Temporomandibular disorders (TMDs) is the collective term used to describe not only orofacial pain related to the jaw muscles and the temporomandibular joint (TMJ) but also functional jaw limitations including joint-related disorders that manifest as jaw catching and locking. This is reflected in the internationally adopted Diagnostic Criteria for TMDs 1, which contains three main pain diagnoses, and five intra-articular diagnoses related to internal derangements of the TMJ 1. The most common symptom related to an intra-articular diagnosis is joint sounds – clicking, due to disc displacement. Such clicking is common in the general population and in most cases only cause minor functional limitations 2. A less common, but still significant, intra-articular condition, with a prevalence of almost five percent in the general population 2,3, is frequent catching and locking of the jaw. The aetiology of intra-articular conditions is not fully understood but is likely related to both intraindividual factors such as joint laxity and external factors such as trauma, including bruxism and other oral behaviours 4. Due to the substantial role of the TMJ in jaw movements, the individual consequences from such joint-related functional jaw disturbances can be extensive and affect essential tasks such as eating and communication. Joint-related functional jaw disturbances can therefore substantially impact daily living and quality of life 5,6. In addition to the clinical parameters on functional jaw disturbances, the use of patient reported outcome measures (PROMs) can be beneficial and are recommended 7. Despite this, most available screening instruments for TMDs only regard the pain-related aspects 8,9. Thus, there is currently limited understanding of patient reported outcomes as a screening method for limitations in jaw movements and oral behaviours that cause functional jaw disturbances.

As a part of providing evidence-based medicine and to easily detect individuals with a possible TMDs in clinical practice, three screening questions, the 3Q/TMD, have been introduced in 2010 in the public dental health services (PDHS) in large parts of Sweden. A screening procedure should ideally identify individuals at a higher risk of a condition10; and in specific relation to TMDs, this could enable an early intervention and prevent chronification 11. In contrast to most other commonly used screening methods for TMDs, the 3Q/TMD contains screening for both pain and functional jaw disturbances, which enables identification of individuals who would benefit from a further TMD examination. The 3Q/TMD includes two questions on frequent orofacial pain and pain on function (Q1 and Q2, respectively) along with a third question on frequent functional jaw disturbances (Q3). These questions have been extensively evaluated 12, 13, 14, and Q1 and Q2 have shown convincing validity in relation to a clinical TMD pain diagnosis. The diagnostic accuracy for Q3 is not as conclusive12, 13, 14, even though a positive screening outcome is associated with treatment need 15. Given the importance of the use of patient reported outcomes in screening and assessment of TMDs 16, knowledge regarding associations not only with pain but also with functional jaw disturbances is important in the development and evaluation of available screening systems. Therefore, the aim of this study was to evaluate the association between a single screening question for functional disturbances and disease-specific PROMs for functional jaw limitations and oral behaviours. We hypothesized that self-reported functional disturbances are associated with both jaw limitations and oral behaviours.