Healing of horizontal root fractures.

The roots of six anterior maxillary and mandibular teeth were intentionally fractured in three monkeys. The teeth were then rigidly splinted for 12 wk. The healing of the fractured roots was examined clinically, radiographically, and histologically for a period of 6 months. Five of six fracture sites healed by either dense connective tissue or mineralized hard tissue which appeared to enter the fracture sites from the periodontal ligament. The canal spaces in these teeth were reduced substantially by calcific deposits. The remaining pulp tissue appeared vital histologically, but with areas of odontoblastic layers absent. The fractured root which failed to heal showed presence of necrotic pulp in both apical and coronal segments and the fracture site was infiltrated by inflammatory cells.