• The Journal of Advanced Prosthodontics
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• 제15권4호
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• pp.171-178
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• 2023

PURPOSE. The purpose of this study was to determine the effect of the connector configuration on the fracture load in conventional and translucent zirconia of three-unit fixed dental prostheses (FDPs). MATERIALS AND METHODS. Six different three-unit FDPs were prepared (n = 6) from three types of zirconia (3Y-TZP (Katana ML^®), 4Y-TZP (Katana STML^®), and 5Y-TZP (Katana UTML^®)) in combination with two connector configurations (4 × 2.25, 3 × 3 mm). The CoCr master models were scanned, and the FDPs were designed and fabricated using CAD-CAM. The FDPs were cemented on the metal model and then loaded with a UTM at a crosshead speed of 1 mm/min until failure. Two-way ANOVA and Tukey's test were used for statistical analysis (α = .05). RESULTS. Fracture loads of 3Y-TZP (2740.6 ± 469.2 and 2718.7 ± 339.0 N for size 4 × 2.25 mm and 3 × 3 mm, respectively) were significantly higher than those of 4Y-TZP (1868.3 ± 281.6 and 1663.6 ± 372.7 N, respectively) and 5Y-TZP (1588.0 ± 255.0 and 1559.1 ± 110.0 N, respectively) (P < .05). No significant difference was found between fracture loads of 4Y-TZP and 5Y-TZP (P > .05). The connector configuration within 9 mm² was found to have no effect on the fracture loads on all three types of zirconia (P > .05). CONCLUSION. Fracture loads of three-unit FDPs were affected by the type of zirconia. The fracture loads of conventional zirconia were higher than those of translucent zirconia. However, it was not affected by the connector configuration when the connector had a cross-sectional area of 9 mm².

• The Journal of Advanced Prosthodontics
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• 제16권1호
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• pp.12-24
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• 2024

PURPOSE. This study aimed to evaluate the maximum vertical wear, volume wear, and surface characteristic of antagonist enamel, opposing monolithic zirconia or lithium disilicate crowns. MATERIALS AND METHODS. The study comprised 24 participants (n = 12), who were randomly allocated to receive either a 5 mol% Y-TZP or a lithium disilicate crown in positions which would oppose the natural first molar tooth. The contralateral first molar along with its antagonist was considered as the enamel opposing natural enamel control. Data collection was performed using an intraoral scanner and polyvinylsiloxane impression. The means of the maximum vertical loss and the volume loss at the occlusal contact areas of the crowns and the various natural antagonists were measured by 3D comparison software. A scanning electron microscope was subsequently used to assess the wear characteristics. RESULTS. The one-year results from 22 participants (n = 11) indicated no significant differences when comparing the zirconia crown's antagonist enamel (40.28 ± 9.11 ㎛, 0.04 ± 0.02 mm³) and the natural enamel wear (38.91 ± 7.09 ㎛, 0.04 ± 0.02 mm³) (P > .05). Also, there is no significant differences between lithium disilicate crown's antagonist enamel (47.81 ± 9.41 ㎛, 0.04 ± 0.02 mm³) and the natural enamel wear (39.11 ± 7.90 ㎛, 0.04 ± 0.02 mm³) (P > .05). CONCLUSION. While some studies suggested that monolithic zirconia caused less wear on opposing enamel than lithium disilicate, this study found similar wear levels to enamel for both materials compared to natural teeth.

• The Journal of Advanced Prosthodontics
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• 제16권2호
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• pp.91-104
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• 2024

PURPOSE. The objectives of the current study were to estimate the influence of self-reinforced hollow structures with a graded density on the dimensional accuracy, weight, and mechanical properties of Co-Cr objects printed with the direct metal laser sintering (DMLS) technique. MATERIALS AND METHODS. Sixty-five dog-bone samples were manufactured to evaluate the dimensional accuracy of printing, weight, and tensile properties of DMLS printed Co-Cr. They were divided into Group 1 (control) (n = 5), Group 2, 3, and 4 with incorporated hollow structures based on (spherical, elliptical, and diamond) shapes; they were subdivided into subgroups (n = 5) according to the volumetric reduction (10%, 15%, 20% and 25%). Radiographic imaging and microscopic analysis of the fractographs were conducted to validate the created geometries; the dimensional accuracy, weight, yield tensile strength, and modulus of elasticity were calculated. The data were estimated by one-way ANOVA and Duncan's tests at P < .05. RESULTS. The accuracy test showed an insignificant difference in the x, y, z directions in all printed groups. The weight was significantly reduced proportionally to the reduced volume fraction. The yield strength and elastic modulus of the control group and Group 2 at 10% volume reduction were comparable and significantly higher than the other subgroups. CONCLUSION. The printing accuracy was not affected by the presence or type of the hollow geometry. The weight of Group 2 at 10% reduction was significantly lower than that of the control group. The yield strength and elastic modulus of the Group 2 at a 10% reduction showed means equivalent to the compact objects and were significantly higher than other subgroups.

• 대한치과보철학회지
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• 제56권4호
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• pp.338-346
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• 2018

엇갈린 교합 환자의 치료 방법은 피개의치, 이중관 의치를 사용하여 치료하거나 결손 부위에 임플란트를 식립함으로써 교합 지지를 회복해주는 방법이 있다. 잔존 치조골의 양이 양호하고 심미적, 기능적으로 임플란트 식립이 가능한 경우 임플란트 고정성 보철물 수복을 통해 환자에게 적절한 교합지지 및 기능, 편안함을 제공할 수 있다. 이 증례는 발치 후 심한 치조골 흡수가 동반되어 좌우 엇갈린 교합이 된 환자에서 상악동 골이식술 및 수직, 수평적 치조골 증대술을 실시하였다. 이후, 보철적으로 이상적 위치에 임플란트를 식립하였고 임시 보철물로 환자의 고유의 기능 및 심미를 평가한 후 이를 반영할 수 있는 double scanning technique을 사용하여 최종 보철물을 제작하였다. 이를 통해 엇갈린 교합을 성공적으로 극복하였으며, 저작 및 심미를 회복하여 만족스러운 결과를 얻었기에 이를 보고하고자 한다.

• 대한치과보철학회지
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• 제43권4호
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• pp.466-477
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• 2005

Statement of problem : Problem of matching the appearance of porcelain restorations with the patient's natural dentition has always been a concern to dental clinicians. Recently, demands for esthetics, even in restorations requiring strength, has brought a revolution to dentistry and increased use of zirconia. Among the various factors, shade and translucency or the core can significantly affect the overall esthetics of the restoration and should be considered when selecting an all-ceramic system. Purpose : The purpose of this study was to spectrophotometrically evaluate the influence of different zirconia systems and core thickness on the final shade of all-ceramic restorations using the CIEL$^*a^*b^*$ system. Material and Methods: Core specimens (n : 20 per group) of In-Ceram Alumina, In-Ceram Zirconia, Digident CAD/CAM Zirconia, Cercon Zirconia were fabricated 20mm in diameter. 10 specimens of each group were fabricated at core thickness of 0.5mm and 0.7mm. These core specimens were veneered with shade Al & A3 porcelain of the recommended manufacturer. CIEL$^*a^*b^*$ coordinates were recorded for each specimen with a spectrophotometer (Model CM-2600d, Minolta, Japan). Color differences were calculated using the equation ${\Delta}E^*=[({\Delta}L^*)^2+({\Delta}a^*)^2+({\Delta}b^*)^2]^{\frac{1}{2}}$. Results : 1. Specimens of core thickness 0.5mm and 0.7mm did not exhibit clinically perceived color difference. 2. Regarding shade reproducibility, In-Ceram Alumina and In-Ceram Zirconia showed significant difference within each group. 3. Cercon Zirconia group showed the highest $L^*$ value and Digident Zirconia group showed lowest $a^*$ & $b^*$ value. 4. Generally the shade difference between materials was higher in the A3 shade group than in the Al shade group. Conclusion: Within the limitations of this study, there was no color difference after increase in core thickness and every all-ceramic system has color characteristics that clinicians have to consider when selecting materials. Also, manufacturers of different porcelain systems must make every effort to achieve color reproducibility.

• 대한치과보철학회지
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• 제59권1호
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• pp.43-54
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• 2021

디지털기술의 급격한 발전으로 보철 수복치료에 있어서도 많은 기술들이 활용되고 있다. 특히 최근에는 구강스캐너와 3D printing 기술이 광범위하게 사용되고, 더 나아가 안면스캔 기술 또한 접목되어 활용되고 있다. 본 증례는 37세 여성환자에서 전통적인 방식으로 제작되고 장착되어 충분히 평가된 전악 고정성 임시수복상태를 구강스캐너와 안면스캐너, 3D printing 등의 다양한 디지털 기술을 활용하여 안모와 조화를 이루는 최종보철물로 이행하는 과정을 거쳤다. 이를 통해 안정적인 교합을 회복하고 기능적, 심미적으로 만족할만한 결과를 얻었기에 보고하는 바이다.

• 대한치과보철학회지
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• 제59권1호
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• pp.116-125
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• 2021

디지털 치의학에서의 주요한 발전 중 하나인 3차원 구강스캐너는 최근 고정성 보철물에 널리 사용되고 있으며 가철성 보철물에서도 사용이 증가하고 있다. 전신성 피부경화증에 의한 안면부 연조직의 경화는 개구량 제한을 일으켜 치아상실을 야기하며 기존의 통상적인 보철 치료를 어렵게 한다. 본 증례에서는 디지털 치의학의 발전을 통한 3차원 구강스캐너를 이용하여 개구량 제한과 그에 따른 소구증을 가진 전신성 피부경화증 환자에서 3차원 구강구조를 광학인상 채득하고, 이를 바탕으로 3D 프린터를 이용한 임시의치 제작을 통해 3차원 구강스캐너를 통한 가철성 보철물 제작의 가능성을 확인하였다. 이후 최종 지대치 정리 후 최종 광학인상 채득하여 국소의치 금속구조물을 제작하였다. 금속구조물의 적합도는 임상적으로 만족스러웠으며 이후 최종 국소의치 제작, 장착하여 상실부위에 대한 수복을 진행, 임상적으로 만족스러운 결과를 얻을 수 있었다.

• 대한치과보철학회지
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• 제60권3호
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• pp.283-292
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• 2022

임플란트를 이용한 고정성 보철 치료를 위해서는 보철 치료에 적합한 위치에 임플란트가 식립되어야 하며 이를 위해 guided implant surgery와 CAD-CAM을 활용한 보철물 제작이 최근 널리 사용되고 있다. 수술 시에는 surgical guide를 이용해 flapless 방식으로 최소침습 보철수복이 가능 하다. 본 증례의 환자는 86세 남성 환자로 기존 의치 사용 시 불편함으로 치료를 원하였다. 환자는 전신질환으로 인해 가철성 국소의치 사용이 어려워 상악은 총의치, 하악의 경우 임플란트 고정성 보철물 수복하였다. 전신질환으로 인해 높은 출혈 위험성을 가지므로 surgical guide를 사용해 flapless 방식으로 임플란트를 식립하였다. 최종적으로 상악 총의치 및 하악 나사 유지형 지르코니아를 보철물을 제작하였으며, 만족스러운 기능 및 심미 회복을 보였기에 보고하는 바이다.

• The Journal of Advanced Prosthodontics
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• 제13권3호
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• pp.160-171
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• 2021

Purpose. This in-vitro study evaluated and compared the color stability of 3D-printed and conventional heat-polymerized acrylic resins following aging, mechanical brushing, and immersion in staining medium. Materials and methods. Forty disc-shaped specimens (10 mm in diameter and 3 mm thick) were prepared from two 3D-printed [DentaBASE (DB) and Denture 3D+ (D3D)] and one conventional polymethylmethacrylate (PMMA) denture materials. The specimens were thermo-cycled, subjected to mechanical brushing, and were immersed in either coffee, lemon juice, coke, or artificial saliva (AS) to simulate one and two years of oral use. Color measurements of the specimens were recorded by a spectrophotometer at baseline (T0), and after one (T1) and two years (T2) of simulation. The color changes (ΔE) were determined and also quantified according to the National Bureau of Standards (NBS) units. Descriptive statistics, followed by factorial ANOVA and Bonferroni post-hoc test (α=.05), were applied for data analysis. Results. The independent factors, namely material, staining medium, and immersion time, and interaction among these factors significantly influenced ΔE (P<.009). Irrespective of the materials, treatments, and time, the highest and the lowest mean ΔEs were observed for PMMA in lemon juice (4.58 ± 1.30) and DB in AS (0.41 ± 0.18), respectively. Regarding the material type, PMMA demonstrated the highest mean ΔE (2.31 ± 1.37), followed by D3D (1.67 ± 0.66), and DB (0.85 ± 0.52), and the difference in ΔE between the materials were statistically significant (P<.001). All the specimens demonstrated a decreased color changes at T2 compared to T1, and this difference in mean ΔE was statistically significant (P<.001). Conclusion. The color changes of 3D-printed denture resins were low compared to conventional heat polymerized PMMA. All the tested materials, irrespective of the staining medium used, demonstrated a significant decrease in ΔE values over time.

• 구강회복응용과학지
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• 제38권4호
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• pp.249-256
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• 2022

성공적인 상악전치부의 임플란트 식립은 많은 고려를 필요로 한다. 환자를 만족시키며 기능적이며 심미적인 보철수복을 위해서는, 치료에 앞서 정확한 진단이 선행되어야 하며 이는 구내스캔, 콘빔시티, 그리고 안면스캔을 중첩함으로 시도해 볼 수 있다. 구내스캔을 통해 얻어지는 환자의 교합양상과 콘빔시티에서 얻어지는 환자의 치조골의 양상 및 질, 그리고 안면스캔에서 얻어지는 환자의 특성과 구외평가를 어우르는 진단은 보다 성공적인 보철수복을 위한 발판이 될 수 있다. 다양한 정보의 중첩을 통해, 보철적으로 이상적인 치관의 위치를 우선순위에 두지만, 환자의 생물학적 한계를 포용하는 "탑다운"형식의 임플란트 진단은, 이를 고려한 서지컬 가이드를 3D 프린팅하고, 수술에 사용함으로써 구현되었다. 환자의 치조골 소실로 인한 임플란트 식립위치의 한계점은, 치아의 선각과 착시효과를 이용한 보철수복을 통하여 극복하려고 노력하였다. 이후, 임시수복물을 사용하고 환자가 가장 편하다고 느끼는 보철물을 장착한 뒤 디지털 교합장비(Arcus Digma II)를 이용하여 전방유도와 하악의 운동을 측정하여 이를 최종보철물에 적용하였다.