• 대한치과보철학회지
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• 제38권2호
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• pp.169-177
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• 2000

The purpose of this study was to compare the retention of complete cast crown over amalgam ores, composite resin cores, and cast gold cores when cemented with three different luting agents. Eighteen core specimens each of amalgam(Bestaloy, Dong Myung, Seoul, Korea), composite resin (Z100, 3M Dental product, st. Paul, Minn) and type IV gold alloy (Ba-4, Heesung Engelhard Corp., Korea) were made in a customized milling stainless steel die. A wax pattern with a loop attached to occlusal surface was made for each core and a type II gold alloy casting was fabricated. The castings which had clinically acceptable marginal fit were used as test samples. The following luting cements were used to cement cast crowns on each core material : (1) zinc phosphate cement (Confi-dental Products Co., USA) (2) glass-ionomer cement (Fuji Plus, GC Industrial Corp., Tokyo, Japan) (3) resin cement (Panavia 21, Kuraray Co., USA). All cements were mixed according to manufacturers' instructions. A static load of 5kg was then applied for 10 minutes on the crowns. All specimens were stored in saline solution for 24 hours at $37^{\circ}C$ and thermocycled for 500 cycles. After storage and cycling, the tensile bond strengths were measured by using a universal testing machine (Instron Corp., Canton, Mass.) at a crosshead speed of 0.5mm/min. The results were as follows 1. The retentive strength of resin cement was the highest of alt three types of cement for resin core (p<0.05). 2. There was no statistical difference among the retentive strengths of three cements for amalgam core (p>0.05). 3. The retentive strength of resin cement was higher than that of zinc phosphate for cast core, but there was no difference between the retentive strength of glass ionomer cement and those of rein and zinc phosphate cement. 4. The retentive strength of the zinc phosphate cement for amalgam core was the highest of all type of cores.

• 대한치과보철학회지
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• 제42권5호
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• pp.597-607
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• 2004

Purpose: This study was peformed to investigate the retrievability of the cemented crown from the cementation type implant abutment. Material and method: The cementation type implant abutments (NEOBIOTECH implant abutment regular, 3 degree taper, 10mm length, 4mm diameter, Ti grade III, machined surface. Hwasung, Kyunggi-do) and cemented crowns were divided into 3 groups, depending on their hole angles formed in the crowns for their retrievability. The abutments and crowns were luted with 4 kinds of cements and separation test using metal wedge was executed with Instron 4465 Universal Testing Machine and the maximum impact force of the modified crown ejector was measured. Results and conclusion : 1. All of the cementation type implant abutments and cemented crowns were separated with relatively small force by metal wedge. 2. The retrieving force was minimum when the metal wedge was applied perpendicular to the axis of abutment. 3. The force for retrieving crowns from abutments was maximum in resin cement group, and reduced in orders of zinc phosphate cement, glass ionomer cement and zinc oxide eugenol cement. 4. The maximum force obtained by the crown ejector was higher than the retrieval force in ZOE and GI cement and lower than that in ZPC and resin cement. 5. If it has similar conditions clinically, the cemented crowns luted with 2 types of cements (ZOE, GI cement) can be safely retrieved from the cementation type implant abutments by the modified crown ejector.

• 대한소아치과학회지
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• 제47권2호
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• pp.205-212
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• 2020

이 연구의 목적은 파절강도와 반투명도 측정을 통해 Computer Aided Design/Computer Aided Manufacturing (CAD/CAM)으로 제작한 유전치 지르코니아 전장관의 임상적 적용 가능성을 확인하는 것이다. 기성 유전치 모형 중 #61을 스캔하여 얻은 3차원 형상 데이터로 CAD 디자인 프로그램을 이용하여 전장관을 디자인하고, 지르코니아 블록으로 CAM 밀링 기계를 이용하여 전장관을 제작하였다. 지르코니아 전장관은 두께에 따라 0.3, 0.5, 그리고 0.7 mm의 3군으로 나누어 1.0 mm 두께의 레진 전장관과 파절강도를 비교하였다. 파절강도는 만능시험기를 이용하여 30° 각도에서 1 mm/min 속도로 절단면에 하중을 가하여 측정하였다. 반투명도는 가로와 세로가 7.0 mm, 그리고 두께가 각각 0.3, 0.5, 0.7 mm 인 사각형 지르코니아 시편을 제작하여 분광측색장치로 측정하였다. 파절강도 측정 결과 지르코니아 전장관은 두께가 증가할수록 파절강도가 높아졌으며 모든 두께의 지르코니아 군에서 대조군인 레진 전장관보다 파절강도가 높았다(p < 0.05). 반투명도는 0.3 mm 군에서 가장 높았으며 0.5, 0.7 mm로 두께가 증가할수록 감소하였다(p < 0.05). CAD/CAM으로 제작한 지르코니아 전장관은 개별 치아에 맞추어 얇게 디자인 및 제작 가능하며, 얇은 전장관을 이용한 수복은 임상적으로 치아 삭제량과 치수노출 위험성 감소 뿐만 아니라, 더 심미적인 수복을 가능하게 해줄 것이다.

• 대한치과기공학회지
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• 제22권1호
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• pp.5-12
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• 2000

The gaps between the die margin worked and the casting body were measured with an optical microscope and compared after making crown prosthetic materials using three kinds of die material - dental stone, extra hard stone, epoxy resin - used in crown prosthesis. The results are as follows : 1. All the gaps between the cast cervical margin and the casting bodies were relatively good regardless of die materials used with the gaps under $50{\mu}m$, the allowable limit. 2. The cervical margin suitability of epoxy resin die was the highest among the three kinds of die material with the suitability value of $30.28{\pm}12.67$. 3. Among the four surfaces(buccal, lingual, mesial, distal) of all the casting bodies, buccal surface was the highest in the cervical margin suitability with the value of $25.93{\pm}15.51$.

• 대한소아치과학회지
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• 제36권2호
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• pp.288-292
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• 2009

치관-치근 파절(crown-root fracture)은 법랑질, 상아질, 백악질에 파급된 파절이며 치수노출을 수반하는 것과 수반하지 않는 것이 있다. 치근부위만 파절된 경우와 달리 치관-치근 파절의 경우 치수와 치주조직을 통해 세균감염이 발생하기 때문에 치유를 기대하기 힘들다. 파절은 치근을 따라 다양한 부위에서 일어나기 때문에 치료방법은 파절 정도에 따라 결정된다. 치근의 파절선이 치관부에 근접 한 경우 느슨한 치아 파절편을 제거 한 후, long junctional epithelium이 형성되도록 치은을 노출된 상아질에 맞게 적합시키거나, 외과적으로 파절 부위를 노출시키거나, 교정적 또는 외과적으로 치아를 정출시키는 방법 등을 고려해 볼 수 있지만 파절선이 깊은 경우 발치가 일반적이다. 그러나 최근 논문에서 수직 치관-치근 파절된 치아에 대해 발치대신 레진으로 파절선을 수복한 후 재식하여 성공한 사례가 발표되었다. 이 방법으로 치아를 보존할 수 있으며 이러한 방법이 전치 부에서는 예후가 좋다고 보고되었다. 본 증례에서는 외상으로 인하여 상악중절치의 치관-치근 파절이 발생한 10세 환아에서 해당 치아를 발치하여 레진으로 파절부위를 재부착한 후 재식하였다. 그러나 18개월간 주기적으로 관찰한 결과 문헌에서와 같은 좋은 결과를 나타내지는 않았다.

• 대한심미치과학회지
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• 제10권1호
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• pp.48-54
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• 2001

아름다움이라는 것은 완전히 객관적이기도 하지만 극히 주관적인 표현의 결과일 수 있다. 심미치의학은 얼굴에서 표현되는 이러한 주관적인 면과 객관적인 면을 조화시킬 수 있는 학문이기에 21세기에도 여전히 치과 치료에 있어서 중요한 화두 중의 하나임에 틀림이 없다. 과거 심미적인 치료로 행하였던 많은 치료 술식들(open faced crown, resin faced crown,3/4 crown,7/8crown등)이 치과 치료 술식의 발달과 함께 재료와 치아 보철물 제작술 등의 발달로 인해 점차 사라지거나 변화하고 있는 것이 사실이다. 지금 소개하는 증례들은 현재 치과계에서 심미적인 치료 술식으로 인정하고 있기에 이러한 치료 술식에 대한 이해가 필요할 것이다. 우리 임상가들의 최종목표는 환자들에게 자연스러운 얼굴과 웃음을 회복시켜주는 것이다. 각 증례에 대한 한계에 대해 미리 알 수 있는 방법을 모색해 보고, 예측 가능한 치료를 시행하기위한 과정들을 살펴보고자 한다.

• Restorative Dentistry and Endodontics
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• 제19권1호
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• pp.85-96
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• 1994

In this study, 24 curved resin blocks were prepared by one of the following four methods: 1) Conventional technique using K-flexo files 2) Step-back technique using K-flexo files 3) Crown-down technique using K-flexo files 4) Canal Master instrumentation using Canal Master Resin blocks were sectioned, photographed, and evaluated the mean centering ratio and the mean area of dentin removed before and after the instrumentation. The results were as follows : I. the mean centering ratio 1. In the level 1 and level 3, there was no significant difference in the mean centering ratio. 2. In the level 2, Step-back technique showed the worst mean centering ratio among the tested groups(p<0.001) and there was no significant difference between the other three groups. 3. In the level 4, Canal Master instrumentation and Step-back technique showed better mean centering ratio than the other two techniques(p<0.001) and there was no significant difference between the two techniques. II. the mean area of dentin removed 1. In the level l and level 3, there was no significant difference in the mean area of dentin removed. 2. In the level 2, Canal Master instrumentation removed less dentin than the other three techniques(P<0.01). 3. In the level 4, Crown-down technique removed less dentin than the other three techniques(P<0.05).

• 구강회복응용과학지
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• 제18권4호
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• pp.313-320
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• 2002

The purpose of the present study was to evaluate the marginal discrepancy and topography of artificial crown on teeth extracted due to severe periodontal disease. Twenty specimens were invested into metamethylacrylate resin and cutted into vertical slices along with the long axis of tooth. The selected marginal discrepancy between the outer edge of the crown and the finishing line of abutment was examined by stereo- microscope(Olympus, PM-VSP-3, Japan) at magnification of up to 10, and the topography of finishing margin on crown was observed by stereomicroscopeat magnification of up to $70{\times}$. The results were as follows. (1) The mean marginal discrepancy between extracted tooth and artificial crown were $50.82{\mu}m$. (2) There was a considerable difference in the microstructure of finishing margins among specimens. Microscopic Structure on finishing margin showed indefinite line, poor fit (open, underextended and overextended), distorted margin, and surface roughness. This study suggested that there could be necessary to consider the response of periodontium to the emergence profile of natural tooth and precision of marginal geometry while establishing treatment planning for the reconsruction of the artificial crown.

• 대한소아치과학회지
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• 제24권2호
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• pp.475-483
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• 1997

Fracture of the crown in a permanent incisor is relatively common. When it occurs with pulp exposure, it presents both restorative and endodontic problems. In the restoration of a fractured incisor, reattachment of the original fragment or restoration with a composite resin is preferred over a temporary crown. If fractured fragment is intact, the tooth can be restored with reattachment of the fragment. An exposed pulp in a young crown-fractured incisor is usually treated with either pulp capping or pulpotomy depending on the size of an exposure and time elapsed since injury. However, in teeth showing vital and/or hyperplastic pulp tissue at the exposure, only superficial layers of the pulp and surrounding dentin should be removed : i.e. partial pulpotomy can be performed in immature as well as mature teeth. This paper reports 2 cases of crown-fractured permanent incisors with pulp exposure that had been treated by reattachment of original fragment followed by partial pulpotomy or partial pulpectomy. The following results are obtained. ; 1. Fragment reattachment is an acceptable semi-permanent restoration of crown fractured young permanent incisor. 2. Partial pulpotomy is recommended as the treatment of choice in crown-fractured permanent teeth with pulp exposure.

• 통합자연과학논문집
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• 제6권3호
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• pp.151-157
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• 2013

The ion exchange resins were synthesized from 1-aza-18-crown-6 macrocyclic ligand attached to styrene (2th petroleum in 4th class hazardous material) divinylbenzene (DVB) copolymer with crosslinks of 1%, 6%, and 15% by substitution reaction. These synthetic resins were confirmed by chlorine content, elementary analysis, surface area, and IR-spectrum. The object of this study was to seperate the metal ion absorbed in reinforcement water fire extinguishing agent. As the results of the effects of pH, equilibrium arrival time, and crosslink of synthetic resin on metal ion adsorption for resin adsorbent, the metal ions were showed high adsorption at pH 3 or over and adsorption equilibrium of metal ions was about 2 hours. In addition, adsorption selectivity for the resin in water was the order of Al (III) > Ni (II) > Sm (III) ions, adsorbability of the metal ions was in the crosslinks order of 1%, 6%, and 15%.