Mandibular coronoid hyperplasia in pediatric patients.

Bilateral coronoid hyperplasia is a relatively rare condition in the pediatric population and yet may be an unrecognized cause of limited mouth opening in children. There are multiple theories as to the causes of the hyperplasia, which include temporalis hyperactivity, hormonal stimulus, and genetic inheritance. The resulting excess growth of the coronoids results in impingement on the zygomatic processes leading to mandibular hypomobility. The diagnosis is confirmed with plain films and computed tomography scans. Treatment involves bilateral coronoidectomies to relieve impingement on the zygoma. Postoperative physical therapy is crucial for success; the therapy focuses on maintaining the mouth opening achieved at the time of surgery. Outcome reports have been variable despite good physical therapy, suggesting that the exact pathology of the condition is not well understood.