Fluoride

Everyone knows that fluoride is good for your teeth, however few people realize that there are actually two different mechanisms by which Fluoride can be introduced to tooth structure. First is a systemic introduction through ingestion which occurs inside the jaw and before exposure to the oral cavity. Second is a topical application to teeth that have already erupted.
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. Moreover, epidemiologists have cast doubt on the validity of the 'old' studies dealing with fluoride use. The concept of the posteruptive fluoride effect is supported by in vitro and in situ investigations demonstrating that the mode of action of fluoride can be attributed mainly to its influence on de- and remineralization of dental hard tissues. Therefore, topical fluoride application in the form of fluoridated dentifrices(tooth paste or mouthwash) should be encouraged.