Coronoid hyperplasia: A review

Coronoid hyperplasia is one of the rare causes of progressive limitation of mouth opening due to impingement of the enlarged coronoid process of the mandible on the zygomatic bone. A review was performed on all cases reports and case series on coronoid hyperplasia. Gender, age at treatment, age of onset, types of hyperplasia (unilateral/bilateral), associated history, treatment, surgical approach, preoperative mouth opening, intraoperative mouth opening, mouth opening at follow up and follow up period were recorded and analyzed. A total of 82 articles which reported 115 cases were included. Coronoid hyperplasia was commonly reported at mean age of 22.64 years old with male preponderance. Most of the cases were diagnosed and treated between the age of 11-20 years old. This condition commonly involved bilateral coronoid process of mandible. The mean width of preoperative mouth opening was 16.5mm and was improved to a mean mouth opening of 36.3mm intraoperatively. Mean mouth opening was 34.8mm at an average follow up of 19 months. While the etiopathogenesis of coronoid hyperplasia is still not conclusive, treatment with either coronoidectomy or coronoidotomy produced good improvement in mouth opening.