FREIRE, W. P.; http://lattes.cnpq.br/0858443814426502; BARBOSA, Waldênia Pereira Freire.
Abstract:
Glass-ionomer cements (GIC) are composed of a mixture of silicon and
aluminum oxides together with fluoride in an aqueous solution of a polyalkenoic
acid. Through a set of acid-base reactions, a salt forms in a hydrogel matrix that
acts as a stabilizer of the cement. They are widely used in dentistry and also in
medicine, however, there is necessity of research on the compositions of these
materials in order to obtain a better clinical performance. So the purpose of this
study was the characterization of commercial GICs: OG GIC and VM GIC, in
order to observe the morphology, chemical composition, crystal structure and
the degree of hydrophilicity of these materials. To compare the experimental
data, four experimental compositions of GICs were developed: GICs A, B, C
and D. All cements were characterized by techniques of Fourier-transform
infrared Spectroscopy (FTIR), x-ray diffraction (XRD), analysis of surface
tension (TS), scanning electron microscopy (SEM) and energy dispersive
spectrometry by x-ray (XRD). Through x-ray diffraction the commercial GICs did
not exhibit any peaks of the crystalline phase; however, for experimental GICs
the presence of crystalline phases was confirmed. In infrared spectroscopy
showed the typical bands of these materials. The fluoride appeared in
experimental GICs between 460 and 400 cm- 1 and commercial GICs around
900 cm"1. The C=C, C=0 and Si-0 bonds appeared more intense in all
experimental GICs, but in the commercial GICs these bands are more tenuous.
Bands attributed to the presence of water were found in the range of 3400 to
3600 cm"1 and 640 cm"1 for experimental GICs, however for commercial GICs
these bands were situated from 3400 to 3600 cm"1, related to the presence of
carboxylic groups. In the tests of surface tension (TS), both cements were
hydrophilic with angles near 60°, but among commercial GICs, VM GIC showed
lower hydrophilic character. For the experimental GICs, the values were
statistically equal; however, GIC B showed less hydrophilic character. The
analysis by scanning electron microscopy and energy dispersive spectrometry
by x-ray revealed that among the commercial GICs, VM GIC showed greater
interaction between solid and liquid and experimental GICs presented only a subtle liquid-solid interaction showing a significant difference in energy between
the surface phases.