There is a small chamber in the hard tissue of the teeth in which is found the blood vessels and nerves (dental pulp) which go though the deepest end of the root and give life to the teeth. This structure which enables the growth and maintenance of the teeth also functions as alarm when the tooth is decaying. Tooth decays which are not treated in the early stages reach the dental pulp and cause severe pains by leading to inflammatory changes here.
The acids secreted by the bacteria in the latter stages kills the dental pulp. The toxins (poisons) caused in this way spread to the jaw bone from the rooth apex. The inflammation in the jaw bone causes loss of the tooth and leads to damage in the tissues nearby. Before reaching that stage, the tooth and the tissues nearby might be saved by removing the sickly pulp tissue. The pulp tissue is cleaned under anesthesia and the canals are expanded and disinfected. Following these operations, the pulp chamber is filled till the root tip with special substances. As opposed to popular belief, these operations do not cause pain and the teeth treated remain on the mouth for long years.