• 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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• 제56권3호
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• pp.258-268
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• 2018

목적: 본 연구는 보철물의 적합 및 인상의 정확성에 관한 문헌들을 체계적으로 고찰하여 구강 내 스캐너를 이용한 디지털 인상법이 전통적인 인상법을 대체할 만한 정확도를 보이는지 알아보고자 한다. 재료 및 방법: 1997년 8월 1일부터 2017년 7월 31일까지 출판된 영어로 쓰여진 연구를 대상으로 디지털 인상법의 정확성에 대한 문헌을 MEDLINE/PubMed 전자 검색 및 수기탐색을 시행하였다. 조건에 따라 선택된 연구의 데이터를 스프레드 시트에 2명의 검토자가 독립적으로 정리하였다. 결과: 총 35개의 연구가 선택되었고, 26개의 연구는 보철물의 적합성을 비교하였고 9개의 연구는 보철물 없이 스캔 데이터를 통해 인상의 정확성을 비교하였다. 대부분의 연구가 보철물을 이용해 인상법의 정확성을 비교하였다. 결론: 본 고찰에 따르면 자연치열에서 디지털 인상법으로 단일관이나 근원심으로 길이가 짧은 보철물을 제작하는 것은 임상적으로 충분히 신뢰할만한 하다. 그러나 디지털 인상법으로 길이가 긴 보철물을 제작하는 것은 연구가 적어 아직 한계가 있다. 임플란트 보철물 제작에 있어서 구내스캐너를 이용한 디지털 인상법으로 전통적인 인상법을 완전히 대체하기는 아직 어렵다.

• 대한치과기공학회지
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• 제41권1호
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• pp.21-27
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• 2019

Purpose: To evaluate 2D and 3D of occulsal, mesial-occlusal and mesial-occlusal-distal cavity of composite resin inlay. Methods: Abutment tooth 16, 36 of FDI system was selected for the study. Inlay prostheses classified as occlusal cavity (OC group), mesial-occlusal (MOC) and mesial-occlusal-distal cavity (MODC) were prepared using composite resin. Composite resin was injected with composite resin in prepared tooth cavity and then photopolymerized with UV light. Additional thermal polymerization was performed. Marginal gap of composite resin inlays were measured by digital microscope(x160) with silicone replica technique. The data was analyzed from statistical software for Kruskal-Wallis test (${\alpha}=0.05$). 3-dimensional analysis was analyzed through superimposition method. Results: The smallest 2D marginal fit measure of the three groups was $47.0{\pm}21.6{\mu}m$ in the MOC group. The largest 2D marginal was $69.1{\pm}33.8{\mu}m$ in the MODC group. In the trueness of the three groups, the most accurate figure was $14.4{\pm}2.3{\mu}m$ for the MODC group. In Precision, the most accurate figure was $14.5{\pm}4.3{\mu}m$ for the MODC group. Conclusion : In this study, 2D marginal fit of OC, MOC, and MODC cavities fabricated with composite resin was applicable to all clinical applications. In the 3D inner surface accuracy evaluation, the MODC group showed the accuracy results.

• 대한치과기공학회지
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• 제45권2호
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• pp.31-38
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• 2023

Purpose: This in vitro study aimed to compare the trueness of 3-unit fixed dental provisional prostheses (FDPs) fabricated by three different additive manufacturing and subtractive manufacturing procedures. Methods: A reference model with a maxillary left second premolar and the second molar prepped and the first molar missing was scanned for the fabrication of 3-unit FDPs. An anatomically shaped 3-unit FDP was designed on computer-aided design software. 10 FDPs were fabricated by subtractive (MI group) and additive manufacturing (stereolithography: SL group, digital light processing: DL group, liquid crystal displays: LC group) methods, respectively (N=40). All FDPs were scanned and exported to the standard triangulated language file. A three-dimensional analysis program measured the discrepancy of the internal, margin, and pontic base area. As for the comparison among manufacturing procedures, the Kruskal-Wallis test and the Mann-Whitney test with Bonferroni correction were evaluated statistically. Results: Regarding the internal area, the root mean square (RMS) value of the 3-unit FDPs was the lowest in the MI group (31.79±6.39 ㎛) and the highest in the SL group (69.34±29.88 ㎛; p=0.001). In the marginal area, those of the 3-unit FDPs were the lowest in the LC group (25.39±4.36 ㎛) and the highest in the SL group (48.94±18.98 ㎛; p=0.001). In the pontic base area, those of the 3-unit FDPs were the lowest in the LC group (8.72±2.74 ㎛) and the highest in the DL group (20.75±2.03 ㎛; p=0.001). Conclusion: A statistically significant difference was observed in the RMS mean values of all the groups. However, in comparison to the subtractive manufacturing method, all measurement areas of 3-unit FDPs fabricated by three different additive manufacturing methods are within a clinically acceptable range.