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Fracture strength of tooth fragment reattachments with postpone bevel and overcontour reconstruction
No full textAbstract
The purpose of this study was to test the actual resistance against fracture of a crown fragment fractured and reattached using three different techniques of preparation. Forty bovine incisors were randomly assigned into four groups of which the first was the control group. The elements of the three experimental groups were all cut at a fixed distance of 3 mm for the incisal margin on the buccal surface of the crown in a plane normal to the buccal surface itself, and subsequently re-bonded using an adhesive system. After the reattachment, on the teeth of group 2, a circumferential chamfer was performed along the fracture line; on the teeth of group 3 a groove called 'overcontour' was made also along the fracture line; the teeth in group 4 received a chamfer on the buccal surface and an overcontour on the lingual surface. Finally, all the elements were encompassed in chalk blocks and the models were mounted on the 858 Mini Bionix to perform a fatigue load test. A force was applied on the buccal surface of each tooth at 1.5 mm from the incisor margin, with a velocity of 1 mm min(-1), through the use of a steel prick. All the elements of groups 2, 3 and 4 demonstrated a lower resistance to fracture in comparison with the elements of the control group. The teeth of group 2 showed a resistance to fracture equal to 36.1% of the resistance of the elements in the control group; in group 3 the resistance was equal to 50.2%, while in group 4 the resistance reached 55.9%. The difference in resistance between group 3 and group 4 did not result statistically significant (P = 0.82). Reattachment of coronal fragments does not restore the resistance to fracture to an equal level of the intact teeth, in a static test. The different techniques of preparation significantly modify the resistance to the fracture of a re-bonded fragment. The technique of the circumferential chamfer produced results that were less favourable in terms of resistance against fracture.
PMID: 18489478 [PubMed - indexed for MEDLIN
APPROCCIO ESTETICO AL SETTORE ANTERIORE DELLA DENTATURA MEDIANTE RESTAURI ADESIVISI IN CERAMICA: TECNICA OPERATIVA
No full textRIPRISTINO CONSERVATIVO DI ELEMENTI ABRASI NEL SETTORE MANDIBOLARE ANTERIORE: CASE REPORT
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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
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