Cytotoxicity of dental composite (co)monomers and the amalgam component Hg(2+) in human gingival fibroblasts.
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.
Walther-Straub-Institute of Pharmacology and Toxicology, Ludwig-Maximilians-University of Munich, Goethestr. 33, 80336 Munich, Germany. reichl@lmu.de
Franz-Xaver
FX
Reichl
Sabine
S
Simon
Magalie
M
Esters
Mario
M
Seiss
Kai
K
Kehe
Norbert
N
Kleinsasser
Reinhard
R
Hickel
D001973:Bromodeoxyuridine / Q000378:metabolism; D002470:Cell Survival; D002478:Cells, Cultured; D003188:Composite Resins / Q000633:toxicity*; D003723:Dental Amalgam / Q000633:toxicity*; D004305:Dose-Response Relationship, Drug; D005347:Fibroblasts / Q000187:drug effects* / Q000378:metabolism / Q000473:pathology; D005881:Gingiva / Q000187:drug effects* / Q000378:metabolism / Q000473:pathology; D006801:Humans; D007770:L-Lactate Dehydrogenase; D008767:Methylmercury Compounds / Q000633:toxicity*; D008768:Methylmethacrylates / Q000633:toxicity*; D013997:Time Factors
D003188:Composite Resins; D008767:Methylmercury Compounds; D008768:Methylmethacrylates; D003723:Dental Amalgam; D007770:L-Lactate Dehydrogenase; D001973:Bromodeoxyuridine; C004925:methylmercuric chloride