Cell renewal and ground substance formation in replanted cat teeth.

The cellular dynamic pattern of pulpal healing 4, 10, 30, and 60 days after replantation of 47 apicoectomized cat incisors was studied after pulse labeling with 3H-thymidine and 35S-sulfate, autoradiography, and routine histology. In the control teeth the labeling index was less than 0.05%. The apical pulpal cells were capable of ground substance formation and cell proliferation already 4 days after replantation, with a labeling index of 7%, which increased up to 43% within 10 days. A gradual postoperative restitution and reorganization within the pulpal cellular compartment was seen. The maximum cell density, reached after 30 days, was reduced to on average 60% compared with the controls. The tissue reorganization was near completion within all pulpal zones after 60 days, and the labeling index was reduced to 2.5%. In some instances internal resorption in cervical pulpal areas negatively influenced the favorable healing. The present study shows that the pulpal healing in replanted teeth follows a consistent basic pattern in cellular dynamics and in histologic changes. The replanted tooth thus seems to be a suitable model for studies of healing and repair in connective tissues.