1,721,029 research outputs found
Comparing survival rates of endodontically treated teeth restored either with glass-fiber-reinforced or metal posts: A systematic review and meta-analyses
No full textStatement of problem: When restoring endodontically treated teeth, a post system is indicated to retain a core. Clinicians can choose from different post materials and types. However, the literature is inconclusive on the long-term clinical performance of available post systems. Purpose: The purpose of this systematic review and meta-analysis was to analyze the survival and failure rates of endodontically treated teeth restored either with glass-fiber-reinforced or metal posts. Material and methods: The research question was formulated by following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines by using the Population, Intervention, Comparison, Outcome, Study Type (PICOS) tool. Medline (PubMed), Embase, and Scopus searches complemented by manual search were performed for randomized controlled clinical trials with a follow-up of at least 2 years. Two independent authors performed screening and data extraction of the articles. Meta-analyses were performed with the RevMan software program. Homogeneity was checked by using chi2 and I2 tests, and random-effects meta-analyses were applied. Odds ratio and 95% confidence interval were calculated (α=.05). The publication bias was evaluated by using funnel plots and the Begg and Egger tests. Results: A total of 184 studies were retrieved through the electronic searches, and an additional 4 through the hand search. After title- and abstract-level exclusion, 23 studies remained for full-text analyses, of which 7 were selected for data extraction. Meta-analyses revealed an overall survival rate of 92.8% for endodontically treated teeth restored with glass-fiber-reinforced posts compared with 78.1% of those restored with metal posts. No statistically significant difference (P>.05) was found in the survival, success, or failure rates. Conclusions: No statistically significant differences were found between the survival and failure rates of endodontically treated teeth restored either with glass-fiber-reinforced or metal posts. The overall survival rate was 92.8% for glass fiber posts and 78.1% for metal posts. Both are reliable materials when a significant amount of coronal tooth structure is missing and treatment with a post is indicated
Effect of repeated firings on flexural strength of veneered zirconia
No full textChipping and/or delamination represent a clinical failure of porcelain fused to zirconia (PFZ) prostheses. Causes and solutions have not been completely clarified. The present study was aimed at evaluating the effects of number of firings on the flexural strength of PFZ specimen
Performance of CAD/CAM fabricated fiber posts in oval-shaped root canals: An in vitro study
No full textPurpose: To assess the push-out strength, the cement layer thickness and the interfacial nanoleakage of prefabricated fiber posts, CAD/CAM fiber posts and metal cast posts cemented into oval-shaped root canals. Methods: Oval-shaped post spaces were prepared in 30 single-rooted premolars. Roots were randomly assigned to three groups (n=10), according to the post type to be inserted: Group 1: Prefabricated fiber post (D.T. Light-Post X-RO Illusion); Group 2: Cast metal post; Group 3: CAD/CAM-fabricated fiber post (experimental fiber blocks). In Group 3, post spaces were sprayed with scan powder (VITA), scanned with an inEos 4.2 scanner, and fiber posts were milled using an inLab MC XL CAD/CAM milling unit. All posts were cemented using Gradia Core dual-cure resin cement in combination with Gradia core self-etching bond (GC). After 24 hours, the specimens were sectioned perpendicular to the long axis into six 1 mm-thick sections, which were differentiated by the root level. Sections from six roots per group were used to measure the cement thickness and subsequently for the thin-slice push-out test, whereas the sections from the remaining four teeth were assigned to interfacial nanoleakage test. The cement thickness around the posts was measured in micrometers (urn) on the digital images acquired with a digital microscope using the Digimizer software. Thin-slice push-out test was conducted using a universal testing machine at the crosshead speed of 0.5 mm/minute and the bond strength was expressed in megaPascals (MPa). The interfacial nanoleakage was observed under light microscope and quantified by scoring the depth of silver nitrate penetration along the post-cement-dentin interfaces. The obtained results were statistically analyzed by Kruskal-Wallis ANOVA, followed by the Dunn's Multiple Range test for post hoc comparisons. The level of significance was set at P< 0.05. Results: Statistically significant differences were found among the groups in push-out bond strength, cement thickness and interfacial nanoleakage (P< 0.05). CAD/CAM-fabricated fiber posts achieved retention that was comparable to that of cast metal posts and significantly higher than that of prefabricated fiber posts. The cement layer thickness around CAD/CAM-fabricated fiber posts was significantly lower than around prefabricated fiber posts, but higher than that around cast metal posts. Root level was not a significant factor for push-out strength in any of the groups, whereas it significantly affected cement layer thickness only in the prefabricated fiber post group. No differences were observed in interfacial nanoleakage between CAD-CAM fabricated and prefabricated fiber posts, while nanoleakage recorded in cast metal posts was significantly lower. (Am J Dent 2017;30:248-254). Clinical significance: CAD/CAM fabricated fiber posts could represent a valid alternative to traditionally used posts in the restoration of endodontically-treated teeth with oval or wide root canals, offering the advantages of better esthetics, retention, and cement thickness values that are comparable to cast post and cores
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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