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Abstract

In dentistry, 3D intraoral scanners (IOSs) are gaining increasing popularity in the production of dental prostheses. However, the quality of an IOS in terms of resolution remains the determining factor of choice for the practitioner; a high resolution is a quality parameter that can reduce error in the production chain. To the best of our knowledge, the evaluation of IOS resolution is not clearly established in the literature. This study provides a simple assessment of resolution of an IOS by measuring a reference sample and highlights various factors that may influence the resolution. A ceramic tip was prepared to create a very thin object with an edge smaller than the current resolution stated by the company. The sample was scanned with microCT (micro-computed tomography) and an IOS. The resulting meshes were compared. In the mesh obtained with the IOS, the distance between two planes on the edge was approximately 100 micrometers, and that obtained with microtomography was 25 micrometers. The curvature values were 27.46 (standard deviation – SD) 14.71) μm -1 and 5.18 (SD 1.16) μm -1 for microCT and IOS, respectively. These results show a clear loss of information for objects that are smaller than 100 μm. As there is no normalized procedure to evaluate resolution of IOSs, the method that we have developed can provide a positive parameter for control of IOSs performance by practitioners.
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Authors and Affiliations

Alban Desoutter
1
Gérard Subsol
2
Eric Fargier
3
Alexandre Sorgius
3
Hervé Tassery
1
Michel Fages
1
Frédéric Cuisinier
1

  1. Univ. Montpellier, 163 rue Auguste Broussonnet, 34090 Montpellier, France
  2. Laboratory of Computer Science, Robotics and Microelectronics of Montpellier, 161 Rue Ada, 34095 Montpellier, France
  3. Laboratoire National de Métrologie et d’Essais, 1 Rue Gaston Boissier, 75724 Paris Cedex 15, France
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Abstract

Dynamic climate changes have become noticeable in recent decades, especially in the vulnerable region of the West Antarctic. The relatively simple food web of this area relies on krill – Euphausia superba . Presumably, as a result of climatic fluctuations, a de− crease in the number of this crustacean has been recorded, followed by an increase in the population of the gelatinous zooplankter Salpa thompsoni . In the research presented herein, population and morphometric analyses of Salpa thompsoni have been conducted. Specimens for this research were collected from the Drake Passage, using a Bongo net in the summer season of 2010. It has been found that the horizontal distribution of this gelatinous zooplankter was significantly irregular (Kruskal−Wallis test, p < 0.001). In the northern part of the investigated area, both blastozooids and oozooids were recorded, which confirms the dynamic development of this species. The central part of the Drake Passage was characterized by the dominance of blastozooids, with embryos found at different stages of the development. Only in the region of the South Shetland Islands, the salpid population was characterized by reduced or even stopped reproduction. The immense reproductive efficiency observed in the Salpa thompsoni population was mostly induced by the favourable thermal conditions. These observations may suggest that the ongoing climat changes in the West Antarctic will promote the population expansion of this species.
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Authors and Affiliations

Angelika W. Słomska
Anna A. Panasiuk-Chodnicka
Maria I. Żmijewska
Maciej K. Mańko

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