• 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.

• The Journal of Advanced Prosthodontics
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• 제16권4호
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• pp.231-243
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• 2024

PURPOSE. The objective of the study was to analyze the impact of cement, bonding pretreatment, and ceramic abutment material on the overall color results of CAD-CAM ceramic crowns bonded to titanium-based hybrid abutments. MATERIALS AND METHODS. For single implant restoration of a maxillary lateral incisor a total of 51 CAD-CAM-fabricated monolithic lithium disilicate crowns were fabricated and subsequently bonded onto 24 lithium disilicate Ti-base abutments, 24 zirconia Ti-base abutments and 3 resin abutment replicas as a control group. The 48 copings were cemented with three definitive and one provisional cement on both grit-blasted and non-blasted Ti-bases. The color of each restoration and surrounding artificial gingiva was measured spectrophotometrically at predefined measuring points and the CIELAB (ΔE_ab) color scale values were recorded. RESULTS. The color outcome of ceramic crowns bonded to hybrid abutments and soft tissues was affected differently by cements of different brands. Grit-blasting of Ti-bases prior to cementing CAD-CAM copings affected the color results of allceramic crowns. There was a significant difference (P = .038) for the median ΔE value between blasted and non-blasted reconstructions at the cervical aspect of the crown. Full-ceramic crowns on zirconia Ti-base abutments exhibited significantly lower ΔE values below the threshold of visibility (ΔE 1.8). In all subcategories tested, the use of a highly opaque temporary cement demonstrated the lowest median ΔE for both the crown and the artificial gingiva. CONCLUSION. Various cements, core ceramic materials and airborne particle abrasion prior to bonding can adversely affect the color of Ti-base supported ceramic crowns and peri-implant soft tissue. However, zirconia CAD-CAM copings and an opaque cement can effectively mask this darkening.

• 대한치과의사협회지
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• 제54권6호
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• pp.414-428
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• 2016

Objectives: The aim of this study was to assess the morphologic characteristics of two types of stainless steel crowns (SSCs) for the first primary molar using a 3D scanner. Study design: Two types of SSCs, KIDS CROWN (KC) and 3M ESPE ND-96 (ND), for the first primary molars were scanned using a 3D scanner. The mesiodistal and buccolingual diameters at the height of the contour and the cervical margin, occlusocervical diameters on the mesial, distal, buccal, and lingual aspects were measured, and the crown shape ratio, the smooth surface crown height ratio, and the cervical convergence were calculated. Results: In the crown shape ratio of the mandibular SSC, KC was larger buccolingually compared with ND. In the smooth surface crown height ratio, ND was larger than KC in all of the maxilla and mesial, distal, and lingual aspects of the mandible. ND was more convergent to the cervical mesiodistally and buccolingually compared with KC. Conclusion: In the superimposed images of the maxillary SSC, the mesiolingual and distolingual line angles of KC were more prominent compared with ND. In the mandible, ND demonstrated higher cusps and more obvious buccal developmental lobes than KC. ND showed a larger cervical undercut than KC.

• 대한치과재료학회지
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• 제45권4호
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• pp.287-300
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• 2018

본 연구의 목적은 3차원 스캐너를 이용하여 현재 시판중인 두 종류의 대구치용 기성금속관의 형태적 특성을 비교하는 것이며, 또한 crimping 후의 치경부측 형태 변화를 분석 후 비교하는 것이다. 3차원 스캐너를 이용하여 상, 하악 대구치용 기성금속관인 PO-96과 PERMACROWN의 크기, crown index, 치경부 수렴도를 계측하였다. 이후 기성금속관들은 crimping을 통하여 치경부 형태를 조정하였고 3차원 스캐너를 통해 다시 스캔을 시행한 후 형태적 변화를 분석하였다. 상악 기성금속관의 폭경은 PERMACROWN이 PO-96에 비해 협설로 더 컸고 근원심으로는 더 작았으며, 치경부의 근원심 형태는 더 볼록하였다. 하악에서는 PERMACROWN이 PO-96에 비해 폭경은 협설로 작고 근원심으로 컸으며, 치경부의 근원심, 협설측 모두 더 볼록한 형태를 보였다. 그리고 두 기성금속관 모두 crimping 이후 치경부 변연 둘레는 감소하였다. 두 기성금속관은 크기, 형태, 치경부 수렴도에서 형태학적 차이를 보였다. 두 대구치용 기성금속관 모두 치경부 형태가 부여되어있지만 더 나은 변연적합을 위해서는 추가적인 crimping이 필요하다.

• 대한치과의사협회지
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• 제11권12호
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• pp.787-799
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• 1973

Surveying the calcification degree of permanent tooth crown in 719 Korean children (Male 387, female 332) from 2 to 10 years old by orthopantomograph, the author got the following results. 1. Female was earlier than male in calcification of permanent teeth. 2. The results of the complete calcification of the permanent tooth crown were as follows. 3. The completion of calcification in the mandibular crown was seen earlier than that of the maxilla. 4. The order of calcification in permanent tooth crowns was as follows : 1 st molar, central incisor, lateral incisor, canine, 1st premolar, 2nd premolar, and 2nd molar. 5. The completion of calcification of the permanent crowns in Korean children was slightly retarded comparing with the Japanese and the American children.

• 대한치과의사협회지
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• 제50권7호
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• pp.384-393
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• 2012

Successful treatment of a badly broken down tooth with pulpal disease depends not only on good endodontic therapy, but also on good prosthetic reconstruction of the tooth after endodontic therapy is completed. The ideal treatment of endodontically treated teeth has been widely and controversially discussed. Endocrown is a restorative option for endodontically treated teeth. Endocrown design incorporates the core and short post into the crown as a single restoration. The preparation of endocrown consists of a circular equigingival butt-joint margin and central retention cavity of the entire pulp chamber instead of employing intraradicular posts. This design significantly increases the surface area of the preparation available for cementation. It is particularly useful in young patient teeth for long-term provisional restoration and in teeth with short clinical crowns. This technique represents a promising and conservative method for the treatment of endodontically treated teeth that require long-term protection and stability. Endocrown can be considered as a feasible alternative to full crowns or composite overlays for the restoration of non vital teeth.

• 대한치과기공학회지
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• 제37권4호
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• pp.229-234
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• 2015

Purpose: The purpose of this study was to analysis the internal fitness of single crown fabricated by additive method technique. Methods: Study models were fabricated. Ten crowns were manufactured by additive method technique (AM group) and another ten crowns using conventional method were manufactured (CM group). The internal fitness of specimens were measured using silicone replica technique. Silicone replicas were sectioned one times (direction: from mesial to distal). The internal fitness were evaluated using by digital microscope. Statistical analyses were performed with independent samples t-test. (${\alpha}=0.05$). Results: Mean(SD) of all internal fitness were $92.1(20.0){\mu}m$ for AM group and $69.7(12.3){\mu}m$ for CM group. Two groups were statistically significant differences (p<0.001). Conclusion: All internal gaps of AM group were ranged within the clinical recommendation ($120{\ss}{\neq}$).

• 대한심미치과학회지
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• 제12권2호
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• pp.31-38
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• 2003

Amelogenesis imperfecta patients suffered common clinical problems of poor esthetics, teeth sensitivity, and loss of occlusal vertical dimension. Amelogenesis imperfecta is a group of inherited disorders primarily affecting dental enamel. Variants of amelogenesis imperfecta generally classified hypoplastic, hypocalcified, or hypomaturation types based on the primary enamel defects. The mildest problems were found in the pitted hypoplastic type whereas the most severe problems were encountered in the hypocalcified type amelogenesis imperfecta. Management stragies include composite resin veneer and jacket crowns for anterior teeth as well as steel crowns for posterior teeth. Knowledge of the clinical features and dental complications of each variants if amelogenesis impecta helps in the diagnosis of the condition and allows institution of early preventive measures. The objective of this paper is to provide a review of the current concepts of the wide spectrum of etiological factors involved in the pathogenesis of this significance clinical entity in the primary dentition.

• The Journal of Advanced Prosthodontics
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• 제15권2호
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• pp.72-79
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• 2023

PURPOSE. The purpose of this in vitro study was to compare the accuracy of various 3D printers and a milling machine. MATERIALS AND METHODS. The die model was designed using CAD (Autodesk Inventor 2018 sp3). The 30 ㎛ cement space was given to the die and the ideal crown of the mandibular left first molar was designed using CAD (ExoCAD). The crowns were produced using the milling machine (Imes-icore 250i) and the 3D printers (Zenith U, Zenith D, W11) and they were divided into four groups. In all groups, the interior of each crown was scanned (Identica blue) and superimposed (Geomagic Control X) with the previously designed die. The difference between the die and the actual crown was measured at specific points. The Kruskal-Wallis test, the Mann-Whitney test, and Bonferroni's method were performed with a statistical analysis software (P < .008 in inter-group comparison P < .001 in intra-group comparison). RESULTS. In all groups, the center of the occlusal area and the anti-rotational dimple area showed significantly greater difference and the marginal area showed the smallest difference comparatively. The mean value of the difference in each area and the sum of the differences were higher in order of W11, Imes-icore 250i, Zenith D, and Zenith U. CONCLUSION. The digital light processing (DLP) method shows higher accuracy compared to the sereolithography (SLA) method using the same resin material.

• 구강회복응용과학지
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• 제16권3호
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• pp.237-245
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• 2000

The purpose of this study was to compare the fracture strength of the IPS Empress ceramic crown according to the incisal depth(2.0mm, 2.5mm, 3.0mm) and axial inclination($4^{\circ}$, $8^{\circ}$, $12^{\circ}$) of the upper central incisor. After 10 metal dies were made for each group, the IPS Empress ceramic crowns were fabricated and each crown was cemented on each metal die with resin cement. The cemented crowns mounted on the testing jig were inclined 30 degrees and a universal testing machine was used to measure the fracture strength. The results were : 1. The fracture strength of the ceramic crown with 2.5mm depth and $8^{\circ}$ inclination was the highest(965N). Crowns of 2.0mm depth and $4^{\circ}$ inclination had the lowest strength(713N). There were no significant differences of the fracture strength by axial inclination in same incisal depth group. 2. The fracture mode of the crowns was similar. Most of fracture lines began at the loading area and extended through proximal surface perpendicular to the margin irrespective of incisal depth. There had correlation between fracture strength and fractured surface area.