Fluoride is a mineral that is found in soil, water and various foods. Fluoride provides a positive effect on oral health by making teeth resistant to decay. Fluoride can prevent or reverse tooth decay and acid erosion. In most areas public drinking water has fluoride in it as well as most toothpastes and rinses. A dentist often will provide a fluoride treatment with a cleaning to assure that the patient is getting an adequate amount of fluoride for optimal tooth health.