1 Associate Professor of Oral and Maxillofacial Diseases, School of Dentistry, Mashhad University of Medical Sciences, Mashhad,Iran.

2 Clinical Research Development Unit of Akbar Hospital, Faculty of Medicine, Mashhad University of Medical Sciences, Mashhad, Iran.

3 Associate Professor of Oral & Maxillofacial Radiology, School of Dentistry, Mashhad University of Medical Sciences, Mashhad, Iran.

4 Department of Oral and Maxillofacial Medicine, Dental School of Lorestan University of Medical Science, Khorramabad, Iran.

5 Post-graduate student, Department of Pediatric Dentistry, School of dentistry, Ahvaz Jundishapur University of Medical Sciences, Ahvaz, Iran.


Fibrodysplasia ossificans progressiva (FOP) is a rare form of genetic disorder categorized by progressive heterotopic ossification and congenital deformity of the big toes. Heterotopic ossification follows gradual inflammation of the soft tissues (flare-up) and results in limited movements in joints such as the Temporomandibular joint (TMJ). No effective medical treatment has been recognized for the treatment of FOP. FOP is commonly misdiagnosed, especially in the maxillofacial region. Patients with FOP often experience temporomandibular joint ankylosis. Therefore, dental professionals should be careful in planning treatment, including avoiding anesthesia injections, especially in the mandible. This study presents a case of FOP with temporomandibular joint ankylosis. An eight-year-old boy with the chief complaint of reduced mouth opening and clinical and radiological features of FOP.  The patient was referred to Mashhad Dental School in January 2016. He had not previously been diagnosed with FOP.