• 대한치과보철학회지
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• 제40권1호
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• pp.68-78
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• 2002

The post core system has been used for reconstructon of severely damaged crown by caries or trauma. But problems such as crown exfoliation, post core fracture and root fracture have been reported. Ideal mechanical properies of the post require high fracture strength, high elastic limit and high resistance against fatigue and corrosion Modulus of elasticity of the post should be similar with that of dentine. Low hardness is also required for the convenience of post removal in failure. Furthermore, the post itself must be translucent for the esthetical purpose. Several types of the post have been developed to satisfy the criteria above mentioned. The purpose of this study was to find out the mechanical properties of quartz fiber post by comparing with those of gold post and zirconia post. The results of this study were as follows : 1. Maximal fracture strength and stiffness of quartz fiber post were similar with those of gold post and zirconia post. 2. Young's modulus and hardness of quartz fiber post were lower than those of gold post and zirconia post. Mechanical property of quartz fiber post against post fracture was similar with that of gold post and zirconia post. Mechanical property of quartz fiber post against root fracture was higher than that of gold post and zirconia post. Quartz fiber post could be removed easily due to low hardness.

• The Journal of Advanced Prosthodontics
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• 제9권3호
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• pp.170-175
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• 2017

PURPOSE. The aim of the present study was to evaluate the fracture resistances of zirconia, cast nickel-chromium alloy (Ni-Cr), and fiber-composite post systems under all-ceramic crowns in endodontically treated mandibular first premolars. MATERIALS AND METHODS. A total of 36 extracted human mandibular premolars were selected, subjected to standard endodontic treatment, and divided into three groups (n=12) as follows: cast Ni-Cr post-and-core, one-piece custom-milled zirconia post-and-core, and prefabricated fiber-glass post with composite resin core. Each specimen had an all-ceramic crown with zirconia coping and was then loaded to failure using a universal testing machine at a cross-head speed of 0.5 mm/min, at an angle of 45 degrees to the long axis of the roots. Fracture resistance and modes of failure were analyzed. The significance of the results was assessed using analysis of variance (ANOVA) and Tukey honest significance difference (HSD) tests (${\alpha}=.05$). RESULTS. Fiber-glass posts with composite cores showed the highest fracture resistance values ($915.70{\pm}323N$), and the zirconia post system showed the lowest resistance ($435.34{\pm}220N$). The corresponding mean value for the Ni-Cr casting post and cores was reported as $780.59{\pm}270N$. The differences among the groups were statistically significant (P<.05) for the zirconia group, as tested by ANOVA and Tukey HSD tests. CONCLUSION. The fracture resistance of zirconia post-and-core systems was found to be significantly lower than those of fiber-glass and cast Ni-Cr post systems. Moreover, catastrophic and non-restorable fractures were more prevalent in teeth restored by zirconia posts.

• 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.

• 한국세라믹학회지
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• 제47권4호
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• pp.343-352
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• 2010

A zirconia gel/polymer hybrid nanofiber was produced in a nonwoven fabric mode by electrospinning a sol derived from hydrolysis of zirconium butoxide with a polyvinyl butyral. Results indicated that the hydroxyl groups on the vinyl alcohol units in the backbone of the polymer were involved in the hydrolysis as well as grafting the hydrolyzed zirconium butoxide. In addition, use of acetic acid as a catalyst resulted in further hydrolysis and condensation in the sol, which led to the growth of -Zr-O-Zr- networks among the polymer chains. These networks gradually transformed into a crystalline zirconia structure upon heating. The as-spun fiber was smooth but partially wrinkled on the surface. The average fiber diameter was $690{\pm}110\;nm$. The fiber exhibited a strong but broad blue photoluminescence with its maximum intensity at a wavelength of ~410 nm at room temperature. When the fiber was heat-treated at $400^{\circ}C$, the fiber diameter shrunk to $250{\pm}60\;nm$. Nanocrystals which belonged to a tetragonal zirconia phase and were ~5 nm in size appeared. A strong white photoluminescence was observed in this fiber. This suggests that oxygen or carbon defects associated with the formation of the nanocrystals play a role in generating the photoluminescence. Further heating to $800^{\circ}C$ resulted in a monoclinic phase beginning to form In the heat-treated fibers, coloring occurred but varied depending on the heating temperature. Crystallization, coloring, and phase transition to the monoclinic structure influenced the photoluminescence. At $600^{\circ}C$, the fiber appeared to be fully crystallized to a tetragonal zirconia phase.

• Structural Engineering and Mechanics
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• 제70권2호
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• pp.233-243
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• 2019

This paper depicts the development and characterizations of laminated composites made with cellulosic giant cane (Arundinaria gigantea) fiber mats and epoxy resin. Zirconia-toughened mullite (ZTM) is used as a filler material in the laminated composite which was prepared from sillimanite through plasma processing technique. The mechanical characterizations of this composite have been carried out as per ASTM standards to evaluate its usability as a structural material. The effects of varying weight percentages of the filler and two different fiber orientations namely, angle-ply [$+45^{\circ}/-45^{\circ}/+45^{\circ}$] and balanced cross-ply [$0^{\circ}/90^{\circ}/0^{\circ}$] on the physical and mechanical properties such as density, microhardness, impact strength, tensile strength and interlaminar shear strength of the layered composite specimens have been investigated. The study indicates that the inclusion of zirconia-toughened mullite in the composite laminate as filler improves its mechanical properties. Moreover, the use of giant cane fiber mat in the laminate is more eco-friendly than the synthetic fibers. This research also helps in generating additional data to enrich the repository of natural fiber reinforced laminated composites.

• Current Optics and Photonics
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• 제6권1호
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• pp.32-38
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• 2022

Erbium-doped fiber amplifiers (EDFAs) have saturated the technological market but are still widely used in high-speed and long-distance communication systems. To overcome EDFA saturation and limitations, its erbium-doped fiber is co-doped with other materials such as zirconia and bismuth. This article demonstrates and compares the performance using three different fibers as the gain medium for zirconia-erbium-doped fibers (Zr-EDF), bismuth-erbium-doped fibers (Bi-EDF), and commercial silica-erbium-doped fibers (Si- EDF). The optical amplifier was configured with a double-pass amplification system, with a broadband mirror at the end of its configuration to allow double-pass operation in the system. The important parameters in amplifiers such as optical properties, optical amplification and noise values were also examined and discussed. All three fibers were 0.5 m long and entered with different input signals: 30 dBm for low input and 10 dBm for high input. Zr-EDF turned out to be the most relevant optical amplifier as it had the highest optical gain, longest transmission distance, highest average flatness gain with minimal jitter, and relevant noise figures suitable for the latest communication technology.

• 한국세라믹학회지
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• 제32권7호
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• pp.846-852
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• 1995

The multiply reinforced mullite-zirconia composites were prepared with addition of Al2O3 particles, platelets, and fibers. The sinter-HIP specimens (presintered at 1$700^{\circ}C$ and hipped at 1$600^{\circ}C$) showed that the fracture toughness of Al2O3 fiber reinforcement (4.4 MPa.{{{{ SQRT {m} }}) was higher than those of platelet (4.0 MPa.{{{{ SQRT {m} }}) and of particle (3.9MPa.{{{{ SQRT {m} }}) reinforcement, whereas the fracture strength of Al2O3 particle reinforcement (304 MPa) was higher than those of platelet (293MPa) and of fiber (248MPa) reinforcement.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 1992년도 춘계학술대회 논문집
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• pp.18-22
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• 1992

This paper presents the process of manufacturing technology of ceramics ferrule for optical fiber connector. Precision zirconia ceramic ferrules is widely used for high performance and low cost single mode optical fiber connectors. To polish the hole of the zirconia ceramic ferrule, the wire lapping instrument is developed and the machining experiment is conducted. Through the centerless grinding using diamond wheel the surface roughness of zirconia ceramics ferrule is below the 1 .mu. m Rmax.

• 대한치과보철학회지
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• 제52권2호
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• pp.74-81
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• 2014

연구 목적: 포스트로 수복한 치아의 미세누출을 방지하기 위한 다양한 술식이 개발되고 있고 이에 본 연구에서는 다양한 접착시스템을 이용하여 섬유 강화형 포스트로 수복한 치아에서의 치근부 미세누출에 대해 비교 연구하고자 하였다. 연구 재료 및 방법: 36개의 근관치료된 상악 영구 중절치를 3가지 포스트 그룹으로 분류하였다: Zirconia-glass fiber, Quarze-glass fiber, Polyethylene fiber 포스트. 포스트 공간이 형성되었고 각 포스트는 세가지 접착시스템으로 접착되었다: 3-stage total-etch adhesive, 2-stage total-etch adhesive, 1-stage self-etch adhesive. 각 시편들을 2% 메틸렌 블루 용액에 1주일 동안 담구었다. 세척한 시편을 자가중합 아크릴릭 레진에 포매하였다. 각 시편을 치근단, 중앙, 치관 부위로 수평 절단하였다. 메틸렌 블루가 침투된 각 시편의 절단부를 교합면 측에서 stereomicroscope로 측정하였다. 시료 침투량은 메틸렌 블루 침투 표면과 총 상아질 표면의 비율로 평가하였다. 결과: 모든 절단부위에서 모든 군들은 미세 누출을 보였다. 각 절단 부위별로 접착 시스템에 따른 포스트간의 비교에서는 유의한 차이는 없었다. All Bond 2로 접착한 3단계 접착시스템으로 처리한 치아 중앙절편에서 zirconia-glass fiber와 quarze-glass fiber 포스트 간, zirconia-glass fiber와 polyethylene fiber 포스트 간, quarze-glass fiber와 polyethylene fiber 포스트 간에 미세누출에는 유의한 차이가 있었다(P<.05). 각각의 포스트의 치근단과 치관 부위 사이에는 유의한 차이가 있었고, quarze-glass fiber와 polyethylene fiber 포스트에서 치근단과 중앙 부위 사이에 유의한 차이가 있었다(P<.05). 결론: 포스트 종류에 따른 접착 시스템 간에 미세누출의 유의한 차이가 없었다. 각 절단 부위별로 접착 시스템에 따른 포스트간의 비교에서는 유의한 차이는 없었으나, 유일하게 3단계 접착시스템으로 처리한 포스트의 중앙절편에서 zirconia-glass fiber가 다른 포스트에 비해 유의하게 적은 미세누출을 보였다.

• 한국정밀공학회지
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• 제9권3호
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• pp.67-72
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• 1992

This paper presents the process of manufacturing technology of ceramics ferrule for opitcal fiber connector. Precision zirconia ceramic ferrules is widely for high performance and low cost single mode optical fiber connectors. To polish the hole of the zirconia ceramic ferrule, the wire lapping instrument is developed and the machining experiment is conducted. Through the centerless grinding using diamond wheel the surface roughness of zirconia ceramics ferrule is below the 1$\mu$m Rmax.