Tooth decay is a common problem in childhood. There are many reasons behind tooth decay. Cavities, also called tooth decay or caries, are caused by a combination of factors, including bacteria in your mouth, frequent snacking, sipping sugary drinks, and not cleaning your teeth well. Fluoride is called nature’s cavity fighter, and for a good reason. Fluoride, a naturally-occurring mineral, helps prevent cavities in children. In adults, it helps by making the outer surface of your teeth (enamel) more resistant to the acid attacks that cause tooth decay.