The TMD-pain group consisted of 30 children aged between 7.1 and 12.3 with a pain-related TMD diagnosis. All the patients in the TMD-pain group had myogenous or arthrogenous TMD according to the RDC/TMD protocol.

The pain-free TMD group consisted of 30 children between 7.3 and 12.6 years of age. To be included in the pain-free TMD group the participants had to meet Axis I of the RDC/TMD criteria for a pain-free diagnosis.

The non-TMD group comprised 30 children aged between 7.2 and 12.5 without any recognised TMD based on RDC/TMD, Axis I.

Surface electromyography (sEMG) was used as an additional non-invasive tool for assessing patients with TMD.The electromyographical (EMG) potentials of the temporalis and masseter muscles were measured with a DAB-Bluetooth Instrument (Zebris Medical GmbH, Germany) at rest and during maximum voluntary clenching (MVC).

A DAB-Bluetooth Instrument (Zebris Medical GmbH, Germany) was used to take electromyographical (EMG) recordings of the temporalis and masseter muscles at rest and during maximum voluntary contraction (MVC).Disposable, self-adhesive Ag/AgCl bipolar surface electrodes were placed at a fixed inter-electrode distance of 20 mm on the anterior temporal muscles and on the superficial masseter muscles parallel to the muscular fibres. The EMG signals were amplified, digitized and digitally filtered. The EMG results were analysed using the Student t-test, analysis of variance (ANOVA) and a Student-Newman-Keuls post-hoc test.