Somatosensory abnormalities in atypical odontalgia: A case-control study

Somatosensory function in patients with persistent idiopathic types of orofacial pain like atypical odontalgia (AO) is not well described. This study tested the hypothesis that AO patients have significantly more somatosensory abnormalities than age- and sex-matched controls. Forty-six AO patients and 35 controls participated. Inclusion criteria for AO were pain in a region where a tooth had been endodontically or surgically treated, persistent pain >6 months, and lack of clinical and radiological findings. The examination included qualitative tests and a battery of intraoral quantitative sensory testing (QST). Most AO patients (85%) had qualitative somatosensory abnormality compared with few controls (14%). The most common qualitative abnormalities in AO patients were found with pin-prick 67.4%, cold 47.8%, and touch 46.5% compared with 11.4%, 8.6%, and 2.9%, respectively, in the control group (P < 0.001). Between-group differences were seen for many intraoral QST: mechanical detection threshold, mechanical pain threshold (pinprick), dynamic mechanical allodynia (brush), dynamic mechanical allodynia (vibration), wind-up ratio, and pressure pain threshold (P < 0.01). In the trigeminal area, between-group differences in thermal thresholds were nonsignificant while differences in cold detection at the thenar eminence were significant. Individual somatosensory profiles revealed complex patterns with hyper- and hyposensitivity to intraoral QST. Between-group differences in pressure pain thresholds (P < 0.02) were observed at the thenar eminence. In conclusion, significant abnormalities in intraoral somatosensory function were observed in AO, which may reflect peripheral and central sensitization of trigeminal pathways. More generalized sensitization of the nociceptive system may also be part of AO pathophysiology.