This Article Full Text (PDF) References Alert me when this article is cited Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Add to Saved Citations Download to citation manager Request Permissions Request Reprints Add to My Marked Citations Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Citing Articles via Scopus Google Scholar Articles by Pearce, E.I.F. Articles by Dibdin, G.H. Search for Related Content PubMed PubMed Citation Articles by Pearce, E.I.F. Articles by Dibdin, G.H. Pubmed/NCBI databases Compound via MeSH Substance via MeSH Social Bookmarking                         What's this?

The Diffusion and Enzymic Hydrolysis of Monofluorophosphate in Dental Plaque

Dental Research Unit, HRC of NZ, PO Box 27007, Wellington, NZ

G.H. Dibdin

MRC Dental Group, The Dental School, Bristol, England

Although the ability of dental plaque to hydrolyze sodium monofluorophosphate (MFP) has been known for some time, its effect on the F- concentration at the plaque-enamel interface is undefined. We have determined enzyme kinetic values for MFP hydrolysis and diffusion coefficients so that the penetration and degradation of MFP in plaque can be modeled by computer. The KM and Vmax values for natural human plaque were 1.77 mmol/L and 41.4 nmol/min/mg protein, respectively, at pH 8.0. At pH 6.0, the Vmax was lower, 15.6 nmol/min/mg, but KM was not significantly different. Competitive inhibition by orthophosphate gave a Ki of 4.55 mmol/L. The diffusion coefficient for MFP in artificial plaque was 1.91 x 10-6 cm²/sec. When these data were used for mathematical modeling of the effects of rinsing with MFP and F-solutions, compared with an equivalent NaF application, the concentration of F- from MFP was lower at the inner surface of plaque, and the peak occurred later. Both pH and plaque thickness had a marked effect on the amount of MFP that could penetrate: At pH 8.0, almost none reached the inner surface of a 1-mm-thick plaque intact. At pH 6.0, however, more MFP was able to penetrate, due to lower MFPase activity. While MFP diffusion is inherently slower than that of F-, enzymic degradation increases the gradient for inward diffusion. If the conventional view that MFP in toothpaste acts as a source of F- is true, then MFP toothpaste should be formulated to optimize MFPase activity in dental plaque.

Key Words: dental plaque • monofluorophosphate • diffusion • hydrolysis.

Journal of Dental Research, Vol. 74, No. 2, 691-697 (1995)
DOI: 10.1177/00220345950740021101


CiteULike    Complore    Connotea    Del.icio.us    Digg    Reddit    Technorati    Twitter    What's this?

This article has been cited by other articles:

				C.H. Sissons Artificial Dental Plaque Biofilm Model Systems Advances in Dental Research, April 1, 1997; 11(1): 110 - 126. [Abstract] [PDF]

				G. H. Dibdin Mathematical Modeling of Biofilms Advances in Dental Research, April 1, 1997; 11(1): 127 - 132. [Abstract] [PDF]