Journal of Dental Research, Vol 71, 7-12, Copyright © 1992 by International & American Associations for Dental Research Online Journals
An in vitro model for assessment of fluoride uptake from glass-ionomer cements by dentin and its effect on acid resistance
V. Tsanidis and T. Koulourides
Department of Pediatric Dentistry, University of Alabama School of Dentistry, Birmingham 35294.
This investigation presents an experimental model for studying interactions
of glass-ionomer cements (GICs) with bovine dentin slabs. Fluoride
incorporation was studied with five serial abrasion biopsies, each being
approximately 10 microns thick. The time of interaction was a very
important parameter, indicating continuous fluoride release from the GIC
and diffusion into dentin over a 30-day period. Expressed in mass per
volume (mg F/cm3), the fluoride incorporation reached 12.0 mg at the first
and 2.5 mg at the fifth layer, several times greater than the baseline of
0.27 mg/cm3 in bovine dentin. A subsequent test of acid resistance in a
lactic acid buffer (pH 4.0), followed by microradiography of lesions,
showed a characteristic 40-microns-wide acid-resistant zone on surfaces
exposed to the GICs. In contrast, the untreated control surfaces had
lesions demineralized evenly from the surface to the intact tissue, without
the higher-density zone at the surface of the lesion. The model seems
promising for screening fluoride incorporation into dentin from
fluoride-releasing dental materials.
