The starting point for any orthodontic occlusion diagnostics, treatment planning and subsequent therapy should be the physiological mandibular position. A possible discrepancy between maximal intercuspation and occlusion in the physiological mandibular position should be carefully investigated. An unrecognised and therefore untreated temporomandibular dysfunction (TMD) nullifies the success of orthodontic treatment. If there are signs of a TMD in the short screening test, the following detailed functional diagnosis, possibly including the musculoskeletal system (MSS), is necessary. This also includes the diagnosis of analogue or virtual models mounted in a physiological condylar position. Cone beam computed tomography (CBCT) and sometimes also an MRI scan is needed to specify the diagnostics in some patients. Keywords: TMD, temporomandibular system, musculoskeletal system, temporomandibular disorder (TMD), temporomandibular joint (TMJ)