• 대한치과기공학회지
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• 제21권1호
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• pp.115-121
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• 1999

This investing was carried out to evaluate the alteration of stress distribution on teeth and esthetic crowns. Analyzing the stress distribution by the two-dimensional finite element methods, a model of lower 1st molar according to the porcelain fused metal crown an the porcelain fused glass ceramic core crown and the all glass ceramic crown. 1. The pattern of stress distribution showed no apparent differences. 2. The greatest von Mises values were concentrated around the central fossa of all esthetic crowns. The greatest Maximum principle value were concentrated around the interface between the base of esthetic crown and the abutment tooth. It was found that the apatite glass ceramic could be applicable for use in dental crown prosthesis.

• 치위생과학회지
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• 제18권1호
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• pp.42-49
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• 2018

The computer-aided design/computer-aided manufacturing (CAD/CAM) system was introduced to shorten the production time of all-ceramic restorations and the number of patient visits. Among these types of ceramic for dental CAD/CAM, they have been processed into inlay, onlay, and crown shapes using leucite-reinforced glass-ceramics to improve strength. The purpose of this study was to observe the mechanical properties and microstructure of leucite-reinforced glass-ceramics for dental CAD/CAM. Two types of leucite-reinforced glass-ceramic blocks (IPS Empress CAD, Rosetta BM) were prepared with diameter of 13 mm and thickness of 1 mm. Biaxial flexural testing was conducted using a piston-on-three-ball method at a crosshead speed of 0.5 mm/min. Weibull statistics were used for the analysis of biaxial flexural strength. Fracture toughness was obtained using an indentation fracture method. Specimens were observed by field emission scanning electron microscopy to examine the microstructure of the leucite crystalline phase after acid etching with 0.5% hydrofluoric acid aqueous solution for 1 minute. The results of strength testing showed that IPS Empress CAD had a mean value of $158.1{\pm}8.6MPa$ and Rosetta BM of $172.3{\pm}8.3MPa$. The fracture toughness results showed that IPS Empress CAD had a mean value of $1.28{\pm}0.19MPa{\cdot}m^{1/2}$ and Rosetta BM of $1.38{\pm}0.12MPa{\cdot}m^{1/2}$. The Rosetta BM sample exhibited higher strength and fracture toughness. Moreover, the crystalline phase size and ratio were increased in the Rosetta BM sample. The above results are expected to elucidate the basic mechanical properties and crystal structure characteristics of IPS Empress CAD and Rosetta BM. Additionally, they will help develop leucite-reinforced glass-ceramic materials for CAD/CAM.

• 대한치과기공학회지
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• 제39권2호
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• pp.101-107
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• 2017

Purpose: The purpose of this study was to compare the shear bond strength of the metal-heat pressed glass ceramic bilayer structure. Methods: Metal framework specimens were prepared and surface is spreaded opaque(IPS InLine system opaque, IvoclarVivadent, Liechtenstein). There were 10 specimens for each bilayer dental ceramic group. The first group was porcelain fused metal, Press on metal IPS Inline press group, and press on metal HASS prototype group. Specimens measured for the shear bond strength on Schwickerath test by Instron universal testing machine(Instron3345, Instron Corp., USA). Mean average bond strength values of each specimen group were analyzed using a one-way ANOVA analysis of variance Saphiro-wilk's test. Statistical analysis were performed using IBM SPSS 23.0(IBM Co., Armonk, USA) Results: $RMS{\pm}SD$ The highest mean average HASS POM showed a bond strength value ($47.55{\pm}12.80Mpa$). The lowest mean average values Porcelain fused metal ($33.30{\pm}2.00Mpa$). Independent t-test was conduct to analysis the significant difference (p<0.05) (Table 3). Conclusion: Three kinds of Metal/ glass bilayer dental ceramics bond strength were clinical acceptability. Especially, as lithium disilicate containing represents higher bond strength.

• 한국치위생학회지
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• 제18권6호
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• pp.1037-1045
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• 2018

Objectives: The purpose of this study was to evaluation the effect of translucency on CAD/CAM ceramic according to different core/veneer thicknesses. Methods: A total of 42 samples from 2 groups of 7 ceramic cores, each with 3 thickness values (0.8, 1.0, 1.2 mm) were manufactured. The veneers were also manufactured in 3 thicknesses (0.3, 0.5, 0.7 mm). The group names were based on the name of the ceramic core (IPS e.Max CAD; LD, and IPS Empress CAD; LR). The associated number was determined by the combined thickness of the core and veneer: 1 = (0.8 + 0.7); 2 = (1.0 + 0.5); 3 = (1.2 + 0.3). The translucency was measured using a spectrophotometer and defined via the contrast ratio (CR) and translucency parameter (TP). Two-way ANOVA was performed to compare the 2 groups (material and thickness). Results: As the core thickness increased, the TP value also increased, and the CR value (for LR group) decreased. The results of 2-way ANOVA demonstrated that the thicknesses of different core/veneer combinations significantly affected the translucency (p<0.05). Conclusions: The different core and veneer thicknesses affected the translucency of CAD/CAM ceramic.

• 대한치과기공학회지
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• 제42권3호
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• pp.228-233
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• 2020

Purpose: This study aimed to assess and compare the marginal fit of ceramic-based hybrid resin restoration (HYB) and zirconia restoration (ZIR) for dental computer-aided design/computer-aided manufacturing systems. Methods: A stainless steel master model was produced. The impression was first made with silicone, and then stone working models were produced. A total of twenty restorations were fabricated with two different materials: ZIR and HYB. The silicone film thickness of the marginal gap was measured using a digital microscope; digital photos were taken at a magnification of ×160, and then analyzed using a measurement software. The values of the result were evaluated with the independent-sample t-test (α=0.05). All statistical analyses were performed with a statistical software. Results: The mean values for the marginal gap was 37.14±2.96 ㎛ for HYB, compared with 40.37±5.26 ㎛ for ZIR. No significant difference was found between ZIR and HYB (p=0.107). Conclusion: As a result, the marginal fit of the restoration fabricated using the hybrid resin was better than that of the restoration fabricated using zirconia. Also, the marginal fit of all groups was below the clinical acceptable range of 120 ㎛. Thus, HYB for dental CAD/CAM system in this study is expected to be suitable for clinical use in dentistry.

• 대한치과기공학회지
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• 제31권4호
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• pp.15-23
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• 2009

The aim of this study was to evaluate the bond strength of using a Au bonding agent applied on cp-Ti and nonprecious metal-gold-ceramic system. Metallic frameworks(diameter: 5mm, height: 20mm)(N=56, n=7per group) cast in Ni-Cr alloy, Co-Cr alloy and cp-Ti were obtained using acrylic templates and airborne particle abraded with $110{\mu}m$ aluminum oxide. Au bonding agent was applied on wash opaque firing as intermediate layer. SEM and SEM/EDS line profile were performed on the cutting the cross-section of the metal substrate-porcelain with intermediate Au coating. Groups were tested using shear bond strength(SBS) testing at 0.5mm/min. The mean SBS values for the ceramic-Au layer-metal combination were significantly higher than those ceramic-metal combination. While ceramic-Au layer-cp-Ti combinations failed to increase bond strength instead of using a titanium bonding porcelain. The appication of using Au intermediate layer significantly improve the bond strength combination with metal-ceramic system.

• 대한치과기공학회지
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• 제24권1호
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• pp.33-41
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• 2002

In dental prosthetics, the application of metal-ceramic restorations has steadily increased since their introduction. This is due to excellent esthetics in combination with high mechanical stability. In order to optimum bond strength between metal and ceramics, controlled oxidation of metal substructure is essential factor. Beryllium containing and beryllium free Ni-Cr alloys for metal-ceramic restorations were evaluated for the metal-ceramic bond strength by changing heat treatment for oxide formation. A mechanical three-point bending test was employed to evaluate the interfacial bond strength of metal-ceramic. In each metal, plate type specimens were used for mechanical three-point bending test. With Ni-Cr alloys for metal ceramics, mechanical three-point bending test showed that double degassing was more available preheat treatment method than another. It was found that beryllium containing Ni-Cr alloys are more effective than beryllium-free for metal-ceramic bond strength.

• 대한치과의사협회지
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• 제51권11호
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• pp.595-603
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• 2013

The requirements for the successful treatment of all-ceramic restorations are not so different from the ones of conventional restorations. "The provisional restoration followed by an adequate tooth reduction and the accurately fitting prostheses with corresponding to final impression" can be the examples of them. Nevertheless, the one which all-ceramic restorations are distinguished from conventional restorations is the additional procedure of so called "bonding". In addition to the application of resin cement between "inner surface of restoration and outer surface of abutment", bonding technology can be also applied to the treatment process of "Post and Core" in particular if the abutments are non-vital teeth. Core build-up for all-ceramic crown is conducted with fiber post and tooth colored composite by considering the properties of the restorations transmitting light. We know well that a vital abutment is easier than a non-vital one to get the targeted goals for clinical success in connection with esthetics and structure. The creation of "Post and Core" with bonding technique is a decisive factor for a long-term success if the abutment is non-vital tooth with dentinal collapse. I would like to share my clinical experience about "post & core build-up and all-ceramic restoration bonding" out of several success strategies of all-ceramic crown with this presentation.

• 대한치과의사협회지
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• 제56권3호
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• pp.167-174
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• 2018

The development of dental materials has widened the scope of materials by changes in processing methods. CAD/CAM processing enables the use of zirconia as a dental material. Recent esthetic materials development has been made. For aesthetic purposes, a block for CAD/CAM processing by mixing polymer and ceramic materials are fabricated. However there is no guideline of how these materials should be used in actual clinical practice. Mechanical properties, wear and clinical studies were reviewed.

• Restorative Dentistry and Endodontics
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• 제40권1호
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• pp.1-13
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• 2015

Advancements in bio-ceramic technology has revolutionised endodontic material science by enhancing the treatment outcome for patients. This class of dental materials conciliates excellent biocompatibility with high osseoconductivity that render them ideal for endodontic care. Few recently introduced bio-ceramic materials have shown considerable clinical success over their early generations in terms of good handling characteristics. Calcium enriched mixture (CEM) cement, Endosequence sealer, and root repair materials, Biodentine and BioAggregate are the new classes of bio-ceramic materials. The aim of this literature review is to present investigations regarding properties and applications of CEM cement in endodontics. A review of the existing literature was performed by using electronic and hand searching methods for CEM cement from January 2006 to December 2013. CEM cement has a different chemical composition from that of mineral trioxide aggregate (MTA) but has similar clinical applications. It combines the biocompatibility of MTA with more efficient characteristics, such as significantly shorter setting time, good handling characteristics, no staining of tooth and effective seal against bacterial leakage.