Many doctors often ask about how to diagnose functional shift, and how to treated these patients with TMJ problems. Some of these patients’ TMD symptoms and asymmetry are a result of adaptational growth of the condylar head, that had occurred from a functional shift that often resulted from a unilateral cross bite.
In another word, a narrow upper arch often causes a unilateral posterior cross bite, that creates a functional shift, that puts pressure on one of the condylar heads, resulting the mandible being forced to deviate often to the cross bite side. The pressure and force that results from this unilateral deviation, causes one of the condylar heads to grow more than the other, resulting in a asymmetrical mandible.
This study talks about the splint diagnosis and treatment of these cases.