• Journal of Technologic Dentistry
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• v.30 no.2
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• pp.39-45
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• 2008

Titanium and its alloys are widely used as dental implants materials because of their excellent mechanical properties. However, the alumina and zirconia ceramics are preferred to use as the substitute of Ti implants because there is a problems in esthetics and biocompatibility in Ti implant. The the glass infiltrated alumina ceramics are studied to increase the toughness and biocompatibility. The 45S5 and soda-lime glass powder was mixed with ethanol at ratio of 1:1 and brushed on the surface of alumina. Then it was heat treated in the electric furnace at $1400^{\circ}C$ from 30 min. to 5 hours. The glass powder was controlled from 200 to $350{\mu}m$ using ball milling. After heat treatment, the glass infiltrated specimen was tested in universal testing machine to measure the bending strength. The surface microstructure of each specimen was observed with SEM. The biocompatibility of 45S5 and soda-lime glass coated alumina was investigated using PBS at $36.5^{\circ}C$ incubator. The specimen was immersed in PBS for 3, 5, 7, 10 days. After that, the surface morphology was investigated with SEM. As the results of experiment, the 45S5 bioglass infiltrated alumina show the increase of bending strength according to the increasing of heat treatment time from 30 min. to 5 hours at $1400^{\circ}C$ Finally the 1370N bending strength of alumina increased to 1958N at 5 hours heat treatment, which shows 1.4 times higher. In contrast to this, the soda lime glass infiltrated alumina ceramics shows the convex curve according to heat treatment time. Thus it shows maximum bending strength of 1820N at 1 hour heat treatment of $1400^{\circ}C$ It gives 1.3 times higher. However, the bending strength of soda lime glass infiltrated alumina is decreasing with increasing heat treatment time after 1 hour. The precipitation on the surface of 45S5 glass infiltrated alumina was revealed as a sodium phosphate ($Na_{6}P_{6}O_{24}6H_{2}O$) and the amount of precipitation is increasing with increasing of immersion time in PBS. In contrast to this, there is no precipitation are observed on the surface of soda lime glass infiltrated alumina. This implies that 45S5 glass infiltrated alumina brings more biocompatible when it is implanted in human body.

• Journal of Technologic Dentistry
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• v.30 no.1
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• pp.41-47
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• 2008

This study was to evaluate the biaxial flexural strength of zirconia ceramics after glass-infiltration on zirconia core. The zirconia specimens were made with diameter-15mm, thickness-0.6mm using zirconia block which divided into 1) sintered group, 2) heat - treated group, 3) Glass - infiltrated group and experimented fracture strength by each 10 specimens in experimental group. The biaxial flexural test was performed at crosshead speed of 0.1${\beta}\;{\AE}$ min. The experiment result average fracture strength was shown 541.0${\beta}\acute{A}$ in sintered group and glass-infiltrated group as 662.2${\beta}\acute{A}$ river of 22.4% rise appear. Weibull coefficient sintered group is 3.462 and glass-infiltrated group improved believability about fracture strength from melting permeation processing of glass by 4.716.

• Journal of the Korean Ceramic Society
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• v.40 no.3
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• pp.301-308
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• 2003

Glass-infiltrated alumina, which can be used as an all-ceramic dental crown, was prepared. The glasses in the system of SiO$_2$-B$_2$O$_3$-Al$_2$O$_3$-CaO-La$_2$O$_3$with various amount of $Al_2$O$_3$infiltrated into a porous sintered alumina. The effect of $Al_2$O$_3$on the infiltration characteristics and its mechanical strength were studied. The corrosion of the sintered alumina by infiltrated glasses was prevented by increasing the amount of $Al_2$O$_3$in the glass batches, this increased the bending strength of the glass infiltrated alumina composite. The crack like voids in the sintered alumina was a cause of the deteriorating the mechanical strength of the composite, and this can be eliminated by sintering the alumina at 130$0^{\circ}C$. Glass infiltration under the vacuum atmosphere enhanced the hording strength of the composite up to 453$\pm$31 MPa.

• Journal of the Korean Ceramic Society
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• v.40 no.1
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• pp.93-97
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• 2003

Using alumina-glass infiltrated material which has been in the spotlight of biomaterials including dental material, appropriate composition of glass infiltrated material mainly depends on the thermal expansion coefficient. To obtain proper compositional glass of suitable thermal expansion coefficient effiiently. a Taguchi analysis was conducted. The influence of alkali oxide and alkali earths oxide, which affect mostly the thermal expansion coefficient of glass infiltrated material, was infiltrated material, the effect having influenced on the thermal expansion coefficient of glass was presented in this order (Na$_2$O≫K$_2$O ≫MgO≒CaO). The effect of Na$_2$O was about eight times as great as the effects of MgO, CaO and $K_2$O was about four times. Among the interaction affects of each variables the interaction affects of $K_2$O-CaO showed most significantly and thermal expansion property of specified composition was predicted by calculating contribution rate on each level of variables and interaction affects.

• Journal of Technologic Dentistry
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• v.31 no.2
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• pp.9-14
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• 2009

In this study, to improve the flexure strength of Zirconia, on the Zirconia pellet surface measure the flexure strength to melt or permeate the Alumina (Vita Zahnfabrik, Bad Sachkingen, Germany) of private used In-Cream and observe by Scanning election microscope. In the control group(3Y-TZP group), the average of flexure strength was 1623.7MPa, and in the experimental group(Glass-infiltrated 3Y-TZP group) was 1800.2MPa. As a result of observing the interface between glass and zirconia with a scanning election microscope, it was showed that the glass dissolves to permeate into the surface of zirconia, so filled the zirconia with particles.

• The Journal of Korean Academy of Prosthodontics
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• v.35 no.1
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• pp.221-243
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• 1997

The objective of this study was to characterize the mechanical properties of $Y_{2}O_{3}$-containing glass infiltrated ceramic core material, which was made by pressureless powder packing method. A pure alumina powder with a grain size of about $4{\mu}m$ was packed without pressure is silicon mold to form a bar shaped sample, and applied PVA solution as a binder. Samples were sinterd at $1350^{\circ}C$ for 1 hour. After cooling, $Y_{2}O_{3}$-containing glass($SiO_{2},\;Y_{2}O_{3},\;B_{2}O_{3},\;Al_{2}O_{3}$, ect) was infiltrated to the sinterd samples at $1300^{\circ}C$ for 2 hours and cooled. Six different proportions $Y_{2}O_{3}$ of were used to know the effect of the mismatch of the thermal expansion coefficient between alumina powder and glass. The samples were ground to $3{\times}3{\times}30$ mm size and polished with $1{\mu}m$ diamond paste. Flexural strength, fracture toughness, hardness and other physical properties were obtained, and the fractured surface was examined with SEM and EPMA. Ten samples of each group were tested and compared with In-Ceram(tm) core materials of same size made in dental laboratory. The results were as follows : 1. The flexural strengths of group 1 and 3 were significantly not different with that of In-Ceram, but other experimental groups were lower than In-Ceram. 2. The shrinkage rate of samples was 0.42% after first firing, and 0.45% after glass infiltration. Total shrinkage rate was 0.87%. 3. After first firing, porosity rate of experimental groups was 50%, compared with 22.25% of In-Ceram. After glass infiltration, porosity rate of experimental groups was 2%, and 1% in In-Ceram. 4. There was no statistical difference in hardness between two materials tested, but in fracture toughness, group 2 and 3 were higher than In-Ceram. 5. The thermal expansion coefficients of experimental groups were varied to $4.51-5.35{\times}10^{-6}/^{\circ}C$ according to glass composition, also the flexural strengths of samples were varied. 6. In a view of SEM, many microparticles about $0.5{\mu}m$ diameter and $4{\mu}m$ diameter were observed in In-Ceram. But in experimental group, the size of most particles was about $4{\mu}m$, and a little microparticles was observed. The results obtained in this study showed that the mismatch of the thermal expansion coefficients between alumina powder and infiltrated glass affect the flexural strength of alumin/glass composite. The $Y_{2}O_{3}$-containing glass infiltrated ceramic core made by powder packing method will takes less time and cost with sufficient flexural strength similar to all ceramic crown made with slip casting technique.

• The Journal of Advanced Prosthodontics
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• v.9 no.2
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• pp.104-109
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• 2017

PURPOSE. The purpose of this study was to evaluate the influence of acid etching treatment on surface characteristics and biological response of glass-infiltrated zirconia. MATERIALS AND METHODS. A hundred zirconia specimens were divided into four groups depending on surface treatments: untreated zirconia (group Z); acid-etched zirconia (group ZE); glass-infiltrated zirconia (group ZG); and glass-infiltrated and acid-etched zirconia (group ZGE). Surface roughness, surface topography, surface morphology, and Vickers hardness of specimens were evaluated. For biological response test, MC3T3-E1 cell attachment and proliferation on surface of the specimens were examined. The data were statistically analyzed using one-way ANOVA and Tukey's HSD test at a significance level of 0.05. RESULTS. Group ZGE showed the highest surface roughness ($Ra=1.54{\mu}m$) compared with other groups (P < .05). Meanwhile, the hardness of group Z was significantly higher than those of other groups (P < .05). Cell attachment and cell proliferation were significantly higher in group ZGE (P < .05). CONCLUSION. We concluded that effective surface roughness on zirconia could be made by acid etching treatment after glass infiltration. This surface showed significantly enhanced osteoblast cell response.

• Journal of the Korean Ceramic Society
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• v.41 no.12 s.271
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• pp.939-945
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• 2004

Glasses of $SiO_2-B_{2}O_3-Al_{2}O_3-CaO-La_{2}O_3$ with various amounts of $La_{2}O_3$ were infiltrated into a porous alumina to make an alumina-glass composite. The infiltration characterization and bending strength of the composite were examined in terms of glass composition. $La_{2}O_3$ in the glass decreased the high temperature viscosity and this enhanced the wetting behaviour of this glass to alumina, and made glass infiltration easier. The infiltrated glass dissolved the alumina skeleton, and $Al_{2}O_3$ component in the glass melt reprecipitated on the alumina. The grain growth occurred to a specific crystal direction. The glass containing $20mole\%$ of $La_{2}O_3$ was crystallized after infiltration, and this enhanced the bending strength of the composite.

• The Journal of Korean Academy of Prosthodontics
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• v.50 no.4
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• pp.235-242
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• 2012

Purpose: The purpose of this study was to compare the fracture behavior of Zironia, glass infiltrated Alumina and PFM full crown system. Materials and methods: Fifteen crowns for each of 3 experimental groups (Zironia, glass infiltrated Alumina and PFM full crown) were made by the conventional method. The crowns mounted on the testing jig were inclined in 30 degrees to the long axis of the tooth and the universal testing machine was used to measure the fracture strength. Results: 1. The mean fracture strengths were $588.3{\pm}49.6MPa$ for zirconia system, $569.1{\pm}61.8MPa$ for PFM system and $551.0{\pm}76.5MPa$ for glass-infiltrated alumina system (P>.05). 2. The mean shear bond strengths were $25.5{\pm}5.6MPa$ for zirconia system, $38.9{\pm}5.0MPa$ for Ni-Cr alloy system and $39.4{\pm}5.1MPa$ for glass-infiltrated alumina system. 3. The chemical bonding was observed at interfaces between PFM or glass-infiltrated alumina and veneering porcelain, however, no chemical bonding was observed at interface between zirconia and veneering porcelain. Conclusion: With the study, the fracture strengths of PFM crown system had a higher fracture strength than conventional zirconia system crown and glass-infiltrated alumina crowns. and than the shear bond strengths glass-infiltrated alumina system had a higher shear bond strength than conventional PFM system and zirconia system.

• Journal of the Korean Ceramic Society
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• v.35 no.7
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• pp.671-678
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• 1998

Hertzian indentation tests with sphere indenters were used to study the mechanical properties of glass-in-filtrated alumina and spinel composites and evaluated the effect of preform microstructure and evaluated the effect of preform microstructure and glass con-tents on contanct damage and strength. The spinel composite showed more brittle behavior than the alumina composite which is verified from indentation stress-strain curve cone cracks and quasi-plastic deformation developed at subsurface. Failure originated from either cone cracks(brittle mode) or deformation zone(quasi-plastic mode) above critical load for cracking(Pc) and yield ({{{{ {P }_{Y } }}) with the brittle mode more dominant in the spinels and the quasi-plastic mode more dominant in the aluminas. Even though brittle mode was dominant in the spinel composites the strength degradation from accumulation of damage above these critical loads was conspicuously small suggesting that the glass-infiltrated composites should be highly damage tolerant to the blunt contacts.