Abstract
Idiopathic orofacial pain often develops after dental/surgical treatment. However, there are some cases that develop without nociceptive stimuli. Although most cases show little or no discernable pathology, some patients develop disability and catastrophizing. Traditionally, the mechanisms of such idiopathic pain have been explained as neuropathic pain, dysfunction of the descending pain inhibitory system, or central sensitization. However, recent developments in neuroimaging studies have revealed that sensations of pain can be elicited without nociceptive input or tissue damage. More specifically, studies have shown that diverse non-nociceptive stimuli, such as unpleasant pictures/words or social exclusion, among others, can activate the so-called “pain matrix” and elicit sensations of pain. These findings might provide insights into the mechanisms of idiopathic orofacial pain.
We provide commentary on several theories advocated in the field of brain science, such as augmented central pain processing, neuromatrix, threat matrix, and the saliency hypothesis, and report following two example cases.
Case 1 involved a 74-year-old woman who developed excruciating facial pain after an oral surgeon casually suggested tongue cancer. She became totally disabled from pain; unable to eat or speak, and a gastrostomy tube was eventually placed 3 months after onset.
Case 2 involved an 81-year-old woman who developed severe pain in the left central incisor region just after undergoing implant surgery with 6 implants fixtures in the maxillary molar regions （three in each side）. Due to pain and feelings of general malaise, she became bedridden after 6 months.
Although these were fulminant cases, both patients became rapidly pain-free with administration of tricyclic antidepressants （amitriptyline）.
