What is the primary defect in conditions like osteogenesis imperfecta?

Osteogenesis imperfecta is primarily characterized by a defect in collagen formation, specifically type I collagen. This genetic disorder leads to fragile bones that are susceptible to fractures, as collagen is a crucial component of bone structure. The defective collagen results from mutations in the genes responsible for its synthesis, which can lead to issues in bone density, strength, and overall integrity.

While other options involve dental structures, they are not central to the pathology of osteogenesis imperfecta. For instance, defective enamel formation pertains more to conditions like enamel hypoplasia, while dentin and pulp formation defects relate to different dental disorders. In the context of osteogenesis imperfecta, the primary concern and abnormal development directly impact the collagens in the skeletal system, reinforcing why defective collagen formation is the most accurate choice.