Adjusted occlusal splints (AOS) have a wide range of indications in the treatment of functional disorders of the craniomandibular system. Simulation splints add a fully anatomically modeled occlusal appliance to the armamentarium of AOS that enables clinical testing of proposed changes in vertical dimension of occlusion and/or jaw position in complex cases, even during mastication, without the need for invasive tooth preparation. As such, they fill a gap at the decision crossroads between functional therapy and more far-reaching restorative treatment. The present case report describes the integration of simulation splints in treatment based on the example of a temporomandibular dysfunction patient with myopathy, arthropathy, and occlusopathy. The special feature of this case was that 2 years after the successful initial treatment, the patient had a recurrence of temporomandibular joint arthrosis that no longer responded to treatment with conventional equilibration splints. Only the daytime use of a fully anatomical simulation splint, in addition to wearing the positioning splint at night, was able to stabilize this situation and improve the patient’s well-being in the long term. Hence, this approach achieved the goals of pain reduction, improvement of mandibular mobility, and rehabilitation of restricted masticatory function without invasive procedures. Adjuvant physiotherapy had a supportive effect. The present case report demonstrates the use of a fully anatomical simulation splint at the crossroads between classical functional therapy and irreversible restorative treatment. Keywords: Simulation splint, functional therapy, arthritis, chewing function