• Journal of Korean Dental Science
• /
• 제16권2호
• /
• pp.149-155
• /
• 2023

Purpose: The purpose of this study was to evaluate whether the presence of a space maintainer affects the accuracy of an intraoral scanner. Materials and Methods: The maxillary primary first molar typodont tooth was removed from the primary dentition typodont model and a band and loop type space maintainer was delivered. After the model was connected to a dental phantom, intraoral scan was performed using TRIOS 4 (3Shape A/S, Copenhagen, Denmark). The scan was repeated with the same technique without the space maintainer. Each scan was performed 10 times. All scan files into a GOM inspect 2018 software and evaluated the accuracy. The accuracy was evaluated on trueness and precision, and calculated using the root mean square value. Result: When there was a space maintainer in the oral cavity, the trueness value was 0.10±0.02 mm and the precision value was 0.15±0.03 mm. In the absence of the space maintainer, the trueness value was 0.12±0.03 mm and the precision value was 0.16±0.04 mm. There were no significant differences depending on the presence of a space maintainer (P>0.05). Conclusion: Within the limits of this study, the accuracy of the intraoral scanner was not influenced by the presence of space maintainer.

• 대한치과보철학회지
• /
• 제58권4호
• /
• pp.282-289
• /
• 2020

목적:본 연구의 목표는 다른 유형의 엔도크라운(endocrown) 와동 형태를 세 가지 다른 구강스캐너로 디지털 인상을 채득하였을 때의 정확성을 평가하는 것이다. 재료 및 방법: 두 개의 인체 하악 대구치를 협측벽이 있는 것(Class 2)과 협측벽이 없는(Class 3), 두 가지 엔도크라운 지대주 디자인으로 치아형성 하였다. 와동 디자인 2종을 레퍼런스로 탁상용 스캐너(E3, 3shape)와 세 개의 다른 구강스캐너, Trios 3 (3shape, TRI group), Cerec Omnicam (Dentsply Sirona, CER group), i500 (Medit Corp., I5 group)로 스캔하였다. 표준 테셀레이션 언어(.stl) 데이터 세트를 얻어, 계측 소프트웨어에서 불러들였다. 각 구강스캐너로 획득한 반복된 스캔 데이터 사이의 편차에 기초하여 정밀도(precision)를 평가하였다. 기준 데이터와 반복하여 얻은 구강스캔 사이의 편차로서 진도(trueness)를 평가 하였다. 상호작용을 탐지하기 위해 데이터는 일변량 분산분석(ANOVA)을 사용하여 통계적으로 분석하였고, 실험군의 비교 분석을 위해 데이터는 .05의 유의 수준에서 일원 분산분석 및 사후 Tukey 테스트로 분석하였다. 결과: I5 군의 두 와동 형태에 대한 편차값은 진도의 측면에서 다른 구강스캐너 군에 비해 낮았다. 두 와동 디자인 모두에서 TRI 군은 다른 구강스캐너군 보다 우수한 정밀도를 보였다. 결론: 구강스캐너의 다양한 기술과 다양한 엔도크라운 치아형성 디자인이 디지털 스캔의 정확도에 영향을 미쳤다.

• The Journal of Advanced Prosthodontics
• /
• 제14권2호
• /
• pp.63-69
• /
• 2022

PURPOSE. The aim of this in vitro study was to investigate the accuracy (trueness and precision) of five intraoral scanners (IOS) using a novel reference model for standardized performance evaluation. MATERIALS AND METHODS. Five IOSs (Medit i500, Omnicam, Primescan, Trios 3, Trios 4) were used to digitize the reference model, which represented a simplified full-arch situation with four abutment teeth. Each IOS was used five times by an experienced operator, resulting in 25 STL (Standard Tessellation Language) files. STL data were imported into 3D software (Final Surface^®) and examined for inter- and intra-group analyses. Deviations in the parameter matching error were calculated. ANOVA F-test and Kruskal-Wallis test were applied for inter-group comparisons (α = .05); and the coefficient of variation (CV) was calculated for intra-group comparisons (in % ± SD). RESULTS. Primescan (matching error value: 0.015), Trios 3 (0.016), and Trios 4 (0.018) revealed comparable results with significantly higher accuracy compared to Medit i500 (0.035) and Omnicam (0.028) (P < .001). For intra-group comparison, Trios 4 demonstrated the most homogenous results (CV 15.8%). CONCLUSION. The novel reference model investigated in this study can be used to assess the performance of dental scanning technologies in the daily routine setting and in research settings.

• The Journal of Advanced Prosthodontics
• /
• 제15권2호
• /
• pp.55-62
• /
• 2023

PURPOSE. The aim of this study is to evaluate the accuracy of removable partial denture (RPD) frameworks produced using different digital protocols. MATERIALS AND METHODS. 80 frameworks for RPDs were produced using CAD-CAM technology and divided into four groups of twenty (n = 20): Group 1, Titanium frameworks manufactured by digital metal laser sintering (DMLS); Group 2, Co-Cr frameworks manufactured by DMLS; Group 3, Polyamide PA12 castable resin manufactured by multi-jet fusion (MJF); and Group 4, Metal (Co-Cr) casting by using lost-wax technique. After the digital acquisition, eight specific areas were selected in order to measure the Δ-error value at the intaglio surface of RPD. The minimum value required for point sampling density (0.4 mm) was derived from the sensitivity analysis. The obtained Δ-error mean value was used for comparisons: 1. between different manufacturing processes; 2. between different manufacturing techniques in the same area of interest (AOI); and 3. between different AOI of the same group. RESULTS. The Δ-error mean value of each group ranged between -0.002 (Ti) and 0.041 (Co-Cr) mm. The Pearson's Chi-squared test revealed significant differences considering all groups paired two by two, except for group 3 and 4. The multiple comparison test documented a significant difference for each AOI among group 1, 3, and 4. The multiple comparison test showed significant differences among almost all different AOIs of each group. CONCLUSION. All Δ-mean error values of all digital protocols for manufacturing RPD frameworks optimally fit within the clinical tolerance limit of trueness and precision.

• The Journal of Advanced Prosthodontics
• /
• 제15권3호
• /
• pp.145-154
• /
• 2023

PURPOSE. The objective of this study was to investigate how internal structures influence the overall and marginal accuracy of full arch preparations fabricated through additive manufacturing in different printing systems. MATERIALS AND METHODS. A full-arch preparation digital model was set up with three internal designs, including solid, hollow, and grid. These were printed using three different resin printers with nine models in each group. After scanning, each data was imported into the 3D data processing software together with the master cast, aligned and trimmed, and then put into the 3D data analysis software again to compare the overall and marginal deviation whose results are expressed using root mean square values and color maps. To evaluate the trueness of the resin model, the test data and reference data were compared, and the precision was evaluated by comparing the test data sets. Color maps were observed for qualitative analysis. Data were statistically analyzed by one-way analysis of variance and Bonferroni method was used for post hoc comparison (α = .05). RESULTS. The influence of different internal structures on the accuracy of 3D printed resin models varied significantly (P < .05). Solid and grid models showed better accuracy, while the hollow model exhibited poor accuracy. The color maps show that the resin models have a tendency to shrink inwards. CONCLUSION. The internal structure design influences the accuracy of the 3D printing model, and the effect varies in different printing systems. Irrespective of the kind of printing system, the printing accuracy of hollow model was observed to be worse than those of solid and grid models.

• 대한치과교정학회지
• /
• 제52권4호
• /
• pp.249-257
• /
• 2022

Objective: The purpose of this study was to evaluate and compare the dimensional accuracy between thermoformed and direct-printed aligners. Methods: Three types of aligners were manufactured from the same reference standard tessellation language (STL) file: thermoformed aligners were manufactured using Zendura FLX^TM (n = 12) and Essix ACE^TM (n = 12), and direct-printed aligners were printed using Tera Harz^TM TC-85DAP 3D Printer UV Resin (n = 12). The teeth were not manipulated with any tooth-moving software in this study. The samples were sprayed with an opaque scanning spray, scanned, imported to Geomagic^® Control X^TM metrology software, and superimposed on the reference STL file by using the best-fit alignment algorithm. Distances between the aligner meshes and the reference STL file were measured at nine anatomical landmarks. Results: Mean absolute discrepancies in the Zendura FLX^TM aligners ranged from 0.076 ± 0.057 mm to 0.260 ± 0.089 mm and those in the Essix ACE^TM aligners ranged from 0.188 ± 0.271 mm to 0.457 ± 0.350 mm, while in the direct-printed aligners, they ranged from 0.079 ± 0.054 mm to 0.224 ± 0.041 mm. Root mean square values, representing the overall trueness, ranged from 0.209 ± 0.094 mm for Essix ACE^TM, 0.188 ± 0.074 mm for Zendura FLX^TM, and 0.140 ± 0.020 mm for the direct-printed aligners. Conclusions: This study showed greater trueness and precision of direct-printed aligners than thermoformed aligners.

• 한국품질경영학회:학술대회논문집
• /
• 한국품질경영학회 1998년도 The 12th Asia Quality Management Symposium* Total Quality Management for Restoring Competitiveness
• /
• pp.378-383
• /
• 1998

Needless to say, the importance of the quality of observed values shall be emphasized in the field of 'TQM', because, the first step of 'TQM' should be some data - observed values. Usually, meaning of the quality of observed values should be, a) accuracy (trueness and precision), b) detection limit, c) cost and so on. However, the authors will describe mainly on b), in this paper. The definitions of technical terms related to 'Detection Limit' are defined in ISO l1843-1 Capability of detection - Part1:Terms and definitions (1998). The most important terms extracted from the above standard are shown in the following table. The application of the 'Detection Limit' to the actual measurement is discussed in this paper.

• International Journal of Computer Science & Network Security
• /
• 제21권2호
• /
• pp.205-211
• /
• 2021

Plants are important for humanity. They intervene in several areas of human life: medicine, nutrition, cosmetics, decoration, etc. The large number of varieties of these plants requires an efficient solution to identify them for proper use. The ease of recognition of these plants undoubtedly depends on the classification of these species into family; however, finding the relevant characteristics to achieve better automatic classification is still a huge challenge for researchers in the field. In this paper, we have developed a new automatic plant classification technique based on artificial neural networks. Our model uses leaf texture characteristics as parameters for plant family identification. The results of our model gave a perfect classification of three plant families of the Ivorian flora, with a determination coefficient (R2) of 0.99; an error rate (RMSE) of 1.348e-14, a sensitivity of 84.85%, a specificity of 100%, a precision of 100% and an accuracy (Accuracy) of 100%. The same technique was applied on Flavia: the international basis of plants and showed a perfect identification regression (R2) of 0.98, an error rate (RMSE) of 1.136e-14, a sensitivity of 84.85%, a specificity of 100%, a precision of 100% and a trueness (Accuracy) of 100%. These results show that our technique is efficient and can guide the botanist to establish a model for many plants to avoid identification problems.

• 대한치과보철학회지
• /
• 제57권2호
• /
• pp.102-109
• /
• 2019

목적: 이 연구의 목적은 단일 수복물 지대치와 3본 고정성 수복물 지대치 모델에서 3종류의 구강 스캐너에 따른 정확도를 평가하는 것이다. 재료 및 방법: 본 연구에서는 단일 수복물 지대치와 제1대구치가 상실된 3본 고정성 수복물 지대치를 제작하고, 이를 주모형으로 설정하였다. 제작된 주 모형은 산업용 삼차원 스캐너로 스캔하였고, 이를 참조 스캔 데이터로 설정하였다. 3종류의 구강 스캐너(CS3600, CS3500, 그리고 EZIS PO)를 이용하여 주 모형을 5회 스캔 하였다. 이를 평가 스캔 데이터로 설정하였다. 삼차원 비교분석(Geomagic control X)에서 지대치의 스캔 정확도를 평가하기 위해 분할된 지대치를 선택하여 분석하였다. 통계분석은 SPSS 소프트웨어를 이용하여 분석하였다 (${\alpha}=.05$). 구강 스캐너 정확도는 kruskal-wallis test를 실시하여 비교하였고, pairwise test로 사후 검정을 실시하였다. 단일 수복물 지대치 모델과 3본 고정성 수복물 지대치 모델의 정확도 차이는 mann-whitney U test로 분석하였다. 결과: 구강 스캐너에 따른 정확도의 측정결과는 모두 유의한 차이를 보였다 (P < .05). 그리고 단일 수복물 지대치 모델과 3본 고정성 수복물 지대치 모델의 진도(trueness)는 통계적으로 유의한 차이를 보여주었으며, 단일 수복물 지대치에서 더 좋은 진도를 나타냈다 (P < .05). 정밀도(precision)에서는 유의미한 차이가 없었다 (P = .616). 결론: 단일 수복물과 3본 고정성 수복물 지대치의 정확도를 비교한 결과, 스캔 영역이 늘어날수록 지대치 스캔의 오류는 증가하였고, 3종류의 구강 스캐너에서 3본 고정성 수복물 지대치 모델의 스캔 정확도는 임상적으로 허용 가능하다.

• The Journal of Advanced Prosthodontics
• /
• 제11권2호
• /
• pp.138-146
• /
• 2019

PURPOSE. Comparing the accuracy of casts produced from digital workflow to that of casts produced from conventional techniques. MATERIALS AND METHODS. Whole arch alginate (ALG) and polyvinyl siloxane (PVS) impressions were taken with stock trays and custom trays, respectively. The ALG impressions were poured with type III dental stone, while the PVS impressions were poured with type IV dental stone. For the digital workflow, IOS impressions were taken and physical casts were produced by 3D printing. In addition, 3D printed casts were produced from images obtained from a laboratory scanner (LS). For each technique, a total of 10 casts were produced. The accuracies of the whole arch and separated teeth were virtually quantified. RESULTS. Whole arch cast accuracy was more superior for PVS followed by LS, ALG, and IOS. The PVS and ALG groups were inferior in the areas more susceptible to impression material distortion, such as fossae and undercut regions. The LS casts appeared to have generalized errors of minor magnitude influencing primarily the posterior teeth. The IOS casts were considerably more affected at the posterior region. On the contrary, the IOS and LS casts were more superior for single tooth accuracy followed by PVS and ALG. CONCLUSION. For whole arch accuracy, casts produced from IOS were inferior to those produced from PVS and ALG. The inferior outcome of IOS appears to be related to the span of scanning. For single tooth accuracy, IOS showed superior accuracy compared to conventional impressions.