• 대한치과보철학회지
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• 제39권6호
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• pp.641-658
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• 2001

All-ceramic restorations have become an attractive alternative to porcelain-fused-to-metal crowns. In-Ceram, and more recently IPS Empress 2 were introduced as a new all-ceramic system for single crowns and 3-unit fixed partial dentures. But their strength and marginal fit are still an important issue. This study evaluated the fracture resistance and marginal fit of three systems of 3 unit all-ceramic bridge fabricated on prepared maxillary anterior resin teeth in vitro. The 3 all-ceramic bridge systems were: (1) a glass-infiltrated, sintered alumina system (In-Ceram) fabricated conventionally, (2) the same system with copy-milled alumina cores (copy-milled In-Ceram), (3) a heat pressed, lithium disilicate reinforced glass-ceramic system (IPS Empress 2). Ten bridges of each system with standardized design of framework were fabricated. All specimens of each system were compressed at $55^{\circ}$ at the palatal surface of pontic until catastrophic fracture occurred. Another seven bridges of each system were fabricated with standard method. All of the bridge-die complexes were embedded in epoxy resin and sectioned buccolingually and mesiodistally. The absolute marginal discrepancy was measured with stereomicroscope at ${\times}50$ power. The following results were obtained: 1. There was no significant difference in the fracture strength among the 3 systems studied. 2. The Weibull modulus of copy-milled In-Ceram was higher than that of In-Ceram and IPS Empress 2 bridges. 3. Copy-milled In-Ceram($112{\mu}m$) exhibited significantly greater marginal discrepancy than In Ceram ($97{\mu}m$), and IPS Empress 2 ($94{\mu}m$) at P=0.05. 4. The lingual surfaces of the ceramic crowns showed smaller marginal discrepancies than mesial and distal points. There was no significant difference between teeth (incisor, canine) at P=0.05. 5. All-ceramic bridges of three systems appeared to exhibit sufficient initial strength and accept able marginal fit values to allow clinical application.

• The Journal of Advanced Prosthodontics
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• 제6권5호
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• pp.415-422
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• 2014

PURPOSE. The purpose of this study was to evaluate and compare the translucency of shaded zirconia allceramic systems. MATERIALS AND METHODS. Translucency of 3 different zirconia all-ceramic systems colored by different techniques was compared with a lithium disilicate glass-ceramic (IPS e.max Press). Square-shaped specimens with 0.5 mm thickness were fabricated from In-Ceram YZ, ICE Zirkon and Katana systems in A1, A2 and A3.5 shades according to Vitapan Classical shade tab (n=11). Specimens were then veneered and glazed with corresponding veneer ceramic recommended by each zirconia system manufacturer and the total thickness was set to 1.5 mm. Translucency measurements were performed with VITA Easyshade Compact spectrophotometer after each stage and translucency parameter was calculated. Data were statistically analyzed with repeated measures ANOVA and Tukey multiple comparison test. RESULTS. The control group was significantly more translucent than the zirconia systems (P<.05). ICE Zirkon cores showed the least translucency; neither In-Ceram YZ nor Katana systems were superior to each other in terms of translucency. Translucency of all specimens was decreased after veneering, and the translucency rankings were changed. CONCLUSION. Coloring technique did not have a significant effect on translucency of zirconia cores. Although zirconia systems were less translucent than lithium disilicate glass ceramic, they had partial translucency and there were translucency differences among the zirconia systems. Chroma affected the translucency of precolored zirconia cores.

• 대한치과보철학회지
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• 제40권5호
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• pp.493-506
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• 2002

Recently as the esthetic concerns about dental prosthesis have been increased, the nonmetallic post and core systems have been introduced clinically to improve the color and the low optical transmittance of conventional casting metal post and core systems. The purpose of this study was to compare and analyze the optical transmittance and the shade changes of all-ceramic crowns with two nonmetallic post and core systems. The experimental groups were classified as follows : Total 27 specimens(9 samples in each group) were evaluated. Group I : Natural teeth as a control group Group II : CosmoPost and $Empress^{(R)}$ core (Ivoclar-Vivadent, Liechtenstein) Group III : $LIGHT-POST^{TM}$ and $LIGHT-CORE^{TM}$ (Bisco, U.S.A.) In all group, all-ceramic crowns were fabricated with the same shade of IPS $Empress^{(R)}$ II (Ivoclar-Vivadent, Liechtenstein) after abutment preparation, and then two kinds of spectrophotometers, UV 3101 PC (Shimadzu, Japan) and CM 503i (Minolta Co. Ltd. Japan), were used to measure the optical transmittance and the color value. The following results were obtained : 1. The optical transmittance of each group without all-ceramic crowns, was siginificantly decreased in order of Group III, I and II (p<0.05). 2. The optical transmittance of each group with all-ceramic crowns cemented, were siginificantly decreased in order of Group I, II and III (p<0.05). 3. In comparison with the shade of all-ceramic crowns, there were no significant differences between groups regardless of the cementation. 4. In comparison with the shade changes in each group after the cementation of all-ceramic crowns, there were no significant differences between groups. From the above results, it is thought that the selection among materials used in this study doesn't influence greatly the esthetic restoration, because the differences of optical transmittance were so small that those were clinically insignificant.

• 대한치과보철학회지
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• 제42권1호
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• pp.49-57
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• 2004

Statement of problem : The increased awareness of esthetics in dentistry has brought the esthetic consideration in prosthetic restorations . Dental ceramics offer better esthetics for use of prosthetic restorations. Unfortunately, dental ceramic materials are not always the most suitable candidate materials since their inherently brittle nature. In recent years, basic research in ceramic science has led to the recognition or several approaches to strengthen and to enhance esthetics of ceramics. Several all ceramic systems use ceramic core and porcelain build up structures . Ceramic cores influence to strength of all ceramic crowns . So the strength of ceramic cores is important to all ceramic crowns. Purpose : The purpose of this study is to estimate the flexural strength of ceramic cores in some all ceramic systems. Material and method : A biaxial flexure test was conducted on three groups(Cergo, Empress 2, In-Ceram). Each group consisted of 30 discs of nearly identical dimension with a 0.5mm, 1.0mm, 1.5mm thickness and 12mm in diameter. The fracture load was recorded by Instron. Analysis of valiance(ANOVA) and Tukey's tests were performed using SAS statistical software. Results : 1.5mm thickness of specimens were significantly stronger than 0.5mm and 1.0mm thickness of specimens in Cergo and In-Ceram. But each sepecimen group of Empress 2 was no significantly strength by thickness. In order of In-Ceram, Empress 2 and Cergo has significantly stronger strength in the same thickness. Conclusion : In-Ceram is the strongest ceramic material in 3 materials. All the materials can be used according to the required characters.

• The Journal of Advanced Prosthodontics
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• 제10권4호
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• pp.315-320
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• 2018

PURPOSE. Fractures, occlusal adjustments, or marginal corrections after removing excess composite cements result in rough surfaces of all-ceramic FPDs. These have to be polished to prevent damage of the surrounding tissues. The aim of this study was to evaluate the roughness of zirconia, silicate-ceramic, and composite after polish with different systems for intraoral use. MATERIALS AND METHODS. Each set of 50 plates was made of zirconia, silicate-ceramic, and composite. All plates were ground automatically and were divided into 15 groups according to the treatment. Groups Zgrit, Sgrit, and Cgrit received no further treatment. Groups Zlab and Slab received glaze-baking, and group Clab was polished with a polishing device. In the experimental groups Zv, Sv, Cv, Zk, Sk, Ck, Zb, Sb, and Cb, the specimens were polished with ceramic-polishing systems "v", "k", and "b" for intraoral use. Roughness was measured using profilometry. Statistical analysis was performed with ANOVA and $Scheff{\acute{e}}$-procedure with the level of significance set at P=.05. RESULTS. All systems reduced the roughness of zirconia, but the differences from the controls Zgrit and Zlab were not statistically significant (P>.907). Roughness of silicate ceramic was reduced only in group Sv, but it did not differ significantly from both controls (P>.580). Groups Cv, Ck, and Cb had a significantly rougher surface than that of group Clab (P<.003). CONCLUSION. Ceramic materials can be polished with the tested systems. Polishing of interface areas between ceramic and composite material should be performed with polishing systems for zirconia first, followed by systems for veneering materials and for composite materials.

• 대한심미치과학회지
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• 제9권1호
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• pp.82-90
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• 2000

치과 재료분야는 그 동안 많은 발전을 해왔음에도 불구하고 자연치아의 색조 재현 및, 인접 치와의 조화에 따른 심미성과 지대치와의 적합성 등에 많은 문제가 야기되어왔다. 기존 all ceramic 은 단관 제작 시 심미적인 요구가 다소 해결되었으나 bridge work 에 있어서는 그 강도 및, 작업의 효율성은 여전히 문제시되어 오고 있다. 최근 기존 Inceram의 단점을 보안한 Celay Inceram system은 spinell, alumina, zirconia Blanks를 이용하여 더욱더 기능적인 자연스러움으로 접근되어진다. 이에 그 system의 alumina blank를 이용한 bridge work 의 임상 증례를 살펴보기로 한다.

• The Journal of Advanced Prosthodontics
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• 제3권2호
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• pp.57-62
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• 2011

MATERIALS AND METHODS. Ceramics have a long history in fixed prosthodontics for achieving optimal esthetics and various materials have been used to improve ceramic core strength. However, there is a lack of information on how color is affected by fabrication procedure. The purpose of this study was to evaluate the effects of various dentin ceramic thicknesses and repeated firings on the color of zirconium oxide all-ceramic system (LavaTM) fabricated using CAD/CAM technology. MATERIALS AND METHODS. Thirty disc-shaped cores, 12 mm in diameter with a 1 mm thickness were fabricated from zirconium oxide based all ceramic systems ($Lava^{TM}$, 3M ESPE, St Paul, MN, USA) and divided into three groups (n = 10) according to veneering with dentin ceramic thicknesses: as 0.5, 1, or 1.5 mm. Repeated firings (3, 5, 7, or 9) were performed, and the color of the specimens was compared with the color after the initial firing. Color differences among ceramic specimens were measured using a spectrophotometer (VITA Easyshade, VITA Zahnfabrik, Bad $S{\ddot{a}}ckingen$, Germany) and data were expressed in CIELAB system coordinates. A repeated measures ANOVA and Bonferroni post hoc test were used to analyze the data (n = 10, ${\alpha}=.05$). RESULTS. $L^{\ast}a^{\ast}b^{\ast}$ values of the ceramic systems were affected by the number of firings (3, 5, 7, or 9 firings) (P<.001) and ceramic thickness (0.5, 1, or 1.5 mm) (P<.001). Significant interactions were present in $L^{\ast}a^{\ast}b^{\ast}$ values between the number of firings and ceramic thickness (P<.001). An increase in number of firings resulted in significant increase in $L^{\ast}$ values for both 0.5 mm and 1.5 mm thicknesses (P<.01, P=.013); however it decreased for 1 mm thickness (P<.01). The $a^{\ast}$ values increased for 1 mm and 1.5 mm thicknesses (P<.01), while it decreased for 0.5 mm specimens. The $b^{\ast}$ values increased significantly for all thicknesses (P<.01, P=.022). As the dentin ceramic thickness increased, significant reductions in $L^{\ast}$ values (P<.01) were recorded. There were significant increases in both $a^{\ast}$ and $b^{\ast}$ values (P<.01) as the dentin ceramic thickness increased. CONCLUSION. The number of firings and dentin ceramic thickness have a definite effect on the final color of all ceramic system tested. The mean ${\Delta}E$ value increased as the dentin ceramic thicknesses increased for zirconium-oxide based all ceramic specimens tested. However, the mean ${\Delta}E$ values were less than 3.7${\Delta}E$ units which is rated as a match in the oral environment.

• 대한치과보철학회지
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• 제42권5호
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• pp.514-523
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• 2004

Statement of problem: All-ceramic restorations have been advocated for superior esthetics. Various post and core systems have been used to improve the strength of damaged teeth, but it is unclear whether they affect the final shade of finished all-ceramic restorations. Purpose: The influence of different types of post and core systems on light transmission through all-ceramic crowns was assessed by spectrophotometric analysis. Also the masking effect of different thickness of ceramic ingot was evaluated. Material and Methods : Forty-five sample disks (15mm in diameter) at several thickness(1.0, 1.5, 2.0mm) and value(shade 100, 200, 300) were made in heat pressed ceramic(IPS-Empress). Background specimens simulating gold-alloy cast posts(Type III casting gold alloy), metal posts(Ni-Cr casting alloy) and ceramic posts(CosmoPost) were fabrica-ted. Resin composite(Z250, A3 shade) was used as a tooth substrate reference. For each combination, the change in color was measured with a spectrophotometer. Readings were performed for 2 conditions (1) ability of ceramic to mask the core in relation to its thickness(1.0, 1.5, or 2.0mm) ; (2) influence of post and core types on the final color of the ceramic. Data were recorded according to the CIE $L^*a^*b^*$ systems and color difference($\Delta$E) was calculated. Results: 100 shade ingot: when ceramic thickness was 1.0mm, $\Delta$E value for ceramic post larger than 1 but $\Delta$E value for metal and gold post was larger than 2. For ceramic thickness of 1.5mm, only $\Delta$E value for metal was larger than 2, and the other samples' $\Delta$E value was smaller than 2. For ceramic thickness of 2.0mm, $\Delta$E values for all specimens was smaller than 2. 200 shade ingot: when ceramic thickness was 1.0mm, $\Delta$E value for ceramic post was smaller than 1 but $\Delta$E value for metal and gold post was larger than 2. For ceramic thickness of 1.5 mm, only the $\Delta$E value for metal was larger than 2, and the other samples' $\Delta$E value was smaller than 2. For ceramic thickness of 2.0mm, $\Delta$E values for all specimens was smaller than 1. 300 shade ingot: when ceramic thickness was 1.0mm, only $\Delta$E value for metal was larger than 2 and the other samples' $\Delta$E value was smaller than 2. For ceramic thickness of 1.5mm, $\Delta$E values for all specimens was smaller than 1. For ceramic thickness of 2.0mm, $\Delta$E values for all specimens was smaller than 1. Conclusion: The final esthetic result of the IPS-Empress glass-ceramic restoration was not affected by the presence of different core materials when the thickness was more than 2.0 mm. When ceramic thickness decreases to 1.5mm, it is advised to take the substrate aspects into consideration. If the ceramic thickness is less than 1.0mm, using the tooth color matched substrate is strongly recommended.

• 대한치과보철학회지
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• 제39권2호
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• pp.197-207
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• 2001

Development of new ceramics and esthetic needs of patients increase the use of all ceramic restorations. Fractured teeth often need metal post and core as foundation for final restoration. When all ceramic restorations are planned, metal post and core may lead to compromised esthetics because of opacity and gray color of metal post and core. Many techniques have been proposed to solve this problem such as application of an opaque porcelain to the metal core or all ceramic post and core. This study was performed to evaluate effect on color of Empress 2 crown according to various post systems. Color was evaluated by the CIE $L^*a^*b^*$ systems and measured by spectrophotometer (Model CM-3500, Minolta, Japan). Specimens were divided into 4 groups as follows Group 1 : gold cast post specimen + Empress 2 crown specimen Group 2 : application of an opaque porcelain to gold cast post specimen + Empress 2 crown specimen Group 3 : cosmopost specimen + Empress 2 crown specimen Group 4 : In-ceram post specimen + Empress 2 crown specimen. The results obtained as follows, 1. $L^*$ Values showed that group 2, 3, 4 were higher than group 1 with significant difference and group 2, 3, 4 were not significantly different. 2. $a^*$ Values and $b^*$ values also showed that group 2. 3, 4 were higher than group 1 with significant difference and group 2, 3, 4 were not significantly different. 3. ${\Delta}E^* ab$ Values showed that ${\Delta}E^* ab$ 3 was the highest value and ${\Delta}E^* ab$ 5 was the lowest value.

• 대한치과기공학회지
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• 제42권4호
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• pp.307-312
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• 2020

Application of ceramic materials for fabrication of dental restoration materials has been a focus of interest in the field of esthetic dentistry. The ceramic materials of choice are glass ceramics, spinel, alumina, and zirconia. The development of yttrium tetragonal zirconia polycrystal (YTZP)-based systems is a recent addition to all-ceramic systems that have high strength and are used for crowns and fixed partial dentures. Computer-aided design/computer-aided manufacturing (CAD/CAM)-produced, YTZP-based systems are popular with respect to their esthetic appeal for use in stress-bearing regions. The highly esthetic nature of zirconia and its superior physical properties and biocompatibility have enabled the development of restorative systems that meet the demands of today's patients. Many in vitro trials have been performed on the use of zirconia; however, relatively fewer long-term clinical studies have been published on this subject. The use of zirconia frameworks for long-span fixed partial dentures is currently being evaluated; in the future, more in vivo research and long-term clinical studies are required to provide scientific evidence for drawing solid guidelines. Further clinical and in vitro studies are required to obtain data regarding the long-term clinical use of zirconia-based restorations.