• Journal of the Korean Association of Oral and Maxillofacial Surgeons
• /
• v.28 no.1
• /
• pp.16-23
• /
• 2002

To understand the micro-mechanical changes and the effects of the fluoride on rat's femur after administration of sodium fluoride, the three-point bending test, acoustic emission analysis during the three-point bending test and scanning electron microscopy were performed. The obtained results were as follows: 1. Bone strength increased in the rats given 1, 5, 10 and 20 ppm of fluoride but, there were no statistical significances (p>0.05). 2. With increasing the concentration of fluoride, most AE events released rapidly just before the maximum load and smaller events were recorded than the control group's. The average of cumulative AE event counts until maximum load of the femur in 20 ppm group were significantly small with respect to the control group's (p<0.05). 3. Fracture surfaces were well coincide with the results of acoustic emission behavior. Analyses of fracture surfaces indicated that, consistent with its the highest load, rat femur in 20 ppm fluoride group displays the roughest surface.

• Environmental Analysis Health and Toxicology
• /
• v.14 no.3
• /
• pp.113-120
• /
• 1999

Fluorination of drinking water has been used world widely to reduce the incidence of caries. Recently, contradictory results on the cytotoxicity of fluoride compounds are reported. In addition, there are attempts to use fluorosilicate for fluorination of drinking water in Korea, therefore, we tried to analyze the cytotoxicity of fluoride compounds on oral epidermoid carcinoma (KB and A253) and osteosarcoma (HOS and MG-63) cells in this study. We treated cells with 0, 10, 50 and 250 ppm of fluorosilicic acid (domestic or from Fluka, F$\_$6/H$_2$Si), sodium fluorosilicate (F$\_$6/Na$_2$Si), sodium fluoroacetate (FCH$_2$CO$_2$Na), sodium fluoride (NaF) or potassium fluoride(KF) and measured the relative cell survival by MTT assay. At the concentration of < 10ppm, no significant cytotoxicity was observed. At 50 ppm, each cells revealed different response to fluoride treatment. Among cells used in this study, MG-63 was the most resistant to fluoride treatment. Comparable toxicity data from domestic and imported fluorosilicic acids were obtained. When we compared the relative cytotoxicity of fluoride compounds against their fluoride contents, the differences in relative cell survival were smaller. Most of cells showed < 20% of survival at 250 ppm. In order to analyze the pH dependence of the cytotoxicity of fluorosilicates, the pH of cell culture media containing fluorosilicate was adjusted to 7.4 or 6.5 and the relative cytotoxicity was measured. At lower pH, about 10% higher cytotoxicity was obtained. Thus, our data suggested that the toxicity of domestic fluorosilicic acid was similar to that of fluorosilicic acid from Fluka, and the cytotoxicity of fluoride compounds was dependent on the relative content of fluoride and pH.

• Journal of Korean society of Dental Hygiene
• /
• v.10 no.4
• /
• pp.757-764
• /
• 2010

Objectives : The fluoride coating for caries prevention and strengthen enamel use NaF(sodium fluoride, Junsei Chemical Co., Ltd, Japan) 2% gel, SnF2(stannous fluoride, SIGMA-ALDRICH Gmbh, USA)8% gel and APF(acidulated phosphate fluoride, Sultan health care, USA) 1.23% gel. Methods : After put the enamel piece in these fluoride compound gel, we observed density level. And after measuring the vickers hardness, Got the following conclusions. Results : 1. After settling in the APF 1.23% during 6 days, we observed high density level of enamel surface using 250 magnification scanning microscope. The vacuum of surface packed (in) like sardines. 2. After settling in the APF 1.23% during 6 days, we observed reducing the space between the cluster of enamel surface using 50,000 magnification scanning microscope. 3. The vickers hardness change was very much on the all kinds of fluoride compound gel[2% NaF(sodium fluoride)gel, 8% SnF2(stannous fluoride) gel, 1.23% APF(acidulated phosphate fluoride)gel]. It's all because of reducing the space between the cluster of enamel surface(p<0.001). Conclusions : The vickers hardness change was very much on the all kinds of fluoride compound. It's all because of reducing the space between the cluster of enamel surface.

• Journal of Korean Society of Water and Wastewater
• /
• v.17 no.4
• /
• pp.510-518
• /
• 2003

The fluoride work management of water supply conveyance has been recommending by the WHO to prevent of tooth decay. Fluoridation of public water supplies has been practiced since 1945. The present approximately 67 countries reported community water fluoridation benefiting many cities. At our country, Fluoridation began in 1981 in Chongiu and Jinhea. In 2002, approximately 40 cities have large populations consuming fluoridated water. But Chongiu stopped fluoridation water works. Few public health measures have been accorded greater clinical and laboratory research, epidemiological study, clinical trials, and public attention than has water fluoridation. In this study, chemical analysis of Sodium Silicofluoride and Fluoride Feed Equipment analyzed. And this study proposed to Fluoride concentration experimental (lab. and field exp.), economics analysis, prevention effect. This study can be decided on the concentration of fluoride injection in Water Fluoridation. Hereafter, this study will be useful in safety and economics of Water Fluoridation in the future.

• Journal of the korean academy of Pediatric Dentistry
• /
• v.51 no.1
• /
• pp.80-87
• /
• 2024

Silver diamine fluoride, which can arrest dental caries, is alkaline and may cause mild soft tissue irritation. Water-based silver fluoride has a neutral pH, which is closer to the physiological range, and is biocompatible for use in the oral environment. This study aimed to evaluate the effect of water-based silver fluoride on remineralizing early enamel lesions by comparing it with other fluoride agents through microhardness and quantitative light-induced fluorescence measurements. An in vitro study with intact bovine incisors was performed. Artificial enamel lesions were induced and subjected to microhardness and quantitative light-induced fluorescence testing. Specimens were randomly divided into 4 groups for treatment. The specimens in group I were treated with water-based silver fluoride and potassium iodide, group II with silver diamine fluoride and potassium iodide, group III with sodium fluoride varnish, and group IV with distilled water. After 8 days of pH cycling, the specimens were subjected to microhardness and quantitative light-induced fluorescence testing. Water-based silver fluoride and silver diamine fluoride showed the greatest increases in microhardness and quantitative light-induced fluorescence, with no significant differences between the two. Sodium fluoride varnish also exhibited a significant increase in microhardness and quantitative light-induced fluorescence, but the differences were smaller than those for water-based silver fluoride and silver diamine fluoride. Water-based silver fluoride is considered useful in a clinical setting for remineralizing enamel lesions, with the advantages of no risk of tissue burn and improved taste and smell.

• The Journal of the Korean dental association
• /
• v.16 no.8 s.111
• /
• pp.619-624
• /
• 1978

The use of mouth-rinses containing sodium fluoride after tooth brushing has been proposed as a potentially useful measure for the prevention of dental caries in the practice of public health. About 700 middle school girls rinsed their mouths in the school once a week with sodium fluoride sodution after tooth-brushing. Tooth brushing was practiced everyday after meals and the rinses were carried out under the supervision of the teachers. The procedure consisted of gargling 10cc of fluoride solution for one minute and immediately followed by a second rinse with tap water. The rinsing was started in May 1976 and continued for one year. The results were as follows: 1) The inhibition of the 'D' Person rate was 76.04%, 'M' person rate was 80.79%, 'F' person rate was 4.06% and, 'D.M.F.' person rate was 76.86%. 2) the reduction of the 'D.T.' Index was 81.94%, 'M.T.' Index was 85.71%, 'F.T.' Index was 7.69% and, 'D.M.F.T.' Index was 76.83%. 3) Mouth rinsing with 0.3% NaF solution and tooth brushing are of value in the mass control of dental caries.

• Journal of Korean society of Dental Hygiene
• /
• v.15 no.2
• /
• pp.325-332
• /
• 2015

Objectives: The purpose of this study was to investigate tooth whitening maintenance efficacy of several dentifrices containing effective ingredients for tooth whitening. Methods: Hydroxyapatite specimens(HAPs) staining was done by using modified Stookey's methods. HAPs were treated with 2.9% hydrogen peroxide containing strip for whitening, and were shaken with several dentifrice slurry(dentifrice 1 : artificial saliva 2) for 30 minutes. The HAPs were finally dipped in staining solution for an hour. Shaking and dipping were repeated 4 times and lightness values were measured by colorimeter at each step. In clinical test, test 4 dentifrice and control dentifrice were evaluated by 21 subjects for 2 months after receiving institutional review board(IRB) approval. Organoleptic(vita shade guide) and instrumental(SHADEEYE-NCC) evaluation were performed for whiteness change of teeth. Statistical analysis was performed using repeated measures ANOVA, Tukey's post hoc test and ${\chi}^2$-test(p<0.05). Results: All dentifrices showed statistical significance in comparison with control dentifrice containing sodium fluoride and test 4 dentifrice containing sodium pyrophosphate, sodium metaphosphate, candelilla wax, and sodium fluoride showed statistical significance in comparison with other dentifrices by inhibiting staining in vitro(p<0.05). In clinical test, test 4 dentifrice showed better effects than control dentifrice in organoleptic and instrumental evaluation in tooth whitening maintenance efficacy(p<0.05). The awareness toward tooth whitening maintenance efficacy for 2 months use showed that test 4 dentifrice was much better than control dentifrice, but did not show statistically significant(p>0.05). Conclusions: Dentifrice containing sodium pyrophosphate, sodium metaphosphate, candelilla wax and sodium fluoride was more effective in keeping teeth white.

• Journal of dental hygiene science
• /
• v.8 no.2
• /
• pp.89-96
• /
• 2008

Effects of sodium fluoride exposure on the amelogenesis during fetal formation were investigated using 11 days rat incisor of control group and two experimental groups. According to results of morphological analysis using an electron microscope, enamel organ in the rat incisor consisted of presecretory, secretory, and maturation zone, especially maturation zone had ruffle-ended ameloblasts (rAB) that additionally supply inorganic ions and smooth-ended ameloblasts (sAB) that remove water and organic compounds. Such a histological composition was same in fetal and adult rats. According to experimental results using calcein (green fluorescence) in order to reveal the modulation cycle of ameloblast, modulation cycle of experimental group decreased on an average one time than control group, as increase of density of sodium fluoride indicated that thickness of smooth-ended ameloblast decreased. Also ratio of thickness on sagittal total length of sAB increased than rAB in experimental groups than control group. In total length of teeth, an injected 100 ppm sodium fluoride group was similar control group but as injected 200 ppm group became short. In experimental group, thickness of sAB and rAB became narrow to the tip of cutting edge. According to concentration of sodium fluoride grows, the modulation cycle and total length of teeth were decreased, finally it prevented teeth growth.

• Korean Journal of Materials Research
• /
• v.11 no.12
• /
• pp.1047-1051
• /
• 2001

Purity tantalum powder has been produced by sodium reduction of potassium tantalum fluoride($K_2TaF_7$)in a stainless steel bomb. The influence of experimental variable, such as excess of reductant and temperature of reduction on the yield and quality of the Ta powder has been studied. The excesses of reductant were varied from -20%, -10%, 0%, 5%, 10%, 20%. When -20% excess of sodium was used, the un-reacted sodium remained in the reacted product. The yield of 81% of Ta powder has been achieved by reducing 50g of$K_TaF_7$with 5% sodium in excess of stoichiometric amount in presence of 16.8g of sodium chloride in the charge at a reduction temperature of$905{\circ}C$. The proportion of fine fraction(~325mesh) decreased appreciably with the increase of sodium excess, and the yield of tantalum powder improved from 65% to 94%. The average particle size of Ta Powder is improved from 3 microns to 4 microns in the 5% excess sodium.

• The korean journal of orthodontics
• /
• v.52 no.1
• /
• pp.75-79
• /
• 2022

Objective: To investigate remineralizing effect of three fluoride regimens on artificially demineralized enamel around orthodontic bracket by analyzing mineral density (MD) acquired from micro-computed tomography (micro-CT). Methods: Forty-eight bracket bonded bovine incisors were prepared to create demineralized enamel (DE) surface. The samples were divided into four groups according to the fluoride regimen: 1) no fluoridation, 2) 1.23% acidulated phosphate fluoride (APF) gel, 3) fluoridated toothpaste, and 4) 0.05% sodium fluoride mouthwash. Micro-CT was scanned after demineralization (T0), and 2 weeks (T1) and 4 weeks (T2) of fluoridation. Results: APF gel showed highest remineralization of DE during T1-T0 interval among the groups (p < 0.05); followed by toothpaste, mouthwash and no fluoridation. APF gel and toothpaste demonstrated significant increase in MD after 4 weeks of application (p < 0.05). Conclusions: Remineralization effects of three fluoride regimens were depicted through micro-CT analysis, of which APF gel was most effective.