• Journal of Technologic Dentistry
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• v.31 no.1
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• pp.63-74
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• 2009

Partial or complete prosthesis is needed when teeth are lost due to various kinds of reason. Artificial teeth recover occlusion instead of natural teeth. Artificial teeth are required of esthetics, fragile resistance and abrasive resistance. Artificial tooth is made of acrylic resin or porcelain. Nowadays, acrylic resin artificial teeth are mainly used. Acrylic resin teeth are occluded with natural teeth, gold alloy, Ni-Cr alloy or porcelain etc. Acrylic resin teeth have similar translucency, gloss of natural teeth. And it has good chemical bond with denture base material, but it has low wear resistance. The aim of this study is to compare wear resistance among several denture teeth(Endura, SR-orthosit-PE, Planustar) and between artificial resin denture teeth and opposing 3 restorative materials(gold, Ni-Cr alloy, porcelain). Wear tests were conducted with a rotating wear testing apparatus(pin-on-disk type wear tester) under conditions of rpm 180, 75 minutes and constant loading of 50N. The upper part was the cusp of maxillary first molar and the lower part was a disk type restorative materials. To make similar oral environment, water was supplied continually. The acrylic resin teeth wear was determined by weighing the cusp each 5 minutes during 75 minutes test. Vicker's hardness tester was used to evaluate the surface hardness of test specimens. The SEM was used to evaluate the wear surfaces. The results were as follows: 1. Wear rates of acrylic resin teeth opposing to the restorative materials were high in order of Porcelain, Gold, Ni-Cr alloy (p<.05). 2. Wear resistance rate opposing to the Porcelain disk, was shown in order of Endura, SR-orthosit-PE, Planustar. The wear rate of opposing to porcelain disk was above two times more than that of other groups (p<.05). 3. Wear resistance rates opposing to the Gold, Ni-Cr alloy disk, was shown in order of Endura, SR-orthosit-PE, Planustar (p<.05). 4. A degree of the surface hardness is directly proportional to the degree of wear resistance. There are statistically significant differences between each groups (p<.05).

• 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.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2003.07a
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• pp.537-540
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• 2003

This study was investigated to fabricate the porcelain materials with high magnetic characteristics. The high characteristics of the magnetic porcelain materials were achieved at the following conditions; powder sizes of isotropic Sr-ferrites with $1{\sim}2\;mm$ and magnetic powder infraction of 30 wt%. The magnetic tea cups with 3-mm-thick at the optimum conditions indicated the high magnetic characteristics such as the surface flux density of 178 G, the remanent flux density of 240 G, and the intrinsic coercivity of 3910 Oe.

• Korean Journal of Materials Research
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• v.29 no.3
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• pp.137-142
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• 2019

The microstructure, phase, and mechanical properties of three aged porcelain insulators which were manufactured in different years (1973, 1995 and 2008) and which were used in the field for different amounts of time, were investigated. With X-ray 3D computed tomography (CT), defects with ~mm size can be detected without destroying the aged insulators. Defects of small specimens, which are cut from the aged insulators and polished, are analyzed with optical and scanning electron microscopy (OM and SEM), and defects of um size are detected by OM and SEM. The number and size of defects in all the aged insulators are similar. Porcelain insulators manufactured in 1973 contain more $SiO_2$ (quartz and cristobalite) than those manufactured in 2008. Those manufactured in 2008 contain more $Al_2O_3$ than those manufactured earlier. The Vickers hardness of the insulator manufactured in 1973 has the lowest value. The formation of the cristobalite ($SiO_2$) in the insulator manufactured in 1973 which can come from the phase transformation of quartz can cause stress in the insulator by formation of microcracks, which can lead to the low hardness of the insulator.

• The Journal of Advanced Prosthodontics
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• v.5 no.4
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• pp.423-427
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• 2013

PURPOSE. This study evaluated the bond strength between porcelain denture teeth (Bioblend 43D) and four different polymerized denture resins (Lucitone 199, Palapress, Acron MC, Triad) with and without a bonding agent and after four different types of surface treatment (polished, HF etched, sandblasted, air-abraded). MATERIALS AND METHODS. Central incisor porcelain denture teeth were divided into 32 groups of 5 each. Tensile bond strength (MPa) was determined using a testing machine at crosshead speed of 0.5 mm/min. Mean and standard deviation are listed. Data were analyzed by two-way ANOVA. Means were compared by Tukey-Kramer intervals at 0.05 significance level. RESULTS. All surface treatment increased bond strength compared to polished surface and the highest bond strength was found with Palapress resin with etched porcelain surface (8.1 MPa). Bonding agent improved the bond strength of all denture resins to porcelain teeth. Superior bonding was found with Palapress and air-abraded porcelain (39 MPa). CONCLUSION. Resins with different curing methods affect the bond strength of porcelain teeth to denture bases. Superior bonding was found with auto-polymerized resin (Palapress). Application of ceramic primer and bonding agent to porcelain teeth with and without surface treatment will improve the bond strength of all denture resins to porcelain teeth.

• Journal of Technologic Dentistry
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• v.31 no.1
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• pp.23-36
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• 2009

The goal of esthetic restoration is to achieve morphologic, optical, and biologic acceptance. Creation of a natural looking ceramic restoration, which blends harmoniously with surrounding dentition, is not always achieved. A successful color match is an important aspect of any esthetic dental restoration. Since natural enamel has inherent translucency, it is important that ceramic restorations reproduce the translucency and color of the natural teeth. However, the final color match of porcelain crowns to adjacent natural dentition remains some problem. Difficulties related to color matching arise from the structural differences that exist between metal ceramic crowns and natural teeth, the limited range of available ceramic shades, inadequate shade guides, different types of metal alloys, repeated firing, the condensation technique, and varying compositions of ceramic materials. Many factors contribute to the esthetic success of dental restoration: optical properties such as color and its elements of hue, value, and chroma; translucency and opacity; light transmission and scattering; and metamerism and fluorescence. The purpose of this study was to determine the color changes of metal-ceramic system with different veneering porcelain powder after repeated firing. The objectives of this in vitro study were to measure the lightness($L^*$), chromaticity($a^*$), chromaticity($b^*$), chroma($C^*$), hue(h), reflectance(%), color difference(${\Delta}E$). The following conclusions were obtained: 1. An increase in the number of firings resulted in decrease in lightness($L^*$) but increase in chromacticity($a^*$) with all porcelain. After the second sintering resulted in decrease in chromacticity($b^*$) with opaque-dentin porcelain and dentin porcelain but in increase with enamel porcelain and translucency porcelain. And after the second sintering resulted in decrease in chroma($C^*$) with opaque-dentin porcelain and dentin porcelain, but on the whole side in decrease with enamel porcelain and translucency porcelain. 2. After the second firing, a increase in the number of firings resulted in decrease reflectance(%) in all wavelength. 3. There were noticeable color differences(${\Delta}E$) between first sintering and multiple firings(dentin porcelain: 5.29~8.15, opaque-dentin porcelain: 4.83~8.2, enamel porcelain: 8.93~13.15, translucency porcelain: 9.37~12.91), but the color difference(${\Delta}E$) after second sintering were down to 4.87 in all porcelain. 4. Given the NBS Criteria, a 'trace' was not found this study but a 'slight' was found 2-3, 3-5 in dentin porcelain, 2-3 in opaque-dentin porcelain, 3-5, 5-10 in enamel porcelain and translucency porcelain, a 'noticeable' was 2-5, 3-10, 5-10 in dentin porcelain and opaque-dentin porcelain, 2-3, 2-5, 3-10 in enamel porcelain 2-3, 3-10 in translucency porcelain, an 'appreciable' was 1-2, 1-3, 2-10 in dentin porcelain 1-2, 1-3, 2-10, 3-10 in opaque-dentin porcelain, 2-10 in enamel porcelain, 2-5, 2-10 in translucency porcelain, a 'much' was 1-5, 1-10 in dentin porcelain and opaque-dentin porcelain, 1-2, 1-3, 1-5 in enamel porcelain 1-2, 1-3, 1-5, 1-10 in translucency porcelain, a 'very much' was 1-10 in enamel porcelain.

• The Journal of Korean Academy of Prosthodontics
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• v.37 no.1
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• pp.51-70
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• 1999

Dental porcelain is one of the materials of choice for restoration where esthetics is of concern, but has a considerable potentials of wear. The wear of enamel is variable when opposed by different porcelain systems and surface conditions, and the exposed dentine and opaque porcelain due to clinical failure is expected to have high potentials of wear. The purpose of this study was to investigate the wear effects of self-glazed, polished incisal porcelain. polished dentine and opaque porcelain against human enamel in the laboratory by use of a pin-on-disk type wear tester. 4 types of dental porcelain($Vita-{\Omega}$, Ceramco-II, Vintage powder $Vita-{\alpha}$ of In-Ceram system) and type IV gold alloy as cotrol group were used for test specimens. Intact buccal cusps of maxillary premolar were used for enamel specimens, and the cusp converged to a point and was devoid of visible abrasion, caries, decalcification. The upper part was the cusp of a maxillary premolar and the lower part was a porcelain specimen. The enamel wear was deter-mined by weighing the cusp before and after each test. Surface profilometer was used to quantitate wear of the porcelain specimens. Vicker's hardness tester was used to evaluate the surface hardness of test specimens. The SEM was used to evaluate the wear surfaces. The results were as follows : 1 Self-glazed porcelain produced more enamel wear than polished porcelain, especially the enamel wear of $Vita-{\alpha}$ self-glazed porcelain was 3.2 times more than that of other groups. 2. Opaque porcelain produced least porcelain wear, $Vita-{\alpha}$ self-glazed porcelain produce greatest porcelain wear, but there was no statistically significant difference between the groups(p>0.05). 3. The enamel wear of dentine porcelain was 3.8 times more than that of polished inisal porcelain(p<0.05), and the enamel wear of opaque porcelain was 1.9 times more than that of polished inisal porcelain, but there was no statistically significant difference between the groups(p>0.05) 4. Overglazed porcelain produced less enamel wear than self-glazed porcelain, and more enamel wear than polished porcelain, but there was no statistically significant difference between the groups(P>0.05). 5. The hardness number of $Vita-{\Omega}$ dentine and Ceramco-II opaque porcelain was larger, but that of Vintage dentine and $Vita-{\alpha}$ self-glazed porcelain was similar to other groups. 6. Examination of SEM photographs revealed that overglazed porcelain had smoother surface than self-glazed porcelain, and self-glazed porcelain had smoother surface than polished porcelain. Much polishing scratches and larger porosities were observed on the opaque porcelain specimen, and much polishing scratchess and small porosities were observed on the dentine porcelain specimen.

• Corrosion Science and Technology
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• v.15 no.3
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• pp.141-146
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• 2016

By using Ni-Cr and Co-Cr alloys, porcelain fused to metal (PFM) samples were prepared to examine the interface and the surface corrosion behavior. The potentiodynamic polarization analysis showed that the corrosion current density of Co-Cr alloy ($1.61{\times}10^{-6}A/cm^2$) was three times lower than that of Ni-Cr alloy ($4.83{\times}10^{-6}A/cm^2$) at room temperature. A dental prosthesis consisting of the porcelain fused to Ni-Cr alloy extracted from a patient after approximately four years of usage was examined to assess its resistance to corrosion. OM and SEM images of the metal part revealed a typical pitting corrosion. As compared to porcelain fused to Ni-Cr alloy having a thick layer (${\sim}10{\mu}m$) of oxide at the interface, a relatively thin oxide layer (less than $5{\mu}m$) was formed on Co-Cr alloy, indicating that the interface between Co-Cr alloy and porcelain may have a better adhesion strength than the interface between Ni-Cr alloy and porcelain.

• The Journal of Korean Academy of Prosthodontics
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• v.37 no.3
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• pp.313-327
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• 1999

The aim of this study was to compare wear resistance of resin denture teeth opposing various restorative materials. The wear resistance of conventional acrylic resin teeth(Trubyte Biotone) and three high-strength resin teeth(Bioform IPN, Endura, SR-Orthosit-PE) opposing different restorative materials(gold alloys, dental porcelain, composite resin) was compared. Wear tests were conducted with a sliding-induced wear testing apparatus which applied 100,000 strokes to the specimen in a mesio-distal direction under conditions of 100 stroke/min and constant loading of 1Kgf/tooth. Wear resistance of the resin denture teeth was evaluated by the following criteria : 1) wear depth, 2) weight loss, and 3) SEM observation. Results were as follows. 1. When opposed to gold alloys and composite resin, high-strength resin teeth showed superior wear resistance compared to acrylic resin teeth. But, in cases opposing dental porcelain, differences between the wear of the high-strength and acrylic resin teeth were not statistically significant (p<0.05). 2. When comparing wear resistance among high-strength resin teeth, opposing gold alloys, Endura was slightly more resistant and while in cases opposing dental porcelain, SR-Orthosit-PE was showed to be slightly resistant(p<0.05). 3. The wear of high-strength resin teeth was greater by 5 to 7 times when opposing porcelain and 2 to 3 times when opposing composite resin compared to gold alloys(p<0.05). 4. SEM observations of the wear surface showed that wear of resin teeth opposing gold alloys is a fatigue type of wear and wear of resin teeth opposing dental porcelain is fatigue and abrasion type of wear. Trubyte Biotone showed more severe fatigue type of wear than high-strength resin teeth. In conclusion, the use of dental porcelain should seriously be considered as restorative material in cases opposing resin denture teeth and improvement seems to be needed on resin teeth in the areas of wear resistance.

• 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.