Comment by fzeroracer

I think the common consensus is that the primary benefit of fluoride is topical, not systemic:

* Initially, fluoride was considered beneficial when given systemically during tooth development, but later research has shown the importance and the advantages of its topical effects in the prevention or treatment of dental caries and tooth decay. [The Fluoride Debate: The Pros and Cons of Fluoridation; Prev Nutr Food Sci, 2018; https://pmc.ncbi.nlm.nih.gov/articles/PMC6195894].

* The actual mechanism of fluoride action is still a subject of debate. A dogma has existed for many decades, that fluoride has to be ingested and acts mainly pre-eruptively. However, recent studies concerning the systemic effect of fluoride supplementation concluded that the caries-preventive effect of fluoride is almost exclusively posteruptive. [Systemic versus topical fluoride; Carries Res, 2004; https://pubmed.ncbi.nlm.nih.gov/15153698/]

* As noted by Thorrez, your link does not mention topical application vs systemic ingestion. There is a publication from the CDC however stating that the benefit of fluoride is mainly topical:

> Fluoride's caries-preventive properties initially were attributed to changes in enamel during tooth development because of the association between fluoride and cosmetic changes in enamel and a belief that fluoride incorporated into enamel during tooth development would result in a more acid-resistant mineral. However, laboratory and epidemiologic research suggests that fluoride prevents dental caries predominately after eruption of the tooth into the mouth, and its actions primarily are topical for both adults and children (1). [https://www.cdc.gov/mmwr/preview/mmwrhtml/mm4841a1.htm ; 1999].

This material was covered in depositions for TSCA Fluoride trial in 2018, where Casey Hannan (director of the division of oral health at the CDC) was the examinee for the deposition. A temporary upload of a clip from this deposition may be found at https://0x0.st/8Lom.mp4.

When I say "fluoride works topically, not when ingested", I mean there's no benefit to teeth from swallowing fluoride, the only benefit to teeth is from it touching teeth directly. That link doesn't say that there's a tooth health benefit from swallowing fluoride.

Both toothpaste and water supply cause some fluoride to touch the teeth (topical) and some fluoride to be swallowed (ingestion). However, toothpaste has a higher ratio of topical application to swallowing, vs water supply which has a lower ratio of topical application to swallowing. That's why I said toothpaste is focused on topical application and water supply is focused on ingestion.