Intraoral chronic pain: assessment of diagnostic methods and prognosis
Atypical odontalgia (AO) is a severe chronic pain condition, most likely of neuropathic origin and probably related to deafferentation of the tooth pulp nerves, possibly associated with sensitization of higher order trigeminal neurons. Conventional diagnostic tests and examinations are typically designed to detect signs of inflammatory changes, the most common reason for intraoral pain, and have proved to be insufficient to reliably capture the pathologic characteristics of AO. Knowledge regarding the etiology, diagnostics, management and prognosis of AO continues to be limited.
The aims of this project are to (i) better understand the underlying mechanisms of persistent intraoral pain, (ii) improve diagnostic methods for intraoral pain conditions and (iii) examine risk factors that are associated with persistent intraoral pain. Our hypothesis is that neuropathic pain conditions in the jaws can be distinguished from nociceptive pain not by a single measure, but by a combination of clinical measures including somatosensory examination, radiological examination, and psychometric tests.
Quantitative sensory testing (QST) is a somatosensory examination designed to reveal abnormalities in sensory function; common findings in neuropathic pain conditions. Intraorally, QST has not been sufficiently validated to merit clinical use. We have therefore performed a reliability study in healthy subjects which shows that the method is feasible to use intraorally and that inter-examiner and test-retest reliabilities are acceptable for most QST measures. After testing reliability in AO patients, a study comparing the QST findings in healthy controls and patients with the nociceptive pain condition symptomatic apical periodontitis (SAP) and AO respectively will be performed.
Cone Beam Computed Tomography (CBCT) and Magnetic Resonance Imaging (MRI) are modern imaging methods that have the potential to provide additional diagnostic information compared to conventional radiography in the orofacial area. A study comparing the findings with different imaging techniques in AO and SAP patients is in progress.
Knowledge of the natural history and prognosis of AO is limited, but the prognosis of neuropathic pain conditions is generally not as promising as that of nociceptive pain conditions. The identification of positive and negative risk factors for moderate to severe persistent pain intensity in AO patients may conceivably guide treatment planning. The underlying hypothesis is that such risk factors can be identified, and can improve the understanding of mechanisms responsible for pain maintenance. A seven-year follow-up of 46 patients with AO is therefore planned.
The findings of the project are planned to be published in 4-5 papers.