• 한국정밀공학회지
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• 제28권4호
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• pp.474-481
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• 2011

The purpose of this study was to investigate the effect of rigidity of post core systems on stress distribution by the finite element stress analysis method. Three-dimensional finite element models simulating an endodontically treated maxillary central incisor restored with a zirconia crown were prepared. Each model contained cortical bone, trabecular bone, periodontal ligament, 4mm apical root canal filling, and post-and-core. A 50N static occlusal load was applied to the palatal surface of the crown with a $60^{\circ}$ angle to the long axis of the tooth. And three parallel type post (zirconia, glass fiber and stainless steel) and two core (Paracore and Tetric ceram) materials were evaluated, respectively. The differences in stress transfer characteristics of the models were analyzed. von Mises stresses were chosen for presentation of results and maximum displacement and hydrostatic pressure were also calculated. For the Result of the research, the model applied glass fiber to post material has lowest von Mises stress and it is suitable for material of post core systems.

• 대한치과보철학회지
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• 제45권5호
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• pp.567-578
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• 2007

Statement of problem: The endodontically treated tooth is generally restored with post and core, owing to the brittle and the loss of large amount of tooth structure. As periodontal treatment was developed, there are many cases that periodontally involved teeth used in prosthetic treatment. Purpose: The purpose of this study was to analyze the stress distribution in the dentin and post structures by the various post materials and the amount of remaining alveolar bone height. Material and method: The 3-dimensional finite element models of mandible 1st premolars were divided into six types according to the various amount of remaining alveolar bone and post type. All types were modeled using equal length, diameter and shape of the post. Three types of post and core materials were used: prefabricated titaniumpost and amalgam core, prefabricated stainless steel post and amalgam core, and cast gold post and core. 300 Newton force was applied to functional cusp of mandible 1st premolar. Results: The results were as follows: First, there was no apparent difference in the pattern of stress distribution according to the alveolar bone condition concentrate on the post middle area. Second, there was difference in pattern of stress distribution according to the core materials, gold post and core generated same than amalgam core. Third, there was no apparent difference in the pattern of stress distribution within the dentin according to the post and core materials. But a cast gold post and core generated the lowest maximum stress value, a stainless steel post generated the highest maximum stress value. Fourth, in the reduced alveolar bone model, maximum stress value is 1.5 times than that of the normal alveolar bone model. Conclusion: Within the limitations of this study, to provide minimal stress to the root with alveolar bone reduced, the post length may be as long as apical seal was not destroyed. To prevent fracture of tooth, it is rational to use gold alloy which material was good for stress distribution for post materials.

• The Journal of Advanced Prosthodontics
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• 제3권2호
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• pp.90-95
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• 2011

PURPOSE. To compare the fracture resistance and the mode of failure of endodontically treated teeth restored with different post-core systems. MATERIALS AND METHODS. Root canal treatment was performed on 40 maxillary incisors and the samples were divided into four groups of 10 each. For three experimental groups post space preparation was done and teeth were restored with cast post-core (Group B), stainless steel post with composite core (Group C) and glass fiber post with composite core using adhesive resin cement (Group D). Control group (A) samples were selected with intact coronal structure. All the samples were prepared for ideal abutment preparation. All the samples were subjected to a load of 0.5 mm/min at $130^{circ}$.until fracture occurred using the universal testing machine. The fracture resistance was measured and the data were analyzed statistically. The fracture above the embedded resin was considered to be favorable and the fracture below the level was considered as unfavorable. The statistical analysis of fracture resistance between different groups was carried out with t-test. For the mode of failure the statistical analysis was carried out by Kruskal-Wallis test and Chi-Square test. RESULTS. For experimental group Vs control group the fracture resistance values showed significant differences (P<.05). For the mode of failure the chi-square value is 16.1610, which means highly significant (P=.0009) statistically. CONCLUSION. Endodontically treated teeth without post core system showed the least fracture resistance demonstrating the need to reinforce the tooth. Stainless steel post with composite core showed the highest fracture resistance among all the experimental groups. Teeth restored with the Glass fiber post showed the most favorable fractures making them more amenable to the re-treatment.

• 대한치과보철학회지
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• 제42권3호
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• pp.280-293
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• 2004

Statement of problem. Glass fiber post is one of recent developments to accommodate esthetic restoration for endodontically treated teeth. This has many advantages over conventional post system in physical properties, esthetic factor, risk of root and restoration fracture, adhesion to core, radiopacity, removal and retrievabilty, biocompatibility and chemical stability. Purpose. This in vitro study was to evaluate the most suitable type of resin core for the glass fiber post through surveying the fracture modes and the maximum load that fractures the tooth. Material and methods. 50 sound maxillary premolars restored with glass fiber posts($ParaPost^{(R)}$ Fiber White) and different types of resin cores(ParaCore, $Z100^{TM}$, $Rebilda^{(R)}$ and $Admira^{(R)}$) were prepared and loaded to faiure in a universal test machine. The maximum fracture load and fracture mode were investigated in the specimens that were restored with resin and those of metal cast and core. With the data, Wilcoxon rank sum test was used to validate the significance between the test groups, and Tukey' s studentized range test was used to check if there is any significant statistical difference between each test group. Every analysis was approved with 95% reliance. Results. On measuring the maximum fracture load of teeth specimens, there was a significant difference between the maximum fracture loads of the tooth specimens. ParaCore showed the highest mean maximum fracture load followed by $Z100^{TM}$. And, the distribution of fracture mode of tooth specimens showed generally Type D, the three parted fracture of the core around the post was mostly seen(62.5%), and specifically, ParaCore showed 90% and $Z100^{TM}$ showed 100% Type D fracture. Conclusion. Referring to the values of maximum fracture load and mean compressive fracture load, ParaCore and $Z100^{TM}$ had high values and are recommended as tooth colored resin core material for glass fiber post. CLINICAL IMPLICATIONS. This study was carried out intending to be of aid in selecting the appropriate resin core for the glass fiber post. The dual cure type composite resin ParaCore and light cure type composite resin $Z100^{TM}$ have good properties and are recommended as tooth colored resin core material for glass fiber post.

• 대한심미치과학회지
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• 제27권2호
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• pp.75-81
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• 2018

본 연구의 목적은 기존의 다른 포스트-코어 재료와의 유한요소분석(FEA)의 비교를 통한 치과용 포스트-코어 재료로서의 고성능 폴리머 PEKK의 생체역학 및 장기 안전성을 평가하는 데 있다. 상악 중절치를 모델링 하였으며, 구개 표면에서 치아의 장축에 $45^{\circ}$의 각도로 50N의 반복 하중을 가했다. 전통적으로 사용 된 포스트 코어 재료와 비교하기 위해 3가지 재료 (금, 유리 섬유 및 PEKK)를 시뮬레이션하여 결과를 상호 비교 해 보았다. 상아질보다 낮은 탄성 계수를 갖는 PEKK는 종래의 포스트 코어 재료보다 비교적 치근에 유리한 응력 분포를 보여 주었다. 그러나, PEKK 포스트-코어 시스템은 금속 또는 유리 섬유 포스트-코어 시스템보다 장기간의 반복하중에 대해 타락 및 크라운 파손의 가능성이 더 높을 가능성이 있다.

• 대한치과보철학회지
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• 제41권3호
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• pp.288-299
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• 2003

Statement of problem: Many kinds of post and core systems are in the market, but there are no clear selection criteria for them. Purpose: The purpose of this study was to compare the flexural strength and modulus of elasticity of core materials, and measure the bending strength of post systems made of a variety of materials. Material and Methods: The flexural strength and elastic modulus of thirteen kinds core buildup materials were measured on beams of specimens of $2.0{\times}2.0{\times}24{\pm}0.1mm$. Ten specimens per group were fabricated and loaded on an lnstron testing machine at a crosshead speed of 0.25mm/min. A test span of 20 mm was used. The failure loads were recorded and flexural strength calculated with the measured dimensions. The elastic modulus was calculated from the slopes of the linear portions of the stress-stram graphs. Also nine kinds commercially available prefabricated posts made of various materials with similar nominal diameters, approximately 1.25mm, were loaded in a three-point bend test until plastic deformation or failure occurred. Ten posts per group were tested and the obtained data were anaylzed with analysis of variance and compared with the Tukey multiple comparison tests. Results: Clearfil Photo Core and Luxacore had flexural strengths approaching amalgam, but its modulus of elasticity was only about 15% of that of amalgam. The strengths of the glass ionomer and resin modified glass ionomer were very low. The heat pressed glass ceramic core had a high elastic modulus but a relatively low flexural strength approximating that of the lower strength composite resin core materials. The stainless steel, zirconia and carbon fiber post exhibited high bending strengths. The glass fiber posts displayed strengths that were approximately half of the higher strength posts. Conclusion: When moderate amounts of coronal tooth structure are to be replaced by a post and core on an anterior tooth, a prefabricated post and high strength, high elastic modulus core may be suitable. CLINICAL IMPLICATIONS In this study several newly introduced post and core systems demonstrated satisfactory physical properties. However when the higher stress situation exists with only a minimal ferrule extension remaining a cast post and core or zirconia post and pressed core are desirable.

• Restorative Dentistry and Endodontics
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• 제40권3호
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• pp.229-235
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• 2015

Objectives: To determine and compare the fracture resistance of endodontically treated maxillary central incisors restored with different posts and cores. Materials and Methods: Forty-eight upper central incisors were randomly divided into four groups: cast post and core (group 1), fiber-reinforced composite (FRC) post and composite core (group 2), composite post and core (group 3), and controls (group 4). Mesio-distal and bucco-lingual dimensions at 7 and 14 mm from the apex were compared to ensure standardization among the groups. Twelve teeth were prepared for crown restoration (group 4). Teeth in other groups were endodontically treated, decoronated at 14 mm from the apex, and prepared for posts and cores. Resin-based materials were used for cementation in groups 1 and 2. In group 3, composite was used directly to fill the post space and for core build-up. All samples were restored by standard metal crowns using glass ionomer cement, mounted at $135^{\circ}$ vertical angle, subjected to thermo-mechanical aging, and then fractured using a universal testing machine. Kruskal-Wallis and Mann-Whitney U tests were used to analyze the data. Results: Fracture resistance of the groups was as follows: Control (group 4) > cast post and core (group 1) > fiber post and composite core (group 2) > composite post and core (group 3). All samples in groups 2 and 3 fractured in restorable patterns, whereas most (58%) in group 1 were non-restorable. Conclusions: Within the limitations of this study, FRC posts showed acceptable fracture resistance with favorable fracture patterns for reconstruction of upper central incisors.

• Imaging Science in Dentistry
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• 제50권2호
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• pp.141-151
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• 2020

Purpose: This study aimed to quantify the influence of tooth position within the field-of-view (FOV) on cone-beam computed tomography (CBCT) imaging artifacts' intensity when assessing teeth restored with various intracanal materials. Materials and Methods: Seventy single-rooted teeth were divided into 7 groups (10 teeth per group): NiCr post (NC), AgPd post (AP), metal core fiberglass post (MCFG), fiberglass post (FG), anatomical fiberglass post (AFG), fiberglass post cemented with core build-up cement (FGCo), and anatomical fiberglass post cemented with core build-up cement (AFGCo). All posts were cemented using a regular dual-curing resin cement (Allcem), except FGCo and AFGCo which were cemented with a core build-up dual-curing resin cement (AllcemCore). Each tooth was scanned on a CS9000 in 5 positions within the FOV: a central position, anterior horizontal peripheral, peripheral superior, peripheral inferior, and posterior horizontal peripheral position. Hyperdense, hypodense, remaining teeth areas and ROI areas were quantitatively analyzed using ImageJ software. Results: Posterior horizontal peripheral position increased the intensity of artifacts on FGCo and AFGCo post groups (P<0.05), and specifically the hypodense artifact intensity on FG and AFG post groups (P<0.05). NC and AP groups presented greater intensity of artifacts than any other post groups(P<0.05). Conclusion: Artifact intensity increases in the presence of high atomic number materials and when the object is not centered within the FOV. The impact of positioning within the FOV on artifact was greater for fiberglass posts cemented with core build-up dual-curing cement than for metal posts and fiberglass posts cemented with regular dual-curing cement.

• 대한치과보철학회지
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• 제47권1호
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• pp.53-60
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• 2009

연구목적: 오늘날 심미적 요구의 증가로 치아색 포스트 코어에 대한 많은 관심이 모아지고 있으며 다양한 연구가 진행 중이다. 현재 화이버 포스트 (ParaPost fiber White, Coltene Whaledent, Cuyahoga Falls, USA), 지르코니아 포스트 (CosmoPost, Ivoclar Vivadent, Schann, Germany) 등에 관한 논문은 다소 나와 있으나 요즘 여러 분야에서 관심을 받고 있는 CAD/CAM (computer-aided design/computer-aided manufacturing) 방식으로 지르코니아를 가공한 절삭형 지르코니아 포스트 코어에 대한 연구는 많지 않은 실정이다. 이 연구의 목적은 CAD/CAM을 이용한 지르코니아를 비롯하여 근관치료된 치아에서 사용된 세 가지 다른 치아색 포스트 코어에 대해 미세누출 (microleakage)을 비교해 보는 것이다. 연구 재료 및 방법: 발치된 건전한 상악 절치 27개를 채택하여 백악법랑질경계 (CEJ)에서 절단하여 근관치료를 시행하고, 세군 (각 9개)으로 나누었다. 각군들은 화이버 포스트와 콤포짓트 레진 코어 (1군), 지르코니아 포스트와 열가압형 세라믹 코어 (2군), CAD/CAM 절삭형 지르코니아 포스트 코어 (3군)로 수복하였다. $5-55^{\circ}C$ 1000회 열순환 처리 (thermocycling)를 시행하고, 2% 메틸렌 블루로 $37^{\circ}C$에서 24시간 염색하였다. 치아장축과 평행하게 순설방향으로 절단하여 미세누출을 현미경과 컴퓨터 프로그램을 사용하여 분석을 하였다. 데이터는 one-way ANOVA와 Scheffe's multiple range test (${\alpha}=0.05$)로 분석하였다. 결과: 모든 군에서 미세누출을 보였으며, 지르코니아 포스트와 열가압형 세라믹 코어군 (2군)에서 치근계면 입구에서는 다소 많은 미세누출을 보였으나 포스트 끝에 이르러서는 거의 미세누출이 없는 결과를 보였다. 화이버 포스트와 콤포짓트 레진 코어군 (1군)과CAD/CAM 절삭형 지르코니아 포스트 코어군 (3군)에서는 부위별로 균등한 미세누출을 보였다. 결론: 화이버 포스트와 콤포짓트 레진 코어군, 지르코니아 포스트와 열가압형 세라믹 코어군, CAD/CAM 절삭형 지르코니아 포스트 코어군 모두에서 미세누출을 보였고, 이 중에서 지르코니아 포스트와 열가압형 세라믹 코어군이 좀 더 큰 미세누출에 대한 저항성을 보였으며 화이버 포스트와 콤포짓트 레진 코어군, CAD/CAM 절삭형 지르코니아 포스트 코어군은 유사한 양상을 보였으나, 각 실험군 간에 통계적으로 유의한 차이는 인정되지 않았다. (P>.05)

• 대한치과보철학회지
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• 제39권2호
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• pp.197-207
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• 2001

Development of new ceramics and esthetic needs of patients increase the use of all ceramic restorations. Fractured teeth often need metal post and core as foundation for final restoration. When all ceramic restorations are planned, metal post and core may lead to compromised esthetics because of opacity and gray color of metal post and core. Many techniques have been proposed to solve this problem such as application of an opaque porcelain to the metal core or all ceramic post and core. This study was performed to evaluate effect on color of Empress 2 crown according to various post systems. Color was evaluated by the CIE $L^*a^*b^*$ systems and measured by spectrophotometer (Model CM-3500, Minolta, Japan). Specimens were divided into 4 groups as follows Group 1 : gold cast post specimen + Empress 2 crown specimen Group 2 : application of an opaque porcelain to gold cast post specimen + Empress 2 crown specimen Group 3 : cosmopost specimen + Empress 2 crown specimen Group 4 : In-ceram post specimen + Empress 2 crown specimen. The results obtained as follows, 1. $L^*$ Values showed that group 2, 3, 4 were higher than group 1 with significant difference and group 2, 3, 4 were not significantly different. 2. $a^*$ Values and $b^*$ values also showed that group 2. 3, 4 were higher than group 1 with significant difference and group 2, 3, 4 were not significantly different. 3. ${\Delta}E^* ab$ Values showed that ${\Delta}E^* ab$ 3 was the highest value and ${\Delta}E^* ab$ 5 was the lowest value.