Early Diagnosis of Coronoid Process Hyperplasia in a Pediatric Patient With Progressive Mouth Opening Limitation

Limited mouth opening is commonly observed in temporomandibular joint disorders, manifesting as restricted mandibular mobility. This symptom is typically attributed to both intra-articular and extra-articular factors, with the latter involving an uncommon condition of coronoid process hyperplasia. This condition is characterized by abnormal coronoid process enlargement, resulting in mechanical impingement with the zygoma, which leads to progressive and painless limited mouth opening. The early diagnosis of this condition remains challenging, often being misdiagnosed as temporomandibular joint dysfunction. In this report, we present the case of a 12-year-old male who developed limited mouth opening progressively over the course of 1 year. Initial conservative treatments were ineffective. Following clinical examination and CBCT imaging, coronoid process hyperplasia was suspected. After utilizing 2 CBCT-based quantitative measurement techniques—the Tavassol and Stopa methods, bilateral coronoid process hyperplasia was conclusively diagnosed. Surgical intervention, specifically bilateral coronoidectomy, was recommended. However, the patient’s family declined the surgery and opted for regular follow-up every 6 months. This case underscores the need to consider coronoid process hyperplasia when diagnosing limited mouth opening and highlights the importance of CBCT-based imaging techniques in the early detection of this rare etiology.