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 dentino genesis imperfecta (DI) associated with types IB and IVB osteogenesis imperfecta (OI) displayed previously undescribed structures in transmi ssion electron microscopic examination. Vesicles were seen in dentin o f both patients, and abnormally thick collagen fibers (hyperfibers) we re found in dentin of the patient with the rare type IB OI. Both vesic les and hyperfibers were situated in abnormal, atubular areas of denti n. Matrix vesicles, which have normally been identified in mantle dent in only were abundant in selected areas of the affected dentin, thereb y supporting the concept that dentin matrix in OI is elaborated by suc cessive 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.