Fig. 1.

Critical size defect in the pulp of a dog tooth. An immature dog tooth was accessed, a pulpectomy performed, and the canal infected by microbes. After disinfection of the root canal, the space was filled with blood induced from the periapical tissue and the tooth sealed. Three months later the tooth with the surrounding tissues was removed and processed for histological analysis. It was found that some pulp tissue was not removed but healed after disinfection (blue arrow). The odontoblast layer (arrowhead) on the left side of the canal space remained intact. The right side of the pulp tissue was removed and the space filled in by periodontal tissue including soft connective tissue and intracanal cementum (white arrow). The dashed line separates healed pulp tissue (left) and ingrown periapical connective tissue (right). Adapted with permission from Wang et al., 2010 (19).