Fluoride has been used in dentistry for over 100 years for the purpose of preventing dental caries. During this time there has been great debate over the mode of action, the optimum method of delivery, and the potential risks associated with its use. This, the first of three papers, will provide a summary of the history of the use of fluoride, the mode of action, benefits and different methods of delivery. It will also discuss the potential risk of dental fluorosis. CLINICAL RELEVANCE: This article aims to provide a background for general practitioners for the appropriate use of fluorides in dentistry, enable them to understand the wider significance of fluoride in dentistry and to be able to answer non-clinical questions raised by patients.