Topical fluorides: effects on physiologic and biochemical processes

The ingestion of fluoride from dentifrices or mouthrinses can contribute substantially to the total daily intake of the ion, even in communities that provide optimally fluoridated drinking water. It is concluded that the frequent and unsupervised use of these products by children six years of age or younger, especially those living in areas with water fluoridation, places them at risk of dental fluorosis. Recommendations to reduce the risk are presented. The use of 1.23% (12,300 ppm) APF gels, particularly in the absence of suctioning during the application and expectoration after the application, is associated with the swallowing of relatively large quantities of fluoride. The resulting increases in plasma fluoride levels may be sufficient to cause dental fluorosis, as judged by studies with laboratory animals, and a reduction in the kidney's ability to concentrate the urine, as judged by studies with both laboratory animals and humans. The epigastric distress experienced by some patients during or after APF gel applications appears to be due, at least in part, to a direct toxic effect of fluoride on the gastric mucosa. Data from studies with humans and laboratory animals indicate that there may also be associated changes in plasma and tissue cAMP levels, glucose metabolism, and salivary amylase secretion. There is an immediate need for the dissemination to the dental profession of standardized methods for gel application that will minimize the quantities of fluoride available for ingestion and systemic absorption.