each depth. Trayless and tray-based tooth whitening treatments do not significantly affect surface or subsurface enamel microhardness.

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

    International Nuclear Information System (INIS)

    Mattos, Alessandra de Siervi

    2003-01-01

    '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)

  2. Influence of bleaching agents on surface roughness of sound or eroded dental enamel specimens.

    Science.gov (United States)

    Azrak, Birgül; Callaway, Angelika; Kurth, Petra; Willershausen, Brita

    2010-12-01

    The aim of the present in vitro study was to assess the effect of bleaching agents on eroded and sound enamel specimens. Enamel specimens prepared from human permanent anterior teeth were incubated with different bleaching agents containing active ingredients as 7.5 or 13.5% hydrogen peroxide or 35% carbamide peroxide, ranging in pH from 4.9 to 10.8. The effect of the tooth whitening agents on surface roughness was tested for sound enamel surfaces as well as for eroded enamel specimens. To provoke erosive damage, the enamel specimens were incubated for 10 hours with apple juice (pH = 3.4). Afterwards, pretreated and untreated dental slices were incubated with one of the bleaching agents for 10 hours. The surface roughness (R(a)) of all enamel specimens (N = 80) was measured using an optical profilometric device. A descriptive statistical analysis of the R(a) values was performed. The study demonstrated that exposure to an acidic bleaching agent (pH = 4.9) resulted in a higher surface roughness (p = 0.043) than treatment with a high peroxide concentration (pH = 6.15). If the enamel surface was previously exposed to erosive beverages, subsequent bleaching may enhance damage to the dental hard tissue. Bleaching agents with a high concentration of peroxide or an acidic pH can influence the surface roughness of sound or eroded enamel. © 2010, COPYRIGHT THE AUTHORS. JOURNAL COMPILATION © 2010, WILEY PERIODICALS, INC.

  3. Effect of tooth-bleaching on the carbonate concentration in dental enamel by Raman spectroscopy.

    Science.gov (United States)

    Vargas-Koudriavtsev, Tatiana; Herrera-Sancho, Óscar-Andrey

    2017-01-01

    There are not many studies evaluating the effects of surface treatments at the molecular level. The aim of this in vitro study was to analyze the concentration of carbonate molecules in dental enamel by Raman spectroscopy after the application of in-office and home whitening agents. Sixty human teeth were randomly divided into six groups and exposed to three different home bleaching gels (Day White) and three in-office whitening agents (Zoom! Whitespeed and PolaOffice) according to the manufacturer´s instructions. The concentration of carbonate molecules in enamel was measured prior to and during the treatment by means of Raman spectroscopy. Statistical analysis included repeated measures analysis of variance ( p ≤0.05) and Bonferroni pairwise comparisons. At home bleaching agents depicted a decrease in the carbonate molecule. This decrease was statistically significant for the bleaching gel with the highest hydrogen peroxide concentration ( p ≤0,05). In-office whitening agents caused an increase in carbonate, which was significant for all three groups ( p ≤0,05). In-office bleaching gels seem to cause a gain in carbonate of the enamel structure, whilst at-home whitening gels caused a loss in carbonate. Key words: Bleaching, whitening, hydrogen peroxide, carbamide peroxide, Raman spectroscopy, carbonate.

  4. A review of the effect of vital teeth bleaching on the mechanical properties of tooth enamel.

    Science.gov (United States)

    Elfallah, Hunida M; Swain, Michael V

    2013-09-01

    Tooth whitening is considered the easiest and most cost-effective procedure for treating tooth discoloration. Contemporary bleaching agents contain hydrogen peroxide as the active ingredient. It is either applied directly or produced from its precursor, carbamide peroxide. A review of the published literature was undertaken to investigate the potential adverse effects of whitening products on dental enamel, with a focus on its mechanical properties and the influence of various parameters on study outcomes. There appear to be considerable differences in opinion as to whether changes in mechanical properties occur as a result of tooth whitening. However, the mechanical property findings of those studies appear to be related to the load applied during the indentation tests. Most studies which used loads higher than 500mN to determine enamel hardness showed no effect of bleaching, whereas those using lower loads were able to detect hardness reduction in the surface layer of enamel. In conclusion, bleaching reduces the hardness of the enamel surface of enamel, and that is more readily detected with instrumented low load testing systems. This hardness reduction may arise due to degradation or denaturation of enamel matrix proteins by the peroxide oxidation.

  5. 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 (pTooth whitening through home bleaching or laser-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

  6. Titanium dioxide in dental enamel as a trace element and its variation with bleaching.

    Science.gov (United States)

    Vargas-Koudriavtsev, Tatiana; Durán-Sedó, Randall; Herrera-Sancho, Óscar-Andrey

    2018-06-01

    Titanium is a less studied trace element in dental enamel. Literature relates an increased Titanium concentration with a decreased enamel crystal domain size, which in turn is related to a higher color value. The aim of our study was to analyze the effect of tooth bleaching agents on its concentration in dental enamel by means of confocal Raman spectroscopy. Human teeth were randomly distributed in six experimental groups (n=10) and submitted to different bleaching protocols according to the manufacturer´s instructions. Confocal Raman spectroscopy was carried out in order to identify and quantify the presence of titanium dioxide molecules in enamel prior to and during whitening. Statistical analysis included repeated measures analysis of variance ( p ≤0.05) and Bonferroni pairwise comparisons. Titanium dioxide concentration was negatively affected by the longer bleaching protocols (at-home bleaching gels). All in-office whitening products increased significantly the studied molecule ( p ≤0,05). All dental specimens depicted the presence of titanium dioxide as a trace element in dental enamel. Bleaching gels that have to be applied at higher concentrations but for shorter periods of time increase the concentration of titanium dioxide, whilst at-home whitening gels used for longer periods of time despite the lower concentration caused a loss in titanium. Key words: Bleaching, whitening, hydrogen peroxide, carbamide peroxide, Raman spectroscopy, titanium dioxide.

  7. 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.

  8. Effects of at-home and in-office bleaching agents on the shear bond strength of metal, ceramic, and composite brackets to enamel.

    Science.gov (United States)

    Rahul, M; Kumar, P Anil; Nair, Amal S; Mathew, Shino; Amaladas, Antony Shijoy; Ommen, Anna

    2017-01-01

    This study aimed to evaluate the effects of at-home and in-office bleaching on the shear bond strength (SBS) of metal, ceramic, and composite orthodontic brackets and to compare their SBSs. A total of 96 human lower premolar teeth were used for this study. Six teeth were used for scanning electron microscopic study while the remaining ninety were divided into three equal groups. Each group was further subdivided into three subgroups with ten samples each. Three protocols were used. In the at-home bleaching group (n = 30), opalescence non-PF (potassium nitrate and fluoride) bleaching agent (10% carbamide peroxide) was applied onto the teeth daily for 14 days and left for 8 h each day. Teeth in the in-office group (n = 30) were treated twice in consecutive days with Opalescence boost PF (40% hydrogen peroxide). After bleaching, the specimens were stored in distilled water for 1 day before bonding. SBS testing was performed on all teeth using Instron universal testing machine. Analysis of variance indicated a significant difference (P brackets in control group (Ib) and minimum was shown by composite brackets of in-office bleached group (IIIc). The results showed that at-home bleaching did not affect the SBS significantly whereas in-office bleaching reduced SBS of metal, ceramic, and composite brackets significantly. It is preferable to use metal or ceramic brackets than composite brackets for bonding 24 h after bleaching.

  9. Efficacy of quercetin flavonoid in recovering the postbleaching bond strength of orthodontic brackets: A preliminary study.

    Science.gov (United States)

    Shamsedin, Mana; Arash, Valiollah; Jahromi, Masoud Babaei; Moghadamnia, Ali Akbar; Kamel, Manouchehr Rahmati; Ezoji, Fariba; Bijani, Ali; Kavoli, Samira; Ghasemi, Tania; Ramezani, Gholamhossein

    2017-01-01

    To evaluate comparatively the effect of quercetin on postbleaching shear bond strength (SBS) and adhesive remnant index (ARI). Intact maxillary premolars were divided randomly into 12 groups of 10 each: (1) bonding the bracket immediately after bleaching, (2) bonding 1 week after bleaching, (3-8) application of three experimental concentrations of quercetin (0.1%, 0.5%, and 1%) at two time durations (5 and 10 min), (9-10) application of the solvent of quercetin at two time periods (5 and 10 min), (11) application of 10% sodium ascorbate for 10 min, and (12) bonding the brackets on nonbleached teeth. Bleaching was performed using 15% carbamide peroxide gel for 5 days (6 h daily). After incubation and thermocycling, the SBS of brackets was measured. The ARI too was recorded at ×20. The data were analyzed statistically (α =0.05). Bleaching reduced the SBS below 10 Megapascal (MPa) level ( P 0.01). All eight postbleaching treatments had rather similar efficacies ( P = 0.1396). The concentration of quercetin (beta = 0.259, P = 0.042) but not its duration (beta = 0.213, P = 0.093) significantly improved its efficacy. Bleaching can weaken the bond strength of orthodontic brackets below acceptable levels. The application of quercetin or Vitamin C or delaying the bracket bonding improved the postbleaching SBS.

  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 newer antioxidants on the bond strength of composite on bleached enamel

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    M Manoharan

    2016-01-01

    Full Text Available Aim: The study aims to evaluate the effect of the application of two antioxidants on the bond strength of composite resin to bleached enamel. Materials and Methods: Eighty enamel surfaces were obtained from forty human extracted premolars. Specimens were randomly divided into four groups (n = 20. Group 1: No bleaching (control; Group 2a: Bleaching with 15% carbamide peroxide gel; Group 2b: Bleaching, followed by application of 10% sodium ascorbate gel; Group 2c: Bleaching, followed by application of 5% proanthocyanidin agent. Surfaces were etched followed by application of total etch bonding system, and composite resin cylinders were bonded. Specimens were tested for shear bond strength. Statistical Analysis Used: One-way analysis of variance was used for multiple group comparison and post hoc Tukey′s test for individual group-wise comparison. Results: Significantly higher shear bond strength values were observed in Group 2c and 2b as compared with Group 1 and 2a (P < 0.05. Among the antioxidants, Group 2c showed significantly higher shear bond strength values than Group 2b (P < 0.05. Conclusion: It can be concluded that the use of antioxidant before bonding procedures on bleached enamel completely neutralizes the deleterious effects of bleaching and increases the bond strength significantly.

  12. 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

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    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)

  13. Effect of bleaching on color change and surface topography of composite restorations.

    Science.gov (United States)

    Pruthi, Gunjan; Jain, Veena; Kandpal, H C; Mathur, Vijay Prakash; Shah, Naseem

    2010-01-01

    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).

  14. Effect of bleaching agents and soft drink on titanium surface topography.

    Science.gov (United States)

    Faverani, Leonardo P; Barão, Valentim A R; Ramalho-Ferreira, Gabriel; Ferreira, Mayara B; Garcia-Júnior, Idelmo R; Assunção, Wirley G

    2014-01-01

    The effects of carbamide peroxide, hydrogen peroxide and cola soft drink on the topographic modifications of commercially-pure titanium (CP-Ti) and Ti-6Al-4V were investigated. Ti discs were divided into 18 groups (n = 4) based on the solution treatment and Ti type. Specimens were immersed in 3 mL of each solution for 4 h per day (for the remaining 20 h, discs were left dry or immersed in artificial saliva) for 15 days. For control, specimens were immersed in only artificial saliva. Ti surfaces were examined using scanning electron (SEM) and atomic force (AFM) microscopes and their surface roughness (in µm) and surface chemical modifications were investigated. Data were analyzed by ANOVA and Tukey's test (α = 0.05). Groups immersed in 35% hydrogen peroxide showed the highest roughness (Ra) (171.65 ± 4.04 for CP-Ti and 145.91 ± 14.71 for Ti-6Al-4V) (p  0.05). SEM and AFM revealed dramatic changes in the specimens surfaces immersed in the 35% hydrogen peroxide, mainly for CP-Ti. No detectable chemical modifications on the Ti surface were observed. Bleaching agents promoted significant changes in Ti topography, which could affect the longevity of implants treatments. Copyright © 2013 Wiley Periodicals, Inc.

  15. 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.

  16. Effect of tooth bleaching agents on protein content and mechanical properties of dental enamel.

    Science.gov (United States)

    Elfallah, Hunida M; Bertassoni, Luiz E; Charadram, Nattida; Rathsam, Catherine; Swain, Michael V

    2015-07-01

    This study investigated the effect of two bleaching agents, 16% carbamide peroxide (CP) and 35% hydrogen peroxide (HP), on the mechanical properties and protein content of human enamel from freshly extracted teeth. The protein components of control and treated enamel were extracted and examined on sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE). Marked reduction of the protein matrix and random fragmentation of the enamel proteins after bleaching treatments was found. The mechanical properties were analyzed with Vickers indentations to characterize fracture toughness, and nanoindentation to establish enamel hardness, elastic modulus and creep deformation. Results indicate that the hardness and elastic modulus of enamel were significantly reduced after treatment with CP and HP. After bleaching, the creep deformation at maximum load increased and the recovery upon unloading reduced. Crack lengths of CP and HP treated enamel were increased, while fracture toughness decreased. Additionally, the microstructures of fractured and indented samples were examined with field emission gun scanning electron microscopy (FEG-SEM) showing distinct differences in the fracture surface morphology between pre- and post-bleached enamel. In conclusion, tooth bleaching agents can produce detrimental effects on the mechanical properties of enamel, possibly as a consequence of damaging or denaturing of its protein components. Copyright © 2015 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

  17. 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

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

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    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

  19. Effect of Delayed Bonding and Antioxidant Application on the Bond Strength to Enamel after Internal Bleaching.

    Science.gov (United States)

    Kılınç, Halil İbrahim; Aslan, Tuğrul; Kılıç, Kerem; Er, Özgür; Kurt, Gökmen

    2016-07-01

    This study evaluated the effect of delayed bonding and antioxidant application (AA, 10% sodium ascorbate) after internal bleaching (35% carbamide peroxide) on the shear bond strength of an adhesive cement to enamel. Eighty-four human maxillary central incisors were endodontically treated. The control group remained unbleached with no AA. Experimental groups were all internally bleached. The buccal enamel was finished and polished with metallographic paper to a refinement of #600, in order to obtain a 5-mm(2) flat bonding area. An adhesive cement (Clearfil Esthetic) was placed into a plastic tube with internal diameter of 3 mm and a 3-mm height and cured on the enamel. Bonding occurred either immediately after bleaching (group Im), a 7-day delay (group 7), or a 14-day delay (group 14), and half the specimens were treated with antioxidant application (groups Im-AA, 7-AA, and 14-AA). Shear bond strength testing was performed on a universal testing machine, and data were analyzed with ANOVA and Fisher test (5%). Delaying of bonding is a useful factor for enhancing shear bond strength (p adhesive cementation to enamel is recommended only when delayed 14 days, or delayed 7 days with sodium ascorbate application. © 2015 by the American College of Prosthodontists.

  20. The effect of enamel bleaching on the shear bond strengths of metal and ceramic brackets.

    Science.gov (United States)

    Oztaş, E; Bağdelen, G; Kiliçoğlu, H; Ulukapi, H; Aydin, I

    2012-04-01

    The aim of this study was to evaluate the effects of bleaching and delayed bonding on the shear bond strengths of metal and ceramic brackets bonded with light and chemically cure composite resin to human enamel. One hundred and twenty extracted human premolar teeth were randomly divided into three groups of 40 each. The first two groups were bleached with 20 per cent carbamide peroxide (CP) at-home bleaching agent. No bleaching procedures were applied to the third group and served as control. The first two and control groups were divided into equal subgroups according to different adhesive-bracket combinations. Specimens in group 1 (n = 40) were bonded 24 hours after bleaching process was completed while the specimens in group 2 (n = 40) were bonded 14 days after. The specimens in all groups were debonded with a Universal testing machine while the modified adhesive remnant index was used to evaluate fracture properties. No statistically significant differences were found between the shear bond strengths of metal and ceramic brackets bonded to bleached enamel after 24 hours, 14 days, and unbleached enamel with light or chemical cure adhesives (P > 0.05). The mode of failure was mostly at the bracket/adhesive interface and cohesive failures within the resin were also observed. Our findings indicated that at-home bleaching agents that contain 20 per cent CP did not significantly affect the shear bond strength of metal and ceramic orthodontic brackets to enamel when bonding is performed 24 hours or 14 days after bleaching.

  1. Effect of Home Bleaching on Microleakage of Fiber-reinforced and Particle-filled Composite Resins

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    Farahnaz Sharafeddin

    2013-12-01

    Full Text Available Background and aims. Bleaching may exert some negative effects on existing composite resin restorations. The aim of this study was to evaluate the effect of home bleaching on microleakage of fiber-reinforced and particle-filled composite resins. Materials and methods. Ninety class V cavities (1.5×2×3 mm were prepared on the buccal surfaces of 90 bovine teeth. The teeth were randomly divided into 6 groups (n=15 and restored as follows: Groups 1 and 2 with Z100, groups 3 and 4 with Z250, and groups 5 and 6 with Nulite F composite resins. All the specimens were thermocycled. Groups 1, 3 and 5 were selected as control groups (without bleaching and the experimental groups 2, 4 and 6 were bleached with 22% carbamide peroxide gel. All the samples were immersed in 2% basic fuchsin dye for 24 hours and then sectioned longitudinally. Dye penetration was evaluated under a stereomicroscope (×25, at both the gingival and incisal margins. Data were analyzed using Kruskal-Wallis, Mann-Whitney and Wilcoxon tests (α=0.05. Results. Statistical analyses revealed that bleaching gel increased microleakage only at gingival margins with Z250 (P=0.007. Moreover, the control groups showed a statistically significant difference in microleakage at their gingival margins. Nulite F had the maximum microleakage while Z250 showed the minimum (P=0.006. Conclusion. Microleakage of home-bleached restorations might be related to the type of composite resin used.

  2. Home-based chemically-induced whitening of teeth in adults.

    Science.gov (United States)

    Hasson, H; Ismail, A I; Neiva, G

    2006-10-18

    remainder at high risk of bias. All trials were sponsored by the manufacturers of tooth whitening products. Six trials compared different whitening products (gel in trays, paint-on films and whitening strips) with placebo/no treatment and all analyses showed the products to be effective, although most comparisons were based on single trials. Nineteen trials compared different whitening products with each other. There was only one meta-analysis which included more than one trial which showed statistically significant differences between the different whitening products. Strips (5.5% to 6.5% hydrogen peroxide(HP)) are more effective than gel in tray at 10% carbamide peroxide (CP) mean difference 1.82 (95% confidence interval (CI) 0.26 to 3.38). All of these trials were assessed as of high risk of bias. 'Mild' to 'moderate' tooth sensitivity and gingival irritation were the most common side effects. The whitening strips and products with high concentrations of HP caused more users to complain from tooth sensitivity. The protocols for preparation of participants prior to bleaching were inconsistent among the studies. Data on baseline scores of whiteness were not reported by the majority of the studies. The current evidence base on tooth whitening products suffers from methodological and publication biases. There is evidence that whitening products work when compared with placebo/no treatment. There are differences in efficacy between the products, mainly due to the levels of active ingredients, hydrogen peroxide and carbamide peroxide. All trials were however short term and the majority of the studies were judged to be at high risk of bias and were either sponsored or conducted by the manufacturers. There is a need for pragmatic long-term and independent clinical studies that include participants representing diverse populations. There is also a need to evaluate long-term harms. Several studies reported (where measured) the common side effects of tooth sensitivity and gingival

  3. Molecular analysis of tooth enamel by Raman spectroscopy after treatment with bleaching agents at different concentrations; Analisis molecular del esmalte dental por medio de espectroscopia Raman despues del tratamiento con agentes blanqueadores a diferentes concentraciones

    Energy Technology Data Exchange (ETDEWEB)

    Duran Sedo, Randall; Obando Rosabal, Sofia; Saenz Bonilla, Paola; Soto Aguilar, Calendy; Vasquez Rodriguez, Amaya

    2014-07-01

    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) [Spanish] Los cambios en la concentracion de la molecula de fosfato v1 de la superficie del esmalte dental son tratados e investigados con agentes blanqueadores de activacion quimica a base de peroxido de hidrogeno al 9,5% y 14% y peroxido de carbamida al 38%, por un periodo de 28 dias. Espectroscopia Raman fue utilizada y 30 piezas

  4. 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

  5. Tooth whitening: what we now know.

    Science.gov (United States)

    Carey, Clifton M

    2014-06-01

    Current research about tooth whitening shows that it is safe and effective when manufacturer's protocol is followed, yet there are risks of which the profession and users should be aware. This update provides a summary of current research and assessment of the safety and efficacy of tooth whitening regimens. Tooth whitening has become one of the most frequently requested dental procedures by the public. The public has come to demand whiter, more perfect smiles and in response many choices for tooth whitening have been made available. These include home-based products such as toothpastes, gels, and films, as well as in-office based systems where products containing highly concentrated bleaching agents are applied under professional supervision. The profession and public have been aware of certain risks related to tooth whitening such as increased tooth sensitivity and gingival irritation. New research has shown that there are other risks such as tooth surface roughening and softening, increased potential for demineralization, degradation of dental restorations, and unacceptable color change of dental restorations. The new research is also focused on optimizing whitening procedures to reduce tooth sensitivity and to increase the persistence of the whitening. Current reports in the literature are reviewed that are related to the use of peroxide based whitening methods. These reports include in vitro studies for method optimization and mechanism as well as clinical studies on effects of various whitening regimens. When manufacturer's instructions are followed, hydrogen peroxide and carbamide peroxide based tooth whitening is safe and effective. Patients should be informed of the risks associated with tooth whitening and instructed on identification of adverse occurrences so that they may seek professional help as needed. Copyright © 2014 Elsevier Inc. All rights reserved.

  6. Effect of light energy on peroxide tooth bleaching.

    Science.gov (United States)

    Luk, Karen; Tam, Laura; Hubert, Manfred

    2004-02-01

    Light-activated bleaching is a method of tooth whitening. The authors conducted a study to compare the whitening effects and tooth temperature changes induced by various combinations of peroxide bleaches and light sources. The authors randomly assigned 250 extracted human teeth halves into experimental groups (n = 10). A placebo gel (control), a 35 percent hydrogen peroxide or a 10 percent carbamide peroxide bleach was placed on the tooth surface and was irradiated with no light (control); a halogen curing light; an infrared, or IR, light; an argon laser; or a carbon dioxide, or CO2, laser. Color changes were evaluated immediately, one day and one week after treatment using a value-oriented shade guide and an electronic dental color analyzer. The outer enamel and inner dentin surface temperatures were monitored before and immediately after each 30-second application of light using a thermocouple thermometer. Color and temperature changes were significantly affected by an interaction of the bleach and light variables. The application of lights significantly improved the whitening efficacy of some bleach materials, but it caused significant temperature increases in the outer and inner tooth surfaces. The IR and CO2 laser lights caused the highest tooth temperature increases. Dentists performing an in-office bleaching technique with the use of an additional light source to accelerate tooth whitening should consider the specific bleaching agent being used, as well as the potential risks of heating teeth. A specific combination of bleach and light that demonstrates good color change and little temperature rise should be selected for in-office tooth bleaching.

  7. 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.

  8. 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. Copyright © 2016 Elsevier Inc. All rights reserved.

  9. Association Between In-Office And At-Home Tooth Bleaching: A Single Blind Randomized Clinical Trial.

    Science.gov (United States)

    Rodrigues, João Lima; Rocha, Patrícia Souza; Pardim, Silvia Letícia de Souza; Machado, Ana Cláudia Vieira; Faria-E-Silva, André Luis; Seraidarian, Paulo Isaías

    2018-01-01

    This controlled randomized clinical trial evaluated the effect of associating at-home and in-office bleaching procedures on tooth sensitivity (TS) and bleaching effectiveness. Forty patients subjected to on session of in-office bleaching with 38% peroxide hydrogen. Subsequently, the patients were randomly allocated to receive a second session of in-office bleaching or to use a tray containing 10% carbamide peroxide delivered during 7 consecutive days. The worst TS score reported during or after each bleaching procedure was recorded using a verbal rating scale and TS risk (score different from 0) was calculated. Color changes were measured 7 days after each in-office session (for patients receiving in-office procedures only) or after the end of at-home bleaching (for the combined protocol), and 6 months after the last procedure for both bleaching protocols. Color was assessed by a spectrophotometer and by color match with the Vita Classical and Bleach guide scales. Statistical analyses were carried out to assess possible differences between the protocols regarding the outcomes and to analyze the effect of time of assessment on color changes. The bleaching protocol did not affect the risk for and the maximum level of TS reported, irrespective of the time of assessment. In the color evaluation, the bleaching protocol also did not affect the ultimate tooth color. In conclusion, after one in-office bleaching session, there was no difference in bleaching effectiveness and TS between performing a second in-office session and associating it with 1-week at-home bleaching.

  10. Crown discoloration promoted by materials used in regenerative endodontic procedures and effect of dental bleaching: spectrophotometric analysis.

    Science.gov (United States)

    Santos, Luciane Geanini Pena Dos; Felippe, Wilson Tadeu; Souza, Beatriz Dulcineia Mendes de; Konrath, Andrea Cristina; Cordeiro, Mabel Mariela Rodríguez; Felippe, Mara Cristina Santos

    2017-01-01

    To assess tooth crown's color after intracanal treatment with triple antibiotic paste (TAP) or calcium hydroxide (CH); cervical sealing with glass ionomer cement (GIC) or mineral trioxide aggregate (MTA); and bleaching with carbamide peroxide. After pulp removal and color spectrophotometer measurement, 50 bovine incisors were divided into 4 experimental groups and one control (untreated). Experiments were performed in phases (Ph). Ph1: TAP (ciprofloxacin, metronidazole, minocycline), TAPM (ciprofloxacin, metronidazole, amoxicillin), DAP (ciprofloxacin, metronidazole), or CH treatment groups. After 1 and 3 days (d); 1, 2, 3 weeks (w); and 1, 2, 3 and 4 months (m), color was measured and medications were removed. Ph2: GIC or MTA cervical sealing, each using half of the specimens from each group. Color was assessed after 1d, 3d; 1w, 2w, 3w; 1m and 2m. Ph3: Two bleaching sessions, each followed by color measurement. Data were analyzed with ANOVA and post-hoc Holm-Sidak method. Ph1: Specimens of TAP group presented higher color alteration (ΔE) mean than those of TAPM group. No significant difference was found among TAP or TAPM and CH, DAP or Control groups. Ph2: cervical sealing materials showed no influence on color alteration. Ph3: Different ΔE means (from different groups), prior to bleaching, became equivalent after one bleaching session. TAP induces higher color alteration than TAPM; color alteration increases over time; cervical sealing material has no influence on color alteration; and, dental bleaching was able to recover, at least partially, the tooth crown's color.

  11. Fracture resistance of teeth submitted to several internal bleaching protocols.

    Science.gov (United States)

    Leonardo, Renato de Toledo; Kuga, Milton Carlos; Guiotti, Flávia Angélica; Andolfatto, Carolina; Faria-Júnior, Norberto Batista de; Campos, Edson Alves de; Keine, Kátia Cristina; Dantas, Andrea Abi Rached

    2014-03-01

    The aim of this study was to evaluate the fracture resistance of teeth submitted to several internal bleaching protocols using 35% hydrogen peroxide (35HP), 37% carbamide peroxide (37CP), 15% hydrogen peroxide with titanium dioxide nanoparticles (15HPTiO2) photoactivated by LED-laser or sodium perborate (SP). After endodontic treatment, fifty bovine extracted teeth were divided into five groups (n = 10): G1-unbleached; G2-35HP; G3-37CP; G4-15HPTiO2 photoactivated by LED-laser and G5-SP. In the G2 and G4, the bleaching protocol was applied in 4 sessions, with 7 days intervals between each session. In the G3 and G5, the materials were kept in the pulp teeth for 21 days, but replaced every 7 days. After 21 days, the teeth were subjected to compressive load at a cross head speed of 0.5 mm/min, applied at 135° to the long axis of the root using an eletromechanical testing machine, until teeth fracture. The data were submitted to ANOVA and Tukey tests (α = 5%). The 35HP, 37CP, 15HPTiO2 and SP showed similar fracture resistance teeth reduction (p > 0.05). All bleaching treatments reduced the fracture resistance compared to unbleached teeth (p endodontically-treated teeth, but there were no differences between each other. There are several internal bleaching protocols using hydrogen peroxide in different concentrations and activation methods. This study evaluated its effects on fracture resistance in endodontically-treated teeth.

  12. Effect of Green Tea Extract as Antioxidant on Shear Bond Strength of Resin Composite to in-Office and Home-Bleached Enamel

    Directory of Open Access Journals (Sweden)

    Sharafeddin F

    2016-09-01

    Full Text Available Statement of Problem: Shear bond strength (SBS of home and office bleached enamel will be compromised by immediate application of composite restoration. Antioxidant agent may overcome this problem. Objectives: This in vitro study assessed the effect of green tea extract on shear bond strength of resin composite to in-office and home-bleached enamel. Materials and Methods: In this experimental study, 40 extracted intact human incisors were embedded in cylindrical acrylic resin blocks (2.5 ×1.5 cm, with the coronal portion above the cemento enamel junction out of the block. Then, after bleaching labial enamel surfaces of 20 teeth with 15% carbamide peroxide 6 hours a day for 5 days, they were randomly divided into two groups: A1 and A2 (n = 10, depending upon whether or not they are treated with antioxidant. Labial enamel surfaces of the remaining 20 teeth were bleached with 38% hydrogen peroxide before being randomly divided into groups B1 and B2 (n = 10, again depending on whether or not the antioxidant was used in their treatment . The experimental groups (A2,B2 were treated with 5% solution of green tea extract before resin composite restoration was done by a cylindrical Teflon mould (5×2 mm. Shear bond strength of the specimens was tested under a universal testing machine (Zwick/Roell Z020. The SBS data were analyzed by using One-way ANOVA and Tukey HSD tests (p < 0.05. Results: There were no statistically significant differences between shear bond strength of the control group (A1 and treated group (A2 but there were statistically significant differences between the groups B1 and B2 (p < 0.05. Conclusions: Application of antioxidant did not increase the shear bond strength of home-bleached enamel to resin composite but its application increased the shear bond strength of in-office bleached enamel to resin composite.

  13. Cytotoxic effects of chemotherapeutic drugs and heterocyclic compounds at application on the cells of primary culture of neuroepithelium tumors.

    Science.gov (United States)

    Kulchitsky, Vladimir A; Potkin, Vladimir I; Zubenko, Yuri S; Chernov, Alexander N; Talabaev, Michael V; Demidchik, Yuri E; Petkevich, Sergei K; Kazbanov, Vladimir V; Gurinovich, Tatiana A; Roeva, Margarita O; Grigoriev, Dmitry G; Kletskov, Alexei V; Kalunov, Vladimir N

    2012-01-01

    Neuroepithelial tumor cells were cultured in vitro. The biopsy material was taken from 93 children at removal of the brain tumors during neurosurgical operations. The individual features of the cells sensitivity of primary cultures in respect to protocol-approved chemotherapy drugs and changes in the Interleukin-6 (Il-6) level in the culture medium after the application of chemotherapy were established. The initial level of Il-6 exceeded 600.0 pg/ml in the cultural medium with histologically verified pilomyxoid astrocytoma cells, and ranged from 100.0 to 200.0 pg/ml in the medium at cultivation of ganglioneuroblastoma and pilocytic astrocytoma. A decrease in the Il-6 level in the medium culture of primary tumors cells was observed after the application of chemotherapeutic agents on the cells of pilomyxoid astrocytoma, astrocytomas, and pilocytic desmoplastic/nodular medulloblastoma. The production of Il-6 increased after application of cytostatic drugs on the cells of oligoastrocytomas. A decrease in Il-6 level after application of Cisplatin and Methotrexate and a 5-10 fold increase in the level of Il-6 after application of Etoposide, Carboplatin, Cytarabine, and Gemcitabine were registered in the medium with ganglioneuroblastoma. To improve the cytotoxic action of chemotherapeutic agents, the combined application of cytostatics with heterocyclic compounds was carried out. A computer modeling of ligand-protein complexes of carbamide using the Dock 6.4 and USF Chimera program packages was performed with molecular mechanics method. Special attention was drawn to the ability of several isoxazole heterocycles and isothiazolyl to inhibit the tyrosine kinase. It was proved in vitro that the joint application of chemotherapeutic agents and heterocyclic compounds could reduce the concentration of the cytostatic factor by 10 or more times, having maintained the maximum cytotoxic effect. It was assumed that the target amplification of cytotoxic action of chemotherapeutic

  14. Influence of intracanal irrigants on coronal fracture resistance of endodontically treated and bleached teeth: An In vitro Study

    Directory of Open Access Journals (Sweden)

    Maryam Khoroushi

    2017-01-01

    Full Text Available Background: Irrigation has a key role in the success of endodontic treatment. Intracanal irrigant solutions have adverse effects on the physical properties of dentin. Aim: The present study aimed to evaluate the effect of different irrigation protocols on coronal fracture resistance of endodontically treated teeth undergoing bleaching treatment. Design and Materials and Methods: Access cavities were prepared in 120 maxillary premolars which were divided into two groups (n = 60 – Group A: nonbleached, Group B: bleached (B. Each group was subdivided into five subgroups based on irrigation protocol (n = 12; G1: normal saline (NS, G2: 2.5% sodium hypochlorite (NaOCl, G3: 10% citric acid (CA, G4: 17% ethylene diamine tetra acetic acid, and G5: NaOCl plus CA. In Group B, the teeth were bleached using 38% hydrogen peroxide and 20% carbamide peroxide gels as in-office and at-home bleaching techniques for 3 weeks. All the teeth were restored with composite resin, thermocycled, and incubated for 24 h. The specimens underwent fracture resistance tests. Data were analyzed with ANOVA, Tukey honestly significant difference test, t-test, and Chi-squared test (α =0.05. Results: T-test showed significant differences between each two corresponding subgroups (P < 0.0001. In Group A, NS demonstrated significantly higher fracture resistance compared to others; however, minimum fracture resistance recorded in G2. In Group B, the maximum fracture resistance was recorded in G1, with the minimum being recorded in G5. Samples irrigated with NaOCl and NaOCl plus CA exhibited significantly lower fracture resistance compared to NS subgroup (P < 0.05. Conclusions: Within the limitations of this study, it can be concluded that the irrigation protocol used during endodontic treatment with/without bleaching can affect the coronal fracture resistance.

  15. In vitro Assessment of Influence of Various Bleaching Protocols on the Strength of Ceramic Orthodontic Brackets bonded to Bleached Tooth Surface: A Comparative Study.

    Science.gov (United States)

    Iska, Divya; Devanna, Raghu; Singh, Madhvi; Chitumalla, Rajkiran; Balasubramanian, Sai C Bala; Goutam, Manish

    2017-12-01

    Esthetics is one of the common issues because of which patients consult dental orthodontic treatment. Two ways of tooth bleaching are available these days, which includes in-office bleach and home bleach. Various bleaching protocols are available these days for treating the tooth surfaces. Hence, we planned the present study for investigating the impact of various intracoronal bleaching protocols on shear bond strength of ceramic brackets bonded to tooth surface after bleaching. The present study included assessment of 100 extracted maxillary central incisors with the integrated buccal surface. A resin block was made and individual teeth were embedded in each block. Root canal therapy procedure was performed in all the teeth, after which 2 mm short of tooth apex up to the level of cementoenamel junction, removal of the root canal filling was done. All the samples were broadly divided into four study groups with 25 samples in each group. Bleaching procedure was carried in all the samples intracoronally followed by testing of shear bond strength using universal force testing machine. Following the modified adhesive remnant index (AI), assessment of remaining adhesive on the brackets was done. All the results were compiled and analyzed by Statistical Package for the Social Sciences (SPSS) software version 17.0. In the control group, mean shear bond strength was found to be 17.9 MPa. While comparing the carbamide peroxide (CP) group with sodium perborate study group, we observed a statistically significant difference. Nonsignificant results were obtained while comparing the shear bond strength in between sodium perborate group and hydrogen peroxide (HP) group. Intracoronal bleaching does affect the shear bond strength of ceramic brackets. Sodium perborate bleaching influences shear bond strength more strongly than other bleaching agents such as CP and HP. In patients undergoing orthodontic treatment, HP is a preferred agent where bleaching has to be followed by

  16. The effect of long-term use of tooth bleaching products on the human enamel surface.

    Science.gov (United States)

    Polydorou, Olga; Scheitza, Sophia; Spraul, Mathias; Vach, Kirstin; Hellwig, Elmar

    2018-01-01

    The aim of this in vitro study was to evaluate the long-term effect of bleaching on human enamel. Four groups of enamel specimens were prepared (n = 20): group 1: bleaching with Opalescence Boost [40% hydrogen peroxide (H 2 O 2 ), 3 × 20 min/week]; group 2: control group (the specimens were stored in human saliva); group 3: beaching with Vivastyle Paint on Plus (6% H 2 O 2 , 2 × 10 min/day), and group 4: bleaching with Opalescence PF 16% [16% carbamide peroxide (CP), 6 h/day]. After each bleaching session the specimens were stored in human saliva. Knoop microhardness and surface roughness were measured: before bleaching, after 2-week and after 8-week bleaching. After 2-week treatment, surface roughness was significantly increased in all experimental groups (p  0.05). The roughness changes exerted after 8-week bleaching were not significantly higher than the ones after 2 weeks (p > 0.05). After 8-week treatment, the increase in roughness caused by 16% CP was significantly higher (p bleaching on enamel was not shown to be dependent on the method or the H 2 O 2 concentration. Bleaching with CP 16% resulted in higher roughness than bleaching with H 2 O 2 , while 40% H 2 O 2 caused the higher microhardness increase. The present study showed that in-office bleaching with 40% H 2 O 2 seems to be at least as safe as home bleaching as far as their effects on human enamel are concerned.

  17. Effect of bleaching agent extracts on murine macrophages.

    Science.gov (United States)

    Fernandes, Aletéia M M; Vilela, Polyana G F; Valera, Marcia C; Bolay, Carola; Hiller, Karl Anton; Schweikl, Helmut; Schmalz, Gottfried

    2018-05-01

    The aim of this study was to evaluate the cytotoxicity and the influence of bleaching agents on immunologically cell surface antigens of murine macrophages in vitro. RAW 264.7 cells were exposed to bleaching gel extracts (40% hydrogen peroxide or 20% carbamide peroxide) and different H 2 O 2 concentrations after 1 and 24-h exposure periods and 1-h exposure and 23-h recovery. Tests were performed with and without N-acetyl cysteine (NAC) and buthionine sulfoximine (BSO). Cell viability was determined by MTT assay. The expression of surface markers CD14, CD40, and CD54 with and without LPS stimulation was detected by flow cytometry, while the production of TNF-α was measured by ELISA. Statistical analysis was performed using the Mann-Whitney U test (α = 0.05). Extracts of bleaching agents were cytotoxic for cells after a 1-h exposure; cells could not recover after 24 h. This effect can be mitigated by the antioxidant NAC and increased by BSO, an inhibitor of glutathione (GSH) synthesis. LPS stimulated expression of all surface markers and TNF-α production. Exposure to bleaching agent extracts and H 2 O 2 leads to a reduction of TNF-α, CD14, and CD40 expression, while the expression of CD54 was upregulated at non-cytotoxic concentrations. Whereas NAC reduced this effect, it was increased in the presence of BSO. Extracts of bleaching agents were irreversibly cytotoxic to macrophages after a 1-h exposure. Only the expression of CD54 was upregulated. The reactions are mediated by the non-enzymatic antioxidant GSH. The addition of an antioxidant can downregulate unfavorable effects of dental bleaching.

  18. Dental bleaching on teeth submitted to enamel microabrasion 30 years ago-a case report of patients' compliance during bleaching treatment.

    Science.gov (United States)

    Sundfeld, Daniel; Pavani, Caio Cesar; Schott, Timm Cornelius; Machado, Lucas Silveira; Pini, Núbia Inocêncya Pavesi; Bertoz, André Pinheiro de Magalhães; Sundfeld, Renato Herman

    2018-04-20

    The present dental bleaching case report describes a new method that precisely quantifies the daily wearing-times of the bleaching product by inserting a microsensor in the acetate custom tray. The bleaching efficacy was also discussed since the patient was previously submitted to enamel microabrasion. The patient was submitted to enamel microabrasion in 1987, and bleaching treatment was performed in 2005. In 2017, re-bleaching was executed using 10% peroxide carbamide. The electronic microsensor, TheraMon (TheraMon® microelectronic system; Sales Agency Gschladt, Hargelsberg, Austria), was embedded in the labial region of the upper and lower acetate trays to evaluate the wearing-times of the acetate trays/bleaching product. The patient was instructed to wear the tray for 6 to 8 h/day while sleeping. After 24 days of bleaching treatment, the data obtained from the TheraMon electronic devices was collected and interpreted. The patient did not entirely follow the bleaching treatment as recommended, as there was no evidence of use of the upper and lower trays for some days; additionally, the bleaching product was used for shorter and longer periods than was instructed. The TheraMon microeletronic device precisely measured the wearing-times of the acetate tray/bleaching product during the bleaching treatment. Teeth submitted to enamel microabrasion presented with a healthy clinical appearance after 30 years. Measuring the length and frequency of use of an acetate tray/bleaching product can be important to clinicians and patients for obtaining a controlled and adequate bleaching treatment.

  19. Dentin bond strength and nanoleakage of the adhesive interface after intracoronal bleaching.

    Science.gov (United States)

    Cavalli, Vanessa; Sebold, Maicon; Shinohara, Mirela Sanae; Pereira, Patrícia Nóbrega Rodrigues; Giannini, Marcelo

    2018-04-01

    This study evaluated dentin bond strength (BS) and nanoleakage of non- and pre-etched dentin immediately (T 0 ,), 7 days (T 7 ), and 14 days (T 14 ) after bleaching. Bovine incisors (150) were selected and half of them submitted to intrapulpal dentin etching (e). Non- and pre-etched dentin were subjected to the following (n = 15): no bleaching/control (C); 35% carbamide peroxide (CP); 35% hydrogen peroxide (35% HP); 25% hydrogen peroxide (25% HP); and sodium perborate (SP). Bleaching agents were applied to the pulp chamber four times within a 72-h interval. Afterwards, pulp chamber dentin was prepared for the BS test at different evaluation times (n = 5): T 0 , T 7 , and T 14 . Composite blocks were built on pulp chamber and sectioned in slices. Slices were reduced to an hour-glass shape with a cross-sectional area of 0.8 mm 2 and submitted to microtensile BS test. Two additional specimens for each group were prepared for nanoleakage evaluation by transmission electron microscopy (TEM). Results were analyzed by ANOVA (two-way) and Dunnett's test (p bleaching for both sound and pre-etched dentin (p bleached dentin increased for all groups, whereas the pre-etched SPe group presented BS similar to the Ce. Nanoleakage within the hybrid layer was perceptible immediately after bleaching, although a decrease in nanoleakage was observed for all groups at T 14 . Adhesive restorations should be performed 7-14 days after bleaching, according to the bleaching agent used. Intracoronal bleaching should be performed preferably with sodium perborate if previous dentin etching is applied. © 2018 Wiley Periodicals, Inc.

  20. Neurosensory analysis of tooth sensitivity during at-home dental bleaching: a randomized clinical trial

    Science.gov (United States)

    Briso, André Luiz Fraga; Rahal, Vanessa; de Azevedo, Fernanda Almeida; Gallinari, Marjorie de Oliveira; Gonçalves, Rafael Simões; dos Santos, Paulo Henrique; Cintra, Luciano Tavares Angelo

    2018-01-01

    Abstract Objective The objective of this study was to evaluate dental sensitivity using visual analogue scale, a Computerized Visual Analogue Scale (CoVAS) and a neurosensory analyzer (TSA II) during at-home bleaching with 10% carbamide peroxide, with and without potassium oxalate. Materials and Methods Power Bleaching 10% containing potassium oxalate was used on one maxillary hemi-arch of the 25 volunteers, and Opalescence 10% was used on the opposite hemi-arch. Bleaching agents were used daily for 3 weeks. Analysis was performed before treatment, 24 hours later, 7, 14, and 21 days after the start of the treatment, and 7 days after its conclusion. The spontaneous tooth sensitivity was evaluated using the visual analogue scale and the sensitivity caused by a continuous 0°C stimulus was analyzed using CoVAS. The cold sensation threshold was also analyzed using the TSA II. The temperatures obtained were statistically analyzed using ANOVA and Tukey's test (α=5%). Results The data obtained with the other methods were also analyzed. 24 hours, 7 and 14 days before the beginning of the treatment, over 20% of the teeth presented spontaneous sensitivity, the normal condition was restored after the end of the treatment. Regarding the cold sensation temperatures, both products sensitized the teeth (p0.05). In addition, when they were compared using CoVAS, Power Bleaching caused the highest levels of sensitivity in all study periods, with the exception of the 14th day of treatment. Conclusion We concluded that the bleaching treatment sensitized the teeth and the product with potassium oxalate was not able to modulate tooth sensitivity. PMID:29742258

  1. 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.

  2. Nightguard vital bleaching: side effects and patient satisfaction 10 to 17 years post-treatment.

    Science.gov (United States)

    Boushell, Lee W; Ritter, André V; Garland, Glenn E; Tiwana, Karen K; Smith, Lynn R; Broome, Angela; Leonard, Ralph H

    2012-06-01

      The long-term patient satisfaction and safety of nightguard vital bleaching (NGVB) requires further evaluation.   The purpose of this study was to evaluate patients' satisfaction and identify side effects of NGVB up to 17 years post-treatment.   Thirty-one participants who had completed previous NGVB studies using 10% carbamide peroxide were contacted at least 10 years post-treatment (range 10-17 years, average 12.3 years). Participants reported shade satisfaction (very satisfied [VS], partially satisfied [PS], or not satisfied [NS]) as well as potential complications. Participants had teeth # 6 to 11 examined for tooth vitality, gingival inflammation (Löe's Gingival Index [GI]), and radiographically for external cervical resorption (ECR).   All of the participants had successful lightening of their teeth. Sixty-one percent (19) had not retreated their teeth. Of those who had not retreated their teeth and who responded to the question of whitening satisfaction, 31% (4/13) were VS, 54% (7/13) were PS, and 15% (2/13) were NS with their current shade. Of those who had retreated their teeth, all were VS or PS. Ninety-one percent of the examined teeth had GI = 0 (normal), 7% had GI = 1 (mild inflammation), and 2% had GI = 2 (moderate inflammation). Sixty-nine percent of teeth tested responded to a cold stimulus. Radiographs did not detect ECR or apical lesions. No participant reported having a gingival biopsy post-treatment, and 87% would whiten again.   Patient satisfaction with NGVB may last as long as 12.3 years in average (range 10-17 years) post-treatment. GI and ECR findings were considered within the normal expectations for the sample studied, suggesting minimal clinical post-NGVB side effects up to 17 years. Nightguard vital bleaching provides patient satisfaction with minimal side effects up to 17 years post-treatment. © 2011 Wiley Periodicals, Inc.

  3. The influence of a novel in-office tooth whitening procedure using an Er,Cr:YSGG laser on enamel surface morphology.

    Science.gov (United States)

    Dionysopoulos, Dimitrios; Strakas, Dimitrios; Koliniotou-Koumpia, Eugenia

    2015-08-01

    The purpose of this in vitro study was to evaluate the influence of a novel in-office tooth whitening procedure using Er,Cr:YSGG laser radiation on bovine enamel. Forty-eight enamel specimens were prepared from bovine canines and divided into four groups: Group 1 specimens (control) received no whitening treatment; Group 2 received whitening treatment with an at-home whitening agent (22% carbamide peroxide) for 7 days; Group 3 received whitening treatment with a novel in-office whitening agent (35% H(2)O(2)); Group 4 received the same in-office whitening therapy with Group 3 using Er,Cr:YSGG laser in order to accelerate the whitening procedure. The specimens were stored for 10 days after the whitening treatment in artificial saliva. Vickers hardness was determined using a microhardness tester and surface roughness was evaluated using a VSI microscope. Three specimens of each experimental group were examined under SEM and the mineral composition of the specimens was evaluated using EDS. Data were statistically analyzed using one-way ANOVA, Tukey's post-hoc test, Wilcoxon signed rank and Kruskal-Wallis tests (a = 0.05). The surface microhardness of the enamel was reduced after the in-office whitening treatments (Pwhitening treatment (P> 0.05). Moreover, the surface roughness was not significantly changed after tooth whitening. EDS analysis did not show alterations in the enamel mineral composition, while SEM observations indicated changes in the surface morphology, especially after in-office tooth whitening (Pwhitening treatment with Er,Cr:YSGG laser did not affect the alterations in enamel surface compared with the conventional in-office whitening technique. © 2015 Wiley Periodicals, Inc.

  4. Influence of Enamel Thickness on Bleaching Efficacy: An In-Depth Color Analysis.

    Science.gov (United States)

    Públio, Juliana do Carmo; D'Arce, Maria Beatriz Freitas; Catelan, Anderson; Ambrosano, Gláucia Maria Bovi; Aguiar, Flávio Henrique Baggio; Lovadino, José Roberto; Lima, Débora Alves Nunes Leite

    2016-01-01

    This study evaluated the influence of different enamel thicknesses and bleaching agents on treatment efficacy in-depth by spectrophotometry color analysis. Eighty bovine dental fragments were previously stained in black tea solution and randomly assigned into eight groups (n=10), 1.75mm dentin thickness and different enamel thicknesses as follows: 0.5mm, 1.0mm planned, 1.0mm unplanned (aprismatic enamel), and absence of enamel. The 10% carbamide peroxide (CP) and 35% hydrogen peroxide (HP) bleaching gels were applied on the enamel surface following the manufacturer's recommendations. Color of underlying dentin was evaluated at four times: after staining with tea (baseline) and after each one of the three weeks of bleaching treatment, by CIE L*a*b* system using reflectance spectrophotometer (CM 700d, Konica Minolta). The ΔE, ΔL, Δa, and Δb values were recorded and subjected to repeated measures ANOVA and Tukey's test (α=0.05). The results showed an increase on lightness (L*), with decreased redness (a*) and yellowness (b*). At first and second week, bleaching with CP showed higher whitening effectiveness compared to bleaching with HP and the presence of aprismatic enamel significantly reduced ΔE for bleaching with CP. After three weeks of bleaching, few differences were observed between CP and HP groups, and outer enamel layer caused no influence on bleaching effectiveness. Overall, both at-home and in-office bleaching treatments were effective and the presence of aprismatic enamel did not interfere on the whitening efficacy.

  5. Effects of bleaching agents on human enamel light reflectance.

    Science.gov (United States)

    Markovic, Ljubisa; Fotouhi, Kasra; Lorenz, Heribert; Jordan, Rainer A; Gaengler, Peter; Zimmer, Stefan

    2010-01-01

    Tooth whitening has been associated with splitting-up chromogenic molecules by hydrogen peroxides. Though micromorphological alterations are well documented, little is known about optical changes as a function of shifting in wavelengths. Therefore, the aim of the current study was to measure reflectance changes after bleaching in vitro by using a spectrometer. Forty-eight enamel slabs (diameter = 5 mm) were prepared from the sound enamel of extracted human teeth that were: 1) fully impacted, 2) from juveniles ages 10 to 16 years, 3) from adults 35 to 45 years of age and 4) from seniors older than age 65. In all specimens, the baseline total reflectance measurement was performed with a computer-assisted spectrometer (Ocean Optics, Dunedin, FL, USA) within wavelengths (wl) from 430 nm to 800 nm. Four enamel samples of each age group were exposed to either 10% or 15% carbamide peroxide (Illuminé Home, Dentsply, Konstanz, Germany) or 35% hydrogen peroxide (Pola Office, SDI Limited, Victoria, Australia). After surface treatment, all slabs underwent total reflectance measurement again. Statistical analysis was calculated at wl 450, 500 and 750 nm using the Student's paired t-test and one-way variance analysis. Total reflectance significantly increased after bleaching at all enamel maturation stages, irrespective of the bleaching agent concentration, for wl 450 nm (blue) and 500 nm (green) with penamel from adults and seniors (pwhitening of the dental enamel works at different maturation stages, even in impacted teeth. This effect is irrespective of the bleaching protocol used and the bleaching agent concentration.

  6. Spectrophotometric evaluation of dental bleaching under orthodontic bracket in enamel and dentin

    Science.gov (United States)

    Correr, Americo-Bortolazzo; Rastelli, Alessandra-Nara-Souza; Lima, Débora-Alves-Nunes-Leite; Consani, Rafael-Leonardo-Xediek

    2014-01-01

    Aware of the diffusion capacity of bleaching in the dental tissues, many orthodontists are subjecting their patients to dental bleaching during orthodontic treatment for esthetic purposes or to anticipate the exchange of esthetic restorations after the orthodontic treatment. For this purpose specific products have been developed in pre-loaded whitening trays designed to fit over and around brackets and wires, with clinical efficacy proven. Objective: The objective of this study was to evaluate, through spectrophotometric reflectance, the effectiveness of dental bleaching under orthodontic bracket. Material and Methods: Thirty-two bovine incisors crown blocks of 8 mm x 8 mm height lengths were used. Staining of tooth blocks with black tea was performed for six days. They were distributed randomly into 4 groups (1-home bleaching with bracket, 2- home bleaching without bracket, 3- office bleaching with bracket, 4 office bleaching without bracket). The color evaluation was performed (CIE L * a * b *) using color reflectance spectrophotometer. Metal brackets were bonded in groups 1 and 3. The groups 1 and 2 samples were subjected to the carbamide peroxide at 15%, 4 hours daily for 21 days. Groups 3 and 4 were subjected to 3 in-office bleaching treatment sessions, hydrogen peroxide 38%. After removal of the brackets, the second color evaluation was performed in tooth block, difference between the area under the bracket and around it, and after 7 days to verified color stability. Data analysis was performed using the paired t-test and two-way variance analysis and Tukey’s. Results: The home bleaching technique proved to be more effective compared to the office bleaching. There was a significant difference between the margin and center color values of the specimens that were subjected to bracket bonding. Conclusions: The bracket bond presence affected the effectiveness of both the home and office bleaching treatments. Key words:Tooth bleaching, spectrophotometry

  7. High levels of hydrogen peroxide in overnight tooth-whitening formulas: effects on enamel and pulp.

    Science.gov (United States)

    Pugh, George; Zaidel, Lynette; Lin, Nora; Stranick, Michael; Bagley, Daniel

    2005-01-01

    Limited data are available to assess the safety of high levels of hydrogen peroxide in overnight tooth-whitening formulas. The purpose of this study was to assess the effects of hydrogen peroxide on enamel microhardness, pulp penetration, and enamel morphology. Colgate Platinum Professional Overnight Whitening System (Colgate Oral Pharmaceuticals, Inc., Canton, MA, USA) (10% carbamide peroxide, equivalent to 3.5% hydrogen peroxide) was compared with two prototype formulations containing either 7.0% or 12.0% hydrogen peroxide. In the pulp chamber studies, human extracted teeth were exposed to 3.5%, 7.0%, or 12.0% hydrogen peroxide for 30 minutes, 4 hours, or 7 hours. Microhardness, electron spectroscopy for chemical analysis, and atomic force microscopy evaluations were made from enamel blocks cut from human extracted molars. The enamel blocks were evaluated following 14 7-hour treatments (98 h total). At 7 hours' post-treatment, hydrogen peroxide penetrated the pulp chamber at 23.12 +/- 10.09, 24.58 +/- 6.90, and 26.39 +/- 5.43 microg for 3.5%, 7.0%, and 12.0% hydrogen peroxide, respectively. With regard to enamel morphology, pulp penetration, microhardness, and elemental composition, no statistically significant differences were observed between treatment groups following 98 hours of treatment. Hydrogen peroxide does not adversely affect enamel morphology or microhardness. The levels recovered in pulp indicate that hydrogen peroxide is not expected to inhibit pulpal enzymes. Overnight tray products containing levels of hydrogen peroxide of 3.5%, 7.0%, and 12.0% are not expected to adversely affect the enamel or pulpal enzymes. Additional safety studies are needed to assess the potential for tooth sensitivity and gingival irritation.

  8. Effects of different preparation procedures during tooth whitening on enamel bonding.

    Science.gov (United States)

    Wilson, Dustin; Xu, Changqi; Hong, Liang; Wang, Yong

    2009-04-01

    The objective of this study was to assess effects of some clinically related preparation procedures during tooth whitening on enamel bonding properties. Sixty-two extracted human teeth were cleaned and divided into four groups. Forty-two of the teeth were left with their natural surface intact while 20 teeth were polished to form a flat surface. Half of the tooth served as the experimental side and received one of the two whitening products: Opalescence (10% carbamide peroxide) and Crest Whitestrips (6.5% hydrogen peroxide), for 2 weeks. Post-bleaching intervals included: 1 day, 1 week, and 2 weeks. On these days, tooth (10 mm x 1.5 mm x 1.5 mm) sections were evaluated using Raman spectroscopy, scanning electron microscopy and tensile bond strength tests. T-test, ANOVA test, and mixed model regression analysis were used to assess the differences. No significant difference existed between natural surface and polished surface teeth for all groups at both Day One and Week Two (P > 0.05). On Day One, both treated groups had significant lower bond strength than the control group (P = 0.002). After 2 weeks, no significant difference existed between any group (P = 0.381). SEM indicated that resin-enamel interfaces in bleached enamel exhibited more defects in granular formations when compared to the control. Raman results indicated a lower degree of polymerization (DP) of adhesive at the interface for treated teeth surfaces. In summary, pre-bleaching surface treatments such as polish or non-polish, had no effect on bond strength. Bleaching significantly decreased bond strength initially, but after 2 weeks, bleaching had no significant effect on bond strength. Storage time had significant effect on Opalescence treated enamel, but not on control and Whitestrip treated enamel. The decrease of bond strength may be related to interfacial defects and low DP due to oxygen release after bleaching.

  9. In vitro colorimetric evaluation of the efficacy of home bleaching and over-the-counter bleaching products.

    Science.gov (United States)

    Dietschi, Didier; Benbachir, Nacer; Krejci, Ivo

    2010-06-01

    Various bleaching modalities are now offered to patients, either monitored by the dental office or self-directed, for which relative efficiency is unknown. The aim of this in vitro study was to evaluate the ability of bleaching products and protocols to lighten enamel and dentin. Bovine tooth specimens of standardized thickness (2.5 +/- 0.025 mm with similar dentin and enamel thickness) were prepared and stained with whole blood and hemolysate before being submitted to seven supervised or self-directed bleaching regimens: tray-based bleaching using 10% (Opalescence, Ultradent; Nite White, Discus Dental) or light-activated 30% (Metatray, Metatray) carbamide peroxide (CP); 6% (Zoom, Discus Dental) or 9% (TresWhite, Ultradent) hydrogen peroxide (HP); strips (Whitening Strips, Oral B-Rembrandt); and paint-on gel (Paint on Plus, Ivoclar Vivadent) containing 8.1% and 6% HP, respectively. Colorimetric measurements were performed on each specimen side, according to the CIE L*a*b* system, before and after staining, as well as after 5, 10, and the recommended number of bleaching applications. Color change after recommended number of applications (DEr) varied from 15.72 (Metatray) to 29.67 (Nite White) at enamel and 14.91 (Paint on Plus) to 41.43 (Nite White) at dentin side; Nite White (10% CP) and TresWhite (9% HP) were more effective than Metatray (30% CP) and Paint on Plus (6% HP) after 5 or the recommended number of applications. In this in vitro study based on bovine teeth, tray-based systems produced the faster and better bleaching effect, regardless of the product and concentration used, at both enamel and dentin sides.

  10. 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.

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

    International Nuclear Information System (INIS)

    Ilyuschenko, A.; Savich, V.; Pilinevich, L.; Rak, A.

    2001-01-01

    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)

  12. Acid demineralization susceptibility of dental enamel submitted to different bleaching techniques and fluoridation regimens.

    Science.gov (United States)

    Salomão, Dlf; Santos, Dm; Nogueira, Rd; Palma-Dibb, Rg; Geraldo-Martins, Vr

    2014-01-01

    The aim of the current study was to assess the acid demineralization susceptibility of bleached dental enamel submitted to different fluoride regimens. One hundred bovine enamel blocks (6×6×3 mm) were randomly divided into 10 groups (n=10). Groups 1 and 2 received no bleaching. Groups 3 to 6 were submitted to an at-home bleaching technique using 6% hydrogen peroxide (HP; G3 and G4) or 10% carbamide peroxide (CP; G5 and G6). Groups 7 to 10 were submitted to an in-office bleaching technique using 35% HP (G7 and G8) or 35% CP (G9 and G10). During bleaching, a daily fluoridation regimen of 0.05% sodium fluoride (NaF) solution was performed on groups 3, 5, 7, and 9, while weekly fluoridation with a 2% NaF gel was performed on groups 4, 6, 8, and 10. The samples in groups 2 to 10 were pH cycled for 14 consecutive days. The samples from all groups were then assessed by cross-sectional Knoop microhardness at different depths from the outer enamel surface. The average Knoop hardness numbers (KHNs) were compared using one-way analysis of variance and Tukey tests (α=0.05). The comparison between groups 1 and 2 showed that the demineralization method was effective. The comparison among groups 2 to 6 showed the same susceptibility to acid demineralization, regardless of the fluoridation method used. However, the samples from groups 8 and 10 showed more susceptibility to acid demineralization when compared with group 2 (penamel to acid demineralization. However, the use of 35% HP and 35% CP must be associated with a daily fluoridation regimen, otherwise the in-office bleaching makes the bleached enamel more susceptible to acid demineralization.

  13. Recipe and technology development for minced canned products of special purpose based on the underutilized north region fishery object (thorny skate

    Directory of Open Access Journals (Sweden)

    Raibulov S. P.

    2016-09-01

    Full Text Available The paper presents the results of justifying the use of thorny skate in the technology of minced meat canned products of special purpose. The key criterion determined the specialized purpose of canned food is the high content of physiologically functional food ingredient of chondroitin sulfate in the cartilage of thorny skate wings. The high content of chondroitin sulfate in raw materials ensures that the content of the physiologically functional ingredient in the finished canned food will be at the level from 220 to 250 mg per 100 g of product. The method of IR blanching is presented for removing urea from the thorny skate muscle tissue. To confirm the efficiency of the developed method of urea removal, it has been proposed to use a modified photocolorimetric method for determination of mass fractions of urea in feed flour according to the governmental standard GOST R 50032–92 "Feed flour made of fish, marine mammals, crustaceans and invertebrates. Methods of determining the mass fraction of urea and calculation of the crude protein with a given mass fraction of carbamide". With the help of this technique, the efficiency of urea removal from the thorny skate tissue by the proposed method has been determined. The residual urea content in the meat of thorny skate after IR blanching is 0.76 %, which is two times lesser than border value of sensitivity of the person (approximated as 1.2 %. The paper presents the materials of experimental substantiation of optimum formulation of new canned meat based on the method of fuzzy modeling. The ratio of the main components of the meatballs recipe (thorny skate and Atlantic cod close to the optimum is 48 % by weight of meat for each component separately.

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

    International Nuclear Information System (INIS)

    Liu, Changzhen; Meng, Dawei; Wu, Xiuling; Wang, Yongqian; Yu, Xiaohong; Zhang, Zhengjie; Liu, Xiaoyang

    2011-01-01

    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 o C 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.

  15. Effects of at-home and in-office bleaching agents on the shear bond strength of metal, ceramic, and composite brackets to enamel

    Directory of Open Access Journals (Sweden)

    M Rahul

    2017-01-01

    Full Text Available Aims and Objectives: This study aimed to evaluate the effects of at-home and in-office bleaching on the shear bond strength (SBS of metal, ceramic, and composite orthodontic brackets and to compare their SBSs. Subjects and Methods: A total of 96 human lower premolar teeth were used for this study. Six teeth were used for scanning electron microscopic study while the remaining ninety were divided into three equal groups. Each group was further subdivided into three subgroups with ten samples each. Three protocols were used. In the at-home bleaching group (n = 30, opalescence non-PF (potassium nitrate and fluoride bleaching agent (10% carbamide peroxide was applied onto the teeth daily for 14 days and left for 8 h each day. Teeth in the in-office group (n = 30 were treated twice in consecutive days with Opalescence boost PF (40% hydrogen peroxide. After bleaching, the specimens were stored in distilled water for 1 day before bonding. SBS testing was performed on all teeth using Instron universal testing machine. Results: Analysis of variance indicated a significant difference (P < 0.005 among the groups. Maximum SBS was shown by ceramic brackets in control group (Ib and minimum was shown by composite brackets of in-office bleached group (IIIc. Conclusions: The results showed that at-home bleaching did not affect the SBS significantly whereas in-office bleaching reduced SBS of metal, ceramic, and composite brackets significantly. It is preferable to use metal or ceramic brackets than composite brackets for bonding 24 h after bleaching.

  16. 3D Surface Profile and Color Stability of Tooth Colored Filling Materials after Bleaching

    Directory of Open Access Journals (Sweden)

    Bryant Anthony Irawan

    2015-01-01

    Full Text Available This study aims to evaluate the effects of vital tooth bleaching with carbamide peroxide home bleaching and in-office bleaching on the color stability and 3D surface profile of dental restorative filling materials. Thirty discs (n=30 measure 6 mm in diameter and 2 mm thick for each of three restorative materials. These are nanofilled composite Filtek Z350 XT, the submicron composite Estelite Σ Quick, and nanofilled glass ionomer Ketac N100 nanoionomer and were fabricated in shade A2. Each group was further divided into three subgroups (n=10: subgroup A (Opalescence PF, subgroup B (Opalescence Boost in-office bleaching, and subgroup C (distilled water serving as control. Samples were bleached according to the manufacturer’s instructions for a period of two weeks. The Commission Internationale de L’Eclairage (CIE L*, a*, b* system was chosen for image processing, while 3D surface profile was tested with atomic force microscopy (AFM. Statistical analyses were performed with the Mann-Whitney tests and Krusal-Wallis with a P value of ≤0.05. The three restorative materials showed significant color changes (ΔE; P≤0.05. In diminishing order, the mean color changes recorded were Estelite Σ (3.82 ± 1.6 > Ketac Nano (2.97 ± 1.2 > Filtek Z350 XT (2.25 ± 1.0. However, none of the tested materials showed statistically significant changes in surface roughness; P>0.05.

  17. A plugging mud for eliminating absorption of drilling mud

    Energy Technology Data Exchange (ETDEWEB)

    Krylov, V I; Ignatov, S M; Kryukova, T B; Rashchupkina, Ye A; Sukhenko, N I

    1979-01-01

    Developed in the VNIIKRneft' is a plugging mixture (TS) on the basis of urea formaldehyde (carbamide) resin, M-18-62 (SKM), hardened by industrial iron chloride. The studies of the TS showed a reduction in the seizing terms and an increase in the strength of the hardened samples when the hardener content is increased (at a constant temperature) and when the temperature is increased (with a constant hardener content). The density and spreadability of the TS along the AzNII content essentially do not depend on the content of the hardener and are equal to 1.30 gs/cm/sup 3/ and 22-24 cm, respectively. At a temperature above 90/sup 0/C (atmospheric pressure), the hardened samples have a porous structure and a strength of less than 0.4 MPa. With the introduction of sawdust and cord fiber into the TS as a filler, a reduction is observed in the spreadability, strength, seizing terms and the growth in the viscosity with a constant pumpability. With the use of the TS jointly with 1% iron chloride (mineralization in the studies of 300 g/1, included sodium chloride, and chlorides of calcium, sodium and magnesium) established that the additives of mineralized water to 120% per volume increases the seizing times of the TS by 10% and the additive of 200%, by 40%; here, the strength of the hardened rock meets the technical specifications. With the use of a clay solution, the seizing terms sharply grow. A complete absence is established of the seizability of the TS with carbonate rocks. Industrial studies, conducted at well 302 of the Besedinsk site of the Orenburg Oblast, confirmed the high effectiveness of the new plugging solution.

  18. Effects of drying agents on bond strength of etch-and-rinse adhesive systems to enamel immediately after bleaching.

    Science.gov (United States)

    Niat, Alireza Boruzi; Yazdi, Fatmeh Maleknejad; Koohestanian, Niloufar

    2012-12-01

    To determine the effect of drying agents and adhesive solvents on the bond strength of resin composite to enamel immediately after bleaching. Sixty healthy human premolars were bleached using 15% carbamide peroxide gel and randomly divided into three groups according to the immersing solutions applied immediately after bleaching: 70% alcohol, acetone, and distilled water. Each group was randomly divided into two subgroups according to the adhesives that were applied: an alcohol-based adhesive (Single Bond) and an acetone-based adhesive (One Step). By using rubber washers, composite Z100 was placed onto the enamel and shear bond strength was evaluated in a universal testing machine at a crosshead speed of 1 mm/min. The type of failure was also assessed using a stereomicroscope. The data were statistically analyzed by two-way ANOVA and Tukey's post-hoc test (α = 0.05). Fisher's Exact test was used to evaluate differences in the failure modes. Statistical analysis showed that the bond strength of the distilled water groups was significantly lower than that of the other groups, but the bond strengths of the two groups where a drying agent was applied were similar to that of the unbleached group. The acetone-based adhesive (One Step) provided higher bond strength than did the alcohol-based adhesive (Single Bond) (p 0.05). Fisher's Exact test showed there was no significant difference in the failure mode of all the experimental groups (p > 0.05). The application of drying agents improves the bond strength of resin composite to bleached enamel. Furthermore, the acetone-based adhesive used in the study had a higher bond strength to bleached enamel than did the alcohol-based adhesive used.

  19. In vitro Evaluation of Effect of Dental Bleaching on the Shear Bond Strength of Sapphire Orthodontics Brackets Bonded with Resin Modified Glass Ionomer Cement

    Directory of Open Access Journals (Sweden)

    Zainab M Kadhom

    2017-11-01

    Full Text Available Aim: This study aimed to assess the effect of various types of bleaching agents on the shear bond strength of sapphire brackets bonded to human maxillary premolar teeth using resin modified glass ionomer cement (RMGIC and to determine the site of bond failure. Materials and Methods: Thirty freshly extracted maxillary human premolars were selected and assigned into three equal groups, ten teeth in each. The first group was the control (unbleached group; the second group comprised teeth bleached with hydrogen peroxide group (HP 37.5% (in-office bleaching while the third group included teeth bleached with carbamide peroxide group (CP 16% (at-home bleaching. The teeth in the experimental groups were bleached and stored in water one day then bonded with sapphire brackets using RMGIC with the control group and left another day. De-bonding was performed using Instron universal testing machine. To determine the site of bond failure, both the enamel surface and bracket base of each tooth were examined under magnifying lens (20X of a stereomicroscope. Results: Results showed statistically highly significant difference in the shear bond strengths between control group and both of bleaching groups being low in the control group. Score III was the predominant site of bond failure in all groups. Conclusions: RMGIC provides adequate bond strength when bonding the sapphire brackets to bleached enamel; this bonding was strong enough to resist both the mechanical and masticatory forces. Most of the adhesive remained on the brackets, so it reduced the time required for removal of the bonding material’s remnants during enamel finishing and polishing.

  20. A randomized CIE L*a*b* evaluation of external bleaching therapy effects on fluorotic enamel stains.

    Science.gov (United States)

    Knösel, Michael; Attin, Rengin; Becker, Klaus; Attin, Thomas

    2008-05-01

    To evaluate the effect of external bleaching on the color and luminosity of fluorotic stains and adjacent, normally mineralized enamel areas by means of CIE L*a*b* colorimetry. Eighteen adolescents with mild to moderate fluorotic stains were randomly assigned to either bleaching group A (n = 9) or control group B. Eligibility criteria were fluorotic stained maxillary incisors or canines and the informed consent of the participants and their guardians. Using a colorimeter, CIE L*a*b* values of maxillary incisors and canines were assessed at baseline (T1) in the center of the fluorotic stained area (F1) and at adjacent, normally mineralized enamel areas (F2). Then, external bleaching with Illumine office (30% hydrogen peroxide, Dentsply DeTrey) was performed for 60 minutes, followed by color reassessment (T2). After 14 days (T3), a 2-week home bleaching period with a daily bleaching time of 1 hour with Illumine home (15% carbamide peroxide, Dentsply DeTrey) was conducted with subsequent color determination (T4). After completion of bleaching therapy, 96.0% of all fluorotic areas (F1) and 100% of normal enamel areas (F2) showed a significant change within group A, compared to 29.4% in control group B. Comparing the collective DeltaE (L*, a*, b*) of F1 and F2, 60.0% of all areas showed significant differences after completion of bleaching therapy, compared to 88.0% initially. Of group B sites, 82.4% showed color differences in the beginning (T1) and 88.2% at the end (T4). Whereas a single 1-hour session of in-office bleaching with 30% hydrogen peroxide does not significantly affect the color and luminosity of fluorotic teeth, a 14-day period of home bleaching leads to an assimilation of the color of the fluorotic stain with the color of surrounding enamel areas due to different responses of sound and fluorotic enamel to the bleaching regime.

  1. Unusual extrinsic staining following microabrasion in a girl with amelogenesis imperfecta.

    Science.gov (United States)

    Rogers, H J; Yesudian, G; Rodd, H D

    2016-08-01

    Developmental defects of enamel (DDE), such as amelogenesis imperfecta (AI), may present with tooth discolouration that is of aesthetic concern to the affected individual. Children and young people with DDE may therefore seek dental interventions to improve their dental appearance. The most commonly employed approaches include microabrasion, bleaching and/or placement of composite resin veneers. A 13-year-old girl with hypomature AI requested treatment for the 'marks' on her teeth which were having a negative impact on her social interactions. Clinical examination revealed generalised dense white opacities, and a microabrasion approach was performed on 11, 12 and 13 using a commercial preparation of 6.6 % hydrochloric acid. Concerningly, the girl's father phoned the next day reporting that his daughter's teeth had turned 'orange'. An urgent review revealed that the treated teeth had indeed become an orange colour. Further enquiry found that the patient had eaten a tomato pizza immediately after her dental treatment and this was believed to have caused the severe extrinsic staining. The patient was provided with a 16 % carbamide peroxide preparation for night-time use in a laboratory-made tray. A 2-week review revealed complete resolution of the staining. Direct composite resin restorations were subsequently provided for the girl's maxillary anterior teeth to achieve an optimal cosmetic result and she has remained pleased with her dental appearance. Clinicians should be aware of the potential for extrinsic staining following microabrasion or tooth bleaching. Patients should be advised against consuming coloured food and drink for at least 48 h after their treatment.

  2. Effect of bleaching on mercury release from amalgam fillings and antioxidant enzyme activities: a pilot study.

    Science.gov (United States)

    Cakir, Filiz Yalcin; Ergin, Esra; Gurgan, Sevil; Sabuncuoglu, Suna; Arpa, Cigdem Sahin; Tokgoz, İlknur; Ozgunes, Hilal; Kiremitci, Arlin

    2015-01-01

    The aim of this pilot clinical study was to determine the mercury release from amalgam fillings and antioxidant enzyme activities (Superoxide Dismutase [SOD] and Catalase[CAT] ) in body fluids after exposure to two different vital tooth bleaching systems. Twenty eight subjects with an average age of 25.6 years (18-41) having at least two but not more than four Class II amalgam fillings on each quadrant arch in the mouth participated in the study. Baseline concentrations of mercury levels in whole blood, urine, and saliva were measured by a Vapor Generation Accessory connected to an Atomic Absorption Spectrometer. Erythrocyte enzymes, SOD, and CAT activities in blood were determined kinetically. Subjects were randomly assigned to two groups of 14 volunteers. Group 1 was treated with an at-home bleaching system (Opalescence PF 35% Carbamide Peroxide, Ultradent), and Group 2 was treated with a chemically activated office bleaching system (Opalescence Xtra Boost 38% Hydrogen Peroxide, Ultradent) according to the manufacturer's recommendations. Twenty-four hours after bleaching treatments, concentrations of mercury and enzymes were remeasured. There were no significant differences on mercury levels in blood, urine, and saliva before and after bleaching treatments (p > 0.05). No differences were also found in the level of antioxidant enzyme activities (SOD and CAT) before and after treatments (p > 0.05). Mercury release did not affect the enzyme activities (p > 0.05). Bleaching treatments either office or home did not affect the amount of mercury released from amalgam fillings in blood, urine, and saliva and the antioxidant-enzyme activities in blood. Bleaching treatments with the systems tested in this pilot study have no deleterious effect on the mercury release from amalgam fillings and antioxidant enzymes in body fluids. © 2014 Wiley Periodicals, Inc.

  3. Clinical Comparison of At-Home and In-Office Dental Bleaching Procedures: A Randomized Trial of a Split-Mouth Design.

    Science.gov (United States)

    Machado, Lucas Silveira; Anchieta, Rodolfo Bruniera; dos Santos, Paulo Henrique; Briso, André Luiz; Tovar, Nick; Janal, Malvin N; Coelho, Paulo Guilherme; Sundfeld, Renato Herman

    2016-01-01

    The objective of this split-mouth clinical study was to compare a combination of in-office and at-home dental bleaching with at-home bleaching alone. Two applications of in-office bleaching were performed, with one appointment per week, using 38% hydrogen peroxide. At-home bleaching was performed with or without in-office bleaching using 10% carbamide peroxide in a custom-made tray every night for 2 weeks. The factor studied was the bleaching technique on two levels: Technique 1 (in-office bleaching combined with home bleaching) and Technique 2 (home bleaching only). The response variables were color change, dental sensitivity, morphology, and surface roughness. The maxillary right and left hemiarches of the participants were submitted to in-office placebo treatment and in-office bleaching, respectively (Phase 1), and at-home bleaching (Phase 2) treatment was performed on both hemiarches, characterizing a split-mouth design. Enamel surface changes and roughness were analyzed with scanning electron microscopy and optical interferometry using epoxy replicas. No statistically significant differences were observed between the bleaching techniques for either the visual or the digital analyses. There was a significant difference in dental sensitivity when both dental bleaching techniques were used, with in-office bleaching producing the highest levels of dental sensitivity after the baseline. Microscopic analysis of the morphology and roughness of the enamel surface showed no significant changes between the bleaching techniques. The two techniques produced similar results in color change, and the combination technique produced the highest levels of sensitivity. Neither technique promoted changes in morphology or surface roughness of enamel.

  4. Effect of two different bleaching regimens on the gloss of tooth colored restorative materials.

    Science.gov (United States)

    Yalcin, Filiz; Gürgan, Sevil

    2005-05-01

    Vital tooth bleaching with peroxide is one of the most common cosmetic procedures in dentistry and can be accomplished using a variety of methods or regimens. Recently, new generation of tooth color restorative materials were introduced to market. The purpose of this in vitro study was to determine the gloss changes of three different tooth color restorative materials: Flowable composite (Filtek Flow/3M), packable composite (Filtek P60/3M) and ormocer (Definite/DEGUSSA) after two different bleaching regimens (Vivastyle/VIVADENT) and (Crest Professional Whitestrips/PROCTER and GAMBLE). 16 specimens 30 x 30 x 2 mm size were fabricated from each restorative material. After gloss values were measured with gloss meter, at two different angles of illumination (20 and 60 degrees ), 10% carbamide peroxide (Vivastyle) was applied for 2 h per day for fourteen days to the half of the specimens while 6.5% hydrogen peroxide strip bands (Crest Professional Whitestrips) were applied to the remaining eight of the specimens for 30 min twice daily for 14 days. During the test period the specimens were stored in 37 degrees C and 100% relative humidity. At the end of bleaching regimen the gloss measurements were repeated and the data were subjected to statistical analysis. The Wilcoxon Signed Rank Test analysis revealed that the gloss values were affected by both bleaching regimens (P=0.012). Whitestrips decreased the gloss values of Filtek P60 (at 20 and 60 degrees , Pgloss values of Definite did not show any significant change between Vivastyle and Whitestrips application (at 20 degrees P=0.279; at 60 degrees , P=0.279, Mann-Whitney U Test). The gloss values of materials were significantly different before (at 20 degrees Pgloss of tooth colored restorative materials could be affected by bleaching regimens, it is necessary to consider the type of the material before starting the treatment.

  5. 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

    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). 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). 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). 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. 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.

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

    Science.gov (United States)

    Poggio, Claudio; Beltrami, Riccardo; Scribante, Andrea; Colombo, Marco; Chiesa, Marco

    2012-09-01

    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. 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 L(*)a(*)b(*) system after light-polymerization of composite resin specimens, after 7 days, after 14 days, and after bleaching. The color difference h index (DEab(*)) between each measurement was calculated. Statistical analysis was made using analysis of variance (ANOVA). 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. Microhybrid and nanohybrid composite resins had similar in vitro surface discoloration in tea. After bleaching, discoloration was removed from some composite resins tested.

  7. The effect of home bleaching agents on the surface roughness of five different composite resins: A SEM evaluation.

    Science.gov (United States)

    Cengiz, Esra; Kurtulmus-Yilmaz, Sevcan; Ulusoy, Nuran; Deniz, Sule Tugba; Yuksel-Devrim, Ece

    2016-05-01

    The aim of this study was to investigate the effect of hydrogen peroxide (HP) and carbamide peroxide (CP) on the surface roughness of five different composite resins using profilometer and scanning electron microscope (SEM). Thirty-six specimens (1 mm thick, 10 mm in diameter) of five composite resins were fabricated. Each composite group was equally divided into three subgroups as control, CP and HP. In control group, specimens were stored in daily refreshed distilled water during the 14-day testing period. In other groups, 10% HP (Opalescence Treswhite) and 10% CP (Opalescence PF) were applied and surface roughness values (Ra) of each specimen were measured with a profilometer at the end of 14 days. Additionally, SEM analysis was performed to evaluate the surface deformations of composite resins. Data were analyzed with Kruskal-Wallis and Mann-Whitney U tests. Ra values of composite groups exposed to bleaching agents were statistically higher than control group (p composite group while SEM micrographs showed higher surface alterations at HP group compared to CP. Among the composite resins tested, Ceram-X Mono revealed the lowest Ra values after CP and HP applications as seen at SEM images. Home bleaching agents increased the surface roughness of all composites. Except CP applied Ceram-X mono specimens, Ra values of all composite resins evaluated in this study exceeded the critical limit of 0.2 μm. Ceram-X mono was the least affected composite material after bleaching application. SCANNING 38:277-283, 2016. © 2016 Wiley Periodicals, Inc. © Wiley Periodicals, Inc.

  8. Calculation of kinetic parameters of amino-formaldehyde polymers formation in the presence of calcium ions

    Directory of Open Access Journals (Sweden)

    V.V. Arhipova

    2016-05-01

    Full Text Available Calcium carbonate is on of widely used fillers of composite materials. The area of its application depend on disperse structure, particle shape and other. The modification of calcium carbonate by high-molecular polymers allows changing its characteristics and surface properties in a wide range. The modification of calcium carbonate often carried out with use of amino-formaldehyde polymers (AFP. Aim: The aim of this work is to determine the kinetic characteristics of amino-formaldehyde polymers polycondensation process in the presence of calcium ions. Materials and Methods: The mechanism of AFP polycondensation is complex and depends on various factors. Polycondensation of AFP took place under following conditions: the temperature is 20, 30, 60°C; the molar ratio of carbamide to formaldehyde is 1:1.25; the polycondensation duration is 2 hours; the mass ratio of CaCO3:AFP = 1:1. The polycondensation process was carried out in calcium chloride solution with рН=2…5.5. The concentration of formaldehyde and metilol groups determined during the experiment using chemical titrimetric method. Results: It is shown that polycondensation process of AFP in the presence of Сa2+ ions at their concentration from 0 to 2,25 mol/l (0…90 g/l leads to acceleration of process more than by 1.8 times at temperature of 20°C. Further increase of Сa2+ concentration leads to reduction of process speed. At temperature of 30°C the speed of process almost does not change in the range of Сa2+ concentration from 0 to 2,25 mol/l and further decreases slightly. For all range of Сa2+ concentration at temperature of 60°C the reduction of process speed is observed. Influence of Сa2+ on process of polycondensation confirms assumption made earlier of formation of weak bonds between AFP and calcium ions which at low temperatures interfere with hydrolysis of methyleneurea and collapse at increasing of process temperature.

  9. Production of chemical substances in Tajikistan

    International Nuclear Information System (INIS)

    Boboev, Kh.E.; Nazarov, K.M.

    2010-01-01

    Full text: Government of the Republic of Tajikistan has signed Convention "On prohibition of chemical weapon application"and no chemical weapon (CHW) is produced on the territory of republic. However, the potential production of CHW by individual persons or groups can be organized, using available production and obtaining chemical substances from other countries. Chemical substances, which have strong damage effect, easily, can be synthesized in chemical laboratories. These are general toxic substances, as hydrocyanic acid acid, phosgene, mustard gas, lewisite, sarin and others. The similar chemical substances of industrial significance are produced in Tajikistan: ammonia, chlorine, explosives, caustic soda, carbamide, formaldehyde and others. For industrial needs and agriculture from other countries Tajikistan is receiving the following: sodium cyanide and potassium for gold-mining; mineral acids; pesticides and others. Besides, there are different deposits in Tajikistan, reprocessing of which gives an opportunity to obtain different chemical substances. What can be obtained from chemicals produced in Tajikistan? Chlorine - from this reagent the fluoride chlorine, phosgene COCl_2 and many other compounds are easily synthesized, which are CHW components. Obtained cyanic compounds for gold mining can be used as precursor for neuroparalytic action. A big amount of metallic aluminum is produced in the republic. The Al powder for rocket fuel can be obtained from it. Obtained from other countries pesticides are potential components for CHW creation. A strong control and account of pesticides use is necessary. It is extremely important to control materials, equipment and technologies which allow countries and separate groups to create weapons of mass destruction (WMD). The most important factor is goods identification. Firstly - inspection of external view, labeling, packing specifications, license availability and etc. Strong control of checklists is necessary according

  10. 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

  11. Sorbents based on xerogels of zirconium, aluminum and manganese oxyhydroxides

    Directory of Open Access Journals (Sweden)

    R.V. Smotraiev

    2016-05-01

    Full Text Available The actual problem of water supply in the world and in Ukraine, in particular, is a high level of pollution in water resources and an insufficient level of drinking water purification. With industrial wastewater, a significant amount of pollutants falls into water bodies, including suspended particles, sulfates, iron compounds, heavy metals, etc. Aim: The aim of this work is to determine the impact of aluminum and manganese ions additives on surface and sorption properties of zirconium oxyhydroxide based sorbents during their production process. Materials and Methods: The sorbents based on xerogels of zirconium, aluminum and manganese oxyhydroxides were prepared by sol-gel method during the hydrolysis of metal chlorides (zirconium oxychloride ZrOCl2, aluminum chloride AlCl3 and manganese chloride MnCl2 with carbamide. Results: The surface and sorption properties of sorbents based on xerogels of zirconium, aluminum and manganese oxyhydroxides were investigated. X-ray amorphous structure and evolved hydroxyl-hydrate cover mainly characterize the obtained xerogels. The composite sorbents based on xerogels of zirconium oxyhydroxide doped with aluminum oxyhydroxide (aS = 537 m2/g and manganese oxyhydroxide (aS = 356 m2/g have more developed specific surface area than single-component xerogels of zirconium oxyhydroxide (aS = 236 m2/g and aluminum oxyhydroxide (aS = 327 m2/g. The sorbent based on the xerogel of zirconium and manganese oxyhydroxides have the maximum SO42--ions sorption capacity. It absorbs 1.5 times more SO42–-ions than the industrial anion exchanger AN-221. The sorbents based on xerogels of zirconium oxyhydroxide has the sorption capacity of Fe3+-ions that is 1.5…2 times greater than the capacity of the industrial cation exchanger KU-2-8. The Na+-ions absorption capacity is 1.47…1.56 mmol/g for each sorbent. Conclusions: Based on these data it can be concluded that the proposed method is effective for sorbents production based on

  12. Effect of at-home whitening strips on the surface roughness and color of a composite and an ormocer restorative material.

    Science.gov (United States)

    Gurbuz, Ayhan; Ozkan, Pelin; Yilmaz, Kerem; Yilmaz, Burak; Durkan, Rukiye

    2013-01-01

    Oxygenating agents like carbamide peroxide or H(2) O(2) are commonly used whitening agents. They have varying influence on the color and surface roughness of resin-based restorative materials and teeth. The aim of this study was to evaluate the effect of an at-home peroxide whitening agent applied through a whitening strip on the color and surface roughness of a nanofilled composite resin and an ormocer-based resin. Disc-shaped (2 mm thick, 10 mm diameter) nanofilled resin composite (n = 10) and ormocer (n = 10) specimens were prepared. All specimens were treated with a whitening strip. Whitening procedures were performed applying a 6.5% hydrogen peroxide whitening strip (Crest White Strips Professional) for 30 minutes twice each day for a period of 21 consecutive days. During the test intervals, the specimens were rinsed under running distilled water for 1 minute to remove the whitening agents and immersed in 37°C distilled water until the next treatment. Surface roughness and color of the specimens were measured with a profilometer and a colorimeter, respectively, before and after whitening. Color changes were calculated (ΔE) using L*, a*, and b* coordinates. Repeated measures of variance analysis and Duncan test were used for statistical evaluation (α= 0.05). The average surface roughness of composite increased from 1.4 Ra to 2.0 Ra, and from 0.8 Ra to 0.9 Ra for the ormocer material; however, these changes in roughness after whitening were not significant (p > 0.05). Also, when two materials were compared, the surface roughness of restorative materials was not different before and after whitening (p > 0.05). L* and b* values for each material changed significantly after whitening (p composite (11.9) and ormocer (16.1) were not significantly different from each other (p > 0.05). The tested whitening agent did not affect the surface roughness of either resin-based restorative material. Both materials became brighter after whitening. The behavior of the

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

    International Nuclear Information System (INIS)

    Carvalho, Breno Carnevalli Franco de

    2003-01-01

    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 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)

  14. 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

  15. Effect of Different Bleaching Techniques on Microleakage under orthodontic Brackets: In Vitro Study

    Directory of Open Access Journals (Sweden)

    Salehi P

    2018-03-01

    Full Text Available Statement of problem: Numerous studies report significant changes in tooth color that occur during orthodontic treatment. The adverse effects of bleaching procedures during orthodontic treatments have not been studied comprehensively. Objectives: This study investigated the effects of two methods of dental bleaching on the degree of microleakage beneath orthodontic brackets. Materials and Methods: We selected 45 extracted premolar teeth and bonded them to orthodontic brackets. These teeth were stored in normal saline for 24 hours and thermocycled. We randomly divided the samples into 3 groups of 15 teeth per group. The first group (control received no bleach treatment; the second group (office bleaching was treated with 35% hydrogen peroxide (Whiteness HP Maxx; and the third group (home bleaching was treated with 22% carbamide peroxide (Whiteness Perfect. The apices were sealed with sticky wax, rinsed in tap water, and air-dried. We applied nail varnish to the entire surface of each tooth, except for an area approximately 1 mm away from the brackets. The samples were immersed in basic fuchsine and cleaned after 24 hours. Microleakage was determined by direct measurement using a stereomicroscope. Kruskal-Wallis and Dunn post-hoc statistical tests, and SPSS software were used for statistical analysis. The significance level was set at P≤0.05. Results: The office bleaching group had significantly more microleakage scores under the brackets at both the occlusal (P=0.04 and gingival (P =0.040 margins of the brackets compared to the home bleaching group. The home bleaching group showed statistically more significant microleakage scores than the control group in both the gingival (P=0.006 and occlusal (P=0.014 margins of the brackets. All three groups had statistically more significant microleakage at the gingival margins of the brackets than the occlusal margins. Conclusions: Office bleaching caused the most microleakage under the brackets and home

  16. 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

  17. Techno-economic analysis of integrated onshore and offshore UCG-CCS systems to produce electricity, SNG and urea

    Science.gov (United States)

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

    2017-04-01

    profitable in view of the expected future development of natural gas prices. [1] Stanczyk, K., Howaniec, N., Smolinski, A., Swiadrowski, J., Kapusta, K., Wiatowski, M., Grabowski, J., Rogut, J. (2011): Gasification of lignite and hard coal with air and oxygen enriched air in a pilot scale ex-situ reactor for underground gasification. Fuel, 90, p. 1953-1962, doi:10.1016/j.fuel.2010.12.007. [2] Kempka, T., Schlüter, R., Hamann, J., Deowan, S., Azzam, R. (2011): Carbon dioxide utilisation for carbamide production by application of the coupled UCG-Urea process. Energy Procedia, 4, p. 2200-2205, doi.org/10.1016/j.egypro.2011.02.107. [3] Nakaten, N.C., Schlüter, R., Azzam, R. and 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, 66, p. 779-790, doi: 10.1016/j.energy.2014.01.014.

  18. 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