Mixture Of Distilled Water Research Articles

Immunohistochemical distribution and gene expression of transforming growth factor alpha in ovarian tissue of rats treated with capsaicin in puberty

In this study, the effects of capsaicin on the immunohistochemical distribution and gene expression of transforming growth factor alpha (TGF-\alpha) in ovarian tissue of rats at the pubertal age were examined. Materials and methods: Rats (50 days old) were divided into experimental, alimentation, and sham groups. The experimental group was injected with 1 mg/kg doses of capsaicin (10% ethanol and 1% Tween in an 80% distilled water mixture) subcutaneously every day for a period of 1 week. The alimentation group received 1 mg/kg doses of capsaicin (10% ethanol and 1% Tween in an 80% distilled water mixture). The sham group was injected with a solution of 10% ethanol and 1% Tween in a mixture of 80% distilled water. Body weights and ovary weights were compared within the groups. Triple staining methods were used for the histological examinations. The tissue localization of TGF-\alpha was analyzed using an immunohistochemical method and gene expression level was determined using the reverse transcriptase-polymerase chain reaction (RT-PCR) technique. Results: No difference in the structure of the 3 groups was observed histologically. Immunohistochemically, TGF-\alpha immunoreactivity was detected in the primordial follicles, primary follicles, theca cells, and interstitial cells at a medium density in all groups. The effect of capsaicin on TGF-\alpha with mRNA was not found to be significantly different among the 3 groups. Conclusion: The results showed that capsaicin had no effects on ovaries at different developmental stages.

Comparison of the efficacy of ethylene diamine tetraacetic acid and maleic acid in the removal of three calcium hydroxide intra-canal dressings: A spiral computerized tomography volumetric analysis

Aim:To assess the efficacy of 17% ethylene diamine tetra acetic acid and 7% maleic acid in the removal of 3 calcium hydroxide preparations placed as intracanal medicaments.Materials and Methods:The root canals of 60 single rooted premolars were prepared with a step back technique and randomly assigned into 3 experimental groups (n= 20). Group A was filled with plain calcium hydroxide mixed with distilled water in which barium sulfate was added for radio opacity, Group B was filled with Apexcal and Group C was filled with Metapex. After 7 days each group was divided into 2 sub groups (n= 10). The medicaments were retrieved with 17% EDTA (first sub group) and 7% maleic acid (second sub group). Along with the above irrigants manual and ultrasonic agitation was used. The pre and post removal volume of medicaments in root canals were measured using spiral computerized tomography. The percentage difference was calculated and statistically analyzed using Kruskal Wallis and Mann Whitney U test.Results:17% EDTA and 7% maleic acid efficiently removed calcium hydroxide, distilled water mixture (P= 0.218) and Apexcal (P= 0.684), whereas 7% maleic acid showed better retrieval capability of Metapex than 17% EDTA (P= 0.002).Conclusion:Calcium hydroxide, distilled water mixture and polyethylene glycol based calcium hydroxide were efficiently removed by 17% EDTA and 7% maleic acid. 7% maleic acid removed silicone oil based calcium hydroxide preparation better than 17% EDTA.

물-에탄올 기반 이성분 산화탄소나노유체의 특성 비교 연구

A nanofluid is a fluid containing suspended solid particles, with sizes on the order of nanometers. Normally, nanofluids have higher thermal conductivitiest han their base fluids. Therefore, we measured the thermal conductivity and viscosity of oxidized carbon nanofluids based the mixture of distilled water and ethanol (ethanol concentration is 0.2) oxidized carbon nanofluids were made by ultrasonic dispersing oxidized multi-walled carbon nanotubes in the mixture of distilled water and ethanol at the rates of 0.001~ 0.1 vol%. The thermal conductivity and viscosity of oxidized carbon nanofluids were measured by using transient hot-wire method and rotational digital viscometer, respectively. And all of experiments were carried out at the same temperature conditions(, and ). As a result, when volume fraction of nanofluids is 0.1 vol%, thermal conductivity was improved 13.6% (), 15.1% (), and 17.0% (), and its viscosity was increased by 36.0% (), 32.9% () and 19.5% () than the base fluids.

플라즈마 전해 산화 코팅에 있어서 인산염 전해액과 모재 성분 변화가 Al 산화피막 물성에 미치는 영향 II. PEO 층의 결정상 분석

Crystal structure and chemical compositions of Plasma electrolytic oxidized layer of A-1100, A-2024, A-5052, A-6061, A-6063, A7075, ACD-7B and ACD-12 were investigated. The electrolyte for plasma electrolytic oxidation was mixture of distilled water, Na2P2O7, Cu, Cr metal salts and KOH. η-Alumina, as well as α-alumina, was main crystal phase. Another crystals such as (Al0.948Cr0.052)2O3 and (Al0.9Cr0.1)2O3 were also formed in the oxide layer. It was thought that the effect of electrolyte compositions on the physical properties and crystal system of PEO layers was greater than the effect of Al alloy composition variation.

Effects of pH on Properties of Soy Protein Isolate/Guar Gum Composite Films

The objective of this research was to investigate the effect of pH(7.0, 8.0, 9.0, 10.0) on the properties of soy protein isolate (SPI)/guar gum (GG)composite films casted with 0.2 %(w/v)guar gum polysaccharide, 5.0 %(w/v)SPI, 1.5 %(w/v)glycerol plasticizer, and 4:1(v/v) mixture of distilled water and anhydrous alcohol. Composite membranes from different pH conditions were evaluated from following aspects: tensile strength (TS), elongation at break (EB), water vapor permeability (WVP), water solubility (WS) and surface hydrophobicity(SH)

Ultrafine Finishing of Metallic Surfaces with the Ice Bonded Abrasive Polishing Process

In this article, a novel ice bonded abrasive polishing (IBAP) process proposed for producing ultrafine surfaces on metallic surfaces is presented. An IBAP setup was developed for conducting the experiments under cryogenic conditions. The novelty of the process lies in the method of preparing cryogenic polishing tool by freezing the mixture of distilled water and ultrafine abrasive particles with suitable cryogenic fluids. Characterization of tool, by weight balance method, ensured uniform distribution of abrasives throughout the ice matrix. Experiments were conducted on 304L stainless steel and EC grade copper materials in order to examine the improvements in finish on polished surfaces. Experimental studies have revealed the generation of ultrafine surfaces, yielding roughness values in nanometric range, with the adhesive action of ice and abrasive action of material by fine abrasive particles.

An In Vitro Comparative Study of Intracanal Fluid Motion and Wall Shear Stress Induced by Ultrasonic and Polymer Rotary Finishing Files in a Simulated Root Canal Model

Objective. This in vitro study compared the flow pattern and shear stress of an irrigant induced by ultrasonic and polymer rotary finishing file activation in an acrylic root canal model. Flow visualization analysis was performed using an acrylic canal filled with a mixture of distilled water and rheoscopic fluid. The ultrasonic and polymer rotary finishing file were separately tested in the canal and activated in a static position and in a cyclical axial motion (up and down). Particle movement in the fluid was captured using a high-speed digital camera and DaVis 7.1 software. The fluid shear stress analysis was performed using hot film anemometry. A hot-wire was placed in an acrylic root canal and the canal was filled with distilled water. The ultrasonic and polymer rotary finishing files were separately tested in a static position and in a cyclical axial motion. Positive needle irrigation was also tested separately for fluid shear stress. The induced wall shear stress was measured using LabVIEW 8.0 software.

Study the impact of sweet basil extracts (Ocimum basilicum) to reduce blood cholesterol

The study aimed to test the effect of sweet basil extract on hypercholesterolemia. Sweet basil leaves were extracted with distilled water, ethanol and a mixture of distilled water: ethanol (1:3, v/v). Phenolic and flavonoids concentrates were fractionated and identified with High Performance Liquid Chromatograph (HPLC). Two levels of each concentrated extract were used to find its effect on the hypercholesterolemic rats. Six groups of hypercholesterolemic rats received 0.35 or 0.70 g/Kg bw from aqueous, ethanolic and aqueous + ethanolic extracts of sweet basil leaves and were compared with normal control group and hyperlipidemic control group for 30 days. Growth of rats, biochemical biomarks and histopathological examination were evaluated. Results showed that the main phenolic compound was p-Hydroxybenzoic acid. Meanwhile, the main flavonoids compound was rutin. The biological experiment showed that second concentration of sweet basil leaves extracts (ASBL2, ESBL2 and AESBL2) had a positive effect to lower the weight of hypercholesterolemic rats. No significant difference was found in relative organs weight among all tested rat groups. Sweet basil leave extracts had a positive effect to decrease serum triglycerides, total cholesterol, LDL-cholesterol and VLDL-cholesterol of HC rats. The Atherogenic index (Al) was decreased due to sweet basil leaves extracts treated rat groups compared to the hyperlipidemic rats group. Sweet basil leaves extracts may play a role in improving the activity of antioxidant enzymes and decrease the lipid peroxidation (malondialdehyde, MDA) and level of H202 in serum. The serum ALT, AST, ALP and y-GT activities of the second concentration (0.70 g/Kg bw) of sweet basil leaves extracts had no significant difference compared to NC rats group. There was no significant difference in serum uric acid, urea and creatinine among all tested rat groups received sweet basil leaves extracts and NC rats group except for HC rats group. No histopathological changes were observed in liver of rat groups received second concentration (0.70 g/Kg bw) of sweet basil leaves extracts. In conclusion, the obtained results suggest that sweet basil leaves extracts had an important role in lowering the hyperlipidemia in experimental animals especially the second concentration of sweet basil leaves extracts.

Clinical Efficacy of 1% Alendronate Gel as a Local Drug Delivery System in the Treatment of Chronic Periodontitis: A Randomized, Controlled Clinical Trial

Alendronate (ALN), an aminobisphosphonate, is known to inhibit osteoclastic bone resorption and was proposed to have osteostimulative properties in vivo and in vitro as shown by an increase in matrix formation. The present study aims to explore the efficacy of a 1% ALN gel compared to a placebo gel as a local drug delivery system in adjunct to scaling and root planing (SRP) for the treatment of intrabony defects in patients with chronic periodontitis. A total of 66 intrabony defects were treated with a 1% ALN or placebo gel. The ALN gel was prepared by adding ALN to a polyacrylic acid-distilled water mixture. Clinical parameters (modified sulcus bleeding index, plaque index, probing depth [PD], and clinical attachment level [CAL]) were recorded at baseline and 2 and 6 months, and radiographic parameters at baseline and 6 months. The defect fill at baseline and 6 months was calculated on standardized radiographs by using image-analysis software. The mean PD reduction and CAL gain were greater in the ALN group than in the placebo group at 2 and 6 months. Furthermore, a significantly greater mean percentage of bone fill was found in the ALN group (40.4% ± 11.71%) than in the placebo group (2.5% ± 1.02%). Results of the present study shows that the local delivery of 1% ALN into the periodontal pocket stimulated a significant increase in PD reduction, CAL gain, and improved bone fill compared to a placebo gel as an adjunct to SRP. These results can provide a new direction in the field of periodontal healing.

Effect of bore fluid composition on structure and performance of asymmetric polysulfone hollow fiber membrane contactor for CO2 absorption

Porous asymmetric polysolfone (PSf) hollow fiber membranes were fabricated using wet spinning process. Glycerol (4wt.%) was used as additive. Aqueous solutions of 1-methyl-2-pyrrolidone (NMP) with different composition (0, 50, 70 and 90wt.% NMP) were used as bore fluid. Distilled water was used to preparing aqueous NMP solutions. Structure and performance of resulting membranes in measuring of surface porosity, pore size, critical water entry pressure (CEPw) and CO2 absorption in hollow fiber membrane contactor were investigated. The cross-section, the inner skin layer and the inner surface of the membranes were examined via scanning electronic microscopy (SEM). Using distilled water as bore fluid provided the membrane structure with a finger-like macrovoids which extend from the inner and outer surfaces of the membranes to the middle of the hollow fiber wall. Other hollow fiber membranes formed with a finger-like structure near the other surface and a sponge-like structure with holes beneath, which resulted in a high CEPw and CO2 absorption rate. In addition, since a mixture of distilled water and NMP was used as the neutral bore fluid, the membranes showed a skinless inner surface. Results of gas permeation tests showed with increasing NMP concentration in the bore fluid the N2 permeance decrease significantly and the wetting resistance decrease slightly. CO2 absorption by distilled water was conducted through the gas–liquid membrane contactors. By employing 90% NMP in the bore fluid, the PSf membrane showed a CO2 flux of approximately 110% higher than the PSf membrane fabricated with distilled water as the internal coagulant at the absorbent velocity of 7.9×10−4m/s.

Humidity sensing properties of CNT–OD–VETP nanocomposite films

In this study, the blend of orange dye (OD), C 17H 17N 5O 2 (5 wt%), vinyl-ethynyl-trimethyl-piperidole (VETP), C 12H 19NO, (5 wt%) and carbon nanotube (CNT) powder (10 wt%) in a mixture of distilled water (80 wt%) and spirit were drop-casted on glass substrates with pre-deposited surface-type silver electrodes to fabricate CNT–OD–VETP nanocomposite thin films. In the process of thin films deposition, 2 V DC was applied to Ag electrodes. The thicknesses of the CNT–OD–VETP films were in the range of 10–15 μm. The I–V characteristics of the surface-type Ag/CNT–OD–VETP/Ag samples showed rectification behavior. The effect of humidity on the electrical properties of the nanocomposite films was investigated by measurement of the capacitance and dissipation of the samples at two different frequencies of the applied voltage: 120 Hz and 1 kHz. The resistance of the samples was determined from values of dissipation. It was observed that at 120 Hz and 1 kHz, under humidity of up to 90% RH, the capacitance of the cell increased by 7.4×10 3 and 740 times and resistance decreased by 2.3×10 4 and 3.8×10 4 times, accordingly, with respect to 40% RH conditions. The average response and recovery times of the films were obtained by capacitance-time measurements to evaluate the dynamics of the water vapor absorption and desorption processes. The experimental results have been supported by the simulation of the capacitance–humidity relationship. It is assumed that the humidity response of the cell is associated with diffusion of water vapors and doping of the semiconductor nanocomposite by water molecules.

366 SEXING OF GOAT BLASTOCYSTS PRODUCED IN VITRO BY FISH USING CHROMOSOME X AND Y OVINE SPECIFIC PROBES

The aim of this study was to test a FISH approach using ovine-painted probes specific for the chromosomes X and Y, on goat interphase and metaphase nuclei of blastocyst cells. Oocytes of prepubertal goats were recovered at a slaughterhouse and selected by morphological criteria. Oocytes were matured in TCM-199 supplemented with hormones, serum and cysteine at 38.5°C for 27 h. IVM-oocytes were fertilized in vitro and the presumptive zygotes were cultured for 10 days in SOF with 10% FCS at 38.5°C, 5% CO2 and 5% O2. The blastocyst nuclei were spread using a modified Tarkowski method (1966). Briefly, individual embryos were immersed into hypotonic solution for 5 min, followed by fixative solution of methanol/acetic acid (Carnoy’s solution) until the embryos acquired a transparent appearance. Next, the embryos were transferred to a Superfrost plus Slide (Menzel Gläser, Braunschweig, Germany) in a small droplet mixture of distilled water and Carnoy The zona pellucida and the blastomere cytoplasm dissolved gradually and Carnoy solution was added dropwise to the slide before the nuclei dried out. The morphology and total number of nuclei in each embryo were analyzed under phase contrast microscope and stored at -18°C. Embryos with appropriate fixation were then subjected to hybridization with ovine-painted probes specific to chromosomes X (Fluorocrom green-FITC) and Y (Fluorocrom orange-TAMRA) (Chrombios-Molecular Cytogenetics GmbH, Raubling, Germany) according to the manufacturers protocol and adjusted for the caprine species. Briefly, slides were then incubated at 60°C for 1 h. The chromosomal DNA was then denatured by immersing slides in 70% formamide/30% 2 × SSC at 70°C for 1.5 min, and immediately dehydrated in an ethanol series (70%, 90%, and 100%), 4 min duration per solution and air dried. In parallel, X- and Y-probes were added to the hybridization solution (50% deionized formamide, 10% dextran sulfate, 2 × SSC) and denatured at 75°C for 10 min. Aliquots (0.5 to 1.5 μL) of this solution were placed on each slide and sealed with a coverslip and glue prior to incubation at 37°C (Hybrite; Vysis Inc, Dowers Grove, IL, USA). After 22 to 24 h the coverslip was removed and the slides were washed three times. The first and third washes were performed with 2 × SSC at room temperature while the second wash was in a 0.4 × SSC/0.1% Tween at 73°C for 3 min. Nuclear DNA was counterstained with diamino-phenyl-indole solution (DAPI) and examined with a fluorescence microscope (Olympus BX61, Olympus America Inc., Melville, NY, USA) equipped with appropriate filters. From a total of 69 blastocysts, 11 355 blastomeres were analyzed and 7,825 were correctly hybridized (68.9%). The results of the embryo sexing were: 24 embryos XX, 11 XY, 22 polyploid embryos (of which 13 presented more than 80% of cells XX), 3 haploid embryos (X0), 2 tetraploid embryos, and 5 no result. In summary, goat blastocysts were successfully sexed using FISH with painted ovine X- and Y-specific probes. Grant sponsor Spanish Ministery of Science and Innovation.Code: AGL2007-60227-CO2-01.

Influence of climatic conditions and surface roughness on the wettability of medium density fiberboards (MDF)

Wettability of wood surface is measured by the contact angle between the liquid and the surface of the wood. In this study, the wettability of MDF surfaces was measured using different mixtures of distilled water and isopropanol. The results reveal that TF-bonded MDF made from fresh and recycled fibers showed better wettability than the corresponding MUF-bonded MDF. Moreover, the entire results indicate that roughness is one of the most important influencing factors on the wettability of MDF surfaces.

Synthesis of Submicron Silver Powder by the Hydrometallurgical Reduction of Silver Nitrate with Hydrazine Hydrate and a Thermodynamic Analysis of the System

A silver powder of submicron size was produced from the aqueous solutions of its compounds. The silver compounds tried out were silver nitrate and silver oxide, and the reducing agents employed were dimethyl formamide (DMF), hydrazine hydrate, and sodium azide. The solvent mediums were distilled water for the reductions with DMF and sodium azide, and a 2:1 (by volume) mixture of distilled water and ethanol for the reductions with hydrazine hydrate. Of the three reductants, hydrazine hydrate (N2H4·H2O) alone was successful in reducing both the silver compounds to a submicron (<500 nm) metallic silver powder, as revealed by X-ray diffraction (XRD) studies and scanning electron microscopy (SEM) analyses. Additionally, the thermodynamic equilibrium of the system AgNO3-N2H4·H2O in the water–ethanol mixture (2:1) was studied at 298 K; the equilibrium constant data so generated was found to compare very well with those derived from the established data of enthalpies and free energies of formation, and half-cell potentials. The following activity coefficient (Raoultian)–composition relationship for hydrazine hydrate in its dilute solution in water (plus ethanol) at 298 K is proposed: $$ \ln (\gamma_{{{\text{N}_2\text{H}_4}}{\text{.H}_2\text{O}}} ) = 1862( \pm 371) - 2055( \pm 424)(1 - X_{{{\text{N}_2\text{H}_4 \cdot \text{H}_2\text{O}}}} )^{2} $$

Two Step Derivatization for the Analyses of Organic, Amino Acids and Glycines on Filter Paper Plasma by GC-MS/SIM

A rapid dried-filter paper plasma-spot analytical method was developed to quantify organic acids, amino acids, and glycines simultaneously in a two-step derivatization procedure with good sensitivity and specificity. The new method involves a two-step trimethylsilyl (TMS) - trifluoroacyl (TFA) derivatization procedure using GC-MS/ selective ion monitoring (GC-MS/SIM). The dried-filter paper plasma was fortified with an internal standard (tropate) as well as a standard mixture of distilled water and methanol. Methyl orange was added to the residue as an indicator. N-methyl-N-(trimethylsilyl-trifluoroacetamide) and N-methyl-bis-trifluoroacetamide were then added and heated to 60 degrees C for 10 and 15 min to produce the TMS and TFA derivatives, respectively. Using this method, the silylation of carboxylic functional groups was carried out, which was followed by the trifluoroacyl derivatization of the amino functional group. The derivatives were analyzed by GC-MS/SIM. A calibration cure showed a linear relationship for the target compounds between concentrations of 10-500 ng/mL. The limit of detection and quantification on a plasma spot were 10-90 ng/mL (S/N=9) and 80-500 ng/ mL, respectively. The correlation coefficient ranged from 0.938 and 0.999. When applied to the samples from positive patients, the method clearly differentiated normal subjects from the patients with various metabolic disorders such as PKU, MSUD, OTC and a Propionic Aciduria. The new developed method might be useful for making a rapid, sensitive and simultaneous diagnosis of inherited organic and amino acid disorders. In addition, this method is expected to be an alternative method for screening newborns for metabolic disorders in laboratories where expensive MS/MS is unavailable.

COMPARATIVE EFFECTS OF LACTIC ACID, NISIN, COATING COMBINED AND ALONE APPLICATIONS ON SOME POSTMORTEM QUALITY CRITERIA OF REFRIGERATED SARDINA PILCHARDUS

ABSTRACT Fish meat is highly prone to microbiological contamination from hunting and slaughtering stages to the transportation and kitchen, especially by Pseudomonas spp. In this study, effects of nisin (0.04 g/L/kg at pH 5.2), lactic acid (5% at pH 2.9) and their combinations were studied on coated (where vegetable oil, beeswax and distilled water mixture with pH 7.2 was used as the main coating material) and noncoated fish specimens on inhibition of Pseudomonas and mesophilic aerobic bacteria (MAB) at refrigeration temperatures (+4C). Lactic acid, nisin and coating reached 5.95 log units as cfu/mL on total MAB on the seventh day of shelf life at+4C, whereas control has reached 6.62 log on the fifth day. Lactic acid, nisin and coating, and lactic acid and coating applications were determined as the most preservative applications with lowest acidity losses and highest bacterial inhibition, including Pseudomonas spp. (P &lt; 0.01).

Design and construction of thermal diffusion column heated by the flow of recycled water and used to calculate thermal diffusion factor for Ethanol – Distilled Water mixture

Design and construction of thermal diffusion column heated by the flow of recycled water and used to calculate thermal diffusion factor for Ethanol – Distilled Water mixture

Effect of NaCl solution as pore water on the residual shear strength and index properties of soil from mudstone areas

NaCl solution has significant effect on the residual shear strength of soil from mudstone areas. Soil samples were collected from the intact rock (unsheared zone) and sliding surface (sheared zone) of five mudstone landslide areas. Mixtures of distilled water and the intact rock possessed higher electric conductivity than those of distilled water and the sliding surface soil. When these samples were leached with distilled water for five times, they showed a substantial decrease in the electric conductivity. The residual shear strength varies according to the NaCl concentration in the pore water. Ring shear tests were also carried out in the commercial standard clays as bentonite and kaoline to understand the shear strength characteristics of the mudstone soils. When bentonite was treated with NaCl solution as pore water, it showed about three times increase in residual shear strength and decrease to one quarter in liquid limit. The effect of NaCl solution as pore water in kaoline was comparatively low. The residual shear strength of soil from mudstone area also increased when it was treated with NaCl solution as pore water. The result of the X-ray diffraction analysis showed that the proportion of smectite is higher than that of kaolinite in the residual soil from mudstone. These smectite minerals were found to be highly sensitive to NaCl solution. Because of the sensitive changing character of smectite minerals to NaCl solution, soil samples with NaCl rich water showed lower value in consistency limits and higher value in the residual shear strength compared to soil samples with distilled water. The findings suggest that the residual shear strength and index properties should be considered as variable properties as a result of the change in the pore water. Such properties are useful to understand frequent re-activation of the landslide occurring in the mudstone areas.

Soft solution processing of cerium hydroxysulfate powders with different morphologies

Polycrystalline cerium hydroxysulfate powders have been prepared by soft solution processing using various basic solvents. The crystals prepared have varying morphologies, spherical and flaky, depending on the solvent used. The crystals obtained from distilled water–pyridine and aqueous ammonia solvent mixtures are spherical, whereas those obtained from mixtures of distilled water and ethylenediamine or hydrazine hydrate are flaky. All the crystalline cerium hydroxysulfate samples display luminescence properties. It was found that the flaky crystals generally show a much stronger luminescence than their spherical counterparts.

Bleaching effect of carbamide peroxide gel on discolored nonvital teeth

The bleaching of discolored nonvital teeth is conservative treatment that satisfy the cosmetic desire. The most common method for this treatment, walking bleaching, is using 30% hydrogen peroxide and sodium perborate. Many alternatives are suggested for preventing the external cervical root resorption that is the common complication of the nonvital teeth bleaching with 30% hydrogen peroxide The same extent of oxidation reactions as that resulted by the bleaching with the application of 30% hydrogen peroxide and sodium perborate can also be acquired more safely by materials that contain 10% carbamide peroxide, used primarily for the bleaching of vital teeth. Therefore, this study was performed to evaluate the efficacy of 10% and 15% carbamide peroxide bleaching gel in nonvatal teeth bleaching. The internal bleaching of intentionally discolored teeth was performed in vitro with 10% carbamide peroxide (Group 1), 15% carbamide peroxide (Group 2), mixture of distilled water and sodium perborate (Group 3), and mixture of 30% hydrogen peroxide and sodium perborate (Group 4). The bleaching materials were refreshed following 3, 6, 9 and 12 days. To evaluate the bleaching effect, the color change of the crowns was measured at 1, 2, 3, 4, 7 and 15 days of bleaching using the colorimeter. The results were as follows：1. L and E values were increased with time in all bleaching agents (p and E value among bleaching agents. 3. E value higher than 3 was shown after 3 days of bleaching with 10% carbamide peroxide gel, 1 day with 15% carbamide poroxide gel, 4 days with mixture sodium perborate and distilled water and 4 days with mixture sodium perborate and 30% hydrogen peroride, respectively. These results revealed that the use of 10% and 15% carbamide peroxide bleaching gel in non-vital teeth bleaching is as effective as mixture of distilled water and sodium perborate and mixture of 30% hydrogen peroxide and sodium perborate. Accordingly, carbamide peroxide could be used clinically to bleach discolored non-vital teeth.