Each tooth of the oral cavity has a living environment in a compartment known as “pulp tissue”. (Enamel is the only component of the tooth that is not alive). The pulp tissue undergoes inflammatory changes. This results to edema (increase of inter pulpal pressure) with pain and disruption of the homeostasis of the pulpal environment. At times, the pulps inflammation will reverse itself and the sensitive tooth will feel normal again. Younger individuals usually have a wide-open pulp chamber and canals, which facilitate better blood flow and quicker healing. This is why these younger teeth have better chances of reversing there inter pulpal inflammation. An older pulp, however, is usually more constricted and even more calcified. This will result in less blood flow and less chances for the pulp to heal its inflammation.
The persistently inflamed pulp may or may not exhibit any symptoms. It will eventually develop into a dead pulp (necrotic). Given more time, the necrotic pulpal tissue will cause a pulpo-periapical abscess at the apex (tip) of the root; this is why root canal treatments are desired to be performed on teeth with pulpal tissues that are still alive but not completely necrotic.