Journal of Dental Research, Vol 66, 1020-1024, Copyright © 1987 by International & American Associations for Dental Research Online Journals
Intra-oral effects on acid-softened enamel of NaF lozenges administered in divided daily doses
R. E. Corpron, J. W. Clark, J. Arnold, F. G. More, D. Merrill and C. J. Kowalski
The purpose of this investigation was to study the intra-oral effects of
multiple daily applications of NaF lozenges upon acid-softened enamel.
Bovine enamel slabs were softened with 0.1 mol/L lactate buffer at pH 4.0
for 14 hrs and subsequently mounted in a mandibular removable Hawley
appliance. Control slabs were worn for seven days by eight adult male
subjects who brushed their natural dentition daily with a fluoride-free
dentifrice. Test slabs were exposed to one 0.55-mg NaF lozenge (0.25 mg F)
4x/day for seven days and the natural dentition brushed with a
fluoride-free dentifrice. The efficacy of 0.25-mg F lozenges used 4x/day
over that of a 1-mg F lozenge administered 1x/day was established by a
pilot study with two subjects. Microhardness testing was performed after
intra-oral exposure (IOE) and following immersion in 0.01 mol/L lactate
buffer containing Ca and PO4 for 24 hrs at a pH of 4.0. Fluoride uptake was
measured on separate control and test slabs after KOH wash and after
acid-resistance-testing (ART). Recovery of microhardness following IOE was
40.9% for controls and 53.9% for treated slabs, while control slabs
retained 1.3% resistance to ART, compared with 25.6% for test slabs. The F
content of the control slabs was significantly less than that of
lozenge-treated and lozenge-treated-ART slabs throughout the depth of the
lesion. The F content of the lozenge-treated-ART slabs was significantly
less than that of the lozenge-treated slabs only at the 0-5-microns
depth.(ABSTRACT TRUNCATED AT 250 WORDS)
