Proprioceptive test for the temporomandibular joint: An intra-and inter-rater reliability study with healthy adults

Background. Temporomandibular disorders (TMDs) are challenging to manage due to their multifactorial nature. As with other joints, the function of temporomandibular joint (TMJ) is influenced by proprioception, making it an essential factor in TMD management. However, previous studies on the joint position error (JPE) in TMD patients lacked a proper diagnosis and reliability assessment. Objectives. The aim of the present study was to develop a reliable JPE test in healthy adults as a foundation for future evaluation in TMD patients. Material and methods. Two examiners conducted the JPE assessment, utilizing a methodology encompassing between-days intra-rater and within-day inter-rater reliability assessments. A total of 22 healthy participants (7 men and 15 women) with a mean unassisted mouth opening of 46 ±5 mm were recruited. The evaluation targeted specific distances (10 mm, 20 mm and 30 mm) within the participants’ mouth opening range, with proprioceptive accuracy evaluated through the measurement of the absolute error (AE) and the constant error (CE). Results. The CE was consistently lower than AE across all the targeted distances, although with higher standard deviations. Intra-rater reliability varied across the distances, with poor reliability observed for AE at 10 mm, moderate reliability for CE at 10 mm, good reliability for both AE and CE at 20 mm, and moderate reliability for both AE and CE at 30 mm. Inter-rater reliability was moderate at 10 mm and good at 20 mm for both AE and CE, with equally moderate reliability levels at 30 mm. Conclusions. The 20 mm target distance demonstrated good intra-and inter-rater reliability, warranting its evaluation in patients with TMDs in the subsequent investigation phase.