When decay is undetected, or left untreated, the bacteria causing the decay advance deeper into the tooth and close to, or into, the nerve space. This results in a serious dental infection that can be quite painful and leads to a chronic dental infection or abscess if not addressed. However, if there is not too much decay and there is enough uninfected tooth left, a root canal can be performed to save the tooth.
The infected tooth and pulp will be removed and then a sealant will fill the space. Sometimes a crown is recommended as it will prevent the tooth fracturing at a later date.