Evaluation of the Effects of F in Acidified Gelatin Gel on Root Surface Lesion Development in vitro

Oral exposed, natural root surfaces of extracted human teeth were subjected to artificial lesion formation in gels of dialyzed gelatin that contained 75 mM lactic and 25 mM acetic acid and 1, 3, 10, 32, 100, 320, 550, or 1,000 mg F/l at pH 4.3-4.4 and at 36 degrees C. Ca and PO4 demineralization per square millimeter exposed surface and lesion depth decreased with increased F concentrations, except for the levels above 320 mg/l. Quantitative microradiographic image analyses showed that the mean percent mineral content of the entire lesions relative to the adjacent sound tissue was constant at about 64% for the F levels less than 320 mg/l. F above 3 mg/l changed the mineral density profile of the lesions by eliminating subsurface lamination. This showed that sufficient F incorporated at the site of demineralization prevented lesion progression and that the best effect would be obtained for F levels between 100 and 320 mg/l. Higher levels of F may also prove to be beneficial by providing labile F from CaF2 formed in the root surface.