Juvenile idiopathic arthritis (JIA), the most common inflammatory autoimmune rheumatic disease in children, consists of a heterogeneous group of diseases with 7 distinct subtypes. Involvement of the temporomandibular joint (TMJ) in JIA varies from 17% to 87%, and can alter craniofacial growth due to damage to the condylar growth center. This study was a literature review and clinical report of bilateral ankylosis of the TMJ in a 13-year-old patient with polyarticular JIA. Temporomandibular joint reconstruction with a costochondral graft was carried out. The surgery was uneventful and the patient developed a mouth opening of 40 mm during the postoperative period of 24 months. The authors concluded that treatment of TMJ ankylosis should be surgical with removal of the ankylotic mass, and when necessary, joint reconstruction in patients undergoing a growth phase. Costochondral graft is still the gold standard due to its biological similarity and growth potential in patients with JIA. Research and early diagnosis of TMJ diseases should be carried out, because the earlier the identification of the disease, the better the chances of reducing its devastating effects, thus avoiding the worst possible outcome: TMJ ankylosis.