Cavities are heavily influenced by lifestyle, what we eat, how well we take care of our teeth and whether we use trusted dental aids. While cavities are generally more common among children, adults are also at risk. Cavities are very serious. Left untreated, cavities 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.