Effect of bacterial products on inflammatory reactions in the dental pulp

Culture filtrates (extracellular components) and material obtained from disintegrated cells (intracellular components) of cultured plaque bacteria were studied for their capacity to induce inflammatory reactions in the dental pulp. Class V cavities were prepared on the buccal surface of 94 teeth: 42 test and 52 control teeth in six adult monkeys. lyophilized bacterial components were sealed into the test cavities either alone or following an 8-h topical application of a solution of the same components in phosphate-buffered saline (PBS). Culture medium and PBS were applied in two sets of control cavities. A third set was restored with zinc oxide-eugenol cement. The animals were killed 32 h after the initiation of the experiment and the pulps were examined histologically. Teeth treated trophil leukocytes in the area of the pulp subjacent to the cut dentin tubules. Abscess formation was frequently found. The severe reactions which developed were independent of differences between individual animals and differences in thickness of the remaining dentin. The controls showed damage to the odontoblasts but little or no neutrophil infiltration. The findings confirm that products of bacteria applied to exposed dentin initiate inflammatory reactions in the dental pulp.