title: The effect of fluorhydroxyapatite in experimental human dental plaque on its pH, acid production and soluble calcium, phosphate and fluoride levels following glucose challenge.
abstract: Plaque grown on terylene gauze in the mouths of 5 volunteers was treated with a mineralizing solution intermittently for 4 days to deposit fluorhydroxyapatite. Control plaque grown simultaneously was not treated. Sixteen hours after the last treatment, plaque gauzes were incubated in 0.28 M glucose under N2 at 37 degrees C. The mean pH, reached by the 5 mineralized plaques after 30 min, (4.78) was significantly higher than the mean pH reached by control plaques (4.13), a difference that was due neither to unequal microbial mass nor to unequal acid concentrations. Acid neutralization following the dissolution of apatite was probably mainly responsible for the pH differences although a small antiglycolytic effect from leached F could not be ruled out. Mineralized plaque lost on average 24 per cent of its Ca, 25 per cent of its P and 16 per cent of its F, resulting in 0.868 mM Ca, 0.676 mM P and 0.075 mM F in the supernatant. Test plaque fluid was saturated with respect to fluorapatite and only moderately undersaturated with respect to hydroxyapatite at the end of the incubation period; this could explain the pronounced caries-protective effect of plaque fluorhydroxyapatite shown previously.
mesh_terms: D000328:Adult; D001031:Apatites / Q000494:pharmacology; D002118:Calcium / Q000032:analysis*; D002264:Carboxylic Acids / Q000032:analysis*; D003773:Dental Plaque / Q000032:analysis* / Q000378:metabolism; D017886:Durapatite; D005260:Female; D005459:Fluorides / Q000032:analysis*; D005947:Glucose / Q000494:pharmacology*; D006801:Humans; D006863:Hydrogen-Ion Concentration; D006882:Hydroxyapatites / Q000494:pharmacology*; D008297:Male; D008875:Middle Aged; D010710:Phosphates / Q000032:analysis*
chemical_list: D001031:Apatites; D002264:Carboxylic Acids; D006882:Hydroxyapatites; D010710:Phosphates; C028869:fluor-hydroxylapatite; D017886:Durapatite; D005947:Glucose; C025105:fluorapatite; D005459:Fluorides; D002118:Calcium