%0 Journal Article
%T Radiopacity and microhardness changes and effect of X-ray operating voltage in resin-based materials before and after the expiration date
%A Tirapelli
%A Camila
%A Panzeri
%A Fernanda de Carvalho
%A Panzeri
%A Heitor
%A Pardini
%A Luiz Carlos
%A Zaniquelli
%A Osvaldo
%J Materials Research
%D 2004
%I ABM, ABC, ABPol, SBCC, SBCr, SBMM, SBPMat
%R 10.1590/S1516-14392004000300006
%X this study observed alteration in the radiopacity and microhardness of expired resin-based materials compared to non-expired materials and the operating characteristics of the x-ray source used. five 2 mm-thick cured specimens were prepared for each material: composite resins (p60£¿, z100£¿), and a compomer (dyract ap£¿). radiopacity of the specimens was evaluated comparing the density of the resin-based material to an equivalent (mm) density of a 99.5% pure aluminum step wedge using a transmission densitometer. surface microhardness measurements were carried out using a calibrated vickers indenter on three different points of the same surface. anova and tukey tests (pre-set alpha = 0.05) revealed that expired materials showed no significant change in radiopacity. one material (filtek p60) demonstrated lower radiopacity with lower kvp. change in microhardness wa s statistically significant for z100: for this material, the microhardness after expiration was significantly lower than before the expiration date.
%K radiopacity
%K expiration date
%K composites
%K operating voltage
%K microhardness.
%U http://www.scielo.br/scielo.php?script=sci_abstract&pid=S1516-14392004000300006&lng=en&nrm=iso&tlng=en