A structural and ultrastructural study of a fused tooth

A fused mandibular lateral incisor and canine tooth were examined histologically at various levels. A composite reconstruction of the fused mass was compiled and the vascular supply indicated. Light microscopic examination revealed a common pulp chamber and discrete root canals. In the interstitium between the root canals an irregular type of secondary dentin was found. This was characterized by numerous vascular spaces and was termed "vasodentin." A notable feature of the histological examination was the paucity of odontoblasts in the interstitial root canal wall of the minor root canal, while the odontoblast layer was continuous throughout the remainder of the tooth. A theory is presented for the formation of fused teeth.