Publications by authors named "Everton Lucas-Oliveira"

8 Publications

  • Page 1 of 1

Evaluation of curved root canals filled with a new bioceramic sealer: A microcomputed tomographic study using images with different voxel sizes and segmentation methods.

Microsc Res Tech 2021 Jun 28. Epub 2021 Jun 28.

Department of Restorative Dentistry, Sao Paulo State University (UNESP), School of Dentistry, Araraquara, Sao Paulo, Brazil.

The aim of this study was to investigate the filling ability of a new premixed bioceramic sealer in comparison with an epoxy resin-based sealer in curved root canals using different segmentation methods and voxel sizes in micro-CT images. Twelve curved mesial roots of mandibular molars with two separated canals were selected. All root canals were prepared by using HyFlex EDM files size 25/.08 and filled by the single cone technique and Bio-C Sealer or AH Plus (n = 12). The samples were scanned by micro-CT at 5 μm. The images were analyzed at 5, 10, and 20 μm for the volumetric analysis of voids in filling. Visual image segmentation was performed by two examiners, and the automatic segmentation was accomplished for comparison. Radiopacity of the sealers was evaluated by radiographic analysis. Data were submitted to the two-way ANOVA and non-paired t tests at a significance level of 5%. AH Plus had the highest radiopacity (p < .05). Root canals filled with AH Plus or Bio-C had similar low percentage of voids (p > .05). There was no difference interobserver, which had similar results to those obtained with automatic segmentation for all voxel sizes evaluated (p > .05). Bio-C Sealer had appropriate filling ability. Visual and automatic segmentation can be applied to micro-CT images with voxel sizes from 5 to 20 μm to evaluate the filling of sealers with adequate radiopacity. Automatic segmentation should be used as a faster method.
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http://dx.doi.org/10.1002/jemt.23855DOI Listing
June 2021

High accuracy capillary network representation in digital rock reveals permeability scaling functions.

Sci Rep 2021 Jun 15;11(1):11370. Epub 2021 Jun 15.

IBM Research, Rio de Janeiro, RJ, 22290-240, Brazil.

Permeability is the key parameter for quantifying fluid flow in porous rocks. Knowledge of the spatial distribution of the connected pore space allows, in principle, to predict the permeability of a rock sample. However, limitations in feature resolution and approximations at microscopic scales have so far precluded systematic upscaling of permeability predictions. Here, we report fluid flow simulations in pore-scale network representations designed to overcome such limitations. We present a novel capillary network representation with an enhanced level of spatial detail at microscale. We find that the network-based flow simulations predict experimental permeabilities measured at lab scale in the same rock sample without the need for calibration or correction. By applying the method to a broader class of representative geological samples, with permeability values covering two orders of magnitude, we obtain scaling relationships that reveal how mesoscale permeability emerges from microscopic capillary diameter and fluid velocity distributions.
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http://dx.doi.org/10.1038/s41598-021-90090-0DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8206086PMC
June 2021

A benchtop single-sided magnet with NMR well-logging tool specifications - Examples of application.

J Magn Reson 2021 01;322:106871

São Carlos Institute of Physics, University of São Paulo, São Carlos, SP, Brazil. Electronic address:

This article was written in honor of Prof. Bernhard Blümich, who has heavily impacted many areas of Magnetic Resonance and, in particular, low-field and portable NMR with numerous advances, concepts, innovations, and applications of this impressive technology. Many years ago, we decided to research and develop single-sided magnets for the area of petroleum science and engineering to study oil reservoir rocks in the laboratory under well-logging conditions. The global urge to exploit oil reserves requires the analysis of reservoirs, intending to characterize the yields before starting the production. Thus, well-logging tools have been developed to estimate the quality of oil and reservoir productivity. NMR logging is included in these analytical tools, and numerous operations using this kind of device were performed since the early 1950s. To contribute to this vital research area, we show the development of a new benchtop single-sided NMR system, with well-logging tool characteristics, a cylindrical sweet spot with 4 cm of diameter and length, with magnetic field of 47 mT centered at 11 cm from the magnet's surface and a constant gradient of 35.7 G/cm along z. This system was used in self-diffusion, T-T, and D-T measurements of standard liquids and rock cores, demonstrating its functionality.
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http://dx.doi.org/10.1016/j.jmr.2020.106871DOI Listing
January 2021

Use of collagen and auricular cartilage in bioengineering: scaffolds for tissue regeneration.

Cell Tissue Bank 2020 Sep 2. Epub 2020 Sep 2.

Interunit Graduate Program in Bioengineering, University of São Paulo, São Carlos, SP, Brazil.

The aim of this study was the development of collagen and collagen/auricular cartilage scaffolds for application in dermal regeneration. Collagen was obtained from bovine tendon by a 72 h-long treatment, while bovine auricular cartilage was treated for 24 h and divided into two parts, external (perichondrium, E) and internal (elastic cartilage, I). The scaffolds were prepared by mixing collagen (C) with the internal part (CI) or the external part (CE) in a 3:1 ratio. Differential scanning calorimetry, scanning electron microscopy (SEM) analysis, microcomputed tomography imaging (micro-CT) and swelling degree were used to characterize the scaffolds. Cytotoxicity, cell adhesion, and cell proliferation assays were performed using the cell line NIH/3T3. All samples presented a similar denaturation temperature (Td) around 48 °C, while CE presented a second Td at 51.2 °C. SEM micrographs showed superficial pores in all scaffolds and micro-CT exhibited interconnected pore spaces with porosity above 60% (sizes between 47 and 149 µm). The order of swelling was CE < CI < C and the scaffolds did not present cytotoxicity, showing attachment rates above 75%-all samples showed a similar pattern of proliferation until 168 h, whereas CI tended to decrease after this time. The scaffolds were easily obtained, biocompatible and had adequate morphology for cell growth. All samples showed high adhesion, whereas collagen-only and collagen/external part scaffolds presented a better cell proliferation rate and would be indicated for possible use in dermal regeneration.
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http://dx.doi.org/10.1007/s10561-020-09861-0DOI Listing
September 2020

Micro-computed tomography high resolution evaluation of dimensional and morphological changes of 3 root-end filling materials in simulated physiological conditions.

J Mater Sci Mater Med 2020 Jan 21;31(2):14. Epub 2020 Jan 21.

Department of Restorative Dentistry, School of Dentistry, São Paulo State University (Unesp), Araraquara, São Paulo, Brazil.

The aim of this study was to evaluate volumetric and morphological stability of 3 root-end filling materials in addition to porosity and interface voids, using micro-computed tomography (µCT) in high resolution and a highly accurate approach for image analysis. Following root-end resection and apical preparation, two-rooted maxillary premolars were divided into three groups, according to the filling materials: White MTA Angelus, Biodentine, and IRM. Samples were scanned by µCT at 5 µm after the setting time and at time intervals of 7 and 30 days after immersion in phosphate-buffered saline (PBS). Volumetric and morphological changes besides material porosity and interface voids were evaluated by comparing initial values and those obtained after immersion. Data were analyzed statistically, using ANOVA and t-tests (α = 0.05). All materials showed volumetric stability. Regarding the morphological changes, Biodentine had a significant thickness reduction after storage in PBS when compared with MTA. Biodentine also showed an increase in porosity, as well as in percentage and thickness of voids after 30 days of immersion. In conclusion, µCT in high resolution and an accurate image analysis approach may be used to evaluate morphological changes of endodontic materials. Although Biodentine showed suitable adaptability and lower values of porosity than MTA, after PBS immersion there was a dimensional reduction of this material, besides an increase in porosity and interface voids.
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http://dx.doi.org/10.1007/s10856-019-6355-2DOI Listing
January 2020

Computational approach to integrate 3D X-ray microtomography and NMR data.

J Magn Reson 2018 07 4;292:16-24. Epub 2018 May 4.

Instituto de Física de São Carlos, Universidade de São Paulo, CP 369, 13560-970 São Carlos, São Paulo, Brazil.

Nowadays, most of the efforts in NMR applied to porous media are dedicated to studying the molecular fluid dynamics within and among the pores. These analyses have a higher complexity due to morphology and chemical composition of rocks, besides dynamic effects as restricted diffusion, diffusional coupling, and exchange processes. Since the translational nuclear spin diffusion in a confined geometry (e.g. pores and fractures) requires specific boundary conditions, the theoretical solutions are restricted to some special problems and, in many cases, computational methods are required. The Random Walk Method is a classic way to simulate self-diffusion along a Digital Porous Medium. Bergman model considers the magnetic relaxation process of the fluid molecules by including a probability rate of magnetization survival under surface interactions. Here we propose a statistical approach to correlate surface magnetic relaxivity with the computational method applied to the NMR relaxation in order to elucidate the relationship between simulated relaxation time and pore size of the Digital Porous Medium. The proposed computational method simulates one- and two-dimensional NMR techniques reproducing, for example, longitudinal and transverse relaxation times (T and T, respectively), diffusion coefficients (D), as well as their correlations. For a good approximation between the numerical and experimental results, it is necessary to preserve the complexity of translational diffusion through the microstructures in the digital rocks. Therefore, we use Digital Porous Media obtained by 3D X-ray microtomography. To validate the method, relaxation times of ideal spherical pores were obtained and compared with the previous determinations by the Brownstein-Tarr model, as well as the computational approach proposed by Bergman. Furthermore, simulated and experimental results of synthetic porous media are compared. These results make evident the potential of computational physics in the analysis of the NMR data for complex porous materials.
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http://dx.doi.org/10.1016/j.jmr.2018.05.001DOI Listing
July 2018

Simultaneous acquisition for T-T Exchange and T-T correlation NMR experiments.

J Magn Reson 2018 Apr 13;289:63-71. Epub 2018 Feb 13.

São Carlos Institute of Physics, University of São Paulo, PO Box 369, 13560-970, São Carlos, SP, Brazil. Electronic address:

The NMR measurements of longitudinal and transverse relaxation times and its multidimensional correlations provide useful information about molecular dynamics. However, these experiments are very time-consuming, and many researchers proposed faster experiments to reduce this issue. This paper presents a new way to simultaneously perform T-T Exchange and T-T correlation experiments by taking the advantage of the storage time and the two steps phase cycling used for running the relaxation exchange experiment. The data corresponding to each step is either summed or subtracted to produce the T-T and T-T data, enhancing the information obtained while maintaining the experiment duration. Comparing the results from this technique with traditional NMR experiments it was possible to validate the method.
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http://dx.doi.org/10.1016/j.jmr.2018.02.008DOI Listing
April 2018

The effect of platelet-rich plasma on the repair of muscle injuries in rats.

Rev Bras Ortop 2015 Sep-Oct;50(5):586-95. Epub 2015 Aug 29.

Universidade Federal de Mato Grosso do Sul, Campo Grande, MS, Brazil.

Objective: The need for therapeutic options for muscle injuries, which are increasingly frequent among sports practitioners, was the motivation for this experimental study, which had the aim of evaluating the histological effects of platelet-rich plasma (PRP) on repairs to muscle tissues of rats.

Methods: PRP was obtained by means of double centrifugation of blood from five animals. In 30 rats, an injury was produced in the middle third of the belly of the gastrocnemius muscle of each hind limb. These injuries did not receive any treatment in six rats (12 legs). In 24 rats, 0.9% physiological serum was injected into the injury in the left leg and PRP into the injury in the right leg. Samples from the treated and untreated tissue were evaluated histologically 7 and 21 days after the procedures.

Results: The quantity of collagen in the injuries treated with PRP was significantly lower than that in the other injuries, in the evaluation made 7 days after the procedure, but it became equal to the other groups in the evaluation done on the 21st day. There was a significant increase (p < 0.001) in the quantity of collagen from the 7th to the 21st day in the injuries treated with PRP, but this was not seen in the injuries treated using other methods. The inflammatory process was shown to be more intense in the injuries treated with PRP than in the injuries of the other treatment groups, in the evaluation done 7 days after the procedure. However, the morphological aspects of these injuries were seen to be similar to those of the untreated injuries, 21 days after the procedure.

Conclusion: PRP promoted complete tissue restitution between the 7th and 21st days in experimental muscle injuries.
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http://dx.doi.org/10.1016/j.rboe.2015.08.009DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4610980PMC
November 2015
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