MedlinePlus - Tooth decay is damage to a tooth's surface,...

Caries, also known as tooth decay or cavities, is a common oral health problem that occurs when bacteria in the mouth produce acid that erodes the hard, outer surface of the tooth (the enamel) and causes a hole or cavity to form. Tooth decay is caused by a combination of factors, including poor oral hygiene, a diet high in sugar and other refined carbohydrates, and a lack of fluoride. Bacteria called Streptococcus mutans, in particular, play a major role in the development of caries by producing

Cavities and Tooth Decay: Bacterial Causes of Common Dental Issues