Atypical odontalgia – What is it?

Atypical odontalgia (AO) is tooth pain or pain in a site where there once was a tooth in the absence of evidence of any relevant pathology. It was known as phantom tooth pain and currently goes by persistent dentoalveolar pain disorder PDPD, in addition to AO. However, AO is the term the International Association for the Study of Pain and the International Headache Society use.

Orofacial pain blogs – #3 Atypical odontalgia

This is the third in a series of posts about orofacial pain with difficult to diagnosis or unusual origin.

1. Cracked tooth syndrome
2. Trigeminal neuralgia
3. Atypical odontalgia     JADA article Marbach Feb 96 JADA      Great lit review
4. Neuralgia-inducing cavitational osteonecrosis or NICO
5. Referred pain
6. Myofascial pain 
7. Burning Mouth Syndrome
8. Oral dysesthesia
9. First bite syndrome
10. Barodontalgia

Atypical odontalgia Etiology and Symptoms

One of the most challenging pain diagnosis is atypical odontalgia (AO).  This and several other strange diagnosis must be arrived at carefully to insure a serious cancerous tumor or lesion is not being missed, which is not uncommon.  AO also goes by phantom tooth pain, atypical facial pain, idiopathic odontalgia; and is not dissimilar to phantom limb pain.  It is possible that there are a number of different sub-conditions and causes that fall into this diagnosis.

The symptoms of AO are constant, dull, deep ache with some spontaneous severe throbbing pain without any apparent pathology.  It is usually coming from a tooth or a tooth socket but the area of pain will spread.  It is most likely to occur in females in their 40’s in teeth that previously had a root canal.  One interesting characteristic is that the pain disappears when sleeping and may stay gone for a period upon waking.  Another is that anesthetic blocks do not necessarily relieve the pain.  Changes in barometric pressure are the most common worsening factor. This is not a psychological problem, although it may at times seem that way, it is some sort of nervous system problem. 1

Circle size denotes frequency of occurrence in that area

Atypical odontalgia treatment

The treatment for this condition is also gives the definitive diagnosis to the condition.  In other words if the treatment doesn’t work then it is likely the diagnosis is wrong.  Tricyclic antidepressants and/or capsaicin are what an orofacial pain specialist or neurologist uses for treatment.  Any surgery, including nerve surgeries, either do nothing or exacerbate the pain.

The fact that an antidepressant “cures” this pain tells me that there is some sort of misfiring in the nervous system causing the patient to feel pain for none nociceptor triggered reasons.  The fact that trigeminal rhizotomy and mircovascular decompression frequently make the pain worse, anesthetic doesn’t always help, and that it disappears during sleep leads us to believe the problem is higher up the electric line (CNS).  There exists much we do not understand about chronic pain, the nervous system, and the brain; and this is one condition that may not be fully understood and completely properly classified just yet.  For more on chronic pain and phantom bite syndrome check out my TMD and chronic pain blog.

Neurovascular orofacial pain is similar in symptoms but more in the migraine family.  NVOP Benoliel Sept 2010 JADA

Persistent idiopathic facial pain (PIFP)

PIFP is a poorly localized, continuous dull pain that occurs even in the absence of apparent pathological lesions or clinical neurologic deficiency. This is very similar to and possibly the same as atypical odontalgia. It differs from Post-traumatic Trigeminal Neuropathic Pain PPTN because PPTN is sharp vs dull and has more precise location. The likelihood of these two having the same underling cause seems probable. Shin JOI 2022