Volume 87 - Number 1

January - February 2008
Disaster Training Enters the 21st Century

Atraumatic Tooth Preparation

Atypical Odontalgia: A Review

The Dean

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Clinical Feature

Atypical Odontalgia: A Review



Harish Koratkar, B.D.S.*, and Jerome Pedersen, D.D.S.**




ABSTRACT

Since persistent and chronic pain is more common in the head and neck region than in any other part of the body, dentists are more likely to encounter these rather complex cases in their practices. This article is a review and update on atypical odontalgia (AO). AO is a persistent neuropathic pain which may be initiated after deafferentiation of trigeminal nerve fibers following root canal treatment, apicectomy, or tooth extraction, or it may be of idiopathic origin. Details concerning its characteristics, pathophysiology, diagnostic criteria, differential diagnosis, and treatment are made. The aim of this article is to help the clinician with the diagnosis and management of AO.  The prognosis for AO is most often only fair, and the administration of tricyclic antidepressants often resolves symptoms. Invasive and irreversible treatment attempts are not recommended.



Introduction
While it is not uncommon to see cases of non-odontogenic pain in a regular clinical dental practice, it is one of the most challenging diagnoses for both dentist and patient. As clinicians, it is important for dentists to have a thorough knowledge of odontogenic and non-odontogenic causes of orofacial pain and the need for careful diagnosis before undertaking any treatment.1 Since persistent and chronic pain is more common in the head and neck region than in any other part of the body, dentists are more likely to encounter these rather complex cases in their practices.2 Due to the complexities and diagnostic challenges, the misdiagnosis of neuropathic pain is common.3 On most occasions when unnecessary dental treatment is rendered to the patient, it is done with the hope of relieving the pain.

The purpose of this article is to review the literature of atypical odontalgia, to discuss the pathophysiology, illustrate the complexities of diagnosing the condition, and enumerate the treatment options. The literature search was done by using pubmed.gov and scholar.google.com.

Background
In spite of its first description by English surgeon and pathologist John Hunter (1728-1793) more than 200 years ago, the clinical condition of atypical odontalgia was not universally accepted among dentists4 as a pathology. McElin first reported atypical odontalgia5 in the Annals of Internal Medicine in 1947. The term “phantom tooth pain” was first used in 1978, and since then the condition has been validated as a clinical entity.6

Although atypical odontalgia is an accepted clinical condition, cases of AO are seldom reported.6 One problem for the dentist in diagnosing neuropathic pain has been the use of various terms ascribed by different investigators over the years.7 The taxonomy of chronic pain syndromes has included the terms “idiopathic odontalgia”,8 “neurovascular odontalgia”,9 and “oral neuropathic pain”.10 Even though there have been numerous meetings among worldwide authorities on orofacial pain, there is no current consensus on the taxonomy of the different forms of idiopathic orofacial pain, which include stomatodynia, atypical odontalgia, atypical facial pain, and facial arthromyalgia. These conditions on occasion are considered as separate entities and are sometimes grouped together.11 Atypical odontalgia has also been described as a localized form of atypical facial pain.23 The diagnosis and management of this condition can be difficult due to the multifactorial nature of the problem, and a multidisciplinary approach can assist the practitioner in diagnosis and treatment.12

Characteristics of AO
Atypical odontalgia has been defined as severe throbbing pain in a tooth without any pathology.25 The primary symptom of AO is pain located in a tooth or tooth site, which may spread with time involving the entire maxilla or mandible.26 Characteristically, AO presents as throbbing, persistent pain in teeth or alveolar process for a prolonged period of time6 with an absence of any pathological, clinical, or radiological findings.4 AO has been reported to affect all ages, except children, with a preponderance among women in their mid-forties and mostly affecting the maxillary molar and premolars.14 Commonly, AO follows dental or surgical procedures such as pulp extirpation, apicoectomy, tooth extractions, or exenteration of the contents of the maxillary antrum,13 although it can be idiopathic. The pain is chronic; sleep is undisturbed, and the patients may have brief symptom-free periods on waking.5 The results of local anesthetic injections and direct nerve blocks are mostly inconclusive, and patients rarely find relief with analgesics, including narcotics.6,13 Several authors have asserted that psychological factors are the underlying cause of atypical odontalgia, but objective evidence is lacking to support this claim.15 Osteoporosis which appears with menopause and neuralgia-inducing cavitational osteonecrosis (NICO) have also been linked to atypical facial pain.19

Pathophysiology
After extensive research, the pathophysiology of atypical odontalgia still remains uncertain. Pain is an unpleasant sensation, and nociception is a measurable physiological event of a type usually associated with it. A nociceptor is a sensory receptor that sends signals that cause the perception of pain in response to a potentially damaging stimulus. In AO, different neuropathic mechanisms may be at work, among them:
• nociceptor sensitization,
• phenotypic changes and ectopic activity from the nociceptors,
• central sensitization possibly maintained by ongoing activity from initially damaged peripheral tissues,
• sympathetic abnormal activity,
• alteration of segmental inhibitory control, and
• hyper- or hypoactivity of descending controls.19

Marbach18 conjectured the similarity in etiology of the pain of atypical odontalgia with phantom limb pain. The most accepted theory explaining the pathophysiology of AO is deafferentation, which is the elimination or interruption of sensory nerve fibers, caused by traumatic injury with changes occurring at the level of the peripheral, central, and autonomic nervous systems.18,19,24

The neuromatrix theory of pain proposed by Melzack has also been described in the literature to explain the pathophysiology of this pain. The neuromatrix, which is genetically determined and modified by sensory experience, is the primary mechanism that generates the neural pattern that produces pain. Its output pattern is determined by multiple influences, of which the somatic sensory input is only a part, that converge on the neuromatrix.

Diagnostic Criteria
Various investigators have proposed many diagnostic criteria for AO. However, the diagnosis is made by exclusion.4 The diagnostic criteria proposed by S.B. Graff-Radford and W.K. Solberg can be a helpful tool (Table One). This diagnostic criteria is very simple and focuses on all the typical characteristics of AO.24 In 1995, Pertes and colleagues revised the criteria and included the non-responsiveness of pain to dental treatment.17

Differential Diagnosis
The successful diagnosis of orofacial pain depends upon the following:28

1. An accurate and detailed history of the pain.
2. A detailed clinical examination of the face and associated organs.
3. A thorough knowledge of those conditions that may produce facial pain.

It is important to differentiate the pain of AO from pulpal pain, myofacial pain, and from pain of trigeminal neuralgia. A common misdiagnosis is to consider the pain from AO to be of pulpal origin, leading to unnecessary endodontic treatment.

Treatment
Treatment of atypical odontalgia is similar to that for other neuropathic conditions.3 Various drugs have been used to treat AO, among them Gabapentin,29 Clonazepam,29 cocaine,29 monoamine oxidase (MAO) inhibitors,13 and opioids.29,13  Topical capsaicin has been used successfully to control neuropathic pain, and it has been effective in most patients with atypical odontalgia.21 The treatment of choice is a tricyclic antidepressant like Amitriptyline, alone or in combination with a phenothiazine. The outcome is usually fair, with many patients obtaining complete relief from pain.20 Treatment starts with a low dose of 20 mg up to 75 mg of Amitriptyline that needs to be adjusted according to two factors: pain control and adverse reactions. The dose is titrated until an acceptable pain level is achieved, usually reaching up to 75 mg per day,24,30 but the appearance of side effects can prevent the clinician from increasing the dosage. It is important to discuss the side effects of Amitriptyline with the patient. Side effects may include dizziness, drowsiness, headache, xerostomia, constipation, increased appetite, weight gain, nausea, weakness, hypotension, arrhythmias, tachycardia, nervousness, sedation, and diarrhea.31 It is also important to defer any invasive dental procedures until after a definitive diagnosis of AO has been made.22

Conclusion
With regard to diagnosing this condition, Sir William Osler’s maxim should always be remembered: “What you don’t know — you won’t diagnose.”28 The condition of AO can be a challenging case to diagnose and treat. It is important to have a thorough knowledge before initiating any drug treatment. Sometimes it is prudent to refer the patient to a pain specialist.

Neuropathic pain in the head and neck region can be difficult to diagnose, and often the lack of diagnosis can lead to unnecessary dental treatment and frustrating outcomes. Unfortunately, dentists usually consider this diagnosis only after the failure of invasive treatment.16 The dentist and physician need to recognize AO and to remember that a proper diagnosis can prevent unnecessary and irreversible dental treatment. n

References:
1.  Lilly JP, Law AS. Atypical odontalgia misdiagnosed as odontogenic pain: a case report and discussion of treatment. J Endod 1997 May;23(5):337-9.
2.   Shankland WE II. Differential diagnosis of two disorders that produce common orofacial pain symptoms. Gen Dent 2001 Mar-Apr;49(2):150-5.
3.  Matwychuk MJ. Diagnostic challenges of neuropathic tooth pain.  J Can Dent Assoc 2004;70(8):542-6.
4.  Turp JC.  Schweiz Monatsschr Zahnmed 2005;115(11):1,006-11.
5.  McElin TW, Horton DT. Atypical facial pain: a statistical consideration of 65 cases. Ann Intern Med 1947;27:749-53.
6. Marbach JJ. Orofacial phantom pain: theory and phenomenology. JADA 1996 Feb;127(2):221-9.
7. Vickers ER. Neuropathic orofacial pain: a review and guidelines for diagnosis and management. http://hdl.handle.net/2123/806.
8.  Harris M. Psychogenic aspects of facial pain. Br Dent J 1974 Mar 5;136(5):199-202.
9. Mahan PE, Alling CC. Facial Pain. Philadephia: Lea & Febiger, 1991, pages 304-5.
10. Epstein JB, Marcoe JH. Topical application of capsaicin for treatment of oral neuropathic pain and trigeminal neuralgia. Oral Surg Oral Med Oral Pathol 1994 Feb;77(2):135-40.
11.  Woda A et al. Towards a new taxonomy of idiopathic orofacial pain. Pain 2005 Aug;116(3):396-406.
12. Vickers R, Cousins M. Management of chronic orofacial pain. Aust Fam Physician. 1994 Dec;23(12):2315-21.
13.  Marbach JJ. Is phantom tooth pain a deafferentation (neuropathic) syndrome? Part I: Evidence derived from pathophysiology and treatment. Oral Surg Oral Med Oral Pathol 1993 Jan;75(1):95-105.
14.  Klausner JJ. Epidemiology of chronic facial pain: diagnostic usefulness in patient care. JADA 1994 Dec;125(12):1,604-11.
15.  Graff-Radford SB, Solberg WK. Is atypical odontalgia a psychological problem? Oral Surg Oral Med Oral Pathol 1993 May;75(5):579-82.
16. Graff-Radford SB, Solberg WK. Atypical odontalgia. J Craniomandib Disord 1992 Fall;6(4):260-5.
17. Pertes RA, Bailey DR, Milone AS. Atypical odontalgia — a nondental toothache. J N J Dent Assoc 1995 Winter;66(1):29-31, 33.
18.  Marbach JJ Phantom tooth pain. J Endod 1978 Dec;4(12):362-72.
19. Woda A, Pionchon P. A unified concept of idiopathic orofacial pain: pathophysiologic features. J Orofac Pain 2000 Summer;14(3):196-212.
20.  Melis M, Lobo SL, Ceneviz C, Zawawi K, Al-Badawi E, Maloney G, Mehta N. Atypical odontalgia: a review of the literature. 1: Headache. 2003 Nov-Dec;43(10):1,060-74.
21. Vickers ER, Cousins MJ, Walker S, Chisholm K. Analysis of 50 patients with atypical odontalgia. A preliminary report on pharmacological procedures for diagnosis and treatment. Oral Surg Oral Med Oral Pathol Oral Radiol Endod 1998 Jan;85(1):24-32.
22.  Bates RE Jr, Stewart CM. Atypical odontalgia: phantom tooth pain. Oral Surg Oral Med Oral Pathol. 1991 Oct;72(4):479-83.
23.  L Reik Jr. Atypical odontalgia: a localized form of atypical facial pain. Headache. 1984 Jul;24(2):222-4.
24.  Melis M, Secci S.Diagnosis and treatment of atypical odontalgia: a review of the literature and two case reports.  J Contemp Dent Pract 2007 Mar 1;8(3):81-9.
25.  Merskey H, Bogduk N eds. Classification of Chronic Pain: Description of Chronic Pain Syndrome and Definition of Pain Terms, Second Edition. IASP Press;1994.
26. Bates RE, Stewart CM. Atypical odontalgia: phantom tooth pain. Oral Surg Oral Med Oral Pathol 1991 Oct;72(4):479-83.
27. Melzack R. Evolution of the neuromatrix theory of pain. Pain Pract 2005 Jun;5(2):85-94.
28.  Drinnan AJ. Differential diagnosis of orofacial pain. Dent Clin North Am 1987 Oct;31(4):627-43.
29.  Marbach JJ, Raphael KG. Phantom tooth pain: a new look at an old dilemma. Pain Medicine 2000;1:68-77.
30.  Okeson JP. Differential Diagnosis and Management Considerations of Neuralgias, Nerve Trunk Pain, and Deafferentation Pain. In: Okeson JP, ed. Orofacial Pain: Guidelines for Assessment, Diagnosis, and Management. Chicago: Quintessence;1996:73-88.
31.  Lacy CF, Armstrong LL, Goldman MP, Lance LL. Drug Information Handbook, Seventh Edition. Hudson: Lexi-Comp, 1999:62-64.

 

Table One.

Proposed Diagnostic Criteria of Graff-Radford and Solberg.16

Idiopathic Toothache (atypical odontalgia).

A.       Pain in a tooth or a tooth site.

B.       Continuous or almost continuous pain.

C.       Pain persisting more than four months.

D.      No sign of local or referred pain.

E.       Equivocal somatic nerve block.

 

*Dr. Koratkar is a general dentist in private practice in the Twin Cities area. E-mail is koratkar@gmail.com.

**Dr. Pedersen is the director of the Hibbing Dental Clinic of the University of Minnesota’s Department of Primary Dental Care. E-mail is peder080@umn.edu.






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