Pulp reactions to exposure after experimental crown fractures or grinding in adult monkeys.

The purpose of the investigation was to assess the depth of inf lammatory reactions in the exposed pulps of crown-fractured and ground teeth. Thirty-six incisors in 11 adult monkeys were used for the experiments. In 24 teeth, the pu lp was exposed by grinding or by crown fracture, and the pulpal reactions were examined after 3, 48, and 168 hours. In three-hour specimens, the depth of early changes, namely hemorrhage and damage to the odontoblastic layer, did not exceed 2 m m from the exposure surface. The depth of inf lammatory changes in 48-hour specimens ranged from 1.5 to 2.0 mm (mean 1.8 mm), and in 168-hour specimens from 0.8 to 2.2 m m (mean 1.6 mm). Among pulps exposed for 48 and 168 hours, 13 showed hyperplast ic reactions in the exposure; in two teeth, the exposed pulp was only covered wi th fibrin, whereas the pulp in one tooth was necrotic. In the remain ing 12 teeth that were used as a coml~arison group, the pu lp was exposed by preparing a cavity, which was left open for 48 and 168 hours. The depth of inflammatory changes in the pu lps ranged in 48-hour specimens from 1.0 to 9.3 mm (mean 3.8 mm) and in 168-hour specimens from 1.0 to 8.2 m m (mean 4.4 mm). In compar ison wi th g round or crown-fractured teeth, in f lammatory changes in the pulps exposed by cavity preparation were significantly increased (P = 0.01).