Hyperfibers and vesicles in dentin matrix in dentinogenesis imperfecta (DI) associated with osteogenesis imperfecta (OI).

Dentin matrix of deciduous teeth from two patients affected by dentinogenesis imperfecta (DI) associated with types IB and IVB osteogenesis imperfecta (OI) displayed previously undescribed structures in transmission electron microscopic examination. Vesicles were seen in dentin of both patients, and abnormally thick collagen fibers (hyperfibers) were found in dentin of the patient with the rare type IB OI. Both vesicles and hyperfibers were situated in abnormal, atubular areas of dentin. Matrix vesicles, which have normally been identified in mantle dentin only, were abundant in selected areas of the affected dentin, thereby supporting the concept that dentin matrix in OI is elaborated by successive cell generations. The hyperfibers, not previously described in either normal or abnormal human dentin, have possibly been formed by fusion of several collagen fibers. Further ultrastructural studies of dentin in DI with OI may help to clarify the marked clinical variation in teeth of patients affected by OI.