Endodontic Diagnostic Terminology Update

Endodontic Diagnostic Terminology Update

Scott B. McClannahan, D.D.S., M.S.*, Michael K. Baisden, D.D.S.**, and Walter R. Bowles, D.D.S., M.S. Ph.D.†:


It is critically important to have standard diagnostic terminology to facilitate communication among dental professionals. In October of 2008, the American Association of  Endodontists (AAE) convened a conference to review diagnostic terms, and the results of the AAE Consensus Conference on Diagnostic Terminology were released in the Journal of Endodontics in December 2009.1 This update reflects the current terminology. 

The Art of Diagnosis

Diagnosis is defined as “the art of distinguishing one disease from another”.2  Diagnostic procedures should follow a consistent and logical order that includes a review of medical and dental histories as well as radiographic and clinical examinations. The radiographic examination consists of at least one well-centered parallel view and, for posterior teeth, a  mesial and/or distal angled film (shift shot). The clinical examination includes extraoral and intraoral evaluations and diagnostic tests. During examination procedures, assessment and reproduction of the patient’s chief complaint are imperative. The results should culminate in a two-part endodontic diagnosis that includes both a pulpal and an apical diagnosis.3-7 

Pulpal Diagnoses

Normal pulp. This is a clinical diagnostic category in which the pulp is symptom free and will be responsive to the electric pulp tester (EPT). When evaluated by thermal testing, the normal pulp produces a positive response that is mild and subsides immediately when the stimulus is removed. 

Reversible pulpitis. This is a clinical diagnostic category indicating that the pulpal inflammation should resolve and the pulp return to normal. Caries, cracks, restorative procedures, trauma, or occlusal discrepancies may cause a pulp to become inflamed. The patient’s chief complaint is usually sensitivity to cold or hot. Thermal testing produces an exaggerated response, but once the stimulus is removed, the discomfort does not linger. EPT results are responsive.

Symptomatic irreversible pulpitis. This is a clinical diagnostic category indicating that the vital inflamed pulp is incapable of healing. Patients may have a history of spontaneous pain and complain of an  exaggerated response to cold or hot that lingers after the stimulus is removed. EPT results are usually responsive. The involved tooth will often present with a history of an extensive restoration and/or caries, or may have had trauma. Radiographically, the periodontal ligament (PDL) space may appear normal, slightly widened, or demonstrate a  distinct radiolucency.

In certain cases of symptomatic irreversible pulpitis, the patient will avoid temperature extremes to the tooth. For example, the patient may arrive at the dental clinic sipping a glass of ice water or applying ice to the affected area. In this case, cold actually alleviates the patient’s pain, as the dental pulp has developed allodynia and is hyperalgesic. When this happens, normal body temperature is causing the nociceptors in the pulp to discharge.8 Removal of the cold causes return of symptoms and can be used as a  diagnostic test.

Asymptomatic irreversible pulpitis. This is a clinical diagnostic category indicating that the vital inflamed pulp is incapable of healing. Additional descriptors: no clinical symptoms but inflammation produced by  caries, caries excavation, or trauma. Internal resorption and hyperplastic pulpitis (pulp polyp) are additional examples of asymptomatic irreversible pulpitis. 

Pulp necrosis. This is a clinical diagnostic category indicating death of the dental pulp. The pulp will not respond to the EPT – no response (NR) over 80. The pulp will not respond to thermal tests. Teeth with pulp necrosis are usually asymptomatic unless inflammation has progressed to the periradicular tissues. 

Previously treated. This is a clinical diagnostic category indicating that the tooth has been endodontically treated and that the canals are obturated with various materials  other than intracanal medicaments. The tooth should not respond to the EPT or thermal tests. Previously treated teeth are usually asymptomatic unless coronal microleakage has occurred or a canal has been missed. 

Previously initiated therapy. This is a clinical diagnostic category indicating that the tooth has been previously treated by partial endodontic therapy (e.g., pulpotomy,  pulpectomy). The tooth should not respond to the EPT or thermal tests. Teeth with previously initiated therapy are usually asymptomatic unless inflamed tissue remains,  including a missed canal, or coronal microleakage has occurred. 

Apical Diagnoses

Normal apical tissues. Normal apical tissues will be non-sensitive to percussion and palpation testing. Radiographically, the lamina dura surrounding the root is intact, and the PDL space is uniform. 

Symptomatic apical periodontitis. This occurs when there is inflammation of the apical periodontium. Symptomatic apical periodontitis, however, may also occur as the result  of occlusal trauma. The patient will generally complain of discomfort upon biting or chewing. The tooth can present with any pulpal diagnosis. Sensitivity to percussion is a  hallmark diagnostic test result. Palpation testing may or may not produce a sensitive response. Radiographically, the PDL space may appear normal, slightly widened, or demonstrate a distinct radiolucency. 

Asymptomatic apical periodontitis. This condition is characterized by inflammation and destruction of the apical tissues that are of pulpal origin with no clinical symptoms. The inflammatory process causes apical bone resorption that manifests as an apical radiolucency on the radiograph. Clinically, the patient is asymptomatic. Vitality and EPT testing  will be non-responsive. Percussion and palpation testing produce non-sensitive responses. 

Acute apical abscess. This is an inflammatory reaction to pulpal infection and necrosis characterized by rapid onset, spontaneous pain, tenderness of the tooth to pressure, pus formation, and swelling of the associated tissues. Depending upon the location of the apices of the tooth and muscle attachments, a swelling will usually develop in the buccal vestibule, on the lingual/palatal area, or as a fascial space infection. Percussion testing produces a response that is usually exquisitely sensitive. This exaggerated response can  help differentiate between symptomatic apical periodontitis and the early stages of acute apical abscess. Palpation testing produces a sensitive response. Radiographically, the  PDL space may be normal, slightly widened, or demonstrate a distinct radiolucency. This apical pathosis can occur with a necrotic pulp or a tooth that has had endodontic  treatment initiated if continued bacterial contamination and/or leakage occurs. 

Chronic apical abscess. This is an inflammatory reaction to pulpal infection and necrosis characterized by gradual onset, little or no discomfort, and intermittent drainage  through an associated sinus tract. Clinically, the patient is usually asymptomatic because the sinus tract allows drainage of any exudate from the apical tissues. EPT and thermal testing are non-responsive. Percussion and palpation testing usually produce non-sensitive responses. Radiographically, an apical lesion is associated with the involved tooth. This entity can also occur with a pulpless tooth that has been partially or definitively endodontically treated if continued bacterial contamination and/or leakage has occurred. 

Condensing osteitis. This is a diffuse radiopaque lesion representing a localized bony reaction to a low-grade inflammatory stimulus, usually seen at the apex of the tooth. The  chronic inflammatory stimulus could be from a necrotic pulp, extensive restorative history, or a crack. The patient may be asymptomatic or demonstrate a wide range of pulpal  symptoms.  EPT and thermal tests may or may not be responsive. Percussion and palpation testing may or may not be sensitive. Radiographically, the involved tooth will present  with increased radiodensity and opacity around one or more of the roots. Condensing osteitis may be considered a true lesion of endodontic origin (LEO) because 85% of these  apical radiodensities regress after endodontic therapy.9 

Focal osteopetrosis (periapical osteosclerosis). This entity is not a LEO. The patient will be asymptomatic. EPT and thermal testing are responsive and normal. Percussion  and palpation testing will typically be non-sensitive. The involved tooth is usually un-restored or has a normal pulp. Radiographically, the tooth will present with increased  radiodensity and opacity around one or more of the roots. No treatment is necessary, and the tooth should simply be monitored at periodic recall.6 


Determination of the etiology of the patient’s chief complaint and a correct diagnosis are paramount prior to a recommendation of endodontic therapy. Reproduction of the  patient’s chief complaint is critical. If the chief complaint cannot be reproduced, consider consultation with or referral to an endodontist or orofacial pain specialist. 

The diagnostic terminology presented in this update provides for a more accurate description and communication of the health or pathological conditions of both pulpal and apical  tissues. This information is summarized in Table I. 


1. Recommended Terms: AAE Consensus Conference Recommended Diagnostic Terminology. J Endod 35:1,634, 2009.

2. Dorland’s Illustrated Medical Dictionary, 29th Edition. Philadelphia: W.B. Sanders Co., 2000.

3. Berman LH, Hartwell GR. Diagnosis. In: Pathways of the Pulp, Ninth Edition. Cohen S, Hargreaves KM, eds. St. Louis: Mosby, Inc., 2006.

4. Simon JHS, Walton RE, Pashley DH, Dowden WE, Bakland LK. Pulpal pathology. In: Endodontics, Fourth Edition. Ingle JI, Bakland LK, eds. Baltimore: Williams & Wilkins, 1994.

5. Torabinejad M, Walton RE. Periradicular lesions. In: Endodontics, Fourth Edition. Ingle JI, Bakland LK, eds. Baltimore: Williams & Wilkins, 1994.

6. Simon JHS. Periapical pathology. In: Pathways of the Pulp, Seventh Edition. Cohen S, Burns RC, eds. St. Louis: Mosby, Inc., 1998.

7. Nair PNR. Pathobiology of the periapex. In: Pathways of the Pulp, Eighth Edition. Cohen S, Burns RC, eds. St. Louis: Mosby, Inc.; 2002. 

8. Hargreaves, KM. Pain mechanism of the pulpodentin complex. In: Seltzer and Bender’s Dental Pulp. Hargreaves, KM, Goodis, HE, eds. Carol Stream, IL: Quintessence Publishing Co, Inc., 2002.

9. Eliasson S, Halvarsson C, Ljungheimer C. Periapical condensing osteitis and endodontic treatment. Oral Surg Oral Med Oral Pathol 57(2):195-9, 1984

Table I

*Dr. McClannahan is Associate Professor and Director, Division of Endodontics and Graduate Endodontics Program Director, University of Minnesota School of Dentistry, Minneapolis, MN 55455. 

**Dr. Baisden is Assistant Clinical Specialist and Director of Undergraduate Endodonitcs, University of Minnesota School of Dentistry, Minneapolis, MN 55455.

Dr. Bowles is Associate Professor and Director of Preclinical Endodontics, University of Minnesota School of Dentistry, Minneapolis, MN 55455. Email is bowle001@umn.edu.