Although involvement of the temporomandibular joint in patients with ankylosing 
spondylitis (AS, Bechterew disease) has been described previously, hyperplasia 
of the mandibular coronoid process in those patients has not been reported yet. 
Case notes were studied, and records were made of age, sex, clinical symptoms, 
radiography, and treatment in all patients with a confirmed diagnosis of 
coronoid hyperplasia presenting at the Department of Oral and Maxillofacial 
Surgery, University of Bonn, between 1995 and 2007. Sixteen cases of coronoid 
hyperplasia were recruited, of which 12 were bilateral and 4 were unilateral. 
Four patients had AS, 3 of them were HLA-B27-positive. Temporomandibular joint 
symptoms are frequently seen in patients with AS. Nevertheless, it must be 
considered that a limitation of jaw mobility in those patients might also be 
caused by an elongation of the mandibular coronoid process.