Persistent idiopathic dentoalveolar pain (PIDAP) is a persistent unilateral intraoral pain. The pain is localised to the dentoalveolar region such as the teeth or alveolar bone, and rarely involves multiple sites.
Persistent idiopathic facial pain (PIFP) is pain with variable features, in the absence of clinical neurological deficit or preceding causative event. The distribution is often poorly localised to the face and not within a peripheral nerve distribution. It has been reported more often localised to the upper jaw, and may extend to the region of the eyes, nose, cheek and temple.
Other terms for these conditions have included ‘atypical facial pain’, atypical odontalgia; primary persistent dentoalveolar pain disorder (PDAP); and phantom tooth pain, although these terms may encompass other diagnoses.
According to the International Classification of Orofacial Pain-1, these conditions may have variable features but recur daily for more than two hours a day for more than three months, in the absence of any preceding causative event. With time, and central sensitisation, symptoms may spread to a wider area of the craniocervical region and does not have to follow a dermatomal pattern. The pain may have exacerbations and be aggravated by stress.
Sensory abnormalities such as allodynia, hyperalgesia, hypaesthesia, and/or hypoalgesia are rare in PIDAP, although allodynia in the gingival sulcus of the affected teeth appears to be a more common reported feature.
An association with endodontically treated teeth has also been reported with PIDAP. In PIFP, there may be somatosensory changes such as dysesthesia, a subjective sensation of numbness and/ or swelling, but with no objective sensory deficits or swelling.
The aetiopathogenesis and causes of PIFP and PIDAP remains poorly understood. It is generally accepted to be an idiopathic neuropathic pain with centrally mediated mechanisms.
Some patients with PIFP showed neurophysiological findings that may be indicative of peripheral nerve dysfunction including abnormal nerve responses, increased excitability and deficient habituation. On positron emission tomography (PET) studies, PIFP patients have shown blood flow and dopamine receptor changes in areas of the brain and brain stem.
There is a significant association with psychiatric comorbidities such as anxiety disorders, affective disorders, and psychosis. Some cases are associated with functional somatic syndromes with comorbidities such as chronic widespread pain, fibromyalgia, and irritable bowel syndrome.
Due to differences in nomenclature and previous non-standardised diagnostic criteria, epidemiological data is difficult to obtain. There are reports of female predominance.
Patients should see their dentist and the clinical and radiographic examinations should be thorough, so any potential orofacial or dental cause is ruled out, including volumetric imaging such as cone beam computed tomography for the dentition where applicable.
It is important to exclude other potential causes of the pain, such as odontogenic pathology or referred pain. The clinical neurological examination is normal.
Differential diagnoses may include odontogenic pain, traumatic trigeminal neuropathies, regional myofascial pain, atypical neurovascular pains, atypical neuropathic pain, some forms of primary headaches, idiopathic trigeminal neuralgia, and referred pain. If the pain onset is within six months of a causative event, consider post-traumatic trigeminal neuropathic pain.
Misdiagnosis may lead to unnecessary dental treatment, and caution should be exercised to avoid this. Management can be challenging, and different agents and strategies have been trialled, all to variable effect.
Pharmacological therapy may include systemic medications such as tricyclic antidepressants, anxiolytics, gabapentinoids, anticonvulsants, and selective noradrenaline reuptake inhibitors. Topical forms of tricyclic antidepressants, gabapentinoids, anticonvulsants and ketamine have been trialled.
Other management trialled with some limited success include acupuncture, hypnosis and biofeedback. While prognosis of this condition is unknown, it is believed to be poor, and some patients remain unresponsive to medication and management.
Author competing interests – nil