The proposed studies are designed to investigate how variations in the composition of plaque and plaque fluid affect the driving force for enamel demineralization and remineralization, and hence caries activity. The proposed studies will provide direct measurement of the physico-chemical factors, microbiological determinants, and the site-specific nature of the caries process. There are five specific aims.
Specific Aim l proposes to determine the total concentration of individual organic acids, inorganic ions, and pH in plaque fluid before, and at selected times after, a rinse with a sucrose solution. The fluid will be obtained from plaque associated with sound, white spot lesions and cavitated enamel surfaces obtained from teeth of caries-free (CF) and caries-positive (CP;DMFS>l0) subjects.
Specific Aim 2 proposes to study the effect of variations in plaque permeability to fermentable carbohydrate in relation to plaque properties and caries status.
Specific Aim 3 proposes to study the effect of the restriction of dietary sucrose intake by human subjects on (a) the microbial and chemical composition of plaque, (b) metabolic activity in plaque after carbohydrate exposure both in vivo and in vitro, (c) the bacterial cell density of plaque, and (d) plaque buffering capacity.
Specific Aim 4 proposes to further explore the role of calcium phosphate in plaque and the release of fluoride into plaque, following acid production, as additional cariostatic factors.
Specific Aim 5 proposes to conduct in vitro enamel demineralization experiments using demineralizing solutions having compositions similar to plaque fluids associated with cariogenic and non-cariogenic plaques.

National Institute of Health (NIH)
National Institute of Dental & Craniofacial Research (NIDCR)
Research Project (R01)
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Oral Biology and Medicine Subcommittee 1 (OBM)
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Forsyth Institute
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Yamazaki, Hajime; Litman, Amy; Margolis, Henry C (2007) Effect of fluoride on artificial caries lesion progression and repair in human enamel: regulation of mineral deposition and dissolution under in vivo-like conditions. Arch Oral Biol 52:110-20
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Lingstrom, P; van Houte, J; Kashket, S (2000) Food starches and dental caries. Crit Rev Oral Biol Med 11:366-80
Zhang, Y P; Kent Jr, R L; Margolis, H C (2000) Enamel demineralization under driving forces found in dental plaque fluid. Eur J Oral Sci 108:207-13
van Ruyven, F O; Lingstrom, P; van Houte, J et al. (2000) Relationship among mutans streptococci, ""low-pH"" bacteria, and lodophilic polysaccharide-producing bacteria in dental plaque and early enamel caries in humans. J Dent Res 79:778-84
Tanaka, M; Margolis, H C (1999) Release of mineral ions in dental plaque following acid production. Arch Oral Biol 44:253-8
Margolis, H C; Zhang, Y P; Lee, C Y et al. (1999) Kinetics of enamel demineralization in vitro. J Dent Res 78:1326-35
Pearce, E I; Margolis, H C; Kent Jr, R L (1999) Effect of in situ plaque mineral supplementation on the state of saturation of plaque fluid during sugar-induced acidogenesis. Eur J Oral Sci 107:251-9
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