Comparison of Three-Dimensional Accuracy between Digital Models Obtained from Impression Scan and Model Scan

Purpose: The aim of this study was to present a new method to analyze the three-dimensional accuracy of complete-arch dental impressions and verify the reliability of the method. Additionally, the accuracies of conventional and intraoral digital impressions were compared using the new method. Methods: A master model was fabricated using 14 milled polyetheretherketone cylinders and a maxillary acrylic model. Each cylinder was positioned and named according to its corresponding tooth position. Twenty-five definitive stone casts were fabricated using conventional impressions of the master model. An intraoral scanner was used to scan the master model 25 times to fabricate 25 digital models. A coordinate measuring machine was used to physically probe each cylinder in the master model and definitive casts. An inspection software was used to probe cylinders of digital models. A three-dimensional part coordinate system was defined and used to compute the centroid coordinate of each cylinder. Intraclass correlation coefficient (ICC) was evaluated to examine the reliability of the new method. Independent two sample t-test was performed to compare the trueness and precision of conventional and intraoral digital impressions (α = 0.05). Results: ICC results showed that, the new method had almost perfect reliability for the measurements of the master model, conventional and digital impression. Conventional impression showed more accurate absolute trueness and precision than intraoral digital impression for most of the tooth positions (p < 0.05). Conclusions: The new method was reliable to analyze the three-dimensional deviation of complete-arch impressions. Conventional impression was still more accurate than digital intraoral impression for complete arches.

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Comparative Analysis of Digital Models of Objects of Cultural Heritage Obtained by the “3D SLS” and “SfM” Methods

Applied Sciences ◽

10.3390/app11125321 ◽

2021 ◽

Vol 11 (12) ◽

pp. 5321

Author(s):

Marcin Barszcz ◽

Jerzy Montusiewicz ◽

Magdalena Paśnikowska-Łukaszuk ◽

Anna Sałamacha

Keyword(s):

Cultural Heritage ◽

Low Cost ◽

Three Dimensional ◽

3D Models ◽

Silk Road ◽

Digital Models ◽

Global Pandemic ◽

University Of Technology ◽

Three Dimensional Models ◽

3D Digitisation

In the era of the global pandemic caused by the COVID-19 virus, 3D digitisation of selected museum artefacts is becoming more and more frequent practice, but the vast majority is performed by specialised teams. The paper presents the results of comparative studies of 3D digital models of the same museum artefacts from the Silk Road area generated by two completely different technologies: Structure from Motion (SfM)—a method belonging to the so-called low-cost technologies—and by Structured-light 3D Scanning (3D SLS). Moreover, procedural differences in data acquisition and their processing to generate three-dimensional models are presented. Models built using a point cloud were created from data collected in the Afrasiyab museum in Samarkand (Uzbekistan) during “The 1st Scientific Expedition of the Lublin University of Technology to Central Asia” in 2017. Photos for creating 3D models in SfM technology were taken during a virtual expedition carried out under the “3D Digital Silk Road” program in 2021. The obtained results show that the quality of the 3D models generated with SfM differs from the models from the technology (3D SLS), but they may be placed in the galleries of the vitrual museum. The obtained models from SfM do not have information about their size, which means that they are not fully suitable for archiving purposes of cultural heritage, unlike the models from SLS.

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Dimensional Accuracy of Dental Models for Three-Unit Prostheses Fabricated by Various 3D Printing Technologies

Materials ◽

10.3390/ma14061550 ◽

2021 ◽

Vol 14 (6) ◽

pp. 1550

Author(s):

Soo-Yeon Yoo ◽

Seong-Kyun Kim ◽

Seong-Joo Heo ◽

Jai-Young Koak ◽

Joung-Gyu Kim

Keyword(s):

Surface Roughness ◽

Three Dimensional ◽

Dimensional Accuracy ◽

3D Analysis ◽

Digital Light Processing ◽

Test Models ◽

Reference File ◽

Significant Difference ◽

Jet Printing ◽

3D Printed

Previous studies on accuracy of three-dimensional (3D) printed model focused on full arch measurements at few points. The aim of this study was to examine the dimensional accuracy of 3D-printed models which were teeth-prepped for three-unit fixed prostheses, especially at margin and proximal contact areas. The prepped dental model was scanned with a desktop scanner. Using this reference file, test models were fabricated by digital light processing (DLP), Multi-Jet printing (MJP), and stereo-lithography apparatus (SLA) techniques. We calculated the accuracy (trueness and precision) of 3D-printed models on 3D planes, and deviations of each measured points at buccolingual and mesiodistal planes. We also analyzed the surface roughness of resin printed models. For overall 3D analysis, MJP showed significantly higher accuracy (trueness) than DLP and SLA techniques; however, there was not any statistically significant difference on precision. For deviations on margins of molar tooth and distance to proximal contact, MJP showed significantly accurate results; however, for a premolar tooth, there was no significant difference between the groups. 3D color maps of printed models showed contraction buccolingually, and surface roughness of the models fabricated by MJP technique was observed as the lowest. The accuracy of the 3D-printed resin models by DLP, MJP, and SLA techniques showed a clinically acceptable range to use as a working model for manufacturing dental prostheses

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Investigation of dimensional accuracy of metal droplet deposition under repulsion using a lattice Boltzmann approach

Rapid Prototyping Journal ◽

10.1108/rpj-10-2020-0236 ◽

2021 ◽

Vol ahead-of-print (ahead-of-print) ◽

Author(s):

Yanlin Ren ◽

Zhaomiao Liu ◽

Yan Pang ◽

Xiang Wang ◽

Shanshan Gao

Keyword(s):

Lattice Boltzmann ◽

Moving Boundary ◽

Three Dimensional ◽

Metal Droplet ◽

Dimensional Accuracy ◽

Longitudinal Section ◽

Collision Term ◽

Droplet Deposition ◽

Content Type ◽

Deposition Distance

Purpose This paper aims to investigate the influence of droplet infiltration and sliding on the deposition size and make a uniform deposition by controlling the interaction between droplets, using the three-dimensional lattice Boltzmann method (LBM) based on the actual working condition. Design/methodology/approach D3Q19 Shan-Chen LB approach is developed and optimized based on the metal droplet deposition. The Carnahan-Starling equation of state and transition layers are introduced to maintain the greater stability and low pseudo velocities. In addition, an additional collision term is adopted to implement immersed moving boundary scheme to deal with no-slip boundaries on the front of the phase change. Findings The numerical results show that the new¬ incoming droplet wet and slide off the solidified surface and the rejection between droplets are the reasons for the deviation of the actual deposition length. The total length of the longitudinal section negatively correlates with the deposition distance. To improve the dimensional accuracy, the deposition distance and repulsion rate need to be guaranteed. The optimal deposition distance is found to have a negative linear correlation with wettability. Originality/value The numerical model developed in this paper will help predict the continuous metal droplet deposition and provide guidance for the selection of deposition distance.

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On three-dimensional printing of 17-4 precipitation-hardenable stainless steel with direct metal laser sintering in aircraft structural applications

Proceedings of the Institution of Mechanical Engineers Part L Journal of Materials Design and Applications ◽

10.1177/14644207211044804 ◽

2021 ◽

pp. 146442072110448

Author(s):

Rupinder Singh ◽

Rishab ◽

Jashanpreet S Sidhu

Keyword(s):

Stainless Steel ◽

Structural Engineering ◽

Three Dimensional ◽

Surface Hardness ◽

Dimensional Accuracy ◽

Scanning Speed ◽

Laser Sintering ◽

Structural Components ◽

Direct Metal Laser Sintering ◽

Structural Applications

The martensitic 17-4 precipitation-hardenable stainless steel is one of the commercially established materials for structural engineering applications in aircrafts due to its superior mechanical and corrosion resistance properties. The mechanical processing of this alloy through a conventional manufacturing route is critical from the dimensional accuracy (Δ d) viewpoint for development of innovative structural components such as: slat tracks, wing flap tracks, etc. In past two decades, a number of studies have been reported on challenges being faced while conventional processing of 17-4 precipitation-hardenable stainless steel for maintaining uniform thickness of aircraft structural components. However, hitherto little has been reported on direct metal laser sintering of 17-4 precipitation-hardenable stainless steel for development of innovative functional prototypes with uniform surface hardness (HV), Δ d, and surface roughness ( Ra) in aircraft structural engineering. This paper reports the effect of direct metal laser sintering process parameters on HV, Δ d, and Ra for structural components. The results of study suggest that optimized settings of direct metal laser sintering from multifactor optimization viewpoint are laser power 100 W, scanning speed 1400 mm/s, and layer thickness 0.02 mm. The results have been supported with scanning electron microscopy analysis (for metallurgical changes such as porosity (%), HV, grain size, etc.) and international tolerance grades for ensuring assembly fitment.

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Three-Dimensional Accuracy of Digital Static Interocclusal Registration by Three Intraoral Scanner Systems

Journal of Prosthodontics ◽

10.1111/jopr.12714 ◽

2017 ◽

Vol 27 (2) ◽

pp. 120-128 ◽

Cited By ~ 6

Author(s):

Kuan Yee Wong ◽

Roxanna Jean Esguerra ◽

Vanessa Ai Ping Chia ◽

Ying Han Tan ◽

Keson Beng Choon Tan

Keyword(s):

Three Dimensional ◽

Dimensional Accuracy ◽

Intraoral Scanner

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Tooth-size discrepancy: A comparison between manual and digital methods

Dental Press Journal of Orthodontics ◽

10.1590/2176-9451.19.4.107-113.oar ◽

2014 ◽

Vol 19 (4) ◽

pp. 107-113 ◽

Cited By ~ 11

Author(s):

Gabriele Dória Cabral Correia ◽

Fernando Antonio Lima Habib ◽

Carlos Jorge Vogel

Keyword(s):

Three Dimensional ◽

Diagnostic Tools ◽

Tooth Size ◽

Digital Models ◽

Linear Measurements ◽

Length Discrepancy ◽

Technological Advances ◽

Size Discrepancy ◽

Digital Methods ◽

Plaster Models

INTRODUCTION: Technological advances in Dentistry have emerged primarily in the area of diagnostic tools. One example is the 3D scanner, which can transform plaster models into three-dimensional digital models. OBJECTIVE: This study aimed to assess the reliability of tooth size-arch length discrepancy analysis measurements performed on three-dimensional digital models, and compare these measurements with those obtained from plaster models. MATERIAL AND METHODS: To this end, plaster models of lower dental arches and their corresponding three-dimensional digital models acquired with a 3Shape R700T scanner were used. All of them had lower permanent dentition. Four different tooth size-arch length discrepancy calculations were performed on each model, two of which by manual methods using calipers and brass wire, and two by digital methods using linear measurements and parabolas. RESULTS: Data were statistically assessed using Friedman test and no statistically significant differences were found between the two methods (P > 0.05), except for values found by the linear digital method which revealed a slight, non-significant statistical difference. CONCLUSIONS: Based on the results, it is reasonable to assert that any of these resources used by orthodontists to clinically assess tooth size-arch length discrepancy can be considered reliable.

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