Healing of the Traumatized Dental Pulp

¹ Histology Department, Eastman Dental Center, Rochester, New York

Autoradiographic observations were made of the reparative process in the dental pulps of 24 male Sprague-Dawley rats after various degrees of trauma had been induced by grinding the occlusal surfaces of teeth. To study the reparative process, H³-proline was then injected intraperitoneally in doses of 4µc./Gm. of body weight. The rats were sacrificed in groups of three at 4 hours, 8 hours, 12 hours, 1 day, 2 days, 1 week, and 1 month after injection. Autoradiographs were made of 5µ-thick sections by use of a liquid emulsion. Sections then were stained through the emulsion with hematoxylin and eosin; the amounts and location of the exposed silver granules were observed. In the early post-traumatic experimental periods, microscopic analysis revealed the lack of collagen macromolecules. After 24 hours, collagen formation was seen in such regions as evidence of an attempt of the dental pulp to repair the damaged tissue at the injured site. The greatest activity of collagen formation was observed adjacent to the odontoblasts. This observation suggests that these cells are the main cell type involved in the mechanism of reparative dentin and dentinal bridge formation.