Tooth Cavity is a permanently damaged area in the hard surface of the teeth that develop into tiny openings or holes. Cavities, also called tooth decay or caries, are caused by a combination of factors, including bacteria in the mouth, frequent snacking, sipping sugary drinks and not cleaning the teeth well. Cavities and tooth decay are among the world's most common oral problems. They're especially common in children, teenagers, and older adults. But anyone who has teeth can get cavities, including infants. If cavities aren't treated, they get larger and affect deeper layers of your teeth. They can lead to a severe toothache, infection and tooth loss. Regular dental visits and good brushing and flossing habits are your best protection against cavities and tooth decay.