FLUORIDE is a naturally occurring element that prevents tooth decay when ingested systemically or applied topically. Researchers believe that there are several mechanisms by which fluoride achieves its anti-carious effect. It reduces the solubility of enamel in acid by converting hydroxyapatite into less soluble fluoroapatie; it may exert an influence directly on dental plaque, reducing the ability of plaque organisms to produce acid; and it promotes the remineralization of tooth enamel in areas that have been decalcified by acids.
Most likely, fluoride works by a combination of these effects. But the remineralization effect of fluoride is of prime importance, because it results in a reversal of the early caries process, and gives rise to enamel more resistant to decay.
In 1914, fluoride was added to toothpaste, but became more widespread when it was recommended by the American Dental Association (ADA) in the 1950s.  The Centers for Disease Control and Prevention has proclaimed community water fluoridation as one of the 10 great public health achievements of the 20th Century. Most States in the USA have fluoride in their drinking water. However, relatively recently, there has been some reconsideration among the scientific community about this material.
Fluoride, in various forms, is still the most popular active ingredient in toothpaste although Material Safety Data Sheets (MSDS) typically label sodium fluoride as “toxic by ingestion, inhalation and skin contact,” and warn that PPE (personal protective equipment) for handling should include safety glasses and gloves. The United States FDA (Food and Drug Administration) has required that all fluoride toothpastes sold in the U.S. carry a poison warning on the label.

The warning cautions toothpaste users to:
“Keep out of the reach of children under six years of age. If more than used for brushing is accidentally swallowed, get medical help, or contact a Poison Control Center right away.”
An article in the Journal of Dental Research suggests that a potentially fatal dose of fluoride is 5mg per kilogram of bodyweight. This is the “minimum dose that could cause toxic signs and symptoms, including death, and that should trigger immediate therapeutic intervention and hospitalization…This does not mean that doses lower than 5mg F/kg should be regarded as innocuous.”
As commonsense might indicate, death isn’t the only concern with fluoride toothpaste. Other potential problems include gastric problems and fluorosis (characterized by white streaks on teeth).
The question you may now ask yourself is: “Does fluoridated toothpaste do more harm than good?” The answer to that question is: “No, once the toothpaste you choose to use has the ADA seal of acceptance.”
Dentists and consumers have long recognized the ADA Seal of Acceptance as an important symbol of a dental product’s safety and effectiveness. This author is a member of the ADA, and relates closely with current research and development in every sphere of dentistry.
Therefore, as a consumer, you must understand that in order for fluoride toothpaste to get an ADA seal of acceptance, it must meet ADA’s requirements for safety and effectiveness in reducing tooth decay. The manufacturer must provide clinical studies in humans, laboratory studies to determine the amount of available fluoride, the amount of fluoride released in one minute, and the amount of fluoride absorption in normal and weakened tooth enamel.
Such tests are conducted in ADA’s laboratory. With that being said, the seal is your assurance that the fluoridated toothpaste has met the ADA criteria for safety and effectiveness.