Studies on protracted tissue reactions and repair after circulatory and skeletal damage to the rat mandible.

The effect of circulatory and skeletal damage to the distal part of the mandible was studied on young growing rats after interruption of the inferior alveolar artery. The central part of the mandible including the incisor was most vulnerable to circulatory trauma. Maximal damage was seen when the inferior alveolar artery was interrupted combined with bilateral reflection of the mandibular periosteum. The damage produced then was a necrosis of the incisor pulp, odontoblasts and enamel organ and extensive resorption of the centrally-located compact bone. When both sides of the mucoperiosteum remained intact, damage to the main vessels of the mandible did not produce total necrosis of the incisor pulp. Reparative events with production of a fibrous connective tissue of the pulp and osteodentin production were seen. After resorption of sequestered bone was finished, this was replaced by a cell-rich type of bone which also replaced the alveola of those animals which had had their incisors excised. Hypercementosis was seen in the molars after 1 year. No respiratory activity in the incisor pulps was seen after the circulatory damage.