Necrotic Teeth

Basic tooth anatomy (what teeth are made of and what's inside them)
Basic tooth anatomy. The pulp consists of blood vessels, nerves, and many types of cells. Nerve tissue in teeth helps to warn us when there are bacterial invaders (tooth decay), cracks and chips, which can allow micro-organisms access to our body's circulatory system. Blood vessels in teeth bring nourishment to the living cells inside the teeth. For example, "odontoblast" cells living in the pulp continuously produce dentin throughout the life of the tooth. Dentin is a calcified substance that can "patch holes" created by microscopic cracks, and build a dividing wall to slow the advance of bacteria found in tooth cavities.

A necrotic tooth is also called a dead, or non-vital tooth. This means that the tooth pulp no longer has living tissue and no blood supply. When this happens, the hollow root canal and pulp chamber inside the tooth become a potential site of bacterial colonization, open to the inside of the body.

Frequently, when bacteria find their way into the tooth, and are allowed to multiply unchecked by the body's immune system, an abscess will result. Often this is accompanied by pain, swelling, and inability to chew on the affected tooth. Sometimes numbness can occur, due to the pressure the infectious fluid places on nearby nerves in the jaw bone.

Necrotic teeth usually have a history of traumatic injury, extensive tooth decay (caries), periodontal disease, or rapid orthodontic tooth movement. Sometimes, a process called "calcific metamorphosis" occurs, in which the odontoblast cells that form the dentin layer of the tooth are induced to rapidly deposit large amounts of reparative dentin. The result is a tooth which appears to have no root canal (although it usually continues to have a microscopic one). These teeth may test non-vital, like a necrotic tooth.

Last updated: 12/29/2013
Intrinsic stain of dentin from hyperemia after dental injury that left the tooth necrotic
Figure 1: Intrinsic stain. The first clue that a tooth is necrotic may be its darkened hue (see arrow) from the intrinsic staining of the dentin.

Necrotic teeth that do have root canals and pulp chambers are generally diagnosed by their lack of any response to hot, cold or electrical stimuli. Frequently, necrotic teeth appear darker than the other teeth (Figure 1). This finding suggests that the tooth underwent a period in which extensive blood flow to the tooth occurred. Increased blood flow is the body's response to bacteria moving into a tooth, and the method by which immune cells are delivered.

If the tooth has undergone trauma, the body increases blood flow to provide nourishment to the repair cells in the area—the inflammatory response. Increased blood pressure (and volume) forces iron-rich blood pigment (a reddish-brown hue) into the dentin of the tooth, resulting in its darkened appearance.

Last updated: 12/29/2013

A tooth that is diagnosed as necrotic, and which has accessible root canals is generally treated by root canal therapy (endodontics). It is usually possible to eliminate the dark hue of the tooth after endodontic therapy is completed, by placing a bleaching solution in the pulp chamber of the tooth for a few days. Other treatment may be necessary following root canal therapy, including filling the hole the dentist makes to gain access to the root canals; and possibly a crown or onlay, depending on the type of tooth affected, and the amount of remaining tooth structure.

If the necrotic tooth is heavily decayed, chipped or cracked it may require crown lengthening surgery (a periodontal surgery procedure), a core buildup (a very large filling needed to establish enough tooth structure to place a crown on), and a crown.

Sometimes the cost and complexity of procedures necessary to save a necrotic tooth suggest that the tooth should be removed (simple tooth extractions and surgical tooth extractions), and options to replace it should be considered. If the necrotic tooth cannot be saved, or the patient does not want to save it, tooth removal is usually an option.

A tooth that is diagnosed with calcific metamorphosis generally does not require endodontic treatment, and possibly no treatment at all, unless its crown is noticeably darker than the other teeth and is of concern to the patient. An option in such cases might be to veneer the tooth. A periapical radiograph will generally be exposed to see whether a visible root canal is present. Other imaging techniques may also be suggested.

Last updated: 8/6/2013

For a tooth to become necrotic, there is usually a cause that can be identified. The most common causes of necrotic teeth are large caries (tooth decay) and trauma, which most often does not produce chips or cracks. If a tooth chips or cracks from a forceful blow, it often will not become necrotic because the energy from the blow is at least partially dissipated in chipping the tooth.

If the tooth is displaced from the forces of a traumatic injury (luxated), the blood vessels and nerve tissue that insert into the tooth's root tip may be severed, frequently leading to necrosis. Intrinsic stain commonly found in necrotic teeth can be treated (following endodontic treatment), through internal bleaching of the tooth.

Less common causes of tooth necrosis include devitalization from nearby surgical procedures, periodontal disesase (periodontitis), and rapid orthodontic tooth movement.

Necrotic teeth are hollow "potential spaces" open to the inside of the body. If populated with bacteria, a serious abscess may result.

Last updated: 8/6/2013
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Background information

The following articles are intended to provide you with background information on the topic. These articles may or may not influence your decisions about care.

Comparison of Electrical, Thermal, and Pulse Oximetry Methods for Assessing Pulp Vitality in Recently Traumatized Teeth
Gopikrishna, Velayutham, MDS, et al.
Journal of Endodontics
2007 33 (5): 531-535

Pulpal sequelae after trauma to anterior teeth among adult Nigerian dental patients
Oginni, Adeleke O. and Adekoya-Sofowora, Comfort A.
BioMed Central Oral Health
2007 7

Using mouthguards to reduce the incidence and severity of sports-related oral injuries
ADA Council on Access, Prevention and Interprofessional Relations—ADA Council on Scientific Affairs
The Journal of the American Dental Association
2006 137 (12): 1712-1720

Calcific metamorphosis (PDF, 33K)
Munley, Patrick J., DC, USN and Goodell, Gary G., DC, USN
Clinical Update: Naval Postgraduate Dental School, National Naval Medical Center, Bethesda
2005 27 (4)

State of the art and science of endodontics
Shabahang, Shahrokh, DDS, MS, PhD, et al.
The Journal of the American Dental Association
2005 136 (1): 41-52

The advantages of minimally invasive dentistry
Christensen, Gordon J., DDS, MSD, PhD
The Journal of the American Dental Association
2005 136: 1563-1565

Minimally invasive dentistry
Murdoch-Kinch, Carol Anne, DDS, PhD, and McLean, Mary Ellen, DDS
The Journal of the American Dental Association
2003 134: 87-95

Herpes zoster associated with pulpless teeth
Gregory, Worth B., et al.
Journal of Endodontics
1975 1 (1): 32-35

Read before treatment

The following articles, if read before treatment, may influence your decisions about care.

Clinical Efficiency of 2% Chlorhexidine Gel in Reducing Intracanal Bacteria
Wang, Ching S., DDS, et al.
Journal of Endodontics
2007 33 (11): 1283-1289

Disinfection of Dentinal Tubules with 2% Chlorhexidine, 2% Metronidazole, Bioactive Glass when Compared with Calcium Hydroxide as Intracanal Medicaments
Krithakaatta, Jogikalmat, MDS, et al.
Journal of Endodontics
2007 33 (12): 1473-1476

Dental management of patients receiving oral bisphosphonate therapy: Expert panel recommendations
The Journal of the American Dental Association
2006 137 (8): 1144-1150
Notes: Association Report by American Dental Association Council on Scientific Affairs

Minimally invasive operative techniques using high tech dentistry (PDF, 148K)
Brostek, Andrew M. Dr., et al.
Dental Practice
2006: 106-106
Editor's notes: Online publication date September/October 2006.

The Clinical Significance of Pulpless Teeth
Lacey, J. Mark MD and Johnson, Clayton R. MD
Calif West Med.
1928 28 (5): 658-660

Last updated: 7/10/2011