Effect of fluoride on overdenture abutments

This study evaluated the caries preventive effects of high concentrations of fluoride on overdenture abutment teeth. Twenty-four extracted caries-free teeth were randomly selected from a pool of patients aged 50-70 and prepared as for overdenture abutments. The teeth were sectioned mesiodistally into two halves. All surfaces on the teeth were painted with a protective varnish except for a window on the root surface and one on the cut dentin of the occlusal. The 48 root halves were randomly divided into four groups of 12 specimens. Each group received a different 4-minute treatment prior to being placed in a demineralizing solution for 6 hours. The treatment groups were (1) distilled H2O only; (2) 1,000 ppm F-; (3) 5,000 ppm F-; and (4) 10,000 ppm F-. The teeth were cycled for 6 hours in the demineralizing solution and 17 hours in a fluoride-free remineralizing solution for 17 days. Sections were cut at 100 +/- 10 microns through the windows. Standardized photomicrographs were made under polarized light using distilled H2O and quinoline as the imbibing media. Microradiographs were made of the same specimens and these were also photographed at the same magnification. The depths of the lesions were measured from drawings of the lesions projected on a digitizer screen. The amount of demineralization was calculated by subtracting the width of the mineralizing bands from the depth of the lesion. The conclusions were: (1) Lesions on the root surface were much shallower than on the occlusal; (2) A dose response to the fluoride concentration of the topical application was evident.