Fluoride itself is a very controversial topic so the aim of this book is to know about the mechanism of fluoride and toxicity of fluoride. Public health authorities throughout the world find a medical consensus that water fluoridation at appropriate levels is a safe and effective means to prevent dental caries.[1] Authorities' views on the most effective fluoride therapy for community prevention of tooth decay are mixed; some state water fluoridation is most effective, while others see no special advantage and prefer topical application strategies.