Craniofacial features in osteogenesis imperfecta: a cephalometric study

Osteogenesis imperfecta (OI) is a heterogeneous group of connective tissue diseases that mainly manifest as bone fragility and skeletal deformity. In most families it segregates as a dominant trait and results from mutations in type I collagen genes. In this study we analyzed the size and form of the bony structures in heads of 59 consecutive patients with OI types I, III, or IV (Sillence classification), using lateral radiographs. Paired controls were matched for gender and age. The purpose was to obtain baseline information of craniofacial development in OI patients that have not received bisphosphonate treatment. In OI type I we found smaller than normal linear measurements, indicating a general growth deficiency, but no remarkable craniofacial deformity. In OI types III and IV, the growth impairment was pronounced, and the craniofacial form was altered as a result of differential growth deficiency and bending of the skeletal head structures. We found strong support both for an abnormally ventral position of the sella region due to bending of the cranial base, and for a closing mandibular growth rotation. Vertical underdevelopment of the dentoalveolar structures and the condylar process were identified as the main reasons for the relative mandibular prognathism in OI. Despite of the widespread intervention with bisphosphonates, the facial growth impairment will probably remain characteristic for many OI patients, and their orthodontic treatment should be further developed.