1,720,961 research outputs found
a review
No full textThis review describes various forms of fluoride applications for reducing dental erosive lesions induced by acidic substances. Fluoride admixtures to acidic solutions in a concentration excluding toxicologically side-effects seem unable to arrest erosive lesions. By contrast, topical fluoride applications of toothpastes, oral rinses, gels or varnishes appear to be an effective agent for reducing demineralization by erosion. In particular, high-concentrated fluoride applications are able to increase abrasion resistance and decrease the development of erosions in enamel and dentin
a review
No full textThis review describes various forms of fluoride applications for reducing dental erosive lesions induced by acidic substances. Fluoride admixtures to acidic solutions in a concentration excluding toxicologically side-effects seem unable to arrest erosive lesions. By contrast, topical fluoride applications of toothpastes, oral rinses, gels or varnishes appear to be an effective agent for reducing demineralization by erosion. In particular, high-concentrated fluoride applications are able to increase abrasion resistance and decrease the development of erosions in enamel and dentin
Reparaturrestaurationen: Umfrage bei ZahnärztInnen im Kanton Zürich
No full textThe aim of this study was to carry out a representative survey on the implementation of and experience with repairs of single-tooth restorations among dentists in the Canton of Zurich, Switzerland. An anonymous questionnaire was sent to all 1,411 dentists registered in the Canton of Zurich; 38.9% of the delivered questionnaires were returned and 35.3% could be evaluated. The statistical analysis comprised Kendall's rank correlation coefficient (tau), Wilcoxon signed-rank tests, and Kruskal-Wallis tests. The level of significance was set at p≤0.05. Repair restorations are frequently made (composite: 98.5%, ceramic: 88.9%, crowns: 86.5%, metal: 54.6%, amalgam: 51.5%). Main indications for repairs were the partial loss of an existing restoration or of the adjacent dental hard substance, while restoration failures due to secondary caries were repaired to a lesser extent. The decision to repair is largely dependent on the size of the defect (90%), the size of the original restoration (63%), and the material of the failed restoration (84%). Repair restorations are most frequently made with composite following adequate conditioning of the repair surface. A majority of the dentists rate the lifespan of repair restorations as reduced in comparison with newly made restorations. In summary, repairs of defective single-tooth restorations are frequently performed by dentists in the Canton of Zurich, Switzerland, and constitute a well-established treatment procedure
Relation between examinees' true knowledge and examination scores: systematic review and exemplary calculations on Multiple-True-False items
No full textMultiple-True-False questions are one specific type of multiple-choice item that can be used to assess knowledge in written examinations. Within Multiple-True-False items, a number of statements within a single item are given, and each statement has to be marked separately as true or false. Various scoring methods for Multiple-True-False items exist and there is no consensus as to the ideal scoring method. The study aimed to systematically identify available scoring methods for Multiple-True-False items and to assess their usability and statistical parameters (i.e. available information included and expected chance scores from random guessing). Another objective was to examine the relation between examinees’ true knowledge and expected scoring results. Data presented in this manuscript may help educators make informed choices about the scoring method to be selected and corresponding pass marks required for testing a certain level of true knowledge of examinees
Effectiveness of a universal adhesive for repair bonding to composite and amalgam
No full textThe study aimed to compare the repair bond strength of aged composite and amalgam repaired with resin composite after various mechanical and adhesive surface treatments. Specimens were aged by thermal cycling (10,000 cycles, 5-55°C) and randomly subjected to one of three surface treatments: diamond bur abrasion, aluminum oxide air abrasion, or silica coating. Conventional bonding or a universal adhesive with incorporated silane was applied afterward (each n = 16) and resin composite was attached. In the control groups (each n = 16), resin composite was attached using one of the above adhesives without prior mechanical surface conditioning. After further thermal cycling, the shear bond strength (SBS) and failure modes were assessed. Statistical analyses were performed using ANOVA, Weibull statistics, two sample t-tests, and Chi2-test (P < 0.05). The SBS of the repaired amalgam was significantly lower than that of the composite and mechanical pretreatment significantly increased SBS. The universal adhesive significantly improved the SBS of the repaired amalgam compared to the conventional bonding agent and mechanical pretreatment increased the number of cohesive/mixed failures. Amalgam restorations may be repaired using resin composites, but the resulting SBS is lower than that obtained with composite
Reparaturrestaurationen: Umfrage bei ZahnärztInnen im Kanton Zürich
No full textThe aim of this study was to carry out a representative survey on the implementation of and experience with repairs of single-tooth restorations among dentists in the Canton of Zurich, Switzerland. An anonymous questionnaire was sent to all 1,411 dentists registered in the Canton of Zurich; 38.9% of the delivered questionnaires were returned and 35.3% could be evaluated. The statistical analysis comprised Kendall's rank correlation coefficient (tau), Wilcoxon signed-rank tests, and Kruskal-Wallis tests. The level of significance was set at p≤0.05. Repair restorations are frequently made (composite: 98.5%, ceramic: 88.9%, crowns: 86.5%, metal: 54.6%, amalgam: 51.5%). Main indications for repairs were the partial loss of an existing restoration or of the adjacent dental hard substance, while restoration failures due to secondary caries were repaired to a lesser extent. The decision to repair is largely dependent on the size of the defect (90%), the size of the original restoration (63%), and the material of the failed restoration (84%). Repair restorations are most frequently made with composite following adequate conditioning of the repair surface. A majority of the dentists rate the lifespan of repair restorations as reduced in comparison with newly made restorations. In summary, repairs of defective single-tooth restorations are frequently performed by dentists in the Canton of Zurich, Switzerland, and constitute a well-established treatment procedure
In vitro study on the preventive effect of children’s toothpastes on erosive tooth wear of primary bovine enamel and dentin
No full textAbstract This in vitro study aimed to analyse the effect of various children’s toothpastes on erosive tooth wear of primary bovine enamel and dentin. Enamel and dentin specimens (n = 12) were cyclically eroded (6 × 60 s/d, citric acid, pH 2.4) and brushed (2 × 15 s/d, 2 N) over 5 days. Nine fluoride toothpastes (500 to 1450 ppm) and eight toothpastes containing no fluoride or other active ingredients (hydroxyapatite and/or xylitol) were tested. Unbrushed specimens served as control. Tissue loss was quantified using widefield confocal microscopy and statistically analysed using two-way and one-way ANOVAs followed by Scheffe’s (enamel) or Tamhane’s (dentin) post-hoc tests (p < 0.05). Only one fluoride toothpaste (1400 ppm) was able to reduce erosive wear of enamel significantly by 15% compared to the control (padj. = 0.002). All fluoridated toothpastes reduced dentin surface loss significantly by 32 to 69% compared to the control (padj. ≤ 0.001), while fluoride-free toothpastes were unable to reduce dentin loss significantly (padj. ≥ 0.971). Most fluoridated toothpastes caused less erosive wear compared to fluoride-free toothpastes. Children toothpastes containing fluoride were more effective in reducing erosive wear compared to toothpastes containing no fluoride or other active ingredients
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
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