• Title/Summary/Keyword: Vickers Hardness(VHN)

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Effect of 15% Hydrogen Peroxide on Color Change and Microhardness of Bovine Teeth according to the Time (15% Hydrogen Peroxide 전문가용 치아미백 후 시간경과에 따른 색상변화와 미세경도의 변화)

  • Park, Mi-Young
    • Journal of dental hygiene science
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    • v.13 no.1
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    • pp.13-19
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    • 2013
  • This study evaluated the change of color and the microhardness according to time-out using the office bleaching with in vitro test after bleaching one time 1 day per week, total three times, for the control group and three times per 1day for the experimental group. $L^*$ was increased in both groups. Group 1 showed a significant increase statistically between before and after tooth whitening (p<0.05). Group 2 showed a significant increase statistically between before and after tooth whitening (p<0.05). ${\Delta}E^*$ was huge in both groups. In group 1, it was great in terms of statistical significance between 1 day and 7 days after tooth whitening (p<0.05). In group 2, it was the greatest between before and 1 day after tooth whitening and was significant statistically as well (p<0.05). Vickers hardness number (VHN) decreased in both groups. In group 1, VHN decreased over time and the difference was significant statistically (p<0.05). In group 2, VHN decreased over time and the difference was significant statistically (p<0.05). Percentage microhardness loss was great in both groups. In group 1, it was the greatest between 1 day and 7 days after the treatment, and it was significant statistically (p<0.05). In group 2, it was the greatest between before and 1 day after the treatment, and it was significant statistically (p<0.05). Put together, the more frequent tooth whitening a day is, the longer the period of tooth whitening when applying the same frequency, the greater color change was, however the microhardness decreased, in regard to the results over time using 15% hydrogen peroxide tooth whitening product for professionals.

COMPARATIVE STUDY OF THE REMINERALIZATION EFFECTS USING CPP-ACP AND FLUORIDE ON THE ARTIFICIAL ENAMEL LESION (CPP-ACP 함유 크림과 불소가 초기 인공우식 법랑질에 미치는 재광화 효과에 대한 비교 연구)

  • Kim, Ki-Baek;Choi, Nam-Ki;Kim, Seon-Mi;Yang, Kyu-Ho
    • Journal of the korean academy of Pediatric Dentistry
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    • v.36 no.1
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    • pp.38-45
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    • 2009
  • The aim of this study was to examine efficacy of the commercially available 10% CPP-ACP cream (Tooth mousse, GC Co., Japan) and/or 0.05% NaF solution on the remineralization of artifical caries-like lesion in the bovine teeth enamel. Sixty bovine teeth were embedded in orthodontic resin and flattened. The enamel surface in 3 mm diameter was exposed with nail varnish. Specimens were stored in demineralizing solution and divided 5 groups; Group 1 (No treatment), 2 (0.05% NaF solution 1 min), 3 (Tooth mousse 3 min), 4 (After 0.05% NaF solution, Tooth mousse treatment), and 5 (After Tooth mousse treatment, soaking in 0.05% NaF solution during 1 min). After treatment by groups, all specimens was stored in artificial saliva for 30 min. After the process described as above was performed during 10 days without pH cycling, surface hardness (Vickers Hardness Number, VHN) was tested and analyzed by paired t-test and one-way ANOVA test with SPSS 14.0. In intragroup comparison between surface hardness of pre and post-treatment, group 3, 4, 5 showed statistically significant increase (P < 0.05). In intergroup comparison among surface hardness increase of all groups, difference of group 5 between pre and post-treatment ($15.80{\pm}12.21$) was the highest, and followed by group 4 ($14.27{\pm}11.73$), 3 ($4.05{\pm}5.18$), 2 ($1.15{\pm}6.83$), 1 ($0.78{\pm}6.21$). Tooth mousse can be a good alternative agent for the fluoride, and the combination use with fluoride might have the additional anticariogenic effect.

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Evaluation of In-Vitro Efficacy of Active Ingredients in Dentifrice Used for Different Treatment Times (치약용 약효제의 적용시간에 따른 실험실적 효능 연구)

  • Ahn, Jae-Hyun;Kim, Ji-Hye;Kim, Ji-Young
    • Journal of dental hygiene science
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    • v.16 no.2
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    • pp.176-182
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    • 2016
  • The purpose of this study was to evaluate the in-vitro efficacy of the active ingredients of dentifrice following treatment time. The whitening effect was evaluated by a change in lightness value relative to the contact time of hydrogen peroxide, by using artificially stained hydroxyapatite discs. The anti-calculus effect was assessed based on the amount of calcium eluted from the human dental calculus by sodium pyrophosphate. Remineralization was evaluated by the Vickers hardness test following the application of sodium fluoride to bovine enamel. In order to view dentinal tubules occlusion, the formation of insoluble calcium salts by bovine dentin specimens was observed using scanning electron microscopy. Change in lightness value (${\Delta}L$) was $5.50{\pm}1.51$ after 1 min of treatment, $5.73{\pm}0.43$ after 3 min, $8.64{\pm}0.24$ after 10 min, $18.93{\pm}0.76$ after 30 min, and $27.35{\pm}0.54$ after 60 min. The amount of calcium eluted from the human dental calculus was $4.23{\pm}0.14ppm$ after 1 min of treatment, $4.51{\pm}0.04ppm$ after 3 min, $12.12{\pm}0.16ppm$ after 10 min, $17.85{\pm}0.81ppm$ after 30 min, and $25.15{\pm}0.32ppm$ after 60 min. The Vickers hardness change value (${\Delta}VHN$) was $1.96{\pm}1.44$ after 1 min, $1.52{\pm}1.06$ after 3 min, $9.06{\pm}0.15$ after 10 min, $10.83{\pm}5.13$ after 30 min, and $12.55{\pm}2.09$ after 60 min. Partial dentinal tubules occlusion was observed at 10 min and complete occlusion was evident at 60 min. In summary, the use of patch type dentifrices for 10, 30, or 60 min were 1.57 to 8.26 times more effective than using the paste type dentifrices for 1 to 3 min. Based on these findings, it is reasonable to expect that the use of patch type dentifrices for 10 min would lead to remineralization, anti-calculus and dentinal tubules occlusion effects, and that use for 30 min would result in a whitening effect.