Dental pulp response to bacterial cell wall material

Lipopolysaccharides (LPS) from Bacteroides oralis and Veillonella parvula and cell wall material from Lactobacillus casei were studied for their capacity to induce leukocyte migration in the dental pulp and in an implanted wound chamber. Three adult monkeys were challenged using lyophilized material sealed into buccal Class V cavities prepared in dentin. Pulp tissue responses were observed histologically eight and 72 hours after initiation of the experiment. Subjacent to cut dentinal tubules, bacterial materials induced polymorphonuclear leukocyte (PMN's) infiltration in the pulp tissue of the majority of test teeth examined. Responses were similar for the three bacterial test materials at both time periods. Topical applications of bovine serum albumin (BSA), used as a control, induced significantly less accumulation of PMN's. Assessments of induced exudate volumes and leukocyte densities in chambers implanted in rats showed comparable rankings with pulpal experiment between test (i.e., bacterial) and control (BSA) materials. Analysis of the data indicates that high-molecular-weight complexes of bacterial cell walls may adversely affect pulpal tissue across freshly exposed dentin.