The causes of ankylosis of teeth is uncertain. The prevalence of tooth ankylosis is still unknown. Follow-ups are often being adopted in the cases of late onset tooth ankylosis. Some research suggests fibrous ankylosis may precede the development of bony ankylosis. Rogan died on September 12, 1905, due to complications from his ankylosis. This led to ankylosis (abnormal rigidity of the skeletal joints). At the advanced stage of ankylosis, joint mobility is completely occluded. Pediatric condylar fractures have higher rates of ankylosis and the potential for growth disturbance. Ankylosis of deciduous teeth may rarely occur. Diagnostic methods of tooth ankylosis include the use of clinical examinations and x-ray. Risk factors of tooth ankylosis can be generally classified into genetic factors and dental trauma. External replacement resorption occurs following ankylosis of the root of the alveolar bone. Surgical luxation is sometimes used to break the ankylosis bridge to restore occlusion. Synostosis within joints can cause ankylosis. Medically, this class includes people with arthritis and osteoporosis, or ankylosis of the knee.