Effects of dentin bonding agents on macrophage mitochondrial activity

Dentin bonding agents (DBA) have been considered for use as root-end fillings. Previous studies have documented the release of DBA components in vivo and in vitro, but the biological implications are not clear. The macrophage is important in wound healing, and likely to be important in any inflammatory response. Therefore, this study determined the concentrations of the components of DBAs that suppress the mitochondrial activity of human macrophages in vitro. THP-1 macrophages were cultured in the presence of four DBA components (2-hydroxyethyl methacrylate (HEMA), 4-methacryloxyethyl trimellitate anhydride (4-META), bisphenol-glycidylmethacrylate (Bis-GMA), and urethane dimethacrylate (UDMA)) at various concentrations and for varying durations. Residual effects were also measured after the resins were removed. Controls received only the vehicle solution, ethanol or water. THP-1 mitochondrial activity was estimated using the MTT assay, and the 50% toxicity concentrations (TC₅₀) were determined graphically. Resin components suppressed the mitochondrial activity of macrophages at different concentrations (TC₅₀ values for HEMA (10,000 μzmol/L), 4-META (3,800 μmol/L), Bis-GMA (130 μmol/L), and UDMA (110 μmol/L) at 24 h, and the effect was time-dependent. Residual effects were observed for all resins.