Cell-mediated immune response to dog pulp tissue altered by N2 paste within the root canal

After pulpal extirpation of twenty teeth in each of four dogs, these animals were primarily immunized intramuscularly with the dogs' own pulp (three dogs) altered by N2 paste and saline solution with pulp (one dog). A fifth dog was used as a control for skin tests. Secondary immunizations were accomplished via the root canal every 7 days over a 28-day period. Cell-mediated skin tests reactions demonstrated less of a response to the N2 paste alone than when the dogs' pulp was altered with this material. In vitro analysis of cell-mediated immune response (lymphocyte proliferation) showed a marked response to the pulp altered by N2 paste as compared to the saline-treated pulp (P less than 0.002). Therefore, dogs' pulp tissue became antigenically altered by the N2 material, recognized by the host, and a specific cell-mediated lymphocyte proliferation resulted.