• Journal of dental hygiene science
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• v.8 no.4
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• pp.255-260
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• 2008

The purposes of this study were to examine the effect of 35% hydrogen peroxide (HP) bleaching agent on the changes in physical and chemical characteristics of tooth. The bleached teeth showed an apparent color changes. The whiteness increased linearly within the tested period as the period of bleaching increased. The microhardness between bleached groups after bleaching showed any statistically significant difference according to the paried t-test. The bleached enamel surface showed any apparent morphological changes compared to the enamel which was stored in distilled water only. The difference of the total mineral contents for the distilled water and hydrogen peroxide did not show statistical significance. These results demonstrated that bleaching using 35% hydrogen peroxide were adversely affects application time of experimental group and may confirm the safety of using these agents for a short time in dentist-monitored bleaching.

• Restorative Dentistry and Endodontics
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• v.16 no.2
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• pp.155-164
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• 1991

The purpose of this study was to evaluate the effects of bleaching agent through the dentinal tubules of cervical area in the intracoronal bleaching of pulpless teeth on cutured fibroblast cells. Extracted human incisors were enlarged to # 40 K-file and obturated with gutta-perella and AH 26 sealer. The gutta-percha was removed to 2mm below the cementoenamel junction of the root The teeth were divided into 3 experimental and control groups. Experimental groups; Experimental group 1: Temporary inlay wax filld with 30% $H_2O_2$ in pulp cavity. Experimental group 2: Temporary inlay wax filld with 30% $H_2O_2$ in pulp cavity after placement of ZOE cement to cementoenamel junction. Experimental group 3: Temporary inlay wax filld with 30% $H_2O_2$ in pulp cavity after application of Copalite to cementoenamel junction. Control group: Temporary inlay wax filled without 30% $H_2O_2$ in pulp cavity under the same condition at each experimental group. Each tooth was immersed in well of multidish cultured fibroblast cell for 48 hours. The cellular multiplication and cell viability were calculated at the interval of 1, 3, 5. 7 hours and the morphological changes in well were observed and their photographs were taken with inverted microscope. The obtained results were as follows : CD The cellurar multiplicaton and cell viability decreased in all experimental groups at 1 hour after experiment and the morphology of fibroblast cell was changed from star shape to round (2) The cell viability was lowered to 34 % in experemental group 1, 44 % in experimental group 2, and 38 % in experemental group 3 at 3 hours after experiment (3) The cell multiplication was decreased to 54% in experemental group 1. 47% in experimental group 2, and 40% in experemental group 3 at 7 hours after experiment. (4) The decrease of cell number and morphological changes of fibroblast cell were remarkable in experimental group 1, group 3 and 2 in order. These results suggest that the fibroblast cells receive severe damage by 30% $H_2O_2$ solution leaked through the dentinal tubules and the dentinal tubules are able to be obturated better by ZOE cement than by Copalite.

• Restorative Dentistry and Endodontics
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• v.19 no.2
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• pp.585-601
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• 1994

The purpose of this study was to evaluate the ability of several intracoronal base materials to prevent cervical leakage of a bleaching agent into the dentinal tubules and along the root canal. In this study, thirty-two anterior teeth were used. After lingual access was prepared in each tooth, tooth was instrumented with a step-back technique to a Nos. 40-50 using K-type files. All teeth were obturated with a lateral condensation technique. Excess gutta percha was removed with a warm instrument to the facial level of the CEJ. Teeth were divided into four groups : Teeth in control group were not filled with base material. Teeth in groups 1, 2, and 3 had 2mm of gutta percha removed with a warm instrument, then Dycal, Fuki II LC and Z-100 were filled with palstic instruments on the top of the gutta percha respectively. All teeth were bleached for 7 days, fresh bleach was added for another 7 days, then a 10 % methylene blue dye was placed inside the access preparation. They were stored at $37^{\circ}C$ and $100^{\circ}C$ humidity for 5 days. Each tooth was sectioned perpendicular to the long axis using a diamond disk. Initial cuts were made at the most coronal level of facial and lingual CEJ's, then another cuts continued appically in the levels of 0.5mm, 1.5mm, and 2.0mm respectively. The amount of dye leakage through the dentinal tubules was determined at each cut section. In addition, when the cut specimen was determined to be last penetration of any dye, this level was recorded as depth of apical leakage from the coronal terminus of the gutta percha, Dycal, Fuji II LC and Z-100. The acquired data were analyzed by Tukey's Multiple Range Test adn Cochran-Mantel-Haenszel Test to see if there was any statistically significant difference in dye penetration and linear apical leakage among the groups. The results were as follows : 1. Control group at levels of CEJ and 0.5mm, group 3 at level of 1.5mm, and group 2 AND 3 at level of 2.0mm showed the least dye penetration through the facial or lingual dentinal tubules, but there were no significant difference among three groups. 2. Group 2 at levels of CEJ and 0.5mm, group 3 at level of 1.5mm, and group 2 and 3 at level of 2.0mm showed the least dye penetration through the proximal dentinal tubules, but there were no significant difference among control group, group 2, and group 3. 3. Group 1 showed the greatest dye penetration through the facial or lingual and proximal dentinal tubules at all levels, and there were significant difference with other three groups. 4. Control group and group 1 showed 2mm apical dye leakage at facial or lingual and proximal aspects, group 2 showed 1.5mm, and group 3 showed 0.5mm.

• Restorative Dentistry and Endodontics
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• v.34 no.2
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• pp.154-161
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• 2009

This clinical study evaluated the whitening effect and safety of polymer based-pen type BlancTis Forte (NIBEC) containing 8.3% carbamide peroxide. Twenty volunteers used the BlancTis Forte whitening agent for 2 hours twice a day for 4 weeks. As a control. Whitening Effect Pen (LG) containing 3% hydrogen peroxide was used by 20 volunteers using the same protocol. The change in shade (${\Delta}E^*$, color difference) was measured using $Shadepilot^{TM}$ (DeguDent) before, during, and after bleaching (2 weeks, 4 weeks, and post-bleaching 4 weeks). A clinical examination for any side effects (tooth hypersensitivity or soft tissue complications) was also performed at each check-up. The following results were obtained. 1. Both the experimental and control groups displayed a noticeable change in shade (${\Delta}E$) of over 2. No significant differences were found between the two groups (p > 0.05), implying that the two agents have a similar whitening effect.2. The whitening effect was mainly due to changes in a and b values rather than in L value (brightness). The experimental group showed a significantly higher change in b value, thus yellow shade, than the control (p < 0.05). 3. None of the participants complained of tooth hypersensitivity or soft tissue complications, confirming the safety of both whitening agents.

• Journal of dental hygiene science
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• v.21 no.3
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• pp.178-184
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• 2021

Background: As the importance of the esthetic function of teeth increases, the use of esthetic restoration materials and whitening treatment are increasing. The purpose of this study was to investigate the color change of esthetic restoration materials upon using staining and whitening toothpaste. Methods: Light curing (LC) packable composite resin, LC flowable resin, LC glass ionomer (GI), and self-curing GI specimens were colored in coffee or curry for three hours a day for seven days. After that, regular toothpaste, whitening toothpaste containing hydrogen peroxide, and whitening toothpaste containing activated charcoal were applied for three minutes three times a day for two weeks. Luminosity (L), chromaticity a (a), and chromaticity b (b) were measured using a spectrophotometer once a week. Results: In the coffee-colored group, the change in L^2*a^2*b² (E²) with time was significant (p=0.004), there was no difference for different toothpaste types (p=0.646), and there was significant difference (p<0.001) for different esthetic restorative materials. The change of E² in the curry-colored group was significant only for different esthetic restorative materials (p<0.001). In the coffee-colored group, the L, a, and b values of the light-curing GI showed greater change than other materials after staining and one week after whitening, turning dark, red, and yellow. In the curry-colored group, L did not differ for different materials and times, and a and b showed the greatest difference in light-curing GI after staining and one and two weeks after whitening. Conclusion: The use of whitening toothpaste for two weeks was not different from the use of general toothpaste in the removal of staining or whitening. Since light-curing GI is the most vulnerable to coloration, it is recommended that coloring by food chromogen should be explained in advance, before using light-curing GI for teeth restoration.