• Korean Journal of Human Ecology
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• v.16 no.5
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• pp.1051-1059
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• 2007

This study intends to find out possible variations in physical properties and color of hair depending on dye type(acidic and alkalic) and permanent treatment/hair dyeing procedure. To meet the goals, healthy hair samples were taken from 5 women's hair speciment in 20's without experiencing in any harmful substance via long-term medications. and beauty care using chemicals. To get possible findings depending upon hair dye type and treatment procedure, both acidic and alkalic hair dye were applied on some specimens after permanent treatment, while on other specimens before permanent treatment. In order to determine scale damage, this study used SEM(Hitachi S-2500C) both hair thickness and tensile strength were measured with optical microscope(Nikon, MM-60/L3T) and Instron (4482-standard). Wave configuration was measured transverse and longitudinal round diameter. The chromaticity of each specimen was measured using a spectrocolorimeter(Color Techno System, JP/JX-777) with visual $C/2^{\circ}$ (at $2^{\circ}$ with C light source) monitor fixed to determine Lab and CMYK values. As a result, it was found that hair specimens were more significantly damaged with alkalic hair dye treatment than with acidic hair dye treatment, while hair specimens were more effectively dyed with the former hair dye type than with the latter one. For possible results depending on treatment procedure, it was found that hair specimens were less damaged but more effectively dyed with permanent treatment followed by hair dyeing than vice versa. Therefore, it was concluded that permanent treatment followed by acidic hair dyeing would be more effective in reducing hair damages.

• The Journal of Korean Academy of Prosthodontics
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• v.47 no.2
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• pp.191-198
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• 2009

Statement of problem: Ceramics have been important materials for the restoration of teeth. The demands of patients for tooth-colored restorations and the availability of various dental ceramics has driven the increased use of new types of dental ceramic materials. Improved physical properties of theses materials have expanded its use even in posterior crowns and fixed partial dentures. However, ceramic still has limitation such as low loading capability. This is critical for long-span bridge, because bridge is more subject to tensile force. Purpose: The wire reinforced ceramic was designed to increase the fracture resistance of ceramic restoration. The purpose of this study was to evaluate the fracture resistance of wire reinforced ceramic. Material and methods: Heat pressed ceramic(ingot No.200 : IPS Empress 2, Ivoclar Vivadent, Liechtenstein) and Ni-Cr wire(Alfa Aesar, Johnson Matthey Company, USA) of 0.41 mm diameter were used in this study. Five groups of twelve uniform sized ceramic specimens(width 4 mm, thickness 2 mm, length 15 mm) were fabricated. Each group had different wire arrangement. Wireless ceramic was used as control group. The experimental groups were divided according to wire number and position. One, two and three strands of wires were positioned on the longitudinal axis of specimen. In another experimental group, three strands of wires positioned on the longitudinal axis and five strands of wires positioned on the transverse axis. Three-point bending test was done with universal testing machine(Z020, Zwick, Germany) to compare the flexural modulus, flexural strength, strain at fracture and fracture toughness of each group. Fractured ceramic specimens were cross-sectioned with caborundum disc and grinded with sandpaper to observe interface between ceramic and Ni-Cr wire. The interface between ceramic and Ni-Cr wire was analyzed with scanning electron microscope(JSM-6360, JEOL, Japan) under platinum coating. Results: The results obtained were as follows: 1. The average and standard deviation in flexural modulus, flexural strength and fracture toughness showed no statistical differences between control and experimental groups. However, strain was significantly increased in wire inserted ceramics(P<.001). 2. Control group showed wedge fracture aspects across specimen, while experimental groups showed cracks across specimen. 3. Scanning electron microscopic image of cross-sectioned and longitudinally-sectioned specimens showed no gap at the interface between ceramic and Ni-Cr wire. Conclusion: The results of this study showed that wire inserted ceramics have a high strain characteristic. However, wire inserted ceramics was not enough to use at posterior area of mouth in relation to flexural modulus and flexural strength. Therefore, we need further studies.