Effects of long-term sub-lethal concentrations of dental monomers on THP-1human monocytes

Studies have shown that monomers from dental resins are acutely cytotoxic, but little is known of their long-term effects at sub-lethal concentrations . The current study determined the long-term effects of sub-lethal concentr ations of TEGDMA (triethyleneglycol dimethacrylate) and Bis-GMA (bisphenol- glycidylmethacrylate), two common dental monomers, on the ill vitro cellula r proliferation, succinic dehydrogenase activity, and total cellular protei n production of monocytes. Human THP-I monocytes were exposed to concentrat ions of 100, 200, and 400 mu mol l(-1) of TEGDMA or 1, 5, and 25 mu mol l(- 1) Bis-GMA for 5 weeks. Controls received only vehicle solutions of ethanol . Each week cellular proliferation (hemocytometer), succinic dehydrogenase (SDH) activity (MTT) and total cellular protein (bicinchoninic acid) were a ssessed. The results were compared with ANOVA and Tukey intervals (alpha = 0.05). TEDGMA had no proliferative or cellular protein effects, but increased SDH activity 20-60% in week 1 (p < 0.05). SDH activity then decreased 40% in we ek 2, followed by a gradual increase of 30-40% over week 3-5 (p < 0.05). Bi s-GMA reduced proliferation by 40-60% from 1-5 weeks exposure (p < 0.05). H owever, SDH activity and total protein per cell were not affected. There wa s some indication of increased SDH activity after 5 weeks (20-30%, p < 0.05 ). Sub-lethal concentrations of TEGDMA and Bis-GMA have significant long-te rm effects on monocytes at low-dose 5-week exposures in vitro. Each monomer acted differently.