• Journal of Korea Technical Association of The Pulp and Paper Industry
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• v.33 no.4
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• pp.49-54
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• 2001

This study was carried out to acquire basic data for the bleaching of bamboo chemical pulp. Bamboo chemical pulps (alkaline sulfite (AS)-anthraquinone (AQ) pulp, Kraft pulp) were bleached with two kinds of multistage bleaching methods (CEDED, PDED) using the various kinds of bleaching agents. And, physical properties of bleached pulps were investigated. The conclusions obtained from the results were as follows; The yield of AS-AQ pulp bleached with four-stages bleaching method using the hydrogen peroxide and chlorine dioxide as a bleaching agents was higher than the other bleached pulps. The brightness of kraft pulp bleached with five-stages bleaching method using the chlorine and chlorine dioxide as a bleaching agents was higher than the other bleached pulps. The physical properties of kraft pulp bleached with four-stages bleaching method using the hydrogen peroxide and chlorine dioxide as a bleaching agents was higher than the other bleached pulps.

• Journal of dental hygiene science
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• v.20 no.4
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• pp.252-260
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• 2020

Background: In this study, the bleaching effect and surface damage of two types of over-the-counter home tooth bleaching agents were explored using an in vitro study of bleaching agents applied to bovine teeth specimens for 14 days. Methods: Domestic over-the-counter home tooth bleaching agents of gel and patch form that shared common active ingredients and manufacturers were selected and tested. The experiment specimens were made using composite resin with bovine tooth samples and then measured the initial microhardness. Specimens were then divided into a Gel group and a Patch group and underwent bleaching treatment once a day for two weeks for 30 to 60 minutes (recommended) or 7 hours. All specimens were coffee-stained prior to bleaching. The bleaching effect was measured using a spectrophotometer and surface damage was measured using a microhardness meter. Results: The difference in color following the bleaching procedure was positive in both the Gel and Patch group, although there were no statistically significant differences in bleaching effect between groups. There was no significant difference in bleaching effect based on duration. The microhardness test revealed that both the Gel group and the Patch group had surface damage after bleaching. The greatest surface damage was found in the Patch group that had undergone a 7-hour bleaching treatment, although the differences were not statistically significant. Conclusion: The bleaching effect of the home tooth bleaching agent was visible to the naked eye. However, longer applications than recommended did not result in greater bleaching, unlike consumers' expectations, and instead increased the chance of enamel damage. As such, there is a need for consumers to be alert and adhere to recommendations provided by each company.

• Journal of the Korean Society of Clothing and Textiles
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• v.30 no.2 s.150
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• pp.338-347
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• 2006

Due to the complex environment in the ground, most of excavated costumes undergo deterioration and color change. To reduce the extent and intensity of the staining and to recover the original color or gray fabrics of excavated costumes, bleaching would be required. Excavated historical costumes are very delicate in nature, therefore, special care is needed in bleaching process. Several bleaching agents were selected and applied to the control cotton fabric and pre-deteriorated cotton fabrics to examine the change of color and physical properties after bleaching. A dual bleaching using hydrogen peroxide and sodiumborohydride showed the superior bleaching effect to the other bleaching agents. The strength of pre-deteriorated fabrics slightly increased after dual bleaching. The six historical costumes which belonged to General Duk-Ryung Kim's nephew's wife were dual bleached. They became remarkably cleaned and brightened. The treatments improved the appearance of costumes. By microscopic investigation, it is found that costumes did not show the damage after treatment. In conclusion, it is possible to bleach historical textiles without damage using appropriate bleaching agents like hydrogen peroxide and sodiumborohydride.

• Journal of the Korean Academy of Esthetic Dentistry
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• v.4 no.1
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• pp.12-22
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• 1995

The purposes of this study were to compare the bleaching efficacy of sodium perborate when mixed either with Superoxol or distilled water and to evaluate the efficacy of different location of intracoronal base on the presence of apical leakage of tested bleaching agents. Forty eight extracted human permanent incisors were stained via whole blood and canal fillings with conventional gutta percha were performed after routine biomechanical perparations. The experimental intracoronal base was placed either at the cementoenamel junction(group 3, 4) or 2mm below cementoenamel junction(group 1, 2). Walking bleaching was performed by two different combinations of bleaching agents : sodium perborate with distilled water in group 1, 3 and sodium perbrate with Superoxol in group 2, 4. The roots of the teeth were evaluated for the presence of color change to assess the leakage of bleaching agents and the cervical one-thirds of the crown were evaluated for bleaching effect from the whiteness Indea calculated by spectrophotometer. The results were as follows : 1. At the end of 12 days, all the sample teeth demonstrated the increase of Whiteness Index at cervical 1/3 of crown although there were some minor differences among groups. 2. Regardless of location of the base, sodium perborate with superoxol(group 2, 4) showed better results in bleaching than the sodium perborate with distilled water(group 1, 3). 3. Bleaching agent leaked into the root area when the base was placed 2mm below cementoenamel junction but no leakage was found when the base was placed at the cementoenamel junction.

• Restorative Dentistry and Endodontics
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• v.20 no.2
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• pp.802-811
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• 1995

The purpose of this in vitro study was to compare the bleaching effect and the surface change according to three bleaching agents (Rembrandt, Natural White, Hi-Lite). Teeth were stained by artificial food colorants for 6 weeks and bleached for 4 weeks. The teeth were evaluated with spectrophotometer after bleaching on the 1st week and on the 4th week. The surface change of enamel was evaluated under SEM after exposure to 3 agents for 1 and 24 hours. The results were as follows : 1. All groups showed increased Lightness difference after bleaching. 2. After 1 week, only Rembrandt group showed significant bleaching effect compared to control group. 3. After 4 weeks, Rembrandt group and Hi-Lite group showed significant bleaching effect compared to control group. 4. SEM evaluation revealed that enamel surface underwent considerable change after 24 hours. Scratch disappeared and smooth surface was shown.

• Journal of Technologic Dentistry
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• v.23 no.1
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• pp.85-93
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• 2001

The purpose of this study was to evaluate the effects of commercial home-tooth bleaching agents on the color of tooth. Twenty five sound extracted teeth were randomly divided into five groups. The color differences between before and after treatment with five types of tooth bleaching agents (7.5% hydrogen peroxide Nite White $Excel^{(R)}$, 10% carbamide peroxide Nite White $Excel^{(R)}$, 16% carbamide peroxide Nite White $Excel^{(R)}$, 10% carbamide peroxide Insta-BriteTM, 20% carbamide peroxide Insta-$Brite^{TM}$) were evaluated. The results were as follows: 1. By 2 week home tooth bleaching agent applications, the values ($L^*$) of bovine teeth increased as high as 4.38 $\sim$ 8.80 when comparing to those of the samples before treatment, and the color difference (${\Delta}E^*$) showed as high as 10.16 $\sim$ 15.04. 2. 16% carbamide peroxide Nite White Excel induced significantly greater ${\Delta}L^*$ than other test edgroups except for 7.5% hydrogen peroxide Day White Excel, and significantly greater ${\Delta}E^*$ than other tested groups by 2 week bleaching agent treatments (p<0.01). 3. 16% carbamide peroxide Nite White Excel(${\Delta}L^*$=8.80, ${\Delta}E^*$=15.04) induced significantly greater ${\Delta}L^*$ and ${\Delta}E^*$ than 10% carbamide peroxide Nite White Excel(${\Delta}L^*$=5.01, ${\Delta}E^*$=10.16)(p<0.01), but significant difference between 10% carbamide peroxide Insta-Brite(${\Delta}L^*$=4.38, ${\Delta}E^*$=10.51) and 20% carbamide peroxide Insta-Brite(${\Delta}L^*$=5.63, ${\Delta}E^*$=11.23) was not shown in ${\Delta}L^*$ and ${\Delta}E^*$(p>0.01). 4. 16% carbamide peroxide Nite White Excel(${\Delta}L^*$=8.80, ${\Delta}E^*$=15.04) which were applied in night time induced significantly greater ${\Delta}L^*$ and ${\Delta}E^*$ than 7.5% hydrogen peroxide Day White Excel(${\Delta}L^*$=8.47, ${\Delta}E^*$=12.75) which were applied in day time. Conclusions: These results demonstrate that all the commercial home-tooth bleaching agents have appreciable bleaching effect on teeth, and the effects of home-tooth bleaching agents which are used during night time are affected by content of carbamide peroxide. Especially the whitening effect of home tooth bleaching agents that are used through night time is greater than that of short time-applying tooth bleaching agent.

• Restorative Dentistry and Endodontics
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• v.18 no.1
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• pp.145-155
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• 1993

The purposes of this study were to compare the bleaching efficacy of sodium perborate when mixed either with Superoxol or distilled water and to evaluate the efficacy of different location of intracoronal base on the presence of apical leakage of tested bleaching agents. Forty eight extracted human permanent incisors were stained via whole blood and canal fillings with conventional gutta percha were performed after routine biomechanical perparations. The experimental intracoronal base was placed either at the cementoenamel junction(group 3, 4) or 2mm below cementoenamel junction(group 1, 2). Walking bleaching was performed by two different combinations of bleaching agents : sodium perborate with distilled water in group 1, 3 and sodium perbrate with Superoxol in group 2, 4. The roots of the teeth were evaluated for the presence of color change to assess the leakage of bleaching agnets and the cervical one-thirds of the crown were evaluated for bleaching effect from the whiteness Indea calculated by spectrophotometer. The results were as follows : 1. At the end of 12 days, all the sample teeth demonstrated the increase of Whiteness Index at cervical 1/3 of crown although there were some minor differences among groups. 2. Regardless of location of the base, sodium perborate with superoxol)group 2, 4) showed better results in bleaching than the sodium perborate with distilled water(group 1, 3). 3. Bleaching agent leaked into the root area when the base was placed 2mm below cementoenamel junction but no leakage was found when the base was placed at the cementoenamel junction.

• Restorative Dentistry and Endodontics
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• v.2 no.1
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• pp.11-14
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• 1976

The purpose of this study was to the observe effects of the various bleaching agents on blood clot. Absorbent papers(N9.5) were coated with O type blood and were dried in shadow for 72 hours. Bleaching agents used were 5% NaOCl 30% $H_2O_2$, saturated solutions of $NaBO_3$ $4H_2O$, $Ca(OCl)_2$ and $Na_2O_2$ at $20^{\circ}C$. After the specimens, blood cloted papers were dipped in 10CC of solution for 1 minute, 5 minutes, 30 minutes, 2 hours and 24 hours, specimens were washed with distilled water and dried. Hue Value/Chroma contrived by Munsell was measured in each specimen. The following results were obtained. 1. Superoxol changes 2.5YR 4.5/2 into N9.5 (white) after 24 hours. 2. All bleaching agents except superoxol change YR into Y.

• Restorative Dentistry and Endodontics
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• v.24 no.3
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• pp.453-464
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• 1999

The non-vital bleaching technique has been used widely as a very effective treatment method on discolored non-vital teeth. But periodontal tissue deterioration and cervical external root resorption have been reported because of the high toxicity of hydrogen peroxide in bleaching agents. So in previous studies, placement of base over the root canal obturation prior to bleaching has been suggested in order to prevent microleakage of bleaching agents, however, the effectiveness of base is still controversial. The purpose of this study was to evaluate the effects of base and root canal sealer on prevention of leakage of bleaching agents in non-vital bleaching. Fifty-two extracted sound teeth with single root were used. For root canal obturation, Tubuli seal$^{(R)}$(Kerr Co., USA) was used in 39 teeth and in others, AH-26$^{(R)}$(De Trey Dentsply, Inc., Switzerland) was used as a root canal sealer. 26 teeth among the teeth obturated with Tubuli seal$^{(R)}$ were divided into two groups, and Dentin cement$^{(R)}$(GC corp., Japan) and JRM$^{(R)}$(De Trey Dentsply, Inc. Germany) were used in each group as a intracanal base. In all teeth, non-vital bleaching using bleaching agent mixed with methylene blue dye was performed and all specimens were stored in $37^{\circ}C$ water bath for 72 hours. After sectioning longitudinally, the depth of dye leakage was measured with digital vernier calipers under the stereobinocular microscope using ${\times}40$ magnification. It can be concluded as follows: 1. The microleakage of bleaching agent was observed ill all groups regardless of type of the base and the sealer. 2. The microleakage in the groups using AH-26$^{(R)}$ as a sealer was significantly reduced (p<0.05). 3. In the groups with intracanal base, micro leakage was observed through almost the whole depth of the base and there was no significant difference between Dentin cement$^{(R)}$ and IRM$^{(R)}$ group(p>0.05). In conclusion, all the basing materials and the sealers in this study did not prevent the microleakage of bleaching agent. Therefore further studies and attempts to seal off the pulp chamber will be necessary.

• Journal of Korea Technical Association of The Pulp and Paper Industry
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• v.32 no.3
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• pp.65-74
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• 2000

This study was carried out to acquire basic data necessary for the use of rice-straw chemical pulp. It investigated the proper bleaching conditions when rice-straw chemical pulps(alkaline sulfite-Na2S2O4 pulp) were bleached with the various kinds of bleaching agents. And physical properties of bleached pulps were tested. The results of this study were as follows; 1, The proper conditions of chlorine sequence were determined to be 4% concentration of chlorine 25$^{\circ}C$ of reaction temperature and 50 minutes of reaction time. 2. For calcium hypochlorite sequence the proper conditions of chemical concentration reac-tion temperature and reaction time were 3% 25$^{\circ}C$ and 20 minutes respectively. 3. For chlorine dioxide sequence the proper conditions were 1% concentration of chlorine dioxide 70$^{\circ}C$ of reaction temperature and 2hr. of reaction time. 4. The proper conditions of hydrogen peroxide sequence were 1.5% concentration of hydro-gen peroxide 70$^{\circ}C$ of reaction temperature and 1hr. of reaction time respectively. 5. When the rice-straw chemical pulp were bleached with four kinds of bleaching agents methioned above in the proper conditions respectively brightnesses were the order of chlorine dioxide calcium hypochlorite, chlorine, hydrogen peroxide. And strengthes of pulps bleached with chlorine dioxide and hydrogen peroxide were higher than those of pulps bleached with other bleaching agents.