In most cases the initial treatment approach for a temporomandibular disorder (TMD) is an occlusal splint. The occlusal splint has to be regarded as a reversible therapeutic method. A definitive continuing treatment in orthodontics can only take place after the splint has delivered an improvement of the symptoms. As well as its use for the therapeutic approach, the occlusal splint can also be used as a diagnostic tool, as it allows determination of the physiological, three-dimensional position of the mandible. From this position, definitive orthodontic treatment can be started. Keywords: occlusal splint, temporomandibular disorder (TMD), temporomandibular joint (TMJ)