Tooth decay is another way of saying cavities. Tooth decay is heavily influenced by lifestyle, what we eat, how well we take care of our teeth and whether we use trusted dental aids. While tooth decay is generally more common among children, adults are also at risk. Tooth decay is very serious. Left untreated, decay can destroy your tooth and kill the delicate nerves at its center, which may result in an abscess, an area of infection at the root tip. Once an abscess forms, it can only be treated with a root canal, surgery or by extracting the tooth.