• 대한치과기공학회지
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• 제41권4호
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• pp.287-293
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• 2019

Purpose: To evaluate the accuracy of the 3D printed die models and to investigate its clinical applicability. Methods: Stone die models were fabricated from conventional impressions(stone die model; SDM, n=7). 3D virtual models obtained from the digital impressions were manufactured as a 3D printed die models using a 3D printer(3D printed die models;3DM, n=7). Reference model, stone die models and 3D printed die models were scanned with a reference scanner. All dies model dataset were superimposed with the reference model file by the "Best fit alignment" method using 3D analysis software. Statistical analysis was performed using the independent t-test and 2-way ANOVA (α=.05). Results: The RMS value of the 3D printed die model was significantly larger than the RMS value of the stone die model (P<.001). As a result of 2-way ANOVA, significant differences were found between the model group (P<.001) and the part (P<.001), and their interaction effects (P<.001). Conclusion: The 3D printed die model showed lower accuracy than the stone die model. Therefore, it is necessary to further improve the performance of 3D printer in order to apply the 3D printed model in prosthodontics.

• 대한치과기공학회지
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• 제44권2호
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• pp.31-37
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• 2022

Purpose: The aim of this study was to evaluate the accuracy of provisional crowns manufactured using a milling machine and a digital light processing (DLP) printer. Methods: A full-contour crown was designed using computer-aided design software. Provisional crowns of this design were manufactured using a milling machine and using a DLP three-dimensional (3D) printer (N=20). The provisional crowns were digitized with an extraoral scanner, and 3D deviation analysis was applied to the scanned data to confirm their accuracy. An independent t-test was performed to detect the significant differences, and the Kolmogorov-Smirnov test was used for analysis (α=0.05). Results: No significant differences were found among the precision of marginal surface between the printed and milled crowns (p=0.181). The trueness of marginal and internal surfaces of the milled crowns were statistically higher than those of the printed crowns (p=0.024, p=0.001; respectively). Conclusion: The accuracy of provisional crowns manufactured using a milling machine and a 3D printer differed significantly except with regards to the precision of the internal surface. However, all the crowns were clinically acceptable, regardless of the manufacturing method used.

• The Journal of Advanced Prosthodontics
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• 제15권6호
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• pp.315-332
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• 2023

PURPOSE. This study aimed to investigate whether the accuracy of intraoral scanners is influenced by different scanning strategies in an in vitro setting, through a systematic review and meta-analysis. MATERIALS AND METHODS. This review was conducted in accordance with the PRISMA 2020 standard. The following PICOS approach was used: population, tooth impressions; intervention, the use of intraoral scanners with scanning strategies different from the manufacturer's instructions; control, the use of intraoral scanners following the manufacturers' requirements; outcome, accuracy of intraoral scanners; type of studies, in vitro. A comprehensive literature search was conducted across various databases including Embase, SciELO, PubMed, Scopus, and Web of Science. The inclusion criteria were based on in vitro studies that reported the accuracy of digital impressions using intraoral scanners. Analysis was performed using Review Manager software (version 5.3.5; Cochrane Collaboration, Copenhagen, Denmark). Global comparisons were made using a standardized mean difference based on random-effect models, with a significance level of α = 0.05. RESULTS. The meta-analysis included 15 articles. Digital impression accuracy significantly improved under dry conditions (P < 0.001). Moreover, trueness and precision were enhanced when artificial landmarks were used (P ≤ 0.02) and when an S-shaped pattern was followed (P ≤ 0.01). However, the type of light used did not have a significant impact on the accuracy of the digital intraoral scanners (P ≥ 0.16). CONCLUSION. The accuracy of digital intraoral scanners can be enhanced by employing scanning processes using artificial landmarks and digital impressions under dry conditions.

• The Journal of Advanced Prosthodontics
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• 제13권4호
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• pp.191-204
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• 2021

PURPOSE. The purpose of this study is to present a methodology to evaluate the accuracy of intraoral scanners (IOS) used in vivo. MATERIALS AND METHODS. A specific feature-based gauge was designed, manufactured, and measured in a coordinate measuring machine (CMM), obtaining reference distances and angles. Then, 10 scans were taken by an IOS with the gauge in the patient's mouth and from the obtained stereolithography (STL) files, a total of 40 distances and 150 angles were measured and compared with the gauge's reference values. In order to provide a comparison, there were defined distance and angle groups in accordance with the increasing scanning area: from a short span area to a complete-arch scanning extension. Data was analyzed using software for statistical analysis. RESULTS. Deviations in measured distances showed that accuracy worsened as the scanning area increased: trueness varied from 0.018 ± 0.021 mm in a distance equivalent to the space spanning a four-unit bridge to 0.106 ± 0.08 mm in a space equivalent to a complete arch. Precision ranged from 0.015 ± 0.03 mm to 0.077 ± 0.073 mm in the same two areas. When analyzing angles, deviations did not show such a worsening pattern. In addition, deviations in angle measurement values were low and there were no calculated significant differences among angle groups. CONCLUSION. Currently, there is no standardized procedure to assess the accuracy of IOS in vivo, and the results show that the proposed methodology can contribute to this purpose. The deviations measured in the study show a worsening accuracy when increasing the length of the scanning area.

• 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.

• 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.