• Journal of dental hygiene science
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• v.15 no.4
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• pp.437-444
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• 2015

Due to the attractive benefits with regard to bone health, digestion, and hydration, carbonated water consumption have rapidly grown over the past few years. However, the acidic drink has latent potential for enamel erosion. The most experimental studies about the enamel erosion have focused on the carbonated beverages with sugar and artificial sweeteners. Here, we determined the enamel erosion potential by commercially available carbonated waters with bovine teeth. The erosion was verified by pH value, calcium concentration, and scanning electron microscope. Then plaque accumulation by bacterial adhesion was determined on the enamel erosion surface to measure roughness. In the present study, we observed that the increased calcium content after being immersed in carbonated waters result from the overall enamel erosion. There were no significant differences between general carbonated waters and mineral waters for erosive capacity. Therefore, commercially available carbonated waters are potentially erosive. In addition, oral bacteria strongly adhered to the erosive enamel surfaces thereby facilitating the development of dental plaque. Thus, it is urgently necessary to provide food safety information on the carbonated water as acidic drink to prevent the enamel erosion.

• Journal of Dental Rehabilitation and Applied Science
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• v.37 no.4
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• pp.177-185
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• 2021

Clinical applications of translucent zirconia as well as traditional zirconia (3 mol% yttria stabilized tetragonal zirconia polycrystal, 3Y-TZP) are increasing. For this reason, studies on factors affecting the optical properties of dental zirconia have been continuously reported. The optical effect of dental zirconia may vary depending on the yttria content, the thickness of the prosthesis, the sintering process, polishing, glazing and cementation in laboratory and clinical procedures. Increasing the yttria concentration can reduce the masking effect. Translucency decreases as the thickness of the restoration increases, but the required thickness may vary depending on the properties of the zirconia block. The high-speed sintering method can shorten the manufacturing time, but in some cases, the translucency of the prosthesis may decrease. In addition, the optical properties can be affected by the surface roughness of zirconia and the polishing process. The use of an appropriate colored cement can help with the masking effect of zirconia and can be useful for color matching for more esthetic results.

• Journal of Biomedical Engineering Research
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• v.44 no.6
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• pp.404-413
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• 2023

In this research, we studied the development of a SUS304 microneedle array based on microfabrication technology and the applicability of Parylene-C thin film, a medical polymer material. First of all, four materials commonly used in the field of medical engineering (SUS304, Ti, PMMA, and PEEK) were selected and a 5 ㎛ Parylene-C thin film was deposited. The applicability of Parylene-C coating to each material was confirmed through SEM analysis, contact angle measurement, surface roughness(Ra) measurement, and adhesion test according to ASTM standards for each specimen. Parylene-C thin film was deposited based on chemical vapor deposition (CVD), and a 5 ㎛ Parylene-C deposition process was established through trial and error. Through characteristic experiments to confirm the applicability of Parylene-C, SUS304 material, which is the easiest to apply Parylene-C coating without pretreatment was selected to develop a microneedle array based on CNC micromachining technology. The CNC micromachining process was divided into a total of 5 steps, and a microneedle array consisting of 19 needles with an inner diameter of 200 ㎛, an outer diameter of 400 ㎛, and a height of 1.4 mm was designed and manufactured. Finally, a 5 ㎛ Parylene-C coated microneedle array was developed, which presented future research directions in the field of microneedle-based drug delivery systems.

• Journal of the Korean Society of Food Science and Nutrition
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• v.37 no.9
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• pp.1136-1141
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• 2008

This study was to investigate antiwrinkle effect of mugwort (Artemisia vulgaris) methanol extract in hairless mouse skin induced by UVB-irradiation. Hairless mouse were topically treated with the basic lotion alone (control), ascorbic acid (AA-0.5%, AA-1.0%, AA-2.0%, and AA-5.0%) and mugwort extract (ME-0.5%, ME-1.0%, ME-2.0%, and ME-5.0%) dissolved in a basic lotion. After topical treatment of 30 minutes, the animals were irradiated with increasing doses of UVB radiation ($60{\sim}100\;mJ/cm^2$) for 4 weeks. In our experimental condition, skin thickness of hairless mouse was significantly decreased ($12.5{\sim}21.4%$) in all ME groups compared with control group. Ra value, that is surface roughness parameter induced by skin wrinkling, was significantly decreased ($23.7{\sim}31.1%$) in ME-1.0%, 2.0% and 5.0% group compared with control group. Furthermore, Rq, Rz and Rt value were significantly decreased to $11.2{\sim}21.2%$, $19.8%{\sim}24.5%$, and $14.2%{\sim}22.7%$, respectively. Wrinkle formation of ascorbic acid treatment group as reference group was inhibited, but its effect was less than ME treatment. Matrix metalloproteinase-1 activity was significantly inhibited ($19.7{\sim}22.6%$) compared with control group and collagen content was significantly increased (about 10%) when compared with control group. These results indicate that ME could protect skin aging and wrinkle formation in hairless mouse from photo-irradiation.

• The Journal of Korean Academy of Prosthodontics
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• v.51 no.3
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• pp.190-198
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• 2013

Purpose: The purposes of this study were to investigate osseointegration around zirconia implants which had machined or alumina sandblasted surface, and to compare the results with titanium implants. Materials and methods: The study was performed on the tibia of 6 pigs. Three types of implants were investigated: group T-titanium implant, group Z-machined zirconia implant, group ZS-alumina sandblasting treated zirconia implant. Zirconia implants were manufactured from yttria-stabilized tetragonal zirconia polycrystalline (Acucera Inc., Pocheon, Korea). A total of 36 implants were installed in pigs' tibias. After 1, 4 and 12 weeks of healing period, the periotest and the histomorphometric analysis were performed. The data were analyzed using one-way ANOVA and significance was assessed by the Scheffe test (${\alpha}=.05$). Results: In the measurement of surface roughness, highest Ra value was measured in group T with significant difference. No significant differences were found among groups regarding Periotest values. After 1 week, in comparison of bone to implant contact (BIC), group Z showed higher value with significant difference. In comparison of bone area (BA), group T and group Z showed higher value with significant difference than group ZS. After 4 weeks, in comparison of BIC, group T showed higher value with significant difference. Comparison of BA showed no significant difference among each implant. After 12 weeks, the highest mean BIC values were found in group T with significant difference. Group ZS showed higher BIC value with significant difference than group Z. In comparison of BA, group T and group ZS showed higher value with significant difference than group Z. Conclusion: Zirconia implant showed low levels of osseointegration in this experiment. Modification of surface structure should be taken into consideration in designing zirconia implants to improve the success rate.