Pulpitis is a general term for inflammation of the tooth pulp, which consists of the blood vessels, nerve tissue, and living cells that occupy the hollow interior of teeth (see the Figure). It is characterized by tooth sensitivity that arises from excess blood flow (hyperemia) to the tooth. In some cases, the patient will complain of tenderness in the neck, under the jaw, or under the chin, where lymph nodes are located. Lymph nodes typically enlarge and become tender when there is infection nearby.
Pulpitis can be caused by any adverse event experienced by the tooth, including decay (caries), traumatic injury (a sharp blow to the tooth), heavy biting forces, or drilling on the tooth during dental procedures. Exposure to solutions which dehydrate or demineralize the tooth can cause it. These may include tooth bleach, acids found in food and beverages, and even certain multi-care toothpastes.
Pulpitis is generally divided into two types: Irreversible pulpitis and reversible pulpitis. Irreversible pulpitis is generally characterized by prolonged sensitivity to cold and/or heat, and sometimes to sweets. It is often accompanied by a continuous low-grade ache, which is aggravated by these stimuli. Swelling may be present. The tooth’s ability to sense a mild electrical stimulus may be reduced. With irreversible pulpitis, the nerve tissue is considered vital (alive), but not viable (it won’t remain alive, due to presence of irreversible inflammatory agents in the tooth).
If a tooth has recently undergone dental procedures (fillings, crowns, etc.), it may be sensitive for a period of time afterward. This is known as post-operative sensitivity, essentially a diagnosis of pulpitis. Depending on the nature of the dental procedure, the age and immune status of the patient, the tooth may get better, or the pulpitis may become irreversible. In some cases, the tooth pulp may die.
A dentist is the only one who can diagnose your tooth, and may be able to give you an idea of the likelihood of developing pulpitis before any dental procedures are performed. Keep in mind that teeth are normally living, and that dental procedures on the teeth are surgical procedures, which commonly produce an inflammatory response of some degree. Most often the response is minor; however, if the procedure is involved, irreversible pulpitis may occur.
Teeth have at least two types of nerve tissue inside of them: Myelinated and Un-myelinated. These may be thought of as insulated and un-insulated wires. The Myelinated nerves are like insulated wires, and carry sharp pain stimuli to the brain much faster than un-myelinated nerves. Un-myelinated nerves transmit continuous low-grade pain (dull aches). When both types of nerve are affected, there is a good chance the pulpitis is irreversible.