• The Journal of Advanced Prosthodontics
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• v.7 no.5
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• pp.349-357
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• 2015

PURPOSE. The purpose of this study was to assess the impact of the core materials, thickness and fabrication methods of veneering porcelain on prosthesis fracture in the porcelain fused to metal and the porcelain veneered zirconia. MATERIALS AND METHODS. Forty nickel-chrome alloy cores and 40 zirconia cores were made. Half of each core group was 0.5 mm-in thickness and the other half was 1.0 mm-in thickness. Thus, there were four groups with 20 cores/group. Each group was divided into two subgroups with two different veneering methods (conventional powder/liquid layering technique and the heat-pressing technique). Tensile strength was measured using the biaxial flexural strength test based on the ISO standard 6872:2008 and Weibull analysis was conducted. Factors influencing fracture strength were analyzed through three-way ANOVA (${\alpha}{\leq}.05$) and the influence of core thickness and veneering method in each core materials was assessed using two-way ANOVA (${\alpha}{\leq}.05$). RESULTS. The biaxial flexural strength test showed that the fabrication method of veneering porcelain has the largest impact on the fracture strength followed by the core thickness and the core material. In the metal groups, both the core thickness and the fabrication method of the veneering porcelain significantly influenced on the fracture strength, while only the fabrication method affected the fracture strength in the zirconia groups. CONCLUSION. The fabrication method is more influential to the strength of a prosthesis compared to the core character determined by material and thickness of the core.

• The Journal of Korean Academy of Prosthodontics
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• v.29 no.2
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• pp.67-84
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• 1991

This study was carried out to investiagate the residual stress caused by the mismatch of thermal expansion and the bond failure resistance of alloy-porcelain specimens. The thermal expansions of alloys and porcelains were measured by using a straight push-rod dilatometer. Porcelain glass transition temperatures, thermal expansion coefficients, and thermal compatibility indices were derived from length-versus-temperature curves. Strain gauges were used to experimentally determine the Young's moduli of porcelains, the residual stresses of porcelain surface, and tensile bond strengths of the specimens of simulated porcelain metal crown. The obtained results were as follows: 1. The coefficients of thermal expansion for alloys were the minimum of $13.53\mu/^{\circ}C$ and the maximum of $20.11\mu/^{\circ}C$ in the range of $100\sim600^{\circ}C$ and those for porcelains were the minimum of $7.72\mu/^{\circ}C$ and the maximum of $31.24\mu/^{\circ}C$ in the range of $100\sim500^{\circ}C$. 2. The glass transition temperature of porcelains exhibited the same value without my relation to the healing rate, and the thermal disharmony of porcelain and alloy was more affected by porcelains than by the alloys. 3. The Young's moduli of body porcelains were larger than those of opaque porcelains(P<0.01) 4. It seemed that the residual stresses of porcelain surfaces in the porcelainalloy systems were more affected by porcelains than by alleys. 5. The bond strengths of the procelain-base metal alloy systems were larger than those of the porcelain-precious metal alloy systems. The fracture strengths of porcelain surfaces showed significant difference between porcelains (P<0.05).

• The Journal of Korean Academy of Prosthodontics
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• v.29 no.2
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• pp.117-127
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• 1991

The purpose of this study was to evaluate the effect of surface treatment of fractured metal-ceramic crown on bond strength of porcelain repair resin. The specimens were divided into two groups for metal specimens add five groups for porcelain specimens by surface treatment methods. the metal specimens were treated by 2 methods. : micro-sandblasting with $50{\mu}m$ aluminum oxide and grinding with diamond bur. The porcelain specimens were treated by 5 methods : micro-sandblasting with $50{\mu}m$ aluminum oxide, grinding with diamond bur, etching with porcelain etching agent, combination of micro-sandblasting and etching procedure, and combination of grinding and etching procedure. After surface treatment, each specimen was bonded with composite resin and the bond strength was measured and the surface texture was observed by scanning electromicroscope(SEM). The results were as follows : 1. There was significant difference in shear bond strength between metal specimen and prorcelain specimen. 2. Bood strength of metal specimens treated with diamond bur was higher than that treated with $50{\mu}m$ aluminum oxide sandblasting. 3. Bond strength of porcelain specimen treated with diamond bur was higher than that treated with $50{\mu}m$ aluminum oxide sandblasting and porcelain etching agent. 4. There was no significant difference in shear bond strength between the group treated with diamond bur and combined treatment groups respectively. 5. The large undercuts were observed in group treated with diamond bur by SEM.

• Journal of Dental Rehabilitation and Applied Science
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• v.30 no.2
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• pp.112-120
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• 2014

Purpose: This study compared the shear bond strength of heat pressed and feldspathic porcelain to metal. Through thermocycling, the clinical aspect of heat pressed porcelain fused metal was estimated. Materials and Methods: 90 non-precious metal specimens were made ($4{\times}4{\times}8 mm$) and divided to three groups. All spicimens were treated and built-up with the porcelain ($4{\times}4{\times}3 mm$) by 2 different methods according to group: Group I: $Inspiration^{(R)}$, Group II: Ivoclar, IPS $Inline^{(R)}PoM$, Group III: GC Initial IQ-One $Body^{(R)}PoM$. The half of each group's specimens were thermocycled. All specimens' shear bond strength were measured by Instron universal testing machine. Exact measuring point was far 1 mm from porcelain/metal interface to the porcelain side. For the statistical analysis, 2-way ANOVA was used. Results: In no-thermocycling specimens, the shear bond strength showed no statistical significance between each group (P > 0.05). In comparison between nothermocycling and thermocycling specimens in each group, the shear bond strength was decreased according to thermocycling, but there was no statistical significance (P > 0.05). In thermocycling specimens, there was no statistical significance between each group (P > 0.05). Conclusion: In feldspathic porcelain and other two types heat pressed porcelain, there was no statistical difference in the shear bond strength of porcelain to metal. The heat pressed porcelain seems to be clinically useful for the aspect of the shear bond strength.

• The Journal of Korean Academy of Prosthodontics
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• v.37 no.6
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• pp.800-808
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• 1999

To compare several porcelains made by various manufacturers in shrinkage after firing and investigate the effect of condensation on shrinkage, specimens were prepared and the volume of each body was measured by the phase-shifting profilometry. Baseplate wax was cut by $2.5cm{\times}2cm$ and cast in nonprecious metal(Verabond, U.S.A.), then any surfaces of specimens were abrased and polished on the SiC abrasing papers, preparing 120 specimens. Specimens were divided into six groups according to the porcelain used, and the porcelain used in each group were as follows. Group I : Ceramco dentin porcelain Group B : Creation dentin porcelain Group III : Creation margin porcelain Group IV : Vintage margin porcelain Group V : Vita dentin porcelain Group VI : Vintage dentin porcelain Porcelain was built up on the metal plates using a small spoon and then solution matching to each porcelain was added. The six groups are subdivided into a and b. In subgroup a, only excessive solution was absorbed with tissue and in subgroup b, porcelain was condensed sufficiently. When build-up was completed, the shape was measured using the phase-shifting profilometry. After that, specimens were fired in the furnace programed for each porcelain and then their changed shape were measured again. Using the difference between the two above measurements, the ratio of shrinkage was calculated. Obtained results were as follows ; 1. Regardless of condensation, the volume of fired specimens were not different significantly between the two subgroups a and b in the same group. 2. The ratios of shrinkage were significantly higher in the groups porcelain built-up was condensed than in the groups not condensed 3. The ratios of shrinkage were in the range of 36.81-27.19% in the groups porcelain built up was condensed and 44.52-37.54% in the other groups not condensed.

• Journal of Technologic Dentistry
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• v.21 no.1
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• pp.15-26
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• 1999

This study was carried out by observing to composition of oxide on the surface of dental porcelain low gold alloy with various Indium additions according to the degassing and analysing the change composition of additional elements In on diffusion behaviors of Porcelain-matal surface. The specimens used were Au-Pd-Ag alloys by small indium addition. These specimens were treated for 10min at $1000^{\circ}C$ in vacuum condition. To investigate the microsturcture of oxidized alloy surface, SEM and EDAX were used, and EPMA were used to investigate the diffusion behaviors of porcelain-metal surface. X-ray diffraction were used to observe the morphological changes in the oxidation zone. The results of this study were obtained as follows ; 1) The hardness of alloy increased with increasing amount of In addition. 2) The formation of oxidation increased with increasing In content after heat treatment. 3) Diffusion of indium elements increased with increasing In content in metal-porcelain surface after firing. 4) The oxidations of alloy surface were mainly $In_2O_3$.

• Journal of the korean academy of Pediatric Dentistry
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• v.35 no.2
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• pp.195-204
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• 2008

Orthodontic brackets often need to be bonded to porcelain such as porcelain fused to metal crowns and porcelain jacket crowns. The purpose of this study was to evaluate the clinical usability of direct bonding system on porcelain teeth by measuring shear bond strength according to various conditions and observing adhesive failure patterns. The specimens, 20 maxillary premolars and 80 porcelain teeth that were produced by duplication of the labial surface of a maxillary first premolar were used and randomly divided into four groups of twenty teeth each. The 5 different preparation procedures tested: (1) application of 37% phosphoric acid on natural teeth, (2) sandblasting on porcelain surfaces, (3) sandblasting and application of 9.6% hydrofluoric acid on porcelain surfaces, (4) sandblasting and application of silane on porcelain surface, (5) sandblasting and application of 9.6% hydrofluoric acid and silane on porcelain surfaces. The metal brackets were bonded with Transbond $XT^{(R)}$ bonding material. The shear bond strength was tested by the micro universal testing machine(Kyung-Sung, Korea) and the amount of residual adhesive on the tooth surface after debonding was examined by stereoscope and assessed with an adhesive remnant index. The results of this study suggest that the direct bonding system on porcelain teeth with sandblasting, HF and porcelain primer is clinically useful.

• The Journal of Korean Academy of Prosthodontics
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• v.34 no.4
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• pp.869-902
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• 1996

Flexion of a metal/ceramic fixed partial denture(EPD) frameworks under function can cause fracture of porcelain or deterioration of the cement seal. This study evaluated the flexion characteristics of three-unit mandibular FPD frameworks, repacing the second pre-molar under compressive load(200g, 400g). Testing was accompished with real-time holographic interferometry, using 6 porcelain fused-to metal frameworks. Tested alloys were non-precious alloy(Heracles, Holland), semi-precious alloy(Degudent U, Germany) and precious alloy(Degudent H, Germany). Changes of the fringe patterns according to the heat treatment(porcelain firing cycle), various loads(200g, 400g), occlusal forms(occlusal porcelain veneering, facial porcelain veneering), various alloys and post-soldering units were compared. Dental study model(Nissan dental products, Inc. D51DP-500A, Japan) and six 3-unit metal/ceramic fixed partial denture frameworks were used as experimental materials. 36 holograms were taken on fixed dental study model by using the 10mW He-Ne laser and real-time holographic interferometry. On the basis of this study, the following conclusions can be drawn : 1. In the frameworks for facial porcelain veneering, the semi-precious alloy framework was least deformed and precious alloy framework, non-precious alloy framework orderly before heat treatment, and the deformation was not shown great difference among three alloys after heat treatment and post-soldering. 2. In the frameworks for occlusal porcelain veneering, the precious alloy framework was greatest deformed and the deformation was not difference between semi-precious alloy framework and non-precious alloy framework before, after heat treatment, and the deformation was not shown great difference among three alloys after post soldering. 3. In the non-precious alloy frameworks for facial porcelain veneering and occlusal porcelain veneering, the deformation was greatly decreased after heat treatment and conversely increased after post-soldering. 4. In the semi-precious alloy framework for facial porcelain veneering, the deformation was not detectable after heat treatment and increased after post-solder. And in the frame-work for occlusal porcelain veneering, the deformation was slightly decreased after heat treatment and increased after post-soldering. 5. In the precious alloy framework for facial porcelain veneering, the deformation was greatly decreased after heat treatment and increased after post-soldering, And in the framework for occlusal porcelain veneering, the deformation was greatly decreased after heat treatment and decreased after post-soldering.

• Journal of dental hygiene science
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• v.9 no.4
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• pp.405-412
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• 2009

The purpose of this study investigated the effect of Au coating on adhesion between porcelain matrix and metal substructure interface. Titanium, Ni-Cr alloy and Co-Cr alloy are well known as proper metal for the dental restorations. The success of a porcelain fused to metal (PFM) restoration depends upon the quality of the porcelain-metal bond. However, adhesion between dental alloys and porcelain is related to diffusion of oxygen during ceramic firing. The excessive oxidized layers make hard adhesion between dental alloy and ceramic. Ni-Cr and Co-Cr specimens were divided into test and a control group and Titanium specimens were divided into three test groups and a control group. Each group had 20 specimens. The adhesion characteristics of porcelain and metal with Au coating layer and without Au coating layer were observed with scanning electron microscopy(SEM). The adhesion was evaluated by a biaxial flexure test and volume fraction of adherent porcelain was determined by SEM/EDS analysis. Result of this study suggest that Au coating layer is effective barrier to diffuse oxide layer completely protect non-precious alloys from oxidation during the porcelain firing. The SEM photomicrographs of cross-section specimens showed a smooth interface between Au coating layer and metals and porcelain which suggested proper chemical bonding, and no gap, porosity were observed. The mode of failure was mainly adhesive for Ti tested specimens, but mixed failures with adhesive and cohesive were observed in Ni-Cr and Co-Cr specimens. The adhesion between non-precious metals and porcelain would not be improved by Au coating agent. However, It is suggested that the continuous study is required further investigation and development.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.11 no.2
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• pp.772-779
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• 2010

This study measured the bonding strength of various porcelain prosthesis materials before and after thermocycling to select prosthesis materials that can maximize beauty and tolerance. To measure bonding strength, various porcelain materials were baked on with-Beryllium metals, non-Beryllium metals 8group and Zirconia 1 group among commercially available base alloys, and measured the bonding strength was measured before and after thermocycling. The findings of this study are as follows: 1) PTM(press-to-metal) porcelain non-Beryllium metal showed the, highteat bonding strength each 73.2MPa, 59.2MPa before and after thermocycling. 2) The porcelain materials baked on non-Beryllium metal showed higher bonding strength before and after thermocycling than those baked on with-Beryllium metal. 3) Zirconia products showed the lowest 38.7MPa bonding strength before and after thermocycling.