ISSN : 2234-7550
Coronoid process hyperplasia is a rare condition that causes mouth opening limitation, otherwise known as trismus. The elongated coronoid processes impinge on the medial surfaces of the zygomatic arches when opening the mouth, which limits movement of the mandible and leads to trismus. Pa-tients with trismus due to coronoid process hyperplasia do not have any definitesymptoms such as temporomandibular joint pain or sounds upon clini-cal examination, and no significantabnormal signs are observed on panoramic radiographs or magnetic resonance images of the temporomandibular joint. Thus, the diagnosis of trismus is usually very difficult.However, computed tomography can help with the diagnosis, and the condition can be treated by surgery and postoperative physical therapy. This paper describes four cases of patients who visited our clinic for trismus and were subse-quently diagnosed with coronoid process hyperplasia. Three were successfully treated with a coronoidectomy and postoperative physical therapy.