1,720,957 research outputs found
Twelve-Year Retrospective Follow-Up of Machined Implants in the Posterior Maxilla : Radiographic and Peri-Implant Outcome
No full textPurpose: To retrospectively evaluate the survival rate of machined implants in sinus-lifted posterior maxilla after 12 years, with special reference to radiographic outcome and peri-implantitis. Materials and Methods: From 37 possible candidates, 29 patients with 59 implants were evaluated. Implants were placed in the posterior maxilla in combination with a sinus elevation procedure (27 patients) or 6 months after sinus elevation (2 patients). Marginal bone level changes were radiographically evaluated at baseline and 1, 7, and 12 years post-loading. Probing depth was measured; presence/absence of plaque and bleeding on probing were recorded. Results: Four out of 59 implants failed in 4 out of 29 patients (cumulative survival rate=93.2%). The mean bone loss was 0.78mm (±0.88) after 12 years. Changes in the mean bone level were statistically significant between baseline and all the other follow-up intervals (p<.001). Statistically significant differences could be demonstrated for the first- to 12th-year interval (p<.05) and for the seventh- to 12th-year interval (p<0.001). No statistically significant differences could be demonstrated at the first- to seventh-year interval (p=32). The mean overall probing depth was 2.9±0.66mm. Probing depth was moderately correlated with the marginal bone changes at 7 year and after 12 year follow up (p=05). No signs of peri-implantitis were reported during the 12-year follow-up period. Conclusions: This follow-up demonstrates a very good prognosis when implants with machined surfaces are used. The frequencies of implant failures were very small. Within the limits of the results from this study, the risk of peri-implantitis in the posterior maxilla might be considered a minor problem when implants with machined surfaces are used
Evaluation of the biomechanical effects of the dimensional mismatches between dental bridges and supporting implants
No full textDental bridges supported by osseointegrated implants are commonly used to treat the partially or completely edentulous jaw. The bridges are manufactured in metal alloy using a sequence of technological steps which well match the requirement to get custom overstructures but does not guarantee geometrical and dimensional tolerances. Dentists often experience that a perfect fit of the bridge with the abutments is almost impossible to achieve.When a misfitting bridge is forced on the abutments, deformations may occur
inducing a permanent preload at the fixture/bone interface and the greater the misfit the greater is the preload and the risk of implant failure. This work gives an evaluation of the biomechanical e!ects induced by a misfitting bridge when forced on two supporting dental implants. The strains induced in the bridge have been measured using two purposely designed and fabricated experimental devices allowing different types of misfit. FEM 3D models of the bridge and of the bridge anchored to the bone by implants have been developed. The former has been validated by simulating the same loading conditions as in the experimental tests and comparing the bridge strains. Both models have been used for the evaluation of the stress induced in the bridge and at the fixture/bone interface by bridge length errors. The results show that the method may help to estimate the stress distribution in the bridge and bone as a consequence of different dental bridge misfits
Experimental and computational approach for the evaluation of the biomechanical effects of dental bridge misfit
No full textAn in vitro study on compensation of mismatch of screw versus cement-retained implant supported fixed prostheses
No full text
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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