This pain is often similar to pain from organic dental disease such as periapical periodontitis, or pulpitis (toothache), but unlike normal dental pain, it is not relieved in the long term by dental treatments such as endodontic therapy (root canal treatment) or tooth extraction, and it may even be worsened, return soon after, or simply migrate to other areas in the mouth following dental treatment. Definitions
Atypical facial pain
There is no universally accepted definition of AFP, and it is defined less by what it is as what it is not. Various definitions of AFP include:

"a nonmuscular or joint pain that has no detectable neurologic cause." "a condition characterized by the absence of other diagnoses and causing continuous, variable-intensity, migrating, nagging, deep, and diffuse pain." "a continuous unilateral deep aching pain sometimes with a burning component." "facial pain not fulfilling other criteria" (previous IHS definition, which now uses the term "Persistent idiopathic facial pain", see below). "persistent pain in the maxillofacial region that does not fit the diagnostic criteria of any other orofacial pain and has no identifiable cause." (Neville et al.) Atypical odontalgia
There are no globally accepted definitions of AO, but some suggested definitions are listed below:

"continuous pain in the teeth or in a tooth socket after extraction in the absence of any identifiable dental cause," (International headache society, description included as a side note of "persistent idiopathic facial pain" in the ICHD-2, i.e. with is no separate diagnosis for atypical odontalgia).
"Severe throbbing pain in the tooth without major pathology" (IASP definition in the "Classification of Chronic Pain", listing AO as "tooth pain not associated with lesions"). "pain and hypersensitive teeth in the absence of detectable pathology". "pain of an unidentifiable cause that is perceived to be originating in a tooth or teeth". Naming controversy and proposed replacement terms
The term "atypical facial pain" has been criticized. Originally, AFP was intended to describe a group of individuals whose response to neurosurgical procedures was not typical. Some experts in facial pain have suggested that the term AFP be discarded, as it may serve as a catchall phrase to describe either individuals who have not had an adequate diagnostic assessment or individuals whose pain is purely psychogenic. AFP has also been described as an inappropriate term since many cases in this category conform to a recognizable pattern. Another cited reason for discontinuing use of the term AFP is that some cases appear to follow surgeries or injuries involving the face, teeth and gums, possibly suggesting infectious or traumatic etiologies. Some classifications of facial pain avoid the term in favor of other similar terms. The IHS now use the term "Persistent idiopathic facial pain" in the ICHD-2, defining it as "persistent facial pain that does not have the characteristics of the cranial neuralgias ... and is not attributed to another disorder."