How does Fluoride Interfere With the Decay Process?
Bacteria in the mouth consume sugar and excrete acid. The acid “demineralizes” (dissolves) the tooth. The minerals in saliva then work to remineralize (repair) the tooth. Demineralization and remineralization happen throughout the day.
If, during the remineralization process, there is a fluoride ion present, it becomes incorporated into the tooth surface along with the calcium and phosphorus. This process makes an enamel crystal that is less susceptible to being dissolved by acid. The more frequently fluoride ions are present in the mouth, whether from toothpaste, water, food, rinses, or supplements, the greater the protection against decay. This phenomenon is called the topical effect of fluoride and occurs at any age. The more sugar eaten in the many forms of fructose (fruit sugar), lactose (milk sugar), or sucrose (refined sugar) the greater the need for fluoride. The per capita yearly intake of caloric sweeteners, which has always been high, increased from 132 pounds in 1988 to 152 pounds in 1999.
If fluoride is consumed before the age of 12 when all the teeth are forming, it enters the blood stream briefly and is incorporated into the entire developing tooth. This process is called the systemic benefit of fluoride and gives lifetime decay resistance.
The other major way fluoride reduces decay is when it concentrates in plaque. The presence of fluoride inhibits or prevents the bacteria from making acid from sugar. Fluoride has also been shown to have a mild effect against the bacteria that cause gum disease.