The risk of bisphosphonate-related osteonecrosis of the jaw in children. a case report and literature review

Osteogenesis imperfecta (OI) is part of a group of disorders characterized by increased fragility of bone. OI sufferers are born with defective connective tissue or without the ability to make connective tissue. In some cases, the collagen may be of poor quality, or there may not be enough to support the mineral structure of the bones. Historically, OI has been viewed as an autosomal dominant disorder of type-I collagen. The majority of cases are caused by a dominant mutation to type 1 collagen (COL1A1 or COL1A2) genes. In recent years, there has been the identification of autosomal recessive forms. Two of the recessive types of OI, types VII and VIII, do not involve mutations in the type-I collagen genes. These recessive types of OI result from mutations in two genes that affect collagen: the cartilage-associated protein gene (CRTAP) and the prolyl 3-hydroxylase 1 gene (LEPRE1). There are currently eight different types of OI. The severity of OI ranges from lethal form to milder form and the symptoms vary from person to person. OI type I is the mildest and the most common form of the disorder. OI type II is the most severe form. The estimated prevalence of OI is around 1 in 20,000 to 1 in 30,000 births.1 There are a few dental abnormalities associated with OI. These patients tend to have skeletal Class III malocclusion and often have an open-bite. Tooth development can also be affected, with tooth eruption being delayed or advanced. Permanent molars may fail to erupt or erupt ectopically. In some cases, OI is also associated with dentinogenesis imperfecta (DI). Teeth that are affected by DI are usually discoloured, ranging from amber-brown to grey-blue. The enamel may be hypomineralized and tends to crack away from abnormal dentine. As a result teeth that are affected by DI are prone to attrition.2