[efirman]

Fluoride works both topically and systemically to reduce tooth decay and is delivered through water, salt, milk, toothpaste, varnish, rinse depending on age, country of origin, income etc. For children ages 0-8 it is incorporated into the enamel of the teeth growing under the gums. After that, the mechanism is largely "topical" - however, that includes fluoride ions incorporated into the saliva and plaque in the process of ingesting it. Sipping water throughout the day bathes the teeth in fluoride each time and allows there to be a very small but impactful amount of fluoride in the mouth environment. This assists in the remineralizations of teeth enamel after acid attacks. The "topical vs. systemic" debate is a bit of a red herring. Its asking how does it work, not if it works. The evidence is clear that fluoridation does work to prevent tooth decay.https://fluorideexposed.org/fluoridescience/fluoride-mechani... additionally, a recent economic review of fluoridation found that the benefits in terms of reduced cavity rates and related dental costs outweigh the cost of implementing the strategy. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6171335/