Cytotoxicity of dental composite (co)monomers and the amalgam component Hg2+ in human gingival fibroblasts

Abstract

Unpolymerized resin (co)monomers or mercury (Hg) can be released from restorative dental materials (e.g. composites and amalgam). They can diffuse into the tooth pulp or the gingiva. They can also reach the gingiva and organs by the circulating blood after the uptake from swallowed saliva. The cytotoxicity of dental composite components hydroxyethylmethacrylate (HEMA), triethyleneglycoldimethacrylate (TEGDMA), urethanedimethacrylate (UDMA), and bisglycidylmethacrylate (Bis-GMA) as well as the amalgam component Hg(2+) (as HgCl(2)) and methyl mercury chloride (MeHgCl) was investigated on human gingival fibroblasts (HGFs) at two time intervals. To test the cytotoxicity of substances, the bromodeoxyuridine (BrdU) assay and the lactate dehydrogenase (LDH) assay were used. The test substances were added in various concentrations and cells were incubated for 24 or 48 h. The EC(50) values were obtained as half-maximum-effect concentrations from fitted curves. Following EC(50) values were found [BrdU: mean (mmol/l); SEM in parentheses; n=12]: (24 h/48 h) HEMA 8.860 (0.440)/6.600(0.630), TEGDMA 1.810(0.130)/1.220(0.130), UDMA 0.120(0.010)/0.140(0.010), BisGMA 0.060(0.004)/0.040(0.002), HgCl(2) 0.015(0.001)/0.050(0.006), and MeHgCl 0.004(0.001)/0.005(0.001). Following EC(50) values were found [LDH: mean (mmol/l); SEM in parentheses; n=12]: (24 h/48 h) HEMA 9.490(0.300)/7.890(1.230), TEGDMA 2.300(0.470)/1.950(0.310), UDMA 0.200(0.007)/0.100(0.007), BisGMA 0.070(0.005)/0.100(0.002), and MeHgCl 0.014(0.006)/0.010(0.003). In both assays, the following range of increased toxicity was found for composite components (24 and 48 h): HEMA < TEGDMA < UDMA < BisGMA. In both assays, MeHgCl was the most toxic substance. In the BrdU assay, Hg(2+) was about fourfold less toxic than MeHgCl but Hg(2+) was about fourfold more toxic than BisGMA. In the BrdU test, a significantly (P<0.05) decreased toxicity was observed for Hg(2+) at 48 h, compared to the 24 h Hg(2+)-exposure. A time depending decreased toxicity was observed only for Hg(2+) which can then reach the toxic level of BisGMA.

NAC ameliorates dental composite-induced DNA double-strand breaks and chromatin condensation

“…Here, we exposed HGF cells to xenobiotica at GMA, Bis-GMA, TEGDMA, HEMA and ACR, at their respective EC 50 values and noted relative toxicities ( Table 3) that agree with those obtained in former studies 28,30,55) . To test whether (co)monomer-induced DSB formation is mediated via radicals, we tested whether the antioxidant NAC can reduce the previously noted 28) dental (co)monomer-induced DSB formation and nuclear chromatin condensation in human gingiva fibroblasts.…”

Confocal Time Lapse Imaging as an Efficient Method for the Cytocompatibility Evaluation of Dental Composites

“…The cytotoxicity of dental composites and their components have been widely evaluated using cell culture systems [14][15][16] . These in vitro systems have been developed to assess dental composites biocompatibility in term of: cell growth, and cell apoptosis using THP-1monocytes like cells 17 , cytotoxicity in human gingival fibroblasts 18 , inflammatory potential in HaCaT keratinocytes like cells 2 , cell functionality odontoblast-like MDPC-23 cells 19 , reduction of total RNA levels, and significant increase in induction of apoptosis on human gingival keratinocytes 20 and DNA damage on gingival and pulp fibroblast cells 21 .…”

Distribution and Excretion of BisGMA in Guinea Pigs

“…Despite the fact that the body-weight-adjusted dose of BisGMA administered was more than 20 times higher than that which would be encountered by a human, the highest levels of BisGMA observed in tissue samples taken from guinea pigs, 1.5 nano M in the lung, 1 hr after intraveneous injection are approximately 1000-fold less than the known toxic level for BisGMA (Kostoryz et al, 2003;Schwengberg et al, 2005;Reichl et al, 2006;Schweikl et al, 2006). Similarly, with a dose well in excess of the weightadjusted, expected equivalent in humans, the highest [ 14 C] concentration in the spontaneous urine in guinea pigs was found 4 hrs after the oral [ 14 C] application (1.2% in 1.4 mL).…”