• Journal of Korean society of Dental Hygiene
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• v.6 no.4
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• pp.481-493
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• 2006

The purpose of the review article was to summarize and discuss the available information concerning the effect of bleaching on human teeth and reduced treatment on negative influence. Tooth bleaching effect was differ from extent of concentration and application period of a tooth bleaching agent, certainly full knowledge prior treatment about adverse effect possible appearance and follow clinical treatment for the least reduce. It remains unclear in how far those observation may result in significant adverse effect under clinical conditions. Nevertheless, further investigation are necessary to elucidate these aspect more precisely. The findings of the study were as follows : 1. It is recommended to delay placement of restorations after termination of bleaching therapy for at least 1-3 weeks. 2. Reduced negative influence that is clinical feasibility of catalase in protecting bleached surface against Oxygen radical. 3. The residual peroxide in tooth after bleaching seems to be removed by gradual diffusion and it may be possible to eliminate the adverse effect on tooth by using water displacement solution, ethylalcohol and aceton including it for effective removal of free radical oxygen.

• Restorative Dentistry and Endodontics
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• v.49 no.2
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• pp.14.1-14.13
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• 2024

This study aimed to answer the question through a systematic review: Can carbamide peroxide be as effective as hydrogen peroxide and cause less in-office bleaching sensitivity? A literature survey was performed in PubMed/MEDLINE, Embase, Scopus, ISI Web of Science, and gray literature. Primary clinical trials that compared the efficacy or the in-office bleaching sensitivity between carbamide and hydrogen peroxides were included. The risk of bias was evaluated using the RoB2. The certainty of the evidence was assessed using the GRADE approach. DPI training significantly improved the mean scores of the dental undergraduates from 7.53 in the pre-DPI-training test to 9.01 in the post-DPI-training test (p < 0.001). After 6 weeks, the mean scores decreased marginally to 8.87 in the retention test (p = 0.563). DPI training increased their confidence level from 5.68 pre-DPI training to 7.09 post-DPI training. The limited evidence suggests that the 37% carbamide peroxide may be similarly effective to the 35% hydrogen peroxide for bleaching teeth in-office and causes less bleaching sensitivity. However, more well-designed split-mouth clinical trials are necessary to strengthen the evidence.

• The Journal of the Korea Contents Association
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• v.10 no.11
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• pp.235-242
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• 2010

The purpose of this study was to evaluate tooth whitening and microhardness after treatments with tooth bleaching agents containing dicalcium phosphate dihydrate (DCPD) and 35% hydrogen peroxide (HP) which were used in-office bleaching. Thirty enamel specimens were obtained from human premolars and randomly divided into 3 groups(n=10). Tooth bleaching agents were prepared with DCPD (0 g for controls, 0.1 g and 1 g for experimental groups) and HP solution (35% HP). All groups were applied to enamel surfaces for 60 min for 1 day. The pH of each tooth bleaching agent was measured. Tooth color, microhardness of enamel surfaces were also measured. The tooth bleaching agents containing DCPD showed a significant increase in pH compared to the ones without DCPD(p<0.05). Paired t-tests showed significant difference in color values of enamel before and after bleaching in all the groups(p<0.05). As a result, changes in color, containing DCPD group does not contain a statistically significant difference between groups was observed.(p>0.05). In all groups, tooth hardness after bleaching showed a significant decrease in microhardness (p<0.05). However, the DCPD concentration increased in the bleaching, microhardness values slightly decreased. Based on the above results, tooth bleaching agents containing DCPD and 35%HP were equally effective. Due to increases in pH and effective reduction of tooth surface decalcification, the surface characteristics are exposed to a reduced degree of negative effects, resulting in fewer constituent enamel alterations. Thus, commercial availability of the constituents of tooth whitening materials can be achieved.

• Journal of dental hygiene science
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• v.9 no.5
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• pp.525-530
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• 2009

The purpose of this study was to evaluate color change and enamel surface changes using the plasma arc light source during tooth bleaching treatments. Twenty-four extracted bovine incisors were selected and embedded in the resin blocks. All the specimens were highly polished and discolored with commercial $COCK^{(R)}$. High concentration carbamide peroxide with and without plasma arc were used for bleaching. Specimens were bleached for 1 hour per week during 3 weeks. Color and enamel surface changes were determined with colorimeter (TC-8600A), microhardness tester(MXT-a7), scanning electron microscope(S-4200). All the collected data analyzed with paired t-test, t-test and one-way ANOVA. After the bleaching, both groups showed the color changes(${\Delta}E^*$). Microhardness of two group decreased after tooth bleaching. The SEM evaluation of enamel surface of both group showed a similar morphology of decalcification after tooth bleaching. Office bleaching using the plasma arc application with 35% carbamide peroxide can increase the color change. Office bleaching using the high concentration of carbamide peroxide and plasma arc also detract the outer surface of enamel. It is recommended that careful procedures are needed during office bleaching with high concentration of carbamide peroxide and light source.

• Journal of dental hygiene science
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• v.21 no.2
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• pp.96-103
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• 2021

Background: We aimed to investigate the effect of Citrous limon extract (CLE) on oxidative stress-induced cytotoxicity and nitric oxide (NO) generation and the tooth bleaching effect of CLE as a substitute for hydrogen peroxide (H₂O₂) and determine the feasibility and application of CLE as a safe and effective natural tooth bleaching agent. Methods: The protective effect of CLE on H₂O₂-induced cytotoxicity in Raw264.7 macrophages was investigated by the MTT assay. The inhibitory effect of CLE on the generation of H₂O₂-induced NO was confirmed by the NO assay, and the changes in inducible nitric oxide synthase (iNOS) protein expression were confirmed by western blotting. Stained bovine teeth were treated with/without 15% and/or 35% CLE and H₂O₂, 15% sodium bicarbonate (NaHCO₃) for 3 hours, and were irradiated with/without bleaching light (BL) for 15 minutes. The color change of the treated bovine tooth surface was measured using a colorimeter. Results: The viability of Raw264.7 cells treated with each concentration of CLE and 500 μM H₂O₂ significantly increased as CLE increased, and NO generation and iNOS protein expression were significantly reduced in cells treated with 300 ㎍ CLE+/500 μM H₂O₂+ and 300 ㎍ CLE+/500 μM H₂O₂+/150 ㎍ NaHCO₃+. The bleaching effect of 35% CLE+ was higher than that of 15% CLE+ and 15% NaHCO₃+, and the effect was similar to that of 15% H₂O₂+. The 35% CLE+/15% NaHCO₃+ showed the greatest bleaching effect and was higher than that of the groups irradiated with the BL. The greatest bleaching effect was observed with 35% CLE+/15% NaHCO₃+, followed by 35% H₂O₂+/BL+. Conclusion: CLE inhibited oxidative stress-induced cytotoxicity and NO generation in Raw264.7 cells and, could replace H₂O₂, which causes side effects and risks in teeth breaching treatment. It showed greatest teeth bleaching effect when combined with NaHCO₃. CLE is an effective and safe natural tooth bleaching substitute.

• Journal of Korea Technical Association of The Pulp and Paper Industry
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• v.47 no.4
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• pp.109-114
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• 2015

In this study, the effects of chlorine dioxide (D) bleaching conditions on the delignification of hemp bast fiber were elucidated. Chlorine dioxide bleaching was carried out through three stages (DED) and five stages (DEDED), respectively. Applied amounts of chlorine dioxide at $D_1$ and $D_2$ stages were varied to find the optimum bleaching condition. It was found that the optical properties of its handsheet as well as the delignification of hemp bast fiber increased as the concentration of chlorine dioxide at $D_1$ stage increased. It was also notable that the bleachability of the DEDED bleaching stages was slightly more effective than that of the DED bleaching stages. The burst index of the handsheets made with bleached hemp bast fiber was higher than that of the unbleached samples, but the burst index of these samples decreased as their delignification increased. These results indicated that the higher concentration of chlorine dioxide at $D_1$ stage was major factor to improve the bleaching efficiency of hemp bast fiber.

• Applied Chemistry for Engineering
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• v.2 no.3
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• pp.262-269
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• 1991

Bleaching effect of ozone on unsaturated coloring material was compared quantitatively with the change of composition of reactants through the ozone oxidation of ${\beta}$-carotene. Beeswax colorized by carotenoids was reacted with ozone in water, 0.5 % and 1.0 % sodium hydroxide solution, and 20 % and 95 % acetic acid solution and bleaching effect of each reaction condition was compared with each other. And then the additive effect of hydrogen peroxide was investigated. Decrease of unsaturated double bond of ${\beta}$-carotene was proportioned quantitatively to the bleaching effect of ozone on ${\beta}$-carotene and was in accordance with the bleaching effect on beeswax. The bleaching effect of ozone on coloring material in 1.0 % sodium hydroxide solution was better than any other condition and the absorbance of beeswax at 390 nm was improved to 0.045 with the addition of hydrogen peroxide(2 % of wax). For the bleaching of beeswax, it was concluded that the ozone oxidation was more effective than physical adsorption.

• Korean Journal of Food Science and Technology
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• v.49 no.6
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• pp.584-590
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• 2017

Effects of bleaching and deodorization on the quality of imported palm and canola oils were evaluated. Imported palm oil and deacidified canola oil were bleached with acid clay, followed by deodorization. Oxidation-related quality was evaluated by determining fatty acid composition by GC, acid and peroxide values, induction period by Rancimat, and off-flavor compounds by GC-MS. Tocopherols and benzo(a)pyrene were analyzed by HPLC. Acid and peroxide values were decreased by bleaching and deodorization, and tocopherol content was decreased to 60-70% (p<0.05). Aldehydes were major off-flavor compound class of imported oils, most of which were removed after deodorization. No significant change was observed in benzo(a)pyrene content (${\sim}0.4{\mu}g/kg$) of both oils by bleaching and deodorization (p>0.05). The oxidation-related quality of palm and canola oils was more improved after industrial bleaching than by deodorization. These results suggest that a careful control of bleaching during domestic refining can improve the quality of palm and canola oils.

• Restorative Dentistry and Endodontics
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• v.45 no.1
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• pp.12.1-12.8
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• 2020

Objectives: The aim of this in vitro study was to evaluate the microhardness and surface roughness of composite resins before and after tooth bleaching procedures. Materials and Methods: Sixty specimens were prepared of each composite resin (Filtek Supreme XT and Opallis), and BisCover LV surface sealant was applied to half of the specimens. Thirty enamel samples were obtained from the buccal and lingual surfaces of human molars for use as the control group. The surface roughness and microhardness were measured before and after bleaching procedures with 35% hydrogen peroxide or 16% carbamide (n = 10). Data were analyzed using 1-way analysis of variance and the Fisher test (α = 0.05). Results: Neither hydrogen peroxide nor carbamide peroxide treatment significantly altered the hardness of the composite resins, regardless of surface sealant application; however, both treatments significantly decreased the hardness of the tooth samples (p < 0.05). The bleaching did not cause any change in surface roughness, with the exception of the unsealed Opallis composite resin and dental enamel, both of which displayed an increase in surface roughness after bleaching with carbamide peroxide (p < 0.05). Conclusions: The microhardness and surface roughness of enamel and Opallis composite resin were influenced by bleaching procedures.

• Analytical Science and Technology
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• v.14 no.3
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• pp.266-273
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• 2001

One pulp manufacture facility was selected as surveying facilities to examine the discharged rate and generation mechanism of dioxin in bleaching stag wastewater. The analytical method was established in the wastewater and the sample was collected and analyzed. The outlet concentration of bleaching stage was increased 5 times for 2,3,7,8-TCDF and 7 times for OCDD, and the discharged ratio between PCDFs and PCDDs was surveyed about 2:3. The 2,3,7,8-TCDF and 2,3,7,8-TCDD were mainly detected in acid wastewater of bleaching stage that is known as the typical discharged patterns of chlorine bleaching stage.