Bovine enamel hardness and its Ca-, P-, Mg- and F-contents modified by the bacterium Streptococcus mutans, artificial dental plaque and fluoride.
A layer of cells from buffered Strep. mutans suspension (pH 5.8), with or without sucrose, was centrifuged on bovine enamel surfaces. Fluoride was added to a part of the samples (final F 25 parts/10(6]. Control and test samples were incubated at 37 degrees C for 18 h. The pH of the fermenting plaque dropped to 4.15. When F was present, the final pH was 4.45. Microhardness of the enamel surface was reduced by the presence of sucrose but less in the presence of F. Enamel Ca was liberated during fermentation, but only into the fluid and less in the presence of F. The weight ratio of Ca and P released by sugar fermentation was 3.14 and 1.91 when F was present. The F content of enamel surface was only slightly increased (130 parts/10(6]by the F in distilled water alone. Subsurface enamel gained more F (280 parts/10(6]. When artificial plaque was present, addition of F increased the F content of enamel surface by 450 parts/10(6) and F of subsurface by 210 parts/10(6). The addition of F increased the enamel F content to the greatest extent under the fermenting plaque, 680 parts/10(6) in surface and 400 parts/10(6) in subsurface enamel, compared to the values of the enamel under non-fermenting plaque.
D000818:Animals; D002118:Calcium / Q000378:metabolism; D002417:Cattle; D003743:Dental Enamel / Q000378:metabolism* / Q000382:microbiology; D003773:Dental Plaque / Q000378:metabolism*; D005285:Fermentation; D005459:Fluorides / Q000378:metabolism*; D006244:Hardness; D006863:Hydrogen-Ion Concentration; D008274:Magnesium / Q000378:metabolism; D010758:Phosphorus / Q000378:metabolism; D013295:Streptococcus mutans / Q000378:metabolism*; D013395:Sucrose / Q000378:metabolism
D010758:Phosphorus; D013395:Sucrose; D008274:Magnesium; D005459:Fluorides; D002118:Calcium