Upregulation of MMPs by root canal sealers in human osteoblasts

Objectives: Histological investigations have demonstrated that root canal sealers can induce mild to severe inflammatory alternations. The proteolysis of extracellular matrix by matrix metalloproteinases (MMPs) seems to be a key initiating event for the progression of the inflammatory process. The aim of this study was to investigate the effects of root canal sealers AH26, Canals, and N2 on the expression of MMPs in human osteoblast cell line U2OS cells. Methods: Freshly mixed materials were filled in glass rings (4 mm height and 10 mm in diameter) and eluted in 10 ml of culture medium for 1 day. Subsequently, various dilutions (final dilution: 1/2, 1/4, and 1/8) of these extraction media were prepared for this study. Cytotoxicity was measured by the Hoechst 33258 fluorescence assay. The levels of gelatinolytic activities were measured by the gelatin zymography. Results: The results showed that AH26, Canals, and N2 were cytotoxic to U2OS cells in a concentration-dependent manner (p<0.05). The gelatin zymograms revealed that MMP-2 (72 kDa) and MMP-9 (92 kDa) were secreted by U2OS cells. The exposure of U2OS cells to root canal sealers resulted in the upregulation of MMP-2 and -9 expression (p<0.05). Conclusions: Taken together, the activation of MMP-2 and -9 may play an important role in the pathogenesis of root canal sealers-induced periapical inflammation.