• The Journal of Advanced Prosthodontics
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• 제13권5호
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• pp.281-291
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• 2021

PURPOSE. To evaluate the wear of computer-aided design/computer-aided manufacturing (CAD-CAM) dental ceramic materials opposed by enamel as a function of increased chewing forces. MATERIALS AND METHODS. The enamel cusps of healthy human third molar teeth (n = 40) opposed by materials from CAD-CAM dental ceramic groups (n = 10), including Vita Enamic^® (ENA), a polymer-infiltrated ceramic network (PICN); GC Cerasmart^® (CERA), a resin nanoceramic; Celtra^® Duo (DUO), a zirconia-reinforced lithium silicate (ZLS) ceramic; and IPS e.max ZirCAD (ZIR), a polycrystalline zirconia, were exposed to chewing simulation (1,200,000 cycles; 120 N load; 1 Hz frequency; 0.7 mm lateral and 2 mm vertical motion). The wear of both enamel cusps and materials was quantified using a 3D laser scanner, and the wear mechanisms were evaluated by scanning electron microscopy (SEM). The results were analysed using Welch ANOVA and Kruskal Wallis test (α = .05). RESULTS. ZIR showed lower volume loss (0.02 ± 0.01 mm³) than ENA, CERA and DUO (P = .001, P = .018 and P = .005, respectively). The wear of cusp/DUO [0.59 mm³ (0.50-1.63 mm³)] was higher than cusp/CERA [0.17 mm³ (0.04-0.41 mm³)] (P = .007). ZIR showed completely different wear mechanism in SEM. CONCLUSION. Composite structured materials such as PICN and ZLS ceramic exhibit more abrasive effect on opposing enamel due to their loss against wear, compared to uniform structured zirconia. The resin nano-ceramic causes the lowest enamel wear thanks to its flexible nano-ceramic microstructure. While zirconia appears to be an enamel-friendly material in wear volume loss, it can cause microstructural defects of enamel.

• 대한치과기공학회지
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• 제35권1호
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• pp.49-56
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• 2013

Purpose: The deformation characteristics induced by non-destructive stresses using piezoelectric transducer(PZT) were analyzed for 3-unit fixed partial dentures manufactured PFM, Everest(CAD/CAM) and Zirkonzahn(copy milling, MAD/MAM) by electron speckle pattern interferometery(ESPI). Methods: The ESPI analysis after loading the restoration with PZT by applying electric voltage of 900mV at the points of 10 mm above the base of the prostheses. Results: PFM and All-Ceramic Everest prostheses showed about 0.1 ${\mu}m$ while that of All- Ceramic Zirkonzahn prostheses showed 0.085 ${\mu}m$, demonstrating that Zirkonzahn displaced less. For PFM and All-Ceramic Zirkonzahn prostheses, the displacements were large at just below the loading point, while generalize displacement was shown over the loading point and weak connector areas for All-Ceramic Everest prostheses. Conclusion: We could find that the deformation characteristics induced by non-destructive stresses using PZT analyzed by ESPI were similar to the fracture strengths evaluated using universal testing machine.

• 대한치과보철학회지
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• 제32권3호
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• pp.359-367
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• 1994

The number and the distribution of fixed restorations including crowns, fixed bridges, Maryland bridges, periodontal splints and cast cores were statistically investigated with two thousand seven hundred and thirty cases of crowns and bridges placed at the Department of Prosthodontics of Seoul National University Hospital, from January 4th to December 31st, 1988. The results were as follow : 1. Among the fixed restorarions, single crowns were 46.9% , fixed bridges were 41.9%, Maryland bridges were 5.0%, periodontal splints were 0.6% and cast cores were 5.6%. 2. Three thousand nine hundred and ninty two teeth were restored with the fixed restorations, among them cast gold restorations were 47.2% and metal-ceramic restorations were 52.8%. 3. Cast gold restorations of the maxillary posteriors occupied 98.5% of the maxillary cast gold restorations, and 99.7% of the mandibular cast gold restorations and metal-ceramic restoration of maxillary anteriors occupied 68.4% of the maxillary metal-ceramic restorations, and 38.7% of the mandibular metal- ceramic restorations. 4. It is recommended that the curriculum of the dental school for undergraduated students and graduated students should be changed to accomodate the relative importance of the restorations.

• 대한치과기공학회지
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• 제29권2호
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• pp.213-223
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• 2007

The success of a porcelain fused to metal (PFM) restoration depends upon the quality of the porcelain-metal bond. The adhesion between metal substructure and dental porcelain is related to the diffusion of oxygen to the reaction layer formed on cast-metal surface during firing. The purposed of this investigation was to study the effects of gold based bonding agent on Ni-Cr alloy-ceramic adhesion between porcelain matrix, gold based bonding agent and metal substructure interface. gold based bonding agent have been applied as an intermediate layer between a metal substructure and a ceramic coating. gold based bonding agent(Aurofilm NP, Metalor, Swiss) was applied on Ni-Cr alloy surface by four method. Surfaces only air abraded with 110${\beta}\neq$ Al2O3 particles were used as control. metal ceramic adhesion was evaluated by a biaxial flexure test(N=5) and volume fraction of adherent porcelain was determined by SEM/EDS analysis. Result of this study suggest that the layering sequence of gold based bonding agent is very important and can improve porcelain adherence to PFM.

• 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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• 제36권2호
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• pp.273-292
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• 1998

The purpose of this study was to evaluate marginal fit of four all-ceramic crown systems 1) conventional In-Ceram, 2) copy-milled In-Ceram using Celay system, 3) IPS Empress, 4) OPC(Optimal Pressable Ceramic). All ceramic crowns were made on epoxy dies. The fabricated crowns were sandblasted, cleaned with ultrasonic cleansing, silanated, and cemented with Bistite composite resin cement. the selected marginal areas of the crowns were the labial, lingual, mesial, and distal surface. Each selected area of surface was $0.6{\times}1.6mm$ in dimension. The image of each marginal area was captured to computer files using DT-55 Frame Grabber and light microscope connected CCD camera. The marginal gaps were measured every $70{\mu}m$ using computer image analysis program. The results obtained were summarized as follows : 1. The marginal fit of four all-ceramic crowns were significantly different from each other(p<0.01), and mean marginal fit values obtained were $31.42{\pm}16.52{\mu}m$ in conventional In-Ceram, $55.45{\pm}27.90{\mu}m$ in copy-milled In-Ceram using Celay system, $44.36{\pm}24.59{\mu}m$ in IPS Empress, $47.21{\pm}20.42{\mu}m$ in OPC. 2. In the marginal fit of conventional In-Ceraw and copy-milled In-Ceram crowns using Celay system there was no significant difference between mesiodistal and buccolingual surface, but in the marginal fit of IPS Empress and OPC crowns, there was significant difference between mesiodistal and buccolingual surface(p<0.01). 3. The marginal fit of four kinds of all-ceramic crowns was clinically acceptable.

• 보존과학회지
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• 제27권1호
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• pp.115-121
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• 2011

석조 문화재의 복원을 위하여 우레탄 복원제를 제조하였다. 제조된 우레탄 복원제는 그간 석조 문화재 복원용 재료로 주로 사용해 왔던 에폭시계 복원제 정도의 강한 접착 강도와 인장 강도를 나타내고 있으며, 충진성, 수축성, 도색성 등의 물성 역시 에폭시계 복원제와 유사하게 제조되었다. 특히, 이 우레탄 복원제는 그간 가장 큰 문제점으로 대두되었던 에폭시계 복원제의 황변 현상과 비가역성 문제를 해결함으로서, 석조문화재의 복원의 항구성과 지속적인 안정성을 부여할 수 있을 것으로 보인다. 또 본 복원제를 메움제와 접착제로 직접 적용하여 사용하였으며, 이를 재 용해하여 복원에 사용된 우레탄을 제거할 수 있어 본 복원제의 가역성을 나타내었다. 이 복원제는 작업 환경에 따라 복원자가 가사 시간을 조정할 수 있도록 제조되어 사용의 편리성 또한 증진시켰다. 또 이 복원제는 강한 접착력과 인장 강도를 가지고 있어 석조문화재 이외의 도자기나 금속 문화재 등의 다양한 문화재의 메움제나 접착제로 사용이 가능할 것으로도 사료된다.

• 박물관보존과학
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• 제14권
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• pp.29-35
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• 2013

백자투각연당초문지통과 같이 기형 및 장식기법이 복잡한 도자기의 경우, 기존에 사용되고 있는 복원제는 경화시간이 짧아 정교한 성형이 어려워 틀을 이용하여 복원한다. 하지만 틀을 이용한 복원 또한 시간적, 재료적인 단점이 있기 때문에 직접 복원하는 방법을 연구하고자 하였다. 복원제의 경화시간과 물성은 작업성과 밀접한 관계가 있기 때문에 복잡한 형태의 복원부를 직접 성형할 때는 충분한 가사시간이 확보되는 복원제가 필요하다. 소성점토(Original Sculpey)와 에폭시퍼티(Repair it Quik)를 각기 다른 비율로 혼합하여 가사시간, 색도 변화, 작업성에 대한 실험을 하였다. 실험결과 OS8 : RQ2의 비율로 혼합하였을 경우 가사시간이 충분하고 성형성이 좋았으며 황변도가 낮고 채색성이 좋아 가장 효과적이라는 것을 알 수 있었다.

• 대한치과보철학회지
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• 제49권2호
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• pp.152-160
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• 2011

연구 목적: 상악 중절치에 여러 가지 수복물 설계와 변연부 위치를 설정하여 치아 삭제를 하였을 때 나타나는 치아 삭제량의 변화를 평가하기 위함이다. 연구 재료 및 방법: 36개의 상악 중절치 레진 인공치가 실험에 사용되었다. 수복물의 디자인에 따라 이들은 4개의 군으로 나뉘었다. 그리고 각각의 군은 다시 변연부의 위치에 따라 3개의 세부 군으로 나뉘었다. 삭제되지 않은 치아의 부피가 미세단층촬영을 이용해 측정되었고 같은 방법으로 삭제 후의 치아의 부피가 측정되었다. 이 측정된 영상들을 서로 겹쳐서 비교함으로 삭제 전과 후의 부피 변화를 알아보았다. 결과: 수복물 설계에 따른 삭제 전과 후의 부피 변화량은 다음과 같은 순서로 변화량의 차이를 보였다: traditional laminate veneer < full laminate veneer < all ceramic crown < metal ceramic crown. One-Way ANOVA와 다중비교 Tukey로 유의수준5%에서 통계 분석한 결과 각각의 군에서는 다음과 같은 순서로 변화량의 차이를 보였다: CEJ 1 mm 상방 < CEJ < CEJ 1 mm 하방 (P<.05). 부피 변화를 백분율로 나타낸 수치를 보면 all ceramic crown과 metal ceramic crown 에서는 31 - 48% 로 나타났고 laminate veneer에서는 14 - 30%로나타났다. Laminate veneer에서 나타난 부피 변화량은 metal ceramic crown의 1/3로 나타났다. The full laminate (CEJ 1 mm 하방)와 all ceramic crown (CEJ 1 mm 상방)는 유사한 부피 변화를 보였다. Metal ceramic crown은 all ceramic crown과 비교하였을 때 13.7% 더 많은 부피 변화를 보였다. 결론: 수복물의 설계와 변연부 위치의 변화에 따라 부피 변화의 차이가 존재한다.

• 대한치과보철학회지
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• 제35권3호
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• pp.544-556
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• 1997

All ceramic restorations except In-Ceram Alumina system gave a good esthetics and an exellent marginal fidelity. The flexural strength of them had about 150MPa, so the indication is only single crown. By using In-ceram Alumina System(450Mpa), it is thought to be possible to construct bridge for its high flexural strength. But the prognosis is unclear, The purposes of this study are to clear short term prognosis of In-Ceram bridge restorations, to elucidate its clinical significance. Among 22 In-Ceram Bridge restored in our department, 11 In-Ceram bridges with follow up were used. The period of placement is from 1 to 18 months. The results were as follows : 1. Among follow up 11 bridges, 2 bridges were fractured. One is 4 unit in maxillary lateral incisors, the other is 3 unit bridge in maxillary canine and premolar. Including 11 bridge without follow up, failure rate is very low(2/22). 2. The fracture sites are connector areas between abutment and pontic. To maintain In-Ceram bridge for long term period, it is needed to remove the nonphysiologic occlusal force and to have sufficient thickness of alumina core. For estabilishing clinical use of In-Ceram bridges, it is thought to need clinical research during long term period.