• 대한치과보철학회지
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• 제44권3호
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• pp.275-283
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• 2006

Statement of problem. There have been many studies about marginal discrepancy of single restorations made by various systems and materials. However most of the statistical inferences are not definite because of sample size, measurement number, measuring instruments, etc, and there have been few studies about the marginal fit of the Digident CAD/ CAM zirconia ceramic crowns. Purpose. The purpose of this study was to compare the marginal fit of the anterior single restorations made by using the Digident CAD / CAM zirconia ceramic crowns with metal-ceramic restorations and to obtain more accurate information by using a large enough sample size and by making sufficient measurements per specimen. Material and Methods. The crowns were made from one extracted maxillary central incisor pre-pared with a 1mm shoulder margin and $6^{\circ}$ taper walls by milling machine. The in vitro marginal discrepancies of the digident CAD / CAM zirconia ceramic crowns and control groups(metal ceramic crowns) were evaluated and compared. Twenty crowns per each system were fabricated. Measurements of a crown were recorded at 50 points that were randomly selected for marginal gap evaluation. Parametric statistical analysis was performed for the results. Conclusion. Within the limitations of this in vitro study, the following conclusions were drawn: 1. Mean gap dimensions and standard deviations at the marginal opening for maxillary incisal crowns were $88{\pm}10{\mu}m$ for the control (metal-ceramic crowns), $92{\pm}4{\mu}m$ for Digident CAD / CAM zirconia ceramic crowns. 2. Marginal gap between Digident CAD / CAM zirconia ceramic crowns and metal ceramic crowns did not show significant difference (P>.05). 3. The Digident CAD/ CAM zirconia ceramic crowns and metal ceramic crowns showed clinically acceptable marginal discrepancy.

• The Journal of Advanced Prosthodontics
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• 제5권2호
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• pp.92-97
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• 2013

PURPOSE. All-ceramic crowns are subject to fracture during function. To minimize this common clinical complication, zirconium oxide has been used as the framework for all-ceramic crowns. The aim of this study was to compare the fracture strengths of two computer-aided design/computer-aided manufacturing (CAD/CAM) zirconia crown systems: Lava and Digident. MATERIALS AND METHODS. Twenty Lava CAD/CAM zirconia crowns and twenty Digident CAD/CAM zirconia crowns were fabricated. A metal die was also duplicated from the original prepared tooth for fracture testing. A universal testing machine was used to determine the fracture strength of the crowns. RESULTS. The mean fracture strengths were as follows: $54.9{\pm}15.6$ N for the Lava CAD/CAM zirconia crowns and $87.0{\pm}16.0$ N for the Digident CAD/CAM zirconia crowns. The difference between the mean fracture strengths of the Lava and Digident crowns was statistically significant (P<.001). Lava CAD/CAM zirconia crowns showed a complete fracture of both the veneering porcelain and the core whereas the Digident CAD/CAM zirconia crowns showed fracture only of the veneering porcelain. CONCLUSION. The fracture strengths of CAD/CAM zirconia crowns differ depending on the compatibility of the core material and the veneering porcelain.

• 대한심미치과학회지
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• 제23권1호
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• pp.16-26
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• 2014

CAD/CAM에서 사용할 수 있는 소재는 composite, ceramic, hybrid 그리고 metal이 있다. 그중에 진료실 CAD/CAM에서는 주로 monolithic ceramic 테크닉을 사용하는 데, monolithic ceramic 테크닉이란 한 가지 소재로만 제작하는 방법을 말한다. 블럭상태의 소재를 최종치아형태로 깎아 폴리싱해서 사용하거나, 열을 가해서 사용하는 방법으로, 기존의 도재 축조 작업이 필요 없다. 심미성에서는 다소 부족하지만, 1시간 안에 제작이 가능하므로 1회, 1일 방문으로 치료를 완료할 수 있고, 소재의 안정성이 높으며(녹이거나 상변화를 시키지 않음에 따라 왜곡이 생기거나 강도가 약해질 가능성이 적음), 컴퓨터 조작(CAD 작업)으로 치아를 디자인하여 제작하므로 진료실에서 쉽게 작업할 수 있다는 장점이 있다. 이 테크닉에 사용할 수 있는 소재를 임상적 관점에서 세대별로 따라 분류해 보았다.

• 한국치위생학회지
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• 제16권5호
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• pp.695-700
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• 2016

Objectives: The purpose of the study was to investigate the effect of CAD/CAM ceramic thickness on shade. Methods: 24 disk-shaped ceramic specimens (E.Max CAD & Empress CAD, $12mm{\times}12mm$) were prepared and divided into 4 groups (n=6). Ceramic specimens in 2 thicknesses (0.8 mm, 1.0 mm) were made low translucency(LT) shade A2. All specimens were measured as L*, a*, b* using spectrophotometer. The color differences(${\Delta}E$ values) between the specimen and a control target block ($12{\times}12{\times}1.2mm$) were calculated. Two-way ANOVA performed between 2 groups(material and thickness). Results: As the thickness increased, the $L^*$ (for all groups) and $b^*$ value (for all groups) increased and the $a^*$ value(for LR group) decreased. The mean color differences caused by thickness was acceptible (${\Delta}E$ > 2) for group LD1. But the mean color differences by thickness were not selected (${\Delta}E$ < 2) for group LD2, LR1, LR2. Conclusions: The different thickness can influence the final color of CAD/CAM ceramic.

• The Journal of Advanced Prosthodontics
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• 제15권1호
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• pp.44-54
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• 2023

PURPOSE. To assess the clinical performance of monolithic CAD-CAM lithium disilicate glass-ceramic (LDGC) crowns and metal-ceramic (MC) crowns provided by predoctoral students. This study also assessed the effects of patient and provider-related factors on their clinical performance as well as patient preference for these types of crowns. MATERIALS AND METHODS. Twenty-five patients who received 50 crowns (25 LDGC CAD-CAM and 25 MC) provided by predoctoral students were retrospectively examined. LDGC CAD-CAM crowns were milled in-house using the CEREC Bluecam system and cemented with either RelyX Unicem or Calibra Esthetic resin cements. MC crowns were cemented with RelyX Unicem cement. Clinical assessment of the crowns and the supporting periodontal structures were performed following the modified California Dental Association (CDA) criteria. Patients' preference was recorded using a visual analog scale (VAS). The results were statistically analyzed using log-rank test, Pearson Chi-squared test and Kaplan-Meier survival analysis. RESULTS. Twelve complications were observed in the MC crown group (9-esthetic, 2-technical and 1-biological). In comparison, 2 complications in the LDGC CAD-CAM crown group were observed (1-technical and 1-esthetic). The 6-year cumulative survival rates for MC crowns and LDGC CAD-CAM were 90.8% and 96%, respectively, whereas the success rates were 83.4% and 96%, respectively. Overall, patients preferred the esthetic outcomes of LDGC CAD-CAM crowns over MC crowns. CONCLUSION. The high survival and success rates, low number of complications, and the high level of patients' acceptance of monolithic LDGC CAD-CAM crowns lend them well as predictable and viable alternatives to the "gold standard" MC crowns.

• 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.

• 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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• 제38권3호
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• pp.119-125
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• 2016

Purpose: The purpose of this study is to evaluate the marginal gap of all-ceramic crowns fabricated by CEREC$^{(R)}$ in-office CAD/CAM system. Methods: The mandibular first molar was selected as the abutment for the experiments. Thirty working models were prepared. VITA Mark II(VM) and VITA Enamic(VE), LAVA Ultimate(LU) blocks were milled using CEREC MCXL with CEREC 3D system to construct 10 crowns for each groups. To measure marginal gap, milled restorations were examined under digital microscope with scale under 160x magnifications. The results were statistically analyzed using the one-way ANOVA and Tukey's HSD test(${\alpha}=0.05$). Results: There was no significant difference in the marginal gap regarding to ceramic materials(p>0.05). Conclusion: Single crowns fabricated using CEREC in-office CAD/CAM system provided clinically acceptable marginal gap. This confirmed that the type of ceramic material used does not determine the precision of fit of a prosthesis.

• Restorative Dentistry and Endodontics
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• 제26권6호
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• pp.464-484
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• 2001

When restoring a tooth, the dentist tries to choose the ideal material for existing situation. One criterion that is considered is its suitability for restoring coronal strength. As more tooth structure is removed, the cusps are weakened and susceptible to fracture. Further, this increased deformation may cause the formation of intermittent gaps at the margin between the hard tissue and the restoration, facilitating marginal leakage. The improvements in ceramic materials now make it possible for alternatives to amalgams, composites, and cast metal to be of offered for posterior teeth. Of the materials used, ceramics most closely approximates the properties of enamel. The introduction of computer-aided design/computer-aided manufacture(CAD/CAM) systems to restorative dentistry represents a major technological breakthrough. It is possible to design and fabricate ceramic restorations at a single appointment. Additionally, CAD/CAM systems eliminate certain errors and inaccuracies that are inherent to the indirect method and provide an esthetic restoration. The aim of this investigation was to study the loading characteristics of CAD/CAM ceramic inlay and to compare the stress distribution and displacement associated with different designs of cavity(the isthmus width and cavity depth). A human maxillary left first premolar was prepared with standard mesio-occlusal cavity preparation, as recommended by the manufacturer Ceramic inlay was fabricated with CEREC 2 CAD/CIM equipment and cemented into the prepared cavity. Three dimensional model was made by the serial photographic method. The cavity width was varied $\frac{1}{3}$, $\frac{1}{2}$ and $\frac{2}{3}$ of intercuspal distance between buccal and lingual cusp tip. The cavity depth was varied 1.5mm and 2.3mm. So six models were constructed to simulate six conditions. A point load of 500N was applied vertically onto the first node of the lingual slope from the buccal cusp tip. The stress distribution and displacement were solved using ANSYS finite element program(Swanson Analysis System). (omitted)

• 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.