• 대한치과보철학회지
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• 제55권1호
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• pp.26-31
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• 2017

목적: 지르코니아 프레임워크를 이용한 시멘트 유지형 임플란트-지지 단일 크라운과 연결 크라운의 성공률과 보철적 합병증을 임상적으로 평가하는 것이다. 대상 및 방법: 67명의 환자에서 75개 수복물(단일 51개, 연결 24개)을 지르코니아 프레임워크를 이용한 시멘트 유지형 임플란트-지지 단일 크라운 혹은 연결 크라운으로 수복했다. 모든 수복물은 임시 시멘트로 합착했다. 보철적 합병증과 성공률을 조사하고, 나이, 성별, 보철물의 위치, 대합치, 보철물의 유형이 보철적 합병증에 미치는 영향을 평가했다. 결과:평균 22.2개월의 관찰 결과, 최종 누적 성공률은 66.9 (73.2 - 60.6)%였다. 유지 상실이 16개 보철물(단일 14개, 연결 2개)에서 나타났고, 지대주 나사 풀림과 비니어 도재 파절은 단일 크라운에서만 각각 2개의 보철물에서 나타났다. 단일 크라운과 연결 크라운에 대한 Kaplan-Meier 생존분석 결과, 최종 누적 성공률은 각각 58.9 (66.6 - 51.2)%, 87.5 (96.1 - 78.9)%를 보여 통계적으로 유의한 차이가 있었지만, 다른 고려 요인들은 보철적 합병증에 통계적으로 유의성이 없었다. 결론: 보철적 합병증은 유지 상실이 가장 많았고, 지대주 나사 풀림 및 비니어 도재 파절은 단일 크라운에서만 비교적 적게 관찰되었다. 나이, 성별, 보철물의 위치, 대합치에 따른 보철적 합병증에 미치는 영향은 유의한 차이가 없었지만, 상부 보철물을 연결 크라운으로 제작했을 때, 단일 크라운으로 제작한 경우보다 높은 성공률을 보였다.

• Journal of Periodontal and Implant Science
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• 제28권2호
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• pp.321-337
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• 1998

The aims of this study were firstly to investigate soft tissue reactions around single implant-supported crowns and secondly to compare soft tissue dimensions and conditions of the crowns in relation to interdental papillae, and lastly to investigate patients'esthetic satisfaction with their single implant-supported crowns according to the interdental papillae presence/absence. Twenty-nine patients (41 implants) whose single missing tooth in the maxillary anterior region had been replaced by single implant-supported crown participated for the study and various variables of soft tissue conditions, dimensions and crown dimensions were measured around the single implant-supported crowns at clinical examination and from study models and slides. The results showed that the soft tissue conditions around the single implantsupported crowns were similar to those around implants used for partially or totolly edentulous patients. Except for the high frequency of bleeding on probing, all other parameters revealed healthy conditions. The buccal sites of the crown had a shallow pocket comparing with other sites. At all sites of the crown, similar status of little inflammation was found. Mesial sites and central-incisor positioned implantsupported crowns had lower contact point position than distal sites and lateral-incisor positioned crowns, respectively. Mucositis index, probing depth and contact point position were significantly correlated with papillae index(p < 0.05). More inflammation and lower contact point position were found at the implant-supported crown with no interdental space than that with interdental space. Patients showed high esthetic satisfaction regardless of interdental space presence. The result indicated that, despite of their submucosal crown margins, single implantsupported crowns have soft tissue conditions as good as other implants used for the treatment of the different types of edentulism and a clinician can manipulate interdental papilla height by modifying crown shapes within the limits of not violating total esthetics.

• 대한치과기공학회지
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• 제38권3호
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• pp.185-191
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• 2016

Purpose: The purpose of this study were to evaluate the quality of dental prostheses printed by 3-dimensional printing system. Methods: Mater model was prepared and ten study models were fabricated. Ten single crowns were printed by 3D-printing system(Resin group) and another ten single crowns using casting method were manufactured(Metal group). The marginal adaptation of single crowns were measured using by silicone replica technique. Silicone replicas were sectioned four times. The marginal adaptations were evaluated using by digital microscope. Statistical analyses were performed with Mann-Whitney test(${\alpha}=0.05$). Results: $Mean{\pm}standard$ deviations of all marginal adaptations were $92.1(20.0){\mu}m$ for Metal group and $69.7(12.3){\mu}m$ for Resin group. Two groups were no statistically significant differences(p>0.05). Conclusion: Marginal adaptation of single crowns printed by 3D-printing system were ranged within the clinical recommendation.

• Journal of Periodontal and Implant Science
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• 제28권3호
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• pp.507-517
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• 1998

This study was performed to investigate the soft tissue changes around single implant-supported crowns during followup periods. Twenty patients(31 implants) whose single missing tooth in the maxillary anterior region had been replaced with an single implant-supported crown were recruited for the study. Crown length, soft tissue level and papilla height at the single implant-supported crowns were measured at follow-up examination and calculated from the slides taken at time of crown placement. as well Papilla index was scored from the slides taken at the time of crown placement and follow-up examination. A very little amount of recession occurred and the soft tissue level moved more apically and the papilla height increased significantly (p<0.01). Especially, both mesial and distal papilla index at single implant-supported crowns increased significantly during follow-up periods (p<0.001). When the two slides taken at the time of crown placement and follow-up were compared simultaneously, except one site, papillae size increased at all sites. From the results of the study, the interdental papillae at the single implant-supported crowns seemed to regenerate significantly and their crown margins were stable during follow-up periods. Hence it is indicated that various surgical interventions at on early stage to enhance soft tissue esthetics arourd single implants may be unnecessary.

• 대한치과보철학회지
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• 제44권3호
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• pp.275-283
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• 2006

Statement of problem. There have been many studies about marginal discrepancy of single restorations made by various systems and materials. However most of the statistical inferences are not definite because of sample size, measurement number, measuring instruments, etc, and there have been few studies about the marginal fit of the Digident CAD/ CAM zirconia ceramic crowns. Purpose. The purpose of this study was to compare the marginal fit of the anterior single restorations made by using the Digident CAD / CAM zirconia ceramic crowns with metal-ceramic restorations and to obtain more accurate information by using a large enough sample size and by making sufficient measurements per specimen. Material and Methods. The crowns were made from one extracted maxillary central incisor pre-pared with a 1mm shoulder margin and $6^{\circ}$ taper walls by milling machine. The in vitro marginal discrepancies of the digident CAD / CAM zirconia ceramic crowns and control groups(metal ceramic crowns) were evaluated and compared. Twenty crowns per each system were fabricated. Measurements of a crown were recorded at 50 points that were randomly selected for marginal gap evaluation. Parametric statistical analysis was performed for the results. Conclusion. Within the limitations of this in vitro study, the following conclusions were drawn: 1. Mean gap dimensions and standard deviations at the marginal opening for maxillary incisal crowns were $88{\pm}10{\mu}m$ for the control (metal-ceramic crowns), $92{\pm}4{\mu}m$ for Digident CAD / CAM zirconia ceramic crowns. 2. Marginal gap between Digident CAD / CAM zirconia ceramic crowns and metal ceramic crowns did not show significant difference (P>.05). 3. The Digident CAD/ CAM zirconia ceramic crowns and metal ceramic crowns showed clinically acceptable marginal discrepancy.

• 대한치과보철학회지
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• 제43권3호
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• pp.306-313
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• 2005

Statement of problem. There have been many studies about marginal discrepancy of single restorations made by various systems and materials. But most of statistical inferences are not definite because of sample size, measurement number, measuring , instruments, etc. And there have been few studies about the marginal fit of Computer-aided Cercon crowns. Purpose. The purpose of this study was to compare the marginal fit of the anterior single restorations made using computer-aided milled Cercon crowns with metal-ceramic restorations and to obtain more accurate information by using a large enough sample size and by making sufficient measurements per specimen. Material and methods. The in vitro marginal discrepancies of computer-aided milled Cercon crowns and control groups (metal ceramic crowns) were evaluated and compared. The crowns were made from one extracted maxillary central incisor prepared by milling machine. 30 crowns per each system were fabricated. Measurements of a crown were recorded at 50 points that were randomly selected for marginal gap evaluation. Parametric statistical analysis was performed for the results. Results. The means and standard deviations of the marginal fit were 85$\pm$22$\mu$m for the control group and 91$\pm$15$\mu$m for the Cercon crowns. The t-test of the marginal discrepancies between Cercon crowns and metal-ceramic crowns were performed. Significant differences were not found between groups (P=0.230>.05). Based on the criterion of 120$\mu$m as the limit of clinical acceptability, the mean marginal fits of Cercon crowns and metal-ceramic crowns were acceptable. Conclusion. Within the limitations of this in vitro study, the following conclusions were drawn: 1. Mean gap dimensions and standard deviations at the marginal opening for maxillary incisal crowns were 85$\pm$22$\mu$m for the control (metal-ceramic crowns), 91$\pm$15$\mu$m for Cercon crowns. 2. The Cercon crowns showed slightly larger marginal gap discrepancy than the control but marginal gap between Computer-aided milled Cercon crowns and metal ceramic crowns did not showed significant difference (P>.05). 3. The Cercon crowns and metal ceramic crowns showed clinically acceptable marginal discrepancy.

• The Journal of Advanced Prosthodontics
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• 제10권1호
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• pp.65-72
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• 2018

PURPOSE. The aim of this in vitro study was to investigate the fracture resistance under chewing simulation of implant-supported posterior restorations (crowns cemented to hybrid-abutments) made of different all-ceramic materials. MATERIALS AND METHODS. Monolithic zirconia (MZr) and monolithic lithium disilicate (MLD) crowns for mandibular first molar were fabricated using computer-aided design/computer-aided manufacturing technology and then cemented to zirconia hybrid-abutments (Ti-based). Each group was divided into two subgroups (n=10): (A) control group, crowns were subjected to single load to fracture; (B) test group, crowns underwent chewing simulation using multiple loads for 1.2 million cycles at 1.2 Hz with simultaneous thermocycling between $5^{\circ}C$ and $55^{\circ}C$. Data was statistically analyzed with one-way ANOVA and a Post-Hoc test. RESULTS. All tested crowns survived chewing simulation resulting in 100% survival rate. However, wear facets were observed on all the crowns at the occlusal contact point. Fracture load of monolithic lithium disilicate crowns was statistically significantly lower than that of monolithic zirconia crowns. Also, fracture load was significantly reduced in both of the all-ceramic materials after exposure to chewing simulation and thermocycling. Crowns of all test groups exhibited cohesive fracture within the monolithic crown structure only, and no abutment fractures or screw loosening were observed. CONCLUSION. When supported by implants, monolithic zirconia restorations cemented to hybrid abutments withstand masticatory forces. Also, fatigue loading accompanied by simultaneous thermocycling significantly reduces the strength of both of the all-ceramic materials. Moreover, further research is needed to define potentials, limits, and long-term serviceability of the materials and hybrid abutments.

• Journal of Yeungnam Medical Science
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• 제40권3호
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• pp.302-307
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• 2023

With recent developments in digital dentistry, research on techniques and materials for three-dimensional (3D) printing is actively underway. We report the clinical applications and outcomes of 3D printing of temporary crowns fabricated with polylactic acid (PLA) using a fused deposition modeling (FDM) printer. Five participants were recruited from among patients scheduled to be treated with a single full-coverage crown at a dental clinic in a university medical center from June to August 2022. We used 3D-printed crowns fabricated with PLA using an FDM printer as temporary crowns and were assessed for discomfort, fracture, and dislodging. The 3D-printed temporary crowns were maintained without fracture, dislodging, or discomfort until the permanent prosthesis was ready. The average time required for printing the temporary crowns was approximately 7 minutes. The 3D printing of temporary crowns with PLA using an FDM printer is a convenient process for dentists. However, these crowns have some limitations, such as rough surface texture and translucency; therefore, the 3D printing process should be improved to produce better prostheses.

• The Journal of Advanced Prosthodontics
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• 제11권2호
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• pp.120-127
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• 2019

PURPOSE. To determine wear amount of single molar crowns, made from four different restoratives, and opposing natural teeth through computerized fabrication techniques using 3D image alignment. MATERIALS AND METHODS. A total of 24 single crowns (N = 24 patients, age range: 18 - 50) were made from lithium disilicate (IPS E-max CAD), lithium silicate and zirconia based (Vita Suprinity CAD), resin matrix ceramic material (Cerasmart, GC), and dual matrix (Vita Enamic CAD) blocks. After digital impressions (Cerec 3D Bluecam, DentsplySirona), the crowns were designed and manufactured (Cerec 3, DentsplySirona). A dualcuring resin cement was used for cementation (Variolink Esthetic DC, Ivoclar). Then, measurement and recording of crowns and the opposing enamel surfaces with the intraoral scanner were made as well as at the third and sixth month follow-ups. All measurements were superimposed with a software (David-Laserscanner, V3.10.4). Volume loss due to wear was calculated from baseline to follow-up periods with Siemens Unigraphics NX 10 software. Statistical analysis was accomplished by Repeated Measures for ANOVA (SPSS 21) at = .05 significance level. RESULTS. After 6 months, insignificant differences of the glass matrix and resin matrix materials for restoration/enamel wear were observed (P>.05). While there were no significant differences between the glass matrix groups (P>.05), significant differences between the resin matrix group materials (P<.05) were obtained. Although Cerasmart and Enamic were both resin matrix based, they exhibited different wear characteristics. CONCLUSION. Glass matrix materials showed less wear both on their own and opposing enamel surfaces than resin matrix ceramic materials.

• 대한치과보철학회지
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• 제39권6호
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• pp.599-610
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• 2001

Due to an increasing interest in esthetics and concerns about toxic and allergic reactions to certain alloys, patients and dentists have been looking for metal-free tooth-colored restorations. Recent improvement in technology of new all-ceramic materials and composite materials has broadened the options for esthetic single crown restorations. The aim of this investigation was to study the fracture strength of the metal-free posterior single crowns fabricated using two recently introduced systems, Empress 2 ceramic and Targis-Vectris. Forty premolar-shaped stainless steel dies with the 1mm-wide circumferential shoulder were prepared. Ten cylindrical crowns having a diameter of 8.0mm and total height of 7.5mm were fabricated for each crown system respectively(PFM, Empress staining technique, Empress 2 layering technique, and Targis- Vectris). The crowns were filled with cement and placed on the stainless steel dies with firm finger pressure. The crowns were then stored in distilled water at room temperature for 24 hours before testing. The crowns were tested for fracture strength in an Instron universal testing machine (Instron 6022). With a crosshead speed of 1mm/min the center of the occlusal surface of the crown was loaded using a 4-mm-diameter stainless steel ball until fracture occurred. The fracture surfaces of the crowns were gold coated and examined using scanning electron microscopy(Jeol JSM-840 Joel Ltd., Akishima, Tokyo, Japan). Within the parameters of this study the following conclusions were drawn: 1. The mean fracture strength for PFM crowns was 5829(${\pm}906$)N; for Empress staining technique the fracture strength was 1697(${\pm}604$)N; for Empress 2 Layering technique the fracture strength was 1781N(${\pm}400$)N, and the fracture strength for Targis- Vectris was 3093(${\pm}475$)N. 2. The fracture strength of the PFM crowns was significantly higher than that of the Empress 2 and the Targis-Vectris crowns (P<0.05). 3. The fracture strength of the Targis-Vectris crowns was significantly higher than that of the Empress 2 crowns (P<0.05). 4. No statistical difference was found when Empress staining technique was compared with Empress 2 layering technique. 5. The SEM image of fracture surface of Empress 2 crown showed a very dense microstructure of the lithium disilicate crystals and the SEM image of fracture surface of Targis-Vectris crown showed indentations of Vectris and some fibers tom off from Vectris.