Methods: 16 human permanent teeth with macroscopically sound enamel surfaces were divided into 2 topical fluoride treatment groups. Following a fluoride-free prophylaxis, the buccal surfaces were exposed to the assigned topical fluoride agents: (1) Colgate Fluoro-Foam [1 minute 1.23% APF]; 2) Oral-B Minute-Foam [1 minute 1.23% APF]. Following fluoride treatment, the topical fluoride agent was removed with copious rinsing. An acid-resistant varnish was applied, leaving buccal treated enamel surfaces and lingual untreated control enamel surfaces exposed. Artificial caries were created using a modified ten Cate solution with an exposure time of 7 days. Longitudinal sections were prepared (10 per specimen) for polarized light study (water imbibition) and lesions depths were determined and compared among groups (ANOVA, DMR).
Results: Mean lesion depths were as follows: 186±26µm for Controls; 97±23µm Colgate Fluoro-Foam; and 83±22µm Oral-B Minute-Foam. Both fluoride treatments resulted in significant reductions (P< 0.05) in lesion depth compared with the nontreated control group. Colgate Fluoro-Foam had a 48% reduction in lesion depth; while Oral-B Minute-Foam had a 54% reduction in lesion depth.
Conclusions: Topical fluoride provides a means to substantially lessen in vitro lesion formation in sound enamel. A single 1 minute exposure to APF foam provides a significant degree of caries protection against an in vitro caries challenge.