1,720,982 research outputs found
Dentin Permeability After Toothbrushing with Two Different Toothpastes
No full textThe present study aims to assess the morphology of enamel and dentin after treatments with various toothpastes in powder or paste form recently proposed for home use. Dentin permeability was calculated as hydraulic conductance (Lp). We also assessed the effect of manual brushing for a limited period on dentin morphology. Scanning electron microscopy (SEM) was made to evaluate the morphology of dentin after toothpaste treatment and application. Material Method. We uused teeth (third molars) extracted for orthodontic reasons from patients with a mean age of 32.5 years. Dentin permeability measurement. Each dentin disc was connect to a hydraulic system with a pressure of 30cm/H2O. After preparation, each sample was connected to hydraulic pressure apparatus to evaluate the permeability of dentin with the smear layer produced during the sectioning step. After 5 minutes, dentin was etched with 37% phosphoric acid gel for 2 minutes, washed and gently dried with cotton to measure the permeability after smear layer removal. The next phase was to examine dentin before and after treatments with toothpaste and brushing with scanning electron microscope (SEM).
Results. No particular differences between the three products were seen (ename)l; however, the smear layer appeared modified and removed to a greater extent with Merfluan dental salts. Overall, the smear layer (on both enamel and dentin) was extremely thin, since producing and preparing the sample involved only light, weak movements with abrasive instruments.
Conclusion. This study shows that all the toothpastes tested interact with a substratum, in this case the dentinal smear layer. The enamel smear layer, however, was more compact and less easily modified. Nonetheless, it should borne in mind that a single application of toothpaste and one brushing, however energetic, are unlikely to lead to modifications of a hard surface such a ename
Dentin Permeability After Toothbrushing with Two Different Toothpastes
No full textThe present study aims to assess the morphology of enamel and dentin after treatments with various toothpastes in powder or paste form recently proposed for home use. Dentin permeability was calculated as hydraulic conductance (Lp). We also assessed the effect of manual brushing for a limited period on dentin morphology. Scanning electron microscopy (SEM) was made to evaluate the morphology of dentin after toothpaste treatment and application. Material Method. We uused teeth (third molars) extracted for orthodontic reasons from patients with a mean age of 32.5 years. Dentin permeability measurement. Each dentin disc was connect to a hydraulic system with a pressure of 30cm/H2O. After preparation, each sample was connected to hydraulic pressure apparatus to evaluate the permeability of dentin with the smear layer produced during the sectioning step. After 5 minutes, dentin was etched with 37% phosphoric acid gel for 2 minutes, washed and gently dried with cotton to measure the permeability after smear layer removal. The next phase was to examine dentin before and after treatments with toothpaste and brushing with scanning electron microscope (SEM).
Results. No particular differences between the three products were seen (ename)l; however, the smear layer appeared modified and removed to a greater extent with Merfluan dental salts. Overall, the smear layer (on both enamel and dentin) was extremely thin, since producing and preparing the sample involved only light, weak movements with abrasive instruments.
Conclusion. This study shows that all the toothpastes tested interact with a substratum, in this case the dentinal smear layer. The enamel smear layer, however, was more compact and less easily modified. Nonetheless, it should borne in mind that a single application of toothpaste and one brushing, however energetic, are unlikely to lead to modifications of a hard surface such a ename
Dentine Permeability and Dentine Morphology after Treatment with Sanguinaria Canadensis and Chlorexidine
No full textToothpastes, mouthwashes, liners, that remove smear layer and increase the functional diameter of dentinal tubules may be responsible for hypersensitivity and pain. The aim of this study to evaluate in vitro the effect on dentin permeability of two mouthwashes proposed for periodontal therapy: Periogard with Sanguinaria Canadensis 0.03% (Colgate, USA) and Periogard with Chlorexidine 0.2% (Colgate, USA). Twenty-four occlusally sectioned crown segments from human extracted third molars were divided into four groups and connected to an in vitro hydraulic apparatus as described by Pashely et al. (1978). All groups were etched with 37% phosphoric acid gel (3M, USA) to remove the smear layer and to calculate the maximum permeability. In two groups, smear layer was recreated using #400 3M sandpaper disks. Finally, the undiluted mouthwashes were applied and brushed on the dentin for 3 minutes with a toothbrush (Colgate, USA). Each sample was then washed with water and dentin permeability was evaluated. Four measurements of permeability (expressed as hydraulic conductance in ml/min per cm H2O) were made for each sample the averaged. ANOVA tests and Paired Student's test were used where appropriate. SEM analysis was made on the same samples
Dentine Permeability and Dentine Morphology after Treatment with Sanguinaria Canadensis and Chlorexidine
No full textToothpastes, mouthwashes, liners, that remove smear layer and increase the functional diameter of dentinal tubules may be responsible for hypersensitivity and pain. The aim of this study to evaluate in vitro the effect on dentin permeability of two mouthwashes proposed for periodontal therapy: Periogard with Sanguinaria Canadensis 0.03% (Colgate, USA) and Periogard with Chlorexidine 0.2% (Colgate, USA). Twenty-four occlusally sectioned crown segments from human extracted third molars were divided into four groups and connected to an in vitro hydraulic apparatus as described by Pashely et al. (1978). All groups were etched with 37% phosphoric acid gel (3M, USA) to remove the smear layer and to calculate the maximum permeability. In two groups, smear layer was recreated using #400 3M sandpaper disks. Finally, the undiluted mouthwashes were applied and brushed on the dentin for 3 minutes with a toothbrush (Colgate, USA). Each sample was then washed with water and dentin permeability was evaluated. Four measurements of permeability (expressed as hydraulic conductance in ml/min per cm H2O) were made for each sample the averaged. ANOVA tests and Paired Student's test were used where appropriate. SEM analysis was made on the same samples
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
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
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
Dispelling the Myths Behind First-author Citation Counts
Full text linkWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
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