• Journal of Korean society of Dental Hygiene
• /
• v.14 no.4
• /
• pp.585-591
• /
• 2014

Objectives : The purpose of this study was to investigate of the color change, tooth surface and intra-pulpal temperature of tooth bleaching by light activation Methods : Forty-eight extracted bovine teeth were immersed into a tea solution for 24 hours. The specimens were randomly divided into four groups(n=15):(G1) 15% HP + without light activation, (G2) 15% HP + light activation, (G3) 25% HP + without light activation, (G4) 25% HP + light activation. All specimens were bleached for 15 minutes three times. The spectrophotometer (CM-2600d, Konica Minolta, Osaka, Japan) was used including before bleaching, immediately after bleaching, 1 week, 1 and 3 months after the end of bleaching. The temperature rise were measured in the pulpal chamber and tooth surface with a digital thermocouple thermometer(Termopar Digital Multimeter, Tektronix DMM916, USA). Between the tested time points, the specimens were stored in distilled water. The data were analyzed by ANOVA, t-test and Tukey's post hoc test set at 0.05. Results : There was no significant color change by the use of light after the bleaching treatment(p>0.05). The dental bleaching treatments of teeth with 15% HP and 25% HP did not seem to be more effective when light source was used. There was no difference in color stability between groups within three month(p>0.05). There was an increase in tooth surface and pulp temperature, but it was not sufficient to cause damage to the pulp. Conclusions :The use of light activation has no obvious effective impact on the tooth bleaching effect.

• Journal of Ginseng Research
• /
• v.11 no.2
• /
• pp.91-100
• /
• 1987

This study was investigated and analyzed the side of phenomenological of the chlorophyll bleaching phenomenon on the leaf burning-disease of the Ginseng (Panax ginseng C.A. Meyer) leaf. Red light (660-700 nm) was confirmed as one which induced the bleaching phenomenon and blue light (400-500 nm) did not at all. Temperature as 1 environmental factor had not any influence on chlorophyll bleaching phenomenon at all. Therefore, simple burning (thermal damage) hypothesis was perfectly ruled out by the result of this study. And, low pH accelerated chlorophyll bleaching velocity. A primary factor of chlorophyll bleaching phenomenon may be peculiar structural difference of the Ginseng leaf compared with other plant.

• Korean Journal of Weed Science
• /
• v.9 no.3
• /
• pp.230-237
• /
• 1989

This research was carried out to investigate the influences of temperature and light on the herbicidal activity of oxyfluorfen, oxadiazon and paraquat. Increased temperature from 10 to $35^{\circ}C$ resulted in increase of herbicidal activity in whole plants or leaf discs treated with herbicides. It seemed that temperature affected herbicide penetration into and reaction to the action site rather than appearance process of herbicidal activity (maybe membrane peroxidation after being absorbed. The activity of compounds tested increased with increased light intensity. Paraquat showed similar activities regardless of light qualities but oxyfluorfen and oxadiazon showed the highest activities in blue light spectrum, indicating that they seemed to be closely related to chlorophyll biosynthesis rather than carotenoid biosynthesis or electron transport systems of photosynthesis and respiration.

• Restorative Dentistry and Endodontics
• /
• v.19 no.1
• /
• pp.169-179
• /
• 1994

The purpose of this study was to compare and evaluate the bleaching efficacy of three nonvital bleaching techniques: Walking bleaching, Walking bleaching and heat application, and Walking bleaching and bleaching light application. 36 extracted anterior teeth with intact crowns were immersed in 5 % sodium hypochlorite solution for twenty-four hours to loosen extrinsic debris. Lingual access openings were prepared in all teeth and the pulps were extirpated. The teeth were stored in 5% sodium hypochlorite for twenty-four hours to open the dentinal tubules and they were stained via whole blood. Once the teeth were stained, they were evaluated with Colorimeter. The teeth in each group were ranked from lightest to darkest and divided equally into three experimental groups in which the following bleaching techniques were used. Intracoronal base was placed 2mm below cementoenamel junction. Group 1 Walking bleaching (Superoxol + Sodium perborate) Group 2 Heat application + Walking bleaching (Superoxol+Sodium perborate) Group 3 Light application+Walking bleaching (Superoxol+Sodium perborate) The bleaching agents were changed every 3 days and the teeth were bleached for a total of 14 days. The teeth were evaluated with Colorimeter before the start of any bleaching and on day 14. The results were as follows: 1. At the end of 14 days, all the sample teeth demonstrated the increase of Lightness Index at cervical 1/3 of crown (p<0.05) Lightness Index was significant difference in group 2 and 3, but there were some minor differences among groups (p>0.05). 2. In all groups, there was significant difference in red chromacity (p<0.05), but there were some minor differences among groups (p>0.05). 3. In all groups, there was no significant difference in yellow chromacity (p>0.05).

• Restorative Dentistry and Endodontics
• /
• v.47 no.1
• /
• pp.7.1-7.14
• /
• 2022

Objectives: This study evaluated the bleaching efficacy of different in-office protocols associated with violet light emitting diode (V-LED), and measured the pulpal temperature rise caused by V-LED with or without gel application. Materials and Methods: Bovine incisors were distributed in 4 groups (n = 10): VL - V-LED; HP - 35% hydrogen peroxide (control); HYB - hybrid protocol, V-LED applied without gel for 10 irradiation cycles followed by V-LED applied with gel for another 10 irradiation cycles; and HPVL - gel and V-LED applied for 20 irradiation cycles. Three bleaching sessions were performed with 7-day intervals. Bleaching efficacy was evaluated with ΔE_ab^*, ΔE₀₀ and ΔWI_D. Data were recorded at baseline, 7, 14, 21 and 70 days. For pulpal temperature rise, thermocouples were placed inside the pulp chamber of human incisors. To determine intrapulpal temperature, the teeth were irradiated with V-LED with or without application of bleaching gel. Color difference data were analyzed by 2-way repeated measures ANOVA and Tukey's test. Pulpal temperature was analyzed by t-test (α = 5%). Results: VL exhibited lower color (ΔE_ab^* and ΔE₀₀) and whiteness changes (ΔWI_D) than the other groups. HPVL presented higher color change values than HYB. HYB and HPVL showed not different ΔWI_D values; and HP showed the highest whiteness changes at all times. There were significant differences comparing ΔT with gel (8.9℃) and without gel application (7.2℃). Conclusions: HPLV was more efficient than HYB. The 2 protocols with VL showed similar results to control. Gel application combined with VL promoted higher pulpal temperature than to the no gel group.

• Proceedings of the Korea Technical Association of the Pulp and Paper Industry Conference
• /
• 2006.06b
• /
• pp.381-386
• /
• 2006

Many different types of bleaching chemicals and processes have been globally used for deinked pulp. Besides chlorine-free bleaching chemicals, hydrogen peroxide, and sodium dithionite that could be used without restriction for almost all types of fibers, chlorine-containing chemicals such as chlorine dioxide and sodium hypochlorite have also used throughout the world. Even though hydrogen peroxide is commonly used in newsprint, it could not effectively increase brightness. Experimental evaluation on the possibility of using formamidine sulfinic acid (FAS), a reducing agent, for bleaching a wood-containing deinked pulp has been carried out in this study. The effect of bleaching efficiency for FAS on operational conditions and chemical concentrations compaired to hydrogen peroxide in one and two stages was studied. FAS bleaching showed higher brightness at high temperature and low consistency, and vice versa for peroxide one. Bleaching with sodium silicate and DTPA in FAS and peroxide stage showed better results than cases without them. Sodium silicate and chelant seemed minimize the influence of transition metal ions, including manganese and iron ions, which induce both bleaching agents to decompose. As a result, FAS as a reducing agent seems more effective than hydrogen peroxide for increasing brightness and reducing yellowness. FAS and FAS sequence seemed more efficient than the other two stages of bleaching sequences with regard to the best brightness level obtained. When bleaching was conducted with FAS, COD load was just about one-third compared to peroxide, and brightness stability of the bleached pulp appeared better than peroxide after UV light irradiation.

• Journal of the Korean Academy of Esthetic Dentistry
• /
• v.7 no.1
• /
• pp.6-17
• /
• 1998

Tooth bleaching was being done more than 100 years ago, but the standard for vital tooth bleaching for the last quarter century has been the use of hydrogen peroxide with heat or with a combination of heat and light. The major disadvantages of this process are high cost, unpredictability of results, and patient discomfort. In March, 1989, the dental world was introduced to a new vital tooth bleaching process by Haywood and Heymann in their article "Nightguard vital bleaching(NGVB)." Interestingly enough, this simple technique could have been developed years ago if we had known about the chemical effects of carbamide peroxide on tooth structure. NGVB has created a resurgence in the area of bleaching, primarily because of its relative ease of application, the safety of the materials used, low cost, and the high percentage of successful treatments. This article was to explain simply about all around NGVB(etiology of stains, bleaching chemicals and mechanisms, bleaching effectiveness, side effect, documentation, indications, treatment therapy, laboratory procedure, case reports)

• Restorative Dentistry and Endodontics
• /
• v.25 no.4
• /
• pp.599-605
• /
• 2000

Among the effects of tooth bleaching on composite resins, degree of color change and dye deposition onto composite resins after office bleaching were investigated in vitro. Seventy two disc-shaped resin samples were fabricated with hybrid type composite resin, Z-100 under 3 different environments(24 samples for each environment) characterized by 3 kinds of light-curing intensity and duration($250mW/cm^2$-20sec., $250mW/cm^2$-40sec., $550mW/cm^2$-20sec.). As control, one-third samples of each group were not treated with bleaching agent. The remaining two-thirds samples of each group were treated with bleaching agent(bleaching group). Then, before thermocycling procedure in coffee bath, the half of the samples treated with bleaching agent were polished(polishing group) with polishing system. SofLex, but the other half(not-polishing group) and control group were not polished. Another 72 samples were also made with microfilled type composite resin. Sillux Plus and treated according to the experimental procedures mentioned above. The color of each resin sample was measured before bleaching, after bleaching, and after thermocycling preceded by bleaching. And color difference was evaluated. It was concluded as follows: 1. The amount of color change of resin samples after office bleaching was not statistically significant(p>0.05). But the samples which were treated with bleaching agent showed more color change than that of control group. 2. After thermocycling in coffee bath, the amount of color change of resin samples between control and bleaching group was not statistically significant(p>0.05). 3. After thermocycling in coffee bath, the polishing procedure of resin samples showed no statistically significant difference(p>0.05) between polishing and not-polishing group in the aspect of color change.

• Journal of Ginseng Research
• /
• v.14 no.2
• /
• pp.135-141
• /
• 1990

In order to elucidate the mechanism of the leaf-burning disease of ginseng (Panax ginseng C.A. Meyer), the relationships between thylakoid membrane peroxidation and chlorophyll bleaching were investigated in comparison with the ones of soybean (Glycine max L). When I measured the rate of lipid peroxidation in the thylakoids of ginseng and soybean by irradiation of light(60 w.m-2), it was identified that, the remarkably lower rate of lipid peroxidation was found in the ginseng thylakoid than the case of soybean. When lipid peroxidation of ginseng thylakoid was induced in the dark, chlorophyll contents of thylakoid was not changed. The results suggest that lipid peroxidation does not affect the chlorophyll bleaching in ginseng thylakoid. Thylakoid membrane peroxidation as well as chlorophyll bleaching was closely related with photosynthetic electron transport. But, according to the quenching experiment active oxygen species induced lipid peroxidation may be different species in the case of chlorophyll bleaching.

• Korean Journal of Food Science and Technology
• /
• v.12 no.2
• /
• pp.82-87
• /
• 1980

The red color bleaching phenomena of red pepper powder by the exposure to sun light were studied on the various factors such as drying methods of pepper and the storage conditions of pepper powder, relative humidities, particle sizes, and the amounts and qualities of light. The surface color of red pepper was rapidly bleached by the successive daily exposures until the color retention value (capsanthin remained/original capsanthin content) reached to 0.5, while that of dark storge showed a negligible change. The color changes were related with the cumulative solar energy at various water activities $(a_w)$. As decreasing $a_w$ below 0.5, the bleaching reaction was highly accelerated, and thereafter was slowly progressed. Sun lights transmitted by red-, yellow- and blue-gelatin filters, respectivly, bleached in different degrees and at the shorter wavelength light, the more color bleaching occurred. From this fact a red colored package film could be effectivly used for the color preservation purpose in the red pepper storage.