Effects of multiple dentinal lesions on the rat pulp.

The purpose of this study was to compare the effects of single and multiple dentinal lesions on the dental pulps of rats. 3H-proline was used to measure pulpal reactionary dentin deposition, and 3H-thymidine was used to measure pulpal cell proliferation by radioautography. Data were compared by factorial analysis of variance and a post-hoc Tukey test. A significant increase in radiolabeled collagenous proteins within reactionary dentin and pulpal cell labeling indices were evident coincident to single dentinal injuries, compared with controls (p < 0.001). After double injuries, the radiolabeled collagenous proteins within reactionary dentin and the pulpal labeling indices remained significantly greater than in controls (p < 0.01); however, each was significantly less than after single injuries (p < 0.05). These data suggest that pulpal cell proliferation and collagenous protein deposition into reactionary dentin are decreased subsequent to a previous dentinal injury. Thus, the healing potential of the dental pulp could be decreased by recent tooth cavity preparation.