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Temperature change in pulp cavity in vitro during the polymerization of provisional resins
No full textObjectives. To measure the temperature change in the pulp cavity of an extracted tooth during
the polymerization of provisional resins within impression putty and polyethylene matrices.
The effect of precooling
the putty matrix was also evaluated.
Methods. A freshly extracted premolar tooth had putty impressions recorded prior to crown
preparation. Putty matrices were stored at room temperature, 4 and −12 C prior to use. A
thermocouple placed in the pulp chamber recorded the temperature change every 15 s for
a 10min
duration during polymerization of three resins using putty and clear polyethylene
matrices. Five recordings were made with each material at each storage temperature.
Results. There is a temperature rise of 3.4–5.5 C when the resins were autocured in a putty
matrix. When the polyvinyl matrix was used the temperature rise increased to 4.0–8.2 C
(P < 0.001). The temperature rise was reduced to zero when the putty had been precooled
in the fridge (P < 0.001) and reduced further following precooling
in the freezer (P < 0.001).
Significance. The use of a polyvinyl matrix allows higher pulp temperature rises to occur due
to the exotherm from provisional resins. Lower temperatures were recorded when putty
was used. The temperature rise could be eliminated when the putty was cooled at 4 C prior
to reinsertion
Prophylometric and sem analyse sof fourdifferent finishing methods
Full text linkAdhesion is the pivot of the modern restorative dentistry. Inlays, onlays and veneers have become a valid alternative to the traditional prosthetic treatments even in the rehabilitation of extremely damaged teeth, allowing aconsistent saving of sound tooth tissues. Composite resins and dental adhesive are continously investigated and improved, nevertheless the optimization of thetooth-adhesive interface has to be considered: in fact, the long-term stability of adhesion between tooth and compositematerial depends on the treatment of the amelo-dentinal surfaces.This study investigated the quality of the occlusal walls of a cavity prepared to receive an inlay and finished with four different systems: thin and extra-thin diamond coated burs, a 12-blades carbide burs and a diamond-coated tip driven bysonic instrument. Consequently, prophylometric and SEM analyses were performed on the samples. The average roughness values recordedby the prophylometer were expressed by the parameters Ra and RZ: there is a correspondence between the numeric val-ues and the pictures of the SEM. The results show a better quality (low roughness values) of the surface treated with multi-blade burs, followed by the thisand extrathin diamond coated burs. The 25 micron diamond-coated tip of the sonic instrument obtains the roughest surface and a sensibly higher amount of smear layer than the other tested systems
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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