• 대한치과기공학회지
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• 제33권3호
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• pp.219-224
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• 2011

Purpose: The current study focused on investigating color change of dental zirconia block with respect to the block coloring time. Methods: Three types of dental zirconia blocks(Zirtooth, Pearl-HT, D-Max) were tinted with coloring agent under four different time condition (0 minutes, 1 minutes, 10 minutes, 30 minutes). The quantitative evaluation of the tinted dental zirconia blocks was conducted with spectrophotometer. Results: The Zirtooth and D-Max blocks showed lower H value. The Pearl-HT blocks showed poor reflectivity(L value). Conclusion: The study of color change of zirconia block, which consists the substructure of all ceramic Crown, is applicable for deciding appropriate coloring condition when fabricating one layer ceramic Crown or double layer ceramic Crown.

• The Journal of Advanced Prosthodontics
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• 제8권1호
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• pp.43-52
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• 2016

PURPOSE. This study was conducted to evaluate the effects of full-coverage all-ceramic zirconia, lithium disilicate glass-ceramic, leucite glass-ceramic, or stainless steel crowns on antagonistic primary tooth wear. MATERIALS AND METHODS. There were four study groups: the stainless steel (Steel) group, the leucite glass-ceramic (Leucite) group, the lithium disilicate glass-ceramic (Lithium) group, and the monolithic zirconia (Zirconia) group. Ten flat crown specimens were prepared per group; opposing teeth were prepared using primary canines. A wear test was conducted over 100,000 chewing cycles using a dual-axis chewing simulator and a 50 N masticating force, and wear losses of antagonistic teeth and restorative materials were calculated using a three-dimensional profiling system and an electronic scale, respectively. Statistical significance was determined using One-way ANOVA and Tukey's test (P<.05). RESULTS. The Leucite group ($2.670{\pm}1.471mm^3$) showed the greatest amount of antagonist tooth wear, followed by in decreasing order by the Lithium ($2.042{\pm}0.696mm^3$), Zirconia ($1.426{\pm}0.477mm^3$), and Steel groups ($0.397{\pm}0.192mm^3$). Mean volume losses in the Leucite and Lithium groups were significantly greater than in the Steel group (P<.05). No significant difference was observed between mean volume losses in the Zirconia and Steel groups (P>.05). CONCLUSION. Leucite glass-ceramic and lithium disilicate glass-ceramic cause more primary tooth wear than stainless steel or zirconia.

• The Journal of Advanced Prosthodontics
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• 제5권3호
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• pp.319-325
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• 2013

PURPOSE. The objective of this study was to determine the effect of the color of a background substructure on the overall color of a zirconia-based all-ceramic crown. MATERIALS AND METHODS. Twenty one posterior zirconia crowns were made for twenty subjects. Seven premolar crowns and six molar crowns were cemented onto abutments with metal post and core in the first and second group. In the third group, eight molar crowns were cemented onto abutments with a prefabricated post and composite core build-up. The color measurements of all-ceramic crowns were made before try-in, before and after cementation. A repeated measure ANOVA was used for a statistical analysis of a color change of all-ceramic crowns at ${\alpha}$=.05. Twenty four zirconia specimens, with different core thicknesses (0.4-1 mm) were also prepared to obtain the contrast ratio of zirconia materials after veneering. RESULTS. $L^*$, $a^*$, and $b^*$ values of all-ceramic crowns cemented either on a metal cast post and core or on a prefabricated post did not show significant changes (P>.05). However, the slight color changes of zirconia crowns were detected and represented by ${\Delta}E{^*}_{ab}$ values, ranging from 1.2 to 3.1. The contrast ratios of zirconia specimens were 0.92-0.95 after veneering. CONCLUSION. No significant differences were observed between the $L^*$, $a^*$, and $b^*$ values of zirconia crowns cemented either on a metal cast post and core or a prefabricated post and composite core. However, the color of a background substructure could affect the overall color of posterior zirconia restorations with clinically recommended core thickness according to ${\Delta}E{^*}_{ab}$ values.

• 대한치과보철학회지
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• 제48권2호
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• pp.94-100
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• 2010

연구목적: 본 연구는 상악과 하악의 각 치아부위에 $Lava^{TM}$ All-Ceramic System을 이용하여 지르코니아 전부도재관을 제작하고 각각의 파절강도를 알아보고자 하였다. 연구방법:중절치와 견치는 절단연의 삭제량을 2.0 mm, 소구치와 대구치는 교합면의 삭제량을 1.5 mm, 그리고 축면 경사도는 $8^{\circ}$로하여모두8군의 실험군을 설정하였다. 금속 다이와 지르코니아 도재관을 제작한 후 레진시멘트 (Rely $X^{TM}$ Unicem)를 이용하여 합착하고 만능시험기상에서 치아 장축에 $30^{\circ}$경사지게 하여 중절치와 견치에 제작된 지르코니아 도재관은 절단연 중앙 부위에 하중을 가하였고, 소구치와 대구치에 제작된 지르코니아 도재관은 기능교두의 협설측 경사면 중앙부위에 하중이 가해지도록 한 후 파절강도를 측정하였다. 결과:1. 지르코니아 도재관의 평균 파절강도는 하악 제1대구치에서 2963 N으로 가장 높게 나타났으며, 하악 중절치에서 1035 N으로 가장 낮게 나타났다. 2. 지르코니아 도재관과 IPS Empress 도재관과의 평균 파절강도는 모든 치아에서 지르코니아 도재관이 더 크게 나타났다. 3. 지르코니아 도재관의 파절 양상은 하중이 가해진 중앙 부위에서 치아 장축으로 수직적인 파절상을 보였다. 4. 상악과 하악의 동일 부위에 제작된 지르코니아 도재관의 파절강도는 소구치에서 상악이 하악에 비하여 낮은 것으로 나타났으며 (P< .05), 다른 부위에서는 유의한 차이가 없었다 (P> .05). 결론: 본 실험의 결과로 지르코니아 도재관은 임상에서 활용하기에 만족할 만한 강도를 갖고 있음을 알 수 있었다.

• 한국윤활학회:학술대회논문집
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• 한국윤활학회 2004년도 학술대회지
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• pp.355-361
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• 2004

Ceramic femoral heads in the total hip replacement have been developed to reduce the polyethylene liner wear, Alumina and zirconia (3Y-TZP) having the excellent tribological properties are coupled against acetabular cups of polyethylene and are used in clinical application worldwide. However, alumina has a risk of catastrophic failure, and zirconia has the low temperature degradation in spite of enhanced fracture toughness. Recently, novel zirconia/alumina composite is very attractive due to the low temperature degradation (LTD)-free character and high fracture toughness. In the present study, we focus on the wear of ceramic on ceramic, which are able to be used as femoral heads and acetabular cups. Therefore, LTD-free zirconia/alumina composites with three compositions are made in a form of disk and cylinder, and the wear of the composites is performed on pin-on-disk type wear tester. The wear is conducted with or without lubricant. All the composites fabricated with the different composition show the good wear resistance.

• 대한치과기공학회지
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• 제43권1호
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• pp.6-12
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• 2021

Purpose: This study aimed to compare the shear bond strength between zirconia cores and veneer ceramics as per the sand blasting and liner treatments. Methods: The following 4 groups of zirconia-veneering ceramic specimens were prepared: (1) Group I, untreated; (2) Group II, with 110 ㎛ aluminium oxide (Al2O3) sandblasting; (3) Group III, with liner (IPS e.max ZirLiner; Ivoclar Vivadent); and (4) Group IV, with 110 ㎛ Al2O3 sand blasting and liner. Surface roughness was measured for all the prepared specimens, and the surface morphology was observed using a scanning electron microscope. All the samples (n=40) were fixed with measuring jigs, and shear bond strengths were obtained using a universal testing machine with a crosshead speed of 0.5 mm/min. The shear bond strength data were analyzed using one-way analysis of variance and t-test. The post hoc comparison was performed using the Tukey's test (α=0.05). Results: A significant difference in the surface roughness was observed between the specimens of groups I and II (p<0.05). Surface treatment with liner and sandblasting showed higher shear bond strength between zirconia core and veneering ceramic (p<0.05). Conclusion: The sand blasting and liner treatment increased the shear bond strength between zirconia core and veneering ceramic.

• 구강회복응용과학지
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• 제31권1호
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• pp.45-49
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• 2015

본 증례는 기존의 국소의치에서 파절된 metal-ceramic surveyed crown을 complete contour zirconia surveyed crown으로 전환하는 간단하고 편리한 CAD/CAM 기술을 보고하고 있다. 항암치료를 받고 있는 환자의 기존 metal-ceramic surveyed crown 외형, 형태학적 특성, 레스트 시트를 complete contour zirconia surveyed crown으로 제작하는 복제 기법에 대해 보고한다.

• 구강회복응용과학지
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• 제28권3호
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• pp.253-268
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• 2012

수직적, 수평적 골흡수가 심한 환자에서 임플란트를 이용한 전악수복의 경우 경조직과 연조직 이식을 통해서 임플란트를 원하는 위치에 식립할 수도 있지만, 치은과 치아의 기능과 심미를 회복할 수 있는 fixed detachable prostheses를 대체 술식으로 사용할 수도 있다. 이러한 증례에서 다양한 재료가 수복물의 제작에 사용 가능하지만, metal/acrylic 보철물에서는 레진치아의 파절 및 탈락이 일어날 수 있고, metal/ceramic 혹은 zirconia/ceramic 보철물에서는 도재의 chipping이나 파절과 같은 문제가 발생할 수 있다. 이에 최근에 심미적이면서도 기능적인 보철수복을 위해 zirconia에 도재를 축성하지 않고 임상적으로 적용가능한 monolithic zirconia framework이 출시되어 사용되고 있다. 본 임상 증례는 심미적인 요구도가 높은 완전 무치악 환자에서 임플란트를 식립하고 chipping이나 파절의 위험을 감소시키기 위해 monolithic zirconia framework을 이용해 만들어진 complete fixed detachable 보철물을 이용한 수복에 대해 보고하고자 한다. 이번 증례에서 보철물은 심미적, 기능적으로 만족스러웠으며, 2년 간의 정기검사에서 임상적인 합병증은 보고되지 않았다.

• 한국세라믹학회지
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• 제24권4호
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• pp.357-363
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• 1987

This study consists of two powder preparation process. One is that the synthesized Forsterite at 1400$^{\circ}C$ mixed with Zirconia powder. Another, theoretical Forsterite composition mixed with Zirconia. These two Forsterite bodies were heat-treated at 1400$^{\circ}C$, 1450$^{\circ}C$. Synthesized Foresterite composition showed higher density, strength than Forsterite composite which was directly mixed with Zirconia KIC value was measured by Microhardness Indentation method. It shows the highest value when 15 weight percent Zirconia dispersed.

• 한국세라믹학회지
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• 제28권10호
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• pp.819-823
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• 1991

Pure zirconia ceramic fiber experiences severe volume changes through thermal cyclings of heating and cooling. Zirconia fiber was doped with CaO to stabilize the phase and its effect of CaO was studied on volumetric ratio of each phases, phase transition temperature and microstructure. Tetragonal phase was increased as CaO increases up to 10 mol% and cubic phase was stabilized when CaO was added more than 10 mol%. The average grain size of zirconia fiber was increased as CaO increased and transition temperature was shifted to lower temperature.