Methods: 20 patients (mean age 52 years, range 34–65) diagnosed with AO in the Orofacial Pain Unit, Faculty of Odontology at Malmö University, participated. Inclusion criteria were: chronic pain (>6 months) located in a region where a tooth had been endodontically or surgically treated, with no clear pathological cause detectable clinically or radiographically. The assessments included (i) clinical examination, (ii) self-report questionnaire, (iii) CBCT examination, and (iv) MRI examination. MRI signs of bone marrow oedema in the pain region were recorded. Spearman’s rho correlated MRI findings to CBCT periapical bone destruction. Two neuroradiologists assessed the MRIs, and kappa calculated the observer agreement.
Results: Average pain intensity was 5.6 (±1.8) on a 0–10 numerical rating scale and pain duration 4.3 (±5.2) years. 6/20 patients with AO (30%) had MRI signs of inflammation in the pain region. The correlation to CBCT periapical bone destruction was 0.526 (P=0.003). Of the six teeth with MRI signs of inflammation, three showed periapical bone destruction in CBCT. Two findings were recorded at extraction sites. Observer agreement was excellent at kappa 0.89.
Conclusion: MRI examination found no inflammation in the pain region in a majority of patients with AO. MRI signs of inflammation correlated significantly to CBCT findings.