1) Most animal studies are invalid unless they use animals that do not manufacture Vitamin C., e.g guinea pigs (not rats).
2) Studies using calcium fluoride, are also invalid as this is NOT the chemical used in artificial fluoridation. It does occur naturally* but it is a problem,
see research by Queensland Government with sheep in Queensland drinking artesian water.
3) Studies using sodium fluoride are also invalid as this is NOT the main chemical used in artificial fluoridation, it is too expensive for large plants.
These are toxic waste by-products from industry, that do not occur in nature, They are contaminated with varying levels of aluminium, antimony, arsenic, barium, beryllium, cadmium, chromium, copper, iron, lead, manganese, molybdenum, nickel, potassium, selenium, silver, thallium, vanadium, and zinc.
5) Any suggestion that these chemicals are safe is unscientific, and throws suspicion on the any author or paper that confuses these chemicals and promotes them for human or animal health.
* Also found on Mars