EFFECTS OF ROOT-CANAL SEALERS ON IMMUNOCOMPETENT CELLS IN-VITRO AND IN-VIVO

Over the years of testing biocompatibility of endodontic filling mater ials, little attention has been paid to the potential adverse influenc es on the function of the immune system. Therefore, the purpose of thi s study was to investigate the extent to which extractable components of some commonly used root canal sealing materials (ERCS) may interfer e with immunocompetent cells in vitro. The potential of these material s to cause delayed-type hypersensitivity (DTH) was also addressed in a rat model system. Extractable components were drawn in cell culture m edium from freshly mixed or set material of AH 26, Grossman's sealer, Endomethasone, and Apexit. In-vitro assays included either spleen cell s or rat pulp tissue cells that were released following enzymatic dige stion with collagenase, Purified T cells for the pulpal cell assay wer e obtained from rat mesenteric lymph nodes. The effect of ERCS on the proliferation of concanavalin A (con A) stimulated spleen cell was mea sured by H-3-thymidine incorporation. Pulpal accessory cell function w as monitored by the capacity of pulpal cells, pretreated with componen ts of ERCS, to provide signals to con A stimulated T cells, DTH was te sted after subcutaneous implantation of root canal sealers (RCS) in ra ts and challenge by ear injection, Pretreatment of pulpal cells with l ow dilutions of eluates from extracted AH 26 and Endomethasone resulte d in a strong reduction of the T cell proliferation rate, The effect w as considerably reduced (P < 0.01) when extracts of the solid material were employed, Extracts of Grossmans' sealer and Apexit affected T ce ll proliferation only to a limited extent in the pulpal cell assay. In general, assays on spleen cells showed a similar profile, although in creased cell division was induced by Grossman's sealer at high eluate dilutions and a concentration-dependent decrease of cell division at l ower concentrations of this material, ERCS evoked both immunosuppressi on and, in release DTH.