• Journal of Technologic Dentistry
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• v.38 no.3
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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.

• Journal of Technologic Dentistry
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• v.34 no.2
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• pp.121-128
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• 2012

Purpose: The aim of this study was to determine the reliability and accuracy of measurements in digital models(CEREC$^{(R)}$ AC) compared to stone models. Methods: A master model(500B-1, Nissin Dental Product, Japan) with the prepared upper full arch tooth was used. Conventional impression and then stone model(n=10) were produced from this master model, and on the other hands, digital impressions were made with the CEREC$^{(R)}$ AC intra-oral scanner(n=10). One examiner measured two times the intercanine, intermolar distance, dental arch length. The stone model were measured using a digital caliper. The t-student test for paired samples and intraclass correlation coefficient(ICC) were used for statistical analysis. Results: The measurement of two methods showed very good reliability. At the intra-examiner reliability of measurement, ICC at the stone and CEREC$^{(R)}$ AC model were 0.81 and 0.94. The mean difference between measurements made directly on the stone models and those made on the CEREC$^{(R)}$ AC model was 0.20~0.28mm, and was statistically significant(P=0.001). Conclusion: These in vitro studies show that accuracy of the digital impression is similar to that of the conventional impression. These results will have to be confirmed in further clinical studies.

• Journal of Technologic Dentistry
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• v.33 no.3
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• pp.211-218
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• 2011

Purpose: The purpose of the study was a quantitative evaluation of common errors in digital impression procedure using CEREC$^{(R)}$ AC system. Methods: Two-hundreds digital impression data comprising 174 inlays, 26 onlays by CEREC$^{(R)}$ AC in-office CAD/CAM system were obtained from a dental clinic. One evaluator assessed errors of the digital impression data and divided into five categories of errors: inappropriate scanner positioning (ISP), improper handling with a scanner (IHS), irregular powder arrangement (IPA), improper cavity preparation (ICP), and insufficient scanned data (ISD). Results: The most common errors were IPA(21%), and ISP and ISD were followed by 17% respectively. IHS was found in 14.5% of all digital impression data. ICP comprising only 6.5% was the rarest. Conclusion: Most errors were due to inaccurate manipulation with an intraoral scanner or improper cavity preparation for scanning. A deliberate manipulation to prevent common errors mentioned may deliver an optimal result in the digital impression procedure.

• The Journal of Korean Academy of Prosthodontics
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• v.46 no.3
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• pp.269-279
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• 2008

STATEMENT OF PROBLEM: Recently, various all-ceramic crowns fabricated with CAD/CAM systems have come into wide use in dental clinic. However, there are only few domestic studies on CAD/CAM restorations. PURPOSE: Purpose of this study was to compare the fidelity (absolute marginal discrepancy and internal gap) between various cores fabricated with different CAD/CAM systems (Procera system, Lava system, Cerec inLab system) and conventional metal cast core. MATERIALS AND METHODS: 10 cores per each system were fabricated. The absolute marginal discrepancies were measured using measuring microscope and digital counter. The internal gaps were calculated using a silicone paste. The results were statistically analyzed using the one-way ANOVA test and Tukey's HSD test. RESULTS: Within the limits of this study the results were as follows. 1. The absolute marginal discrepancies were $32.5{\pm}3.7\;{\mu}m$ for metal cast core, $72.2{\pm}7.0\;{\mu}m$ for Procera core, $40.8{\pm}5.4\;{\mu}m$ for Lava core, and $55.3{\pm}8.7\;{\mu}m$ for Cerec inLab core. The internal gaps were $38.4{\pm}5.7\;{\mu}m$ for metal cast core, $71.4{\pm}5.3\;{\mu}m$ for Procera core, $45.9{\pm}7.3\;{\mu}m$ for Lava core, and $51.8{\pm}6.2\;{\mu}m$ for Cerec inLab core. 2. The fidelity of metal cast core showed the smallest gaps, followed by Lava core, Cerec inLab core, and Procera core. CONCLUSION: The fidelities of 4 core groups were all within the clinically acceptable range ($120\;{\mu}m$).

• The Journal of Korean Academy of Prosthodontics
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• v.47 no.2
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• pp.148-155
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• 2009

Statement of problem: The interest in all-ceramic restorations has increased as more techniques have become available. With the introduction of machinable dental ceramics and CAD/CAM systems there is a need to evaluate the quality levels of these new fabrication techniques. Purpose: This study is to evaluate the crown fidelity(absolute marginal discrepancy and internal gap) of various zirconia-based all-ceramic crowns fabricated with different CAD/CAM(computer-assisted design/computer-assisted manufacturing) systems and conventional cast metal-ceramic crowns. Material and methods: A resin tooth of lower right second premolar was prepared. After an impression was taken, one metal master die was made. Then 40 impressions of metal master dies were taken for working dies. 10 crowns per each system were fabricated using 40 working dies. Metal-ceramic crowns were cast by using the conventional method, and Procera, Lava, and Cerec inLab crowns were fabricated with their own CAD/CAM manufactruing procedures. The vertical marginal discrepancies and internal gaps of each crown groups were measured on a metal master die without a luting agent. The results were statistically analyzed using the one-way ANOVA and Tukey's HSD test. Results: 1. Vertical marginal discrepancies were $50.6{\pm}13.9{\mu}m$ for metal-ceramic crowns, $62.3{\pm}15.7{\mu}m$ for Procera crowns, $45.3{\pm}7.9{\mu}m$ for Lava crowns, and $71.2{\pm}2.0{\mu}m$ for Cerec inLab crowns. 2. The Internal gaps were $52.6{\pm}10.1{\mu}m$ for metal-ceramic crowns, $161.7{\pm}18.5{\mu}m$ for Procera crowns, $63.0{\pm}10.2{\mu}m$ for Lava crowns, and $73.7{\pm}10.7{\mu}m$ for Cerec inLab crowns. Conclusion: 1. The vertical marginal discrepancies of, 4 crown groups were all within the clinically acceptable range($120{\mu}m$). 2. The internal gaps of LAVA, Cerec inlab, and metal-ceramic crowns were within clinically acceptable range except Procera crown($140{\mu}m$).

• Journal of Technologic Dentistry
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• v.28 no.1
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• pp.251-257
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• 2006

• Journal of Technologic Dentistry
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• v.30 no.2
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• pp.165-172
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• 2008

• The Journal of Korean Academy of Prosthodontics
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• v.27 no.2
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• pp.7-9
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• 1989

• Journal of Technologic Dentistry
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• v.29 no.2
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• pp.119-128
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• 2007

Although there are many different ways that restorations can be made, it can be said that the biocompatibility of abutment and crown is very important in this experiment. When placed in the actual oral cavity, the differences were obvious. Compared to In-ceram Aluminium, the structure that is obtained after firing reveals a particularly homogeneous distribution of the crystal and glass phase. The In-ceram aluminium system had many problems, such as having weak tensile strength, and having low bonding strength due to the shrinking that occurs after firing. Because of the opaque finish of the metal frame, the two may look similar from the outside, but it is evident that there are differences between using a metal frame and In-ceram. VITA VM9 has been designed as a special ceramic featuring a fine structure or stabilized Zro2 substructures, and so the VITA VM9 excels in its light refraction and reflection behavior, which is similar to natural teeth. It also has outstanding chemical balance, which presents advantages such as considerably reduced accumulation of plaque on the ceramic surface.? This ultimately results in easier care and cleaning for the patient.

• The Journal of Korean Academy of Prosthodontics
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• v.39 no.3
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• pp.243-249
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• 2001

Statement of the problem. The interest in all-ceramic restorations has increased as more techniques have become available. With the introduction of machinable dental ceramics and CAD/CAM systems or Copy-milling systems there is a need for evaluating the quality levels of these new fabrication techniques. Purpose. This study was to evaluate the fitting accuracy of machined all-ceramic crowns made out of an industrially prefabricated feldspathic porcelain. Material and Methods. Three master models with different cutting depth (0.8mm/1.0mm/1.2mm)were produced using a palladium-silver alloy. A total of 36 working dies, 12 of each form, was used for the modellation of prototype resin copings and 36 additional crowns, 12 of each cutting depth, were produced by using the $CEREC^{(R)}2$ system for all crowns. The maginal fit of all 72 crowns was then evaluated on their respective master die at 54 circularly staggered points of measurement per crown under a fixation pressure of 30 N by using a computerized video image system. Results. The medians of the copy-milled $CELAY^{(R)}$ crowns ranged from 29 to $36{\mu}m$. The highest value for the marginal gap was found in group B (cutting depth 1.0mm) at $107{\mu}m$. The median for the $CEREC^{(R)}2$ crowns was found between 43.5 and $70{\mu}m$. The maximum values for all three groups ranged from $181{\mu}m$ to $286{\mu}m$. With $286{\mu}m$ the highest value for marginal gap was found in group C. the Kruskal-Wallis test and multiple comparisons analysis procedure revealed a significant influence of the production technique on the marginal fit in all three groups (p<0,02). Conclusion. 1. The $CELAY^{(R)}$ system is capable to produce all-ceramic crowns with a significantly better marginal fit than the $CEREC^{(R)}2$ system. 2. As far as premolar crowns produced with the $CEREC^{(R)}2$ system are concerned, the cutting depth has a significant influence on fitting accuracy. 3. The production of crowns with an acceptable marginal fit is possible with both systems. However, adhesive luting is recommended for milled feldspathic porcelain crowns.