Tissue response to a new methacrylate-based root canal sealer: preliminary observations in the subcutaneous connective tissue of rats.

Silicone tubes filled with EndoRez, a methacrylate-based root canal sealer, were implanted in the subcutaneous connective tissue of the rat. Solid, silicone rods of the same size as the tubes also were implanted and used as negative controls. The tissue reaction to test and control materials was histologically studied and analyzed by elemental electron-microprobe analysis. After 10, 30, 90, and 120 days of implantation, different grades of tissue reaction to the tested materials were recorded. A granulomatous tissue containing numerous polymorphonuclear leukocytes, lymphocytes, and plasmocytes, as well as macrophages and foreign-body giant cells with engulfed material in their cytoplasm, was initially observed in contact with EndoRez. Fibroblasts and newly formed vessels also were observed. This cellular profile persisted after 30 days. The severity of the reaction decreased with time, and connective tissue healing was observed at the 120-day observation period, even though some specimens exhibited a slight, persistent, inflammatory cell infiltration. The electron-microprobe analysis of the tissues revealed the presence of heavy components of EndoRez in all observation periods. In contact with the controls, there was an initially slight concentration of inflammatory cells. This reaction rapidly subsided after 30 days, and a fibrous connective tissue encapsulation, free of inflammatory cells, could be observed at the 90- and 120-day observation periods.