• The korean journal of orthodontics
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• v.29 no.5 s.76
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• pp.589-597
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• 1999

The purpose of this study was to evaluate the effects of fluoride releasing orthodontic sealants, light-cured (Group L1&L2) and self-cured (Group S1&S2) $FluoroBond^{\circledR}$, on enamel microhardness under artificial carious solution in vitro.112 extracted human premolar teeth were collected for experiments and divided into seven groups. A Tukon microhardness tester equipped with a Knoop diamond indenter was employed to determine microhardness. Tukon 23 program converted the number of microhardness into KHN (Knoop hardness number). The results were as follows: 1. The microhardness of enamel depth of all groups were the least at the depth of $50{\mu}m$ and that of all groups except L2 group, the greatest at the depth of $200{\mu}m$, were the greatest at the depth of $300{\mu}m$. And as the enamel depth of all groups except L2 and S2 group increased, the microhardness value also increased. 2. There was a little preventive effect in enamel decalcification both light-and self-cured orthodontic sealant groups, but had no statistical significance between the groups(p>0.05). 3. Light-cured orthodontic sealant groups had a progressive inhibiting effect in enamel decalcification at the depth of $100{\mu}m,150{\mu}m,\;and\;200{\mu}m$ (p<0.05). 4. Self-cured orthodontic sealant groups had a progressive inhibiting effect in enamel decalcification at the depth of $150{\mu}m$ (p<0.05). 5. There was no difference of the anti-enamel demineralization effect between light- and self-cured orthodontic sealant groups (p>0.05).

• Journal of the korean academy of Pediatric Dentistry
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• v.47 no.3
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• pp.266-276
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• 2020

The purpose of this study was to compare the remineralization effect of 38% silver diamine fluoride (SDF) and 5% sodium fluoride (NaF) varnish on artificially induced enamel caries. The present study standardized the physiochemical characteristics of the tooth structure using bovine teeth, realized the wash-off action of agents using a saliva, reproduced an environment similar to mouth through pH-cycling, and comparatively assessed the remineralization effect of 38% SDF and 5% NaF varnish in a non-destructive method using micro-CT. And the remineralized enamel surface structure was analyzed by scanning electron microscopy (SEM) and energy dispersive X-Ray spectroscopy (EDS). In both SDF and NaF varnish, mineral density (△Hounsfield unit value) and the volume of enamel restored to normal mineral density through remineralization gradually increased with time. And the SDF showed a much higher level of increase in mineral density at all depths and remineralized volume than NaF varnish. According to SEM analysis, the surface roughness decreased in the order of artificial saliva, NaF varnish and SDF. In addition, EDS analysis showed that silver ion was precipitated on the enamel surface in SDF group. In conclusion, SDF had a greater remineralization effect than NaF varnish on demineralized enamel.

• Journal of dental hygiene science
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• v.9 no.5
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• pp.557-561
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• 2009

The purpose of this study was to observe the demineralization effects of commercial drinks on bovine enamel. 12 bovine teeth without dental caries were divided into 3 experimental groups (n = 9) and control groups (n = 3). All the samples immersed in beverages maintained by $37^{\circ}C$ in incubator respectively. The differences of surface microhardness values(${\Delta}VHN$) between before and after 45 hours treatment were $166.97{\pm}51.69$(in Coca-cola), $116.26{\pm}20.81$(in Gatorade), $77.89{\pm}55.88$(in Hite), and $23.44{\pm}29.97$(in Jeju SamDaSoo). Morphological changes by scanning electron microscope were indicated that a sports drink cause significant enamel demineralization effects on the bovine enamel surface among four beverages.

• Journal of the korean academy of Pediatric Dentistry
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• v.36 no.2
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• pp.199-208
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• 2009

This study was performed to improve the conventional $DIFOTI^{TM}$ system(EOS Inc., USA) by developing the prototype of DIFOTI system which consists of light emitting diode(LED) and digital camera. The images of enamel surfaces treated under Carbopol 907 de-mineralizing solution were taken daily during 7 days of experimental periods by both DIFOTI systems. The results of comparative analyses of obtained images can be summarized as follows: 1. Trans-illumination indices of images taken from sample enamel surfaces were decreased with time in both systems. 2. The difference of intensity of luminance between sound and de-mineralized enamel surface in prototype DIFOTI system was shown to be relatively smaller than conventional $DIFOTI^{TM}$ system. The application of LED light source in prototype DIFOTI system could possibly reduce the amount of current consumption and that could ultimately lead us to the successful development of wireless model with battery. The innovative development of digital camera is undoubtedly expected to create much clearer image despite of wireless transfer. LED and digital camera can be combined into a smaller size but a very important task of improving image manager and analyzing program into a simpler and easier one to manipulate has to be solved.

• Restorative Dentistry and Endodontics
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• v.33 no.6
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• pp.507-517
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• 2008

There are considerable in vitro and in vivo evidences for remineralization and demineralization occurring simultaneously in incipient enamel caries. In order to "heal" the incipient dental caries, many experiments have been carried out to determine the optimal conditions for remineralization. It was shown that remineralization is affected by different pH, lactic acid concentrations, chemical composition of the enamel, fluoride concentrations, etc. Eighty specimens from sound permanent teeth without demineralization or cracks, 0.15 mm in thickness, were immersed in lactic acid buffered demineralization solutions for 3 days. Dental caries with a surface zone and subsurface lesion were artificially produced. Groups of 10 specimens were immersed for 10 or 12 days in lactic acid buffered remineralization solutions consisting of pH 4.3 or pH 6.0, and 100, 50, 25, or 10 mM lactic acid. After demineralization and remineralization, images were taken by polarizing microscopy (${\times}100$) and micro-computed tomography. The results were obtained by observing images of the specimens and the density of the caries lesions was determined. 1.As the lactic acid concentration of the remineralization solutions with pH 4.3 was higher, the surface zone of the carious enamel increased and an isotropic zone of the subsurface lesion was found. However, the total decalcification depth increased at the same time. 2.In the remineralization solutions with pH 6.0, only the surface zone increased slightly but there was no significant change in the total decalcification depth and subsurface zone. In the lactic acid buffer solutions with the lower pH and higher lactic acid concentration, there were dynamic changes at the deep area of the dental carious lesion.

• Journal of dental hygiene science
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• v.10 no.2
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• pp.95-100
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• 2010

The purposes of this study were to examine the effect of different fluoridated bleaching solution on the changes in physical and chemical characteristics of tooth. Forty-eight bovine incisors were divided into four groups to receive bleaching treatments, over a 14days period, as follows: no treatment; 10% carbamide peroxide (CP) bleaching; 10% CP containing 0.05% fluoride; and 10% CP containing 0.1% fluoride. All the specimens were highly polished and discolored with commercial COCK.Color and enamel changes were determined with colorimeter, microhardness tester, scanning electron microscope, atomic force microscopy. All the collected data were analyzed with one-way ANOVA. After the bleaching, bleached groups showed the color change(E*). Microhardness of 10% CP group decreased after tooth bleaching. But microhardness of containing fluoride bleached groups increased after tooth bleaching. Enamel surface of 10% CP bleached group showed any apparent morphology and roughness changes compared to the enamel which was stored in distilled water only. These results demonstrated that Fluoridated 10% Carbamide Peroxide have appreciable bleaching effect on bovine teeth and were not adversely affects enamel. Supporting influence of fluoride-containing bleaching solution on remineralization could be observed and further research must be carried out in various active environments to confirm these results clinically.

• Journal of the korean academy of Pediatric Dentistry
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• v.35 no.1
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• pp.83-91
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• 2008

Dental caries which is one of the most common chronic disease complexly developed by the action of oral bacteria, diet, and host factor. Various prevention program enhance resistance of demineralization and reduce the acidogenecity of oral bacteria have been introduced, representative material is fluoride and chlorhexidine. The purpose of the study was to evaluate and compare effectiveness of fluoride varnish and chlorhexidine varnish in vivo. Bovine tooth specimens were implanted in the lower space maintainers and applied with fluoride varnish and chlorhexidine varnish. After seven days in oral environment, metal mesh was covered to make similar condition of plaque accumulation and induce caries. All specimens were analysed by EPMA to evaluate quantitative change of Ca, P and by polarized microscope to identify histological changes. The results were as follows : After initial artificial caries induction in the mouth, there were remarkable enamel caries lesion in the control group under polarized light microscopy. The highest amount of mineral decrease were showed in control group. No statistically significant mineral decrease were showed in fluoride varnish group, while chlorhexidine varnish group showed only significant decrease of P(P<0.05). In conclusion both fluoride varnish and chlorhexidine varnish seemed to be effective for protecting enamel surface from caries activity, although fluoride varnish has more anticariogenic effect than chlorhexidine varnish.

• Journal of the korean academy of Pediatric Dentistry
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• v.43 no.4
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• pp.391-400
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• 2016

The purpose of this study was to evaluate the difference of remineralization effects of various anti-cariogenic toothpastes on artificial carious lesions in primary and permanent teeth using quantitative light-induced fluorescence-digital (QLF-D) system. Sound human primary (n = 48) and permanent teeth (n = 48) were randomly divided into following groups : control group (Group 1), fluoride toothpaste (Group 2), functionalized tricalcium phosphate (fTCP) + fluoride toothpaste (Group 3), and casein phosphopeptide-amorphous calcium phosphate (CPP-ACP) toothpaste (Group 4). Specimens were prepared by exposure in a demineralizing solution and then treated using the different toothpastes twice daily during 14 days. All specimens were analyzed with the QLF-D system. QLF data analysis indicated three different toothpastes showed significant remineralizing effects compared to Group 1 in both primary and permanent teeth. Also, the remineralizing effects in Group 3 and 4 were significantly higher than in Group 2. This study suggested that the toothpastes containing fTCP + fluoride and CPP-ACP have the significant anti-cariogenic effects on enamel demineralization in both primary and permanent teeth, and QLF-D is an useful device to assess the incipient carious lesion and remineralization effects of the anti-cariogenic materials quantitatively. Therefore, clinicians can consider the QLF-D system for the evaluation of demineralization and remineralization in primary and permanent teeth.

• Restorative Dentistry and Endodontics
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• v.32 no.2
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• pp.151-161
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• 2007

Dental caries is the most common disease in the oral cavity However, the mechanism and treatment of dental caries is not completely understood since many complex factors are involved. Especially the effect of pH on remineralization of early stage of dental caries is still controversial In this study, dental caries in dentin was induced by using lactic acidulated buffering solutions and the loss or inorganic substance was measured. Also decalcified specimens were remineralized by three groups of solution with different pH (group of pH 4.3, 5.0, and 5.5). Then, the amount and the area of inorganic substance precipitation was quantitatively analyzed with microradiograph. Also a qualitative comparison of the normal phase the demineralized phase, and the remineralized phase of hydroxyapatite crystal was made under SEM. The results were as follows, 1. In microradiograghic analysis, as the pH increased, the amount of remineralization in decalcified dentin tended to increase significantly As the pH decreaced, deeper decalcification, however, occurred along with remineralization. The group of pH 5.5 had a tendency to be remineralized without demineralization (p<0.05). 2. In SEM view, the remineralization in dentine caries occurred from the hydroxyapatite crystal surface surrounding the mesh of organic matrix, and eventually filled up the demineralized area. 3. 5 days after remineralization, hydroxyapatite crystal grew bigger with deposition of inorganic substance in pH 4.3 and 5.0 group, and the crystal in the remineralized area appeared to return to normal. After 10 days, the crystals in group of pH 4.3 and 5.0, which grew bigger after 5 days of remineralization, turned back to their normal size, but in group of pH 5.5, some crystals were found to double their size. In according to the results of this experiment, the decalcifying and remineralizing process of dentine is neither simple nor independent, but a dynamic process in which decalcification and remineralization occur simultaneously. The remineralization process occurred from the hydroxyapatite crystal surface.

• Journal of the korean academy of Pediatric Dentistry
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• v.26 no.2
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• pp.377-398
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• 1999

Calcium fluoride, created by topical fluoride application, is the reservoir for fluoride ion regulated by pH in the oral environment. Therefore, the amount and the maintenance of calcium fluoride have an important role in preventing dental caries. The aim of this study is to evaluate the effect of Nd:YAG laser irradiation on the generation of calcium fluoride and the acid resistance of tooth enamel. The bovine anterior permanent teeth were prepared (n=276), and divided into following groups : no treatment (control) fluoride application alone, laser irradiation alone, laser irradiation after fluoride application, and fluoride application after laser irradiation. And each group was subdivided based on the application time of 1.23% acidulated phosphate fluoride (APF) (5 min and 30 min) and the irradiation energy of Nd:YAG laser ($20J/cm^2\;and\;40J/cm^2$). In case of fluoride application, each group was divided according to KOH treatment. Twenty three treatment conditions were made for this experiment and twelve specimens were assigned to each treatment condition. In each treatment condition, ten specimens were used for chemical analysis and two specimens were observed under SEM. In groups without treating KOH, fluoride content and the depth of enamel dissolved were measured using enamel biopsy technique. In groups with treating KOH, the amount of calcium fluoride was measured by the treatment with 1 M KOH for 24 hours and enamel biopsy was performed after KOH treatment. The results were analyzed by the fluoride content and the depth of enamel dissolved by enamel biopsy, amount and thickness of calcium fluoride, and the surface structures of enamel. The results are as follows: 1. In groups without treating KOH, the fluoride content of removed enamel showed a positive relationship with the energy density of laser when the laser irradiated before fluoride application 2. In groups without treating KOH, the depth of enamel dissolved decreased more with the combined laser and fluoride treatment than with laser or fluoride treatment, except for the case of $20J/cm^2$ laser irradiation after 5 minute fluoride application (p<0.05). 3. The amount of calcium fluoride did not increased by laser treatment with no statistical significance(p>0.05). 4. The particle size of calcium fluoride increased in case of fluoride treatment after laser irradiation, compared with fluoride application alone. In case of laser treatment after fluoride application, the particle size of calcium fluoride increased and some of the particles fused as well. 5. There were no significant differences in the fluoride content of dissolved enamel between groups without treating KOH and control group, except for the case of laser irradiation after treatment of APF for 30 minutes (p>0.05). 6. In groups with treating KOH, depth of removed enamel in the groups of combined treatment with laser and fluoride was shallower than that in fluoride application groups (p<0.05). 7. In groups without treating KOH, the relationship between fluoride content and the depth of enamel dissolved showed more negative (Spearman correlation coefficient: -0.6281) than in groups with treating KOH (Spearman correlation coefficient: -0.3792). The greater amount of calcium fluoride could be found in case where there was a significant differences of the depth of enamel dissolved between groups with and without treating KOH. From these results, it can be concluded that laser seems to be a little effects on the amount of calcium fluoride formation, but has some effect on the lowering the solubility of calcium fluoride. As the combined treatment of laser and fluoride application showed more effective acid-resistant property, more extended recall period for fluoride application can be achieved with this combined treatment in the clinic.