1,720,996 research outputs found
Comparative analysis of deformation of two implant/abutment connection systems during implant insertion. An in vitro study.
No full textAtr-ftir analysis of orthodontic invisalign® aligners subjected to various in vitro aging treatments
Full text linkClear and removable tooth aligners for orthodontics treatments have become an increasingly popular alternative to fixed appliances. Even if protocols suggest removing aligners before eating or drinking, most patients retain them when they drink beverages. Alterations in the material during the daily use could determine a reduction in the application forces, affecting the desired orthodontic movement; the knowledge of how this material reacts when subjected to different aging processes is mandatory to establish the predictability of the orthodontic treatment. According to this, the aim of the present study was to assess a new objective approach, coupling spectroscopic and chemometric tools, to evaluate the changes occurring in Invisalign® aligners, the most widely used brand, exposed in vitro to coffee, tea, Coca Cola® and UV radiation for 24 and 48 h. In particular, ATR-FTIR spectroscopy was utilized to characterize, at the molecular level, the chemical and color modifications in the surfaces of the appliances; the obtained data were submitted to PCA and one-way ANOVA and Tukey’s multiple comparison test. Moreover, a colorimetry analysis was carried out to evaluate any changes in color and transparency. Coffee and tea samples displayed the major color changes between the tested groups. The differences highlighted in the spectral features of coffee, tea and UV-treated samples were mainly ascribable to color and transparency changes, because the chemical properties remained unaltered
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Restoration of Severe Bone and Soft Tissue Atrophy by Means of a Xenogenic Bone Sheet (Flex Cortical Sheet): A Case Report
Full text linkThe use of xenogenic cortical bone laminas in Guided Bone Regeneration (GBR) has been well described in the literature over the past decade. These biomaterials present a very low degree of complications due to their nature (porcine or equine collagenated bone) and the fact that when they become exposed, they simply hydrolyze without major complications. One of the problems related to the first generation of these laminas was their extreme rigidity and return elasticity, often forcing clinicians to anchor them with pins and/or screws. A new generation of bone laminas called Flex Cortical Sheet (FCS) have recently been introduced with machine-made thicknesses of 0.2, 0.5, and 0.9 mm and increased flexibility and adaptability to ridge defects. This paper has the goal of presenting a case of vertical and horizontal reconstruction performed by means of a 0.5 mm FCS and showing the workflow necessary to successfully restore a complex situation. After 8 months of healing, the GBR resulted in a horizontal and vertical augmentation of 8 mm and 8 mm, respectively. The radiographic examination at 18 months demonstrated great stability of new bone around implants
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Fourier Transform Infrared Imaging analysis of dental pulp inflammatory diseases
No full textObjectivesFourier Transform Infrared microspectroscopy let characterize the macromolecular composition and distribution of tissues and cells, by studying the interaction between infrared radiation and matter. Therefore, we hypothesize to exploit this analytical tool in the analysis of inflamed pulps, to detect the different biochemical features related to various degrees of inflammation.Materials and MethodsIR maps of 13 irreversible and 12 hyperplastic pulpitis, together with 10 normal pulps, were acquired, compared with histological findings and submitted to multivariate (HCA, PCA, SIMCA) and statistical (one-way ANOVA) analysis. The fit of convoluted bands let calculate meaningful band area ratios (meanss.d., P<0.05).ResultsThe infrared imaging analysis pin-pointed higher amounts of water and lower quantities of type I collagen in all inflamed pulps. Specific vibrational markers were defined for irreversible pulpitis (Lipids/Total Biomass, PhII/Total Biomass, CH2/CH3, and Ty/AII) and hyperplastic ones (OH/Total Biomass, Collagen/Total Biomass, and CH3 Collagen/Total Biomass).ConclusionThe study confirmed that FTIR microspectroscopy let discriminate tissues' biological features. The infrared imaging analysis evidenced, in inflamed pulps, alterations in tissues' structure and composition. Changes in lipid metabolism, increasing amounts of tyrosine, and the occurrence of phosphorylative processes were highlighted in irreversible pulpitis, while high amounts of water and low quantities of type I collagen were detected in hyperplastic samples
Appropriate Similarity Measures for Author Cocitation Analysis
Full text linkWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
The ‘Guided Tissue Regeneration (GTR) Effect’ of Guided Bone Regeneration (GBR) with the Use of Bone Lamina: A Report of Three Cases with More than 36 Months of Follow-Up
No full textThe world of dentistry knows the benefits and results of guided bone regeneration. One of the most successful techniques introduced a decade ago utilizes, as a barrier membrane, a sheet made of collagenated xenograft called bone lamina. Indications and applications with different surgical techniques have been well described by several authors. This technique not only presents a very low degree of complications, but also has some added benefits that this article will highlight. The so called ‘GTR effect’ means that the GBR not only reproduces the required bone volume for placing implants, but also improves attachment levels on the teeth adjacent to the augmented area. Bone lamina produces both GBR and GTR effects
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