Validity of functional diagnostic examination for temporomandibular joint disc displacement with reduction

The choice of approach for diagnosing temporomandibular joint (TMJ) anterior disc displacement with reduction (ADDR), viz. functional examination or TMJ imaging, is debatable and complicated by findings of low agreement between these approaches. Our aim was to investigate the validity of functional ADDR diagnostics using clinical examination and opto-electronic mandibular movement recordings versus magnetic resonance imaging (MRI). 53 participants (32 women and 21 men, mean age ± s.d. of 28.7 ± 10.1 years) underwent a clinical examination, mandibular movement recording and MRI of their TMJs within 1 month. All were performed and analysed in a single-blind design by different experienced examiners for each technique. The sensitivity and specificity of each functional diagnostic method was calculated, with MRI as the gold standard. Anterior disc displacement with reduction was diagnosed in 27.6% of the TMJs clinically, in 15.2% using the movement recordings and in 44.8% on MRI. The specificity of the clinical examination for diagnosing ADDR was 81.0%, and of the movement recordings, 96.6%. The sensitivity was 38.3% and 29.8%, respectively. The chance of having a false-positive functional diagnosis of ADDR compared with MRI is low, and disagreement between the functional methods and MRI is mainly due to the high number of MRI diagnoses in asymptomatic subjects. In view of the fact that ADDR becomes clinically relevant only when it interferes with TMJ function, the functional diagnostic approach can be considered benchmark in ADDR recognition.