• Title/Summary/Keyword: Leucite porcelain

Search Result 8, Processing Time 0.021 seconds

A Change of Thermal Expansion Coefficient according to Li2O-added Porcelain for Dental Zirconia (치과용 지르코니아 도재의 Li2O 첨가에 따른 열팽창계수 변화)

  • Yoon, Han-Sok
    • Journal of Technologic Dentistry
    • /
    • v.31 no.4
    • /
    • pp.25-30
    • /
    • 2009
  • Zirconia($ZrO_2$) has attracted much attention in science and technology because of its high refractive index, high melting temperature, hardness, low thermal conductivity and corrosion barrier properties. And it is widely used as the dental restoration material because of its esthetic appearance. In this research, we analyzed the particle size and composition of the imported dental porcelain for zirconia. And the glass frit was produced. To decrease the glass transition temperature and softening temperature of the glass frit, $Li_2O$ was added into it and the effect of $Li_2O$ on the firing temperature was researched. Then the glass which contains leucite crystal with a high coefficient of thermal expansion(CTE) was manufactured and it was mixed with the glass frit to control the CTE. The phase composition were analyzed using the X-ray diffraction. The morphologies of the samples were observed by the scanning electron microscope. The 4wt% $Li_2O$-added glass frit has the optimal glass transition temperature and softening temperature. And 6 wt% leucite crystal was mixed with the glass frit to control the CTE. From the experimental results of crystallization, the crystal phase was found only leucite crystal.

  • PDF

Leucite Synthesis from Solid-State Sintering (고상법에 의한 Leucite 합성)

  • Yoon, Dong-Sup;Lee, Byung-Ha
    • Journal of the Korean Ceramic Society
    • /
    • v.42 no.4
    • /
    • pp.282-286
    • /
    • 2005
  • Leucite crystal has been utilized for dental porcelain due to its high thermal expansion coefficient to meet its counter metal side. Many industrial applications of leucite from the incongruently melting of potassium feldspar are used and its minimum temperature of crystallization is $1150^{\circ}C$. This study aimed to get leucite crystal from lower temperature through congruently melting, and the starting materials are taken from K-feldspar mainly, and aluminum hydroxide and potassium carbonate are additionally supplied to meet stoichiometry of leucite. We report that the leucite crystal can be synthesized in congruently melting from the temperature $950^{\circ}C$ through solid-state sintering with k-feldspar, potassium carbonate and aluminum hydroxide.

Fabrication and Characteristics of Bioceramics for Artificial Dental Crowns (II) Mechanical Characteristics, Color and Color difference (인공치용 바이오 세라믹스의 제조 및 특성(II) 기계적 특성과 색도 및 색차변화)

  • 고영호;한복섭;이준희
    • Journal of the Korean Ceramic Society
    • /
    • v.32 no.10
    • /
    • pp.1203-1211
    • /
    • 1995
  • The tests of three point bending and vickers hardness have been carried out to investigate mechanical characteristics of bioceramics for artificial dental crowns. And color and color difference test has been performed to study chromaticity changes after sintering specimens composited with glass and leucite powders. In addition, thermal dilation test has been carried out to examine bonding relations between dental porcelain and metal frame (Ni-Cr alloy). The result of three point bending test showed a maximum strength of about 68 MPa. Thermal expansion coefficient changed from 8.3$\times$10-6/$^{\circ}C$ to 13.5$\times$10-6/$^{\circ}C$ with increasing leucite content (0~30wt.%) in glass matrix. Bonding between porcelain (25% leucite-75% glass) and Ni-Cr alloy was excellent.

  • PDF

Wear of primary teeth caused by opposed all-ceramic or stainless steel crowns

  • Choi, Jae-Won;Bae, Ik-Hyun;Noh, Tae-Hwan;Ju, Sung-Won;Lee, Tae-Kyoung;Ahn, Jin-Soo;Jeong, Tae-Sung;Huh, Jung-Bo
    • The Journal of Advanced Prosthodontics
    • /
    • v.8 no.1
    • /
    • pp.43-52
    • /
    • 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.

EFFECT OF WATER CONTENT ON THE FLEXURAL STRENGTH DURING REFIRING IN DENIAL PORCELAIN (치과용 도재의 재소성 과정중 수분 함량이 강도에 미치는 영향)

  • Park Hye-Yang;Shim June-Sung;Lee Keun-Woo
    • The Journal of Korean Academy of Prosthodontics
    • /
    • v.41 no.5
    • /
    • pp.656-673
    • /
    • 2003
  • Statement of problem : Long-term exposure of dental porcelain to saliva during temporary cementation of a porcelain-fused to metal (PFM) restoration could affect mechanical strength of dental porcelain if the restoration is refired. Purpose : This work was performed to verify the effect of water on the mechanical strength in aged dental porcelain. Material and method : 63 specimens(Vintage Metalbond opaque and opal powder) were distributed to three experimental groups ; non-water immersed control, immersed and pedried, and immersed and non-predired groups. The changes in flexural strength and fracture toughness after specimen refiring related to Fourier Transform Infrared (FT-IR) spectroscopy. Results : 1. The FT-IR reflectances assigned to molecular bonds of $H_2O$ were noted as significantly different between the first-fired group and three refired groups and between two water-immersed groups and control group after refiring(p<0.05). They were also significantly different between predried group and non-predried group after refiring(p<0.05) 2. For opal specimens, FT-IR absorbances for hydrogen bond of $H_2O$ and silanols were significantly higher in non-predried group than in predreid group(p<0.05). 3 Predried opal group showed the highest mean flexural strength(p<0.05). Non-predried group indicated higher mean flexural strength than control group(p<0.05). 4. The mean fracture toughness for predired group was higher than non-predried group(p<0.05). 5. The difference of leucite crystal size is noted between control group and water-immersed, predried group in scanning electron microscopic study(${\times}10000$).

Optical and Mechanical Properties of Commercial Dental Enamel Porcelain (상용 치과 법랑질 도재의 광학적 및 기계적 특성)

  • Park, Hyung-Rang
    • Journal of Technologic Dentistry
    • /
    • v.26 no.1
    • /
    • pp.115-128
    • /
    • 2004
  • In this study, optical and mechanical properties were investigated with 4 kinds of commercial dental enamels. As a result of EDS analysis $SiO_2,\;Na_{2}O,\;Al_{2}O_3\;and\;K_{2}O$ were the main components of commercial dental enamels. In case of H specimen, content of $SiO_2\;and\;K_2O$ were more than that of another specimens. Starting powder and fired specimens were glass ceramics which were consist of amorphous phase and leucite (crystalline) phase. Crystallization did not occurred during firing process, since the XRD peak intensity was similar between starting powder and fired specimens. As a result of differential thermal analysis, $T_g$ and crystalline temperature was varied with composition in the range of $548\sim576^{\circ}C$ and $735\sim780^{\circ}C$ respectively. 0.5mm thickness dental enamel specimens showed sufficient translucent properties. However, transmittance and reflectance were lower than 5% result from scattering due to the refractive index difference between glass and crystalline phase. 3 point bending strength was in the range of 73.9$\sim$101.8MPa which was similar or slightly higher than enamel of natural teeth and Vickers hardness was higher than enamel of natural teeth more than 100.

  • PDF

Pressable Ceramic을 이용한 심미보철

  • Kim, Jong-Jin
    • Journal of the Korean Academy of Esthetic Dentistry
    • /
    • v.10 no.1
    • /
    • pp.72-78
    • /
    • 2001
  • To maintain the strength obtained with metal ceramic restorations, excellent gradient of translucency, wear resistance in the same range as enamel and good marginal integrity, all ceramics have been developed with many advantages in recent years. Authentic (Ceramay, Germany) is a type of low fusing, leucite-reinforced pressable ceramic that allows both the laying technique and the staining technique or the combination of the two. Two-phase glass ceramic will allow achieving unmatched esthetics even with the simplest laying or staining technique. The ingots and laying porcelain come in Vita shades. Case selection has to be the most crucial thing to achieve optimal esthetics, and cooperation with technician has to be emphasized to satisfy patient's highest esthetic demands.

  • PDF

Influence of Water Infiltration and Flexural Strength Change with Glazing Treatment of Dental Porcelain (치과도재의 Glazing 여부에 따른 수분침투 정도와 굽힘강도에 미치는 영향)

  • Lee, Ju-Hee;Lee, Chae-Hyun;Song, Jeong-Hwan
    • Journal of dental hygiene science
    • /
    • v.17 no.4
    • /
    • pp.358-367
    • /
    • 2017
  • The purpose of this study was to evaluate the influence of water infiltration and flexural strength changes in dental porcelain with glazing treatment. The block specimens were prepared as experimental materials, using feldspar type commercial dental porcelain; then, these were fired at $940^{\circ}C$ for 1 minute. The fired specimens were polished with a dimension of $40{\times}5.5{\times}5mm$. The specimens were distributed to two experimental groups: with and without glazing treatment specimens (n=5), and they were immersed in a solution of pH 7 for 3, 7, and 20 days at $40^{\circ}C$ after fabrication. To evaluate the flexural strength changes with water infiltration treatment in specimens with and without glazing, the 3-point flexural test was performed, using a universal testing machine until failure occurred. Starting powder and fired specimens consisted of amorphous and leucite crystalline phase. The Vickers hardness of fired specimens was more than 1.6 times higher than that of the enamel of natural teeth. According to porosimeter results, the specimens without glazing treatment exhibited a porosity of about 14.7%, whereas the glazed specimens exhibited the lowest porosity at about 1.1%. The average flexural strength of glazed specimens was higher than the flexural strength of specimens without glazing treatment (p<0.05). The flexural strength of all specimens with and without glazing treatment deteriorated with accelerated aging in the solution. In addition, significant differences between these two treatment groups were observed in all of the specimens treated at various water infiltration periods (p<0.05). The exposure of internal pores and micro-cracks in the surface due to polishing of the fired specimens influenced mechanical behaviors. Especially, the flexural strength in specimens without glazing treatment has shown significant degradation with the infiltration of water. Therefore, this study suggests that glazing processes can improve mechanical properties of dental porcelain.