• Restorative Dentistry and Endodontics
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• v.39 no.1
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• pp.39-44
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• 2014

Objectives: The purpose of this study was to evaluate in vitro cytotoxicity of the pozzolan cement and other root-end filling materials using human periodontal ligament cell. Materials and Methods: Endocem (Maruchi), white ProRoot MTA (Dentsply), white Angelus MTA (Angelus), and Super EBA (Bosworth Co.) were tested after set completely in an incubator at $37^{\circ}C$ for 7 days, Endocem was tested in two ways: 1) immediately after mixing (fresh specimens) and 2) after setting completely like other experimental materials. The methods for assessment included light microscopic examination, cell counting and WST-1 assay on human periodontal ligament cell. Results: In the results of microscopic examination and cell counting, Super EBA showed significantly lower viable cell than any other groups (p < 0.05). As the results of WST-1 assay, compared with untreated control group, there was no significant cell viability of the Endocem group. However, the fresh mixed Endocem group had significantly less cell viability. The cells exposed to ProRoot MTA and Angelus MTA showed the highest viability, whereas the cells exposed to Super EBA displayed the lowest viability (p < 0.05). Conclusions: The cytotoxicity of the pozzolan cement (Endocem) was comparable with ProRoot MTA and Angelus MTA. Considering the difficult manipulation and long setting time of ProRoot MTA and Angelus MTA, Endocem can be used as the alternative of retrofilling material.

• Korean Journal of Dental Materials
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• v.45 no.4
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• pp.233-242
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• 2018

The purpose of this study is to evaluate the effect of resin cement color on the color of commercially available zirconia crown. The zirconia and resin cements used for the experiment were $NuSmile^{(R)}$ ZR Zirconia LT Shade (LT), $RelyX^{TM}$ U200 TR, A2, and A3O (TR, A2, A3O). The disks of zirconia and resin cements with diameters of 5 mm and thicknesses of 1 mm were prepared. Five disks were made for each specimen. The CIE $L^*a^*b^*$ values of zirconia, resin cements and the combinations thereof were measured on black and white backgrounds, respectively, using a spectrophotometer. The color effect of resin cement on the color of the zirconia crown was evaluated by calculating translucency parameter (TP), contrast ratio (CR), and color differences (${\Delta}E{^*}_{ab}$) based on the measured CIE $L^*a^*b^*$ values. The statistical significances were verified by one-way ANOVA and the Tukey-multiple comparisons tests. As a result, the TP and CR values were decreased (p<0.05) and increased, respectively, in the combination of zirconia and resin cement disks compared to zirconia disk per se. When using the black background, the ${\Delta}E{^*}_{ab}$ values between zirconia and the combination of the zirconia and three resin cement disks were imperceptible level. The A3O showed the lowest ${\Delta}E{^*}_{ab}$ value among three resin cements. When using the white background, the ${\Delta}E{^*}_{ab}$ values between zirconia and the combination of zirconia and TR resin cement (LT/TR) disks showed acceptable level. However, the ${\Delta}E{^*}_{ab}$ values between zirconia and the combination of zirconia and A2 resin cement (LT/A2) disks showed unacceptable level. Meanwhile, the ${\Delta}E{^*}_{ab}$ values between zirconia and the combination of zirconia and A3O resin cement (LT/A3O) disks showed perceptible but acceptable level. Within the limits of this study, the colors of resin cements did not cause unacceptable color changes of zirconia except the combination of LT/A2 on the white background. The resin cement that gave the least color changes to zirconia was A3O. This means that the resin cement A3O is recommended to use for minimizing color changes when cementing commercially available zirconia crown to tooth.

• Journal of Dental Rehabilitation and Applied Science
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• v.23 no.1
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• pp.79-84
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• 2007

Mineral Trioxide Aggregate(MTA) has been used in Endodontic treatment successfully for more than 10 years. But the high cost of MTA limits its use in endodontics in Korea. Recently many studies have been done to compare MTA and Portland cements. To investigate the chemical constitutions of MTA (Proroot MTA, Tulsa Dental), Gray Portland cement (Lafarge Halla cement), White Portland cement(Union corp), and fast setting cement (SSangyong cement), we performed SEM(scanning electron microscope)(S4700, Hitachi) examination and EDS(Energy dispersive spectrometry)(emax, Horiba) analysis. SEM examination and EDS analysis were committed to and performed in SNU DRI (Seoul National University Dental Research Institute). We found that particles of MTA were relatively round, uniform in size, and compactly packed compared to Portland cements. Chemical constitutions of MTA, GPC, WPC and FSC were similar. It was shown that MTA contains much BiO2 . MTA and WPC showed less heavy metals such as Fe and Mg compared to GPC and FSC. FSC showed remarkably high aluminum content.

• Journal of the Korean Society of Safety
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• v.13 no.3
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• pp.45-50
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• 1998

The low grade domestic kaoline, such as pink-C and white-D, was converted to metakaoline, which has pozzolanic reactivity by heat treatment in the temperature range of $600^{\circ}C$ to 100$0^{\circ}C$ for preparing the spacer. The spacer was used for supporting the reinforced steel rod during construction to improve the safety of architecture. Pink-C and white-D were completely dehydroxylated when burnt at 80$0^{\circ}C$ for 1 hour and converted to metakaoline. The compressive strengths of specimens added calcined pink-C were lower than those of press molding mortar products inspite of calcining conditions. When white-D with calcined 80$0^{\circ}C$ and 100$0^{\circ}C$ for 1 hour was mixed 30% in the weight ratio of cement, the specimens cured 28 days had 338 $kg/cm^2$ and 347 $kg/cm^2$ of compressive strengths, respectively.

• Proceedings of the Korea Concrete Institute Conference
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• 2008.11a
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• pp.673-676
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• 2008

Color concrete utilizes peculiar texture and color sense in external appearance actively as a finish. But, this color concrete is essential use of pigment for required color revelation, and color cone cleat from mixing of this pigment are different existent achromatic color concrete and basic properties of matter. this study progressed slump test and setting time examination through mortar injection resistance examination of mortar that mix Pigment.

• Asian-Australasian Journal of Animal Sciences
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• v.33 no.9
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• pp.1455-1462
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• 2020

Objective: The purpose of this study was to investigate whether goose growth and feather characteristics are influenced by their line and feeding surroundings, inclusive of floor materials and types, since there are no reports regarding these factors. Methods: The 240 White Roman geese which were hatched and sex identified came from 3 commercial goose farms. They were randomly distributed to 24 pens depending on a completely random design. The study continued for 13 weeks and included 3 lines of commercial geese and 2 floor types (cement strip floor [CSF] or cement floor [CF]). Results: The day one gosling weight from A farm was lower than other two farms (96 g vs 107 and 115 g; p<0.001). Afterwards, the body weight, back length, keel length, chest girth and main wing feather length among 3 farms showed no significance difference prior to 12 weeks. The CF group showed heavier body weight, shorter back length, longer keel length, shorter chest girth and shorter main wing feather length than the CSF group prior to 12 weeks. The down weight in the CF was heavier than the CSF group (57.1 g vs 41.8 g; p<0.01) prior to 13 weeks. Conclusion: The body weight showed the positive relations for dry feather weight (r = 0.59), down weight (r = 0.69), percent of the down weight of live body weight prior to 13 weeks (r = 0.61).

• Proceedings of the Korea Concrete Institute Conference
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• 2006.05b
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• pp.457-460
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• 2006

There are many kind of materials decorating outward of building such as paint, tile, brick, wood, stone and so on. But it has been pointed out some problems because of the industrial pollutions and wastes. Color concrete is a method of expressing out surface of exposed concrete. Generally, color concrete is manufactured by adding pigment to concrete. In this paper we used cement paste as a preparation step to apply to concrete. Pigment was added to white cement for easy observance of color difference. And color change was measured by color reader. Finally, we can predict color difference according to amount of pigment. Also, we investigate the color concrete technology for Art type using developed color concrete.

• Journal of the Korean Academy of Esthetic Dentistry
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• v.23 no.2
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• pp.70-76
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• 2014

After extraction of tooth, alveolar ridge resorption is inevitable in most cases. Clinicians confront with horizontal and vertical resorption of alveolar bone. Without massive amount of bone and soft tissue graft, dental implant will be placed apically to gain stability. In those cases, not only white esthetic part, but also pink esthetic part should be restored with pink porcelain. The margin of prosthesis should be located apically to reproduce natural look with adjacent teeth. However, when the margin is located apically, it is always hard to remove remaining cement, thus complications may arise. In this report, a novel design of implant prosthesis is introduced to solve those issues. The novel design is consisted of zirconia framework with pink porcelain and separate crowns on top of the framework. It eliminates the possibility of cement remnants by bringing the crown margin coronally. Pink esthetic part is incorporated in abutment part instead of crown part and the screw hole is covered with separate crowns.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2021.11a
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• pp.80-81
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• 2021

This study attempts to examine the setting time retarding properties of cement paste according to the sugar type change. It was confirmed that the setting time retarding performance was excellent in the order of sugar powder and white sugar, and that the setting time retarding performance of saccharin and aspartame was insignificant.

• Restorative Dentistry and Endodontics
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• v.10 no.1
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• pp.103-114
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• 1984

The purpose of this study was to compare the polished surfaces of two composite resins (Clearfil F and Durafill) with those of glass ionomer cement (Fuji ionomer cement) and to observe what types of polishing devices are valuable, and then to establish a clinically satisfactory procedures. Studies have been undertaken to determine the effects of glass plate matrix and finishing instruments (Carborundum point, White point and Sof-Lex medium) on the surface finish of three restorative materials. The results were examined with profilometer (Kosaka laboratory LTD. Tokyo, Japan) and scanning electron microscopy (JSM-T20: JEOL). The results were as follows: 1. The most satisfactory surface finishes were produced against glass matrix. 2. Coarser finishes were obtained with use of carborundum point. 3. Generally Fuji ionomer cement were left surfaces with higher roughness values. 4. The smoothest finishes were obtained with Sof-lex medium. 5. Clearfil-F was showed more smoother than the other restorative materials.