RESUMO
Osteogenesis imperfecta is a genetic disease that varies in severity and is characterized by fragile bones that fracture easily. Many extra-skeletal manifestations can be noted such as blue sclerotic markings, dentinogenesis imperfecta and impaired hearing or deafness. In most cases, an anomaly of collagen is the cause. It is usually accompanied by a specific Class III type cranio-facial morphology with open bite and increased incidence of impacted permanent molars. Orthodontists called upon to treat the dental aspects of this malady, should be careful to protect their patients against bacterial infection and hemorrhages, and to be well aware of the side affects that can be caused by the biophosphanates that constitute the basis of current medical treatment of osteogenesis imperfecta.