Genotoxicity and cytotoxicity of dental materials in human lymphocytes as assessed by the single cell microgel electrophoresis (comet) assay.
OBJECTIVE
Resin monomers may be released from restorative dental materials and can diffuse into the tooth pulp or the gingiva, and can reach the saliva and the circulating blood. Whereas the cytotoxic potential of some components has been clearly documented, possible genotoxicity in human target cells demands further investigation.


METHODS
The Comet assay was used to quantify DNA single strand breaks, alkali labile and incomplete excision repair sites in lymphocytes of 10 volunteers. The xenobiotics investigated were 2-hydroxyethylmethacrylate (HEMA), triethyleneglycoldimethacrylate (TEGDMA), urethane dimethacrylate (UDMA), and bisphenol A-glycidyl methacrylate (Bis-GMA) with N-methyl-N'-nitro-N-nitrosoguanidine and dimethyl sulfoxide as controls. DNA migration was quantified using the tail moment according to Olive (OTM) and DNA migration was considered to be elevated at OTM levels above 2. Cytotoxicity was monitored using trypan blue.


RESULTS
In the negative controls, OTM ranged between 1.0 and 1.2. With HEMA concentrations above 10(-6)M, TEGDMA 10(-3)M, Bis-GMA 10(-4)M, and UDMA above 10(-6)M relevant enhancements of DNA migration (OTM>2) were achieved. At higher concentrations of up to 2.5x10(-2) induced DNA migration was expressed by OTM of 3.3 for HEMA, 4.5 for TEGDMA, 7.4 for Bis-GMA, and 2.8 for UDMA. Relevant cytotoxic effects were also seen but vitality levels were at a critical range of 71% for Bis-GMA and 73% for TEGDMA, only.


CONCLUSIONS
In higher concentration levels, all tested substances induced significant but minor enhancement of DNA migration in the Comet assay as a possible sign for limited genotoxic effects. However, with the highest levels of DNA migration being combined with elevated cytotoxic effects, a low in vivo genotoxic strain appears to be posed by the resin components.
Kleinsasser
Norbert H
NH
Klinisch experimentelle Onkologie, Department of Otolaryngology-Head and Neck Surgery, Ludwig-Maximilians-University Munich, Munich, Germany. norbert.kleinsasser@klinik.uni-regensburg.de
Wallner
Barbara C
BC
Harréus
Ulrich A
UA
Kleinjung
Tobias
T
Folwaczny
Matthias
M
Hickel
Reinhard
R
Kehe
Kai
K
Reichl
Franz-Xaver
FX
D000328:Adult; D017438:Bisphenol A-Glycidyl Methacrylate / Q000633:toxicity; D020552:Comet Assay; D004249:DNA Damage; D003764:Dental Materials / Q000633:toxicity*; D005260:Female; D006801:Humans; D008214:Lymphocytes / Q000187:drug effects*; D008297:Male; D008422:Materials Testing; D008689:Methacrylates / Q000633:toxicity*; D011092:Polyethylene Glycols / Q000633:toxicity; D011109:Polymethacrylic Acids / Q000633:toxicity; D011140:Polyurethanes / Q000633:toxicity
D003764:Dental Materials; D008689:Methacrylates; D011109:Polymethacrylic Acids; D011140:Polyurethanes; C029824:urethane dimethacrylate luting resin; C020946:triethylene glycol dimethacrylate; D011092:Polyethylene Glycols; D017438:Bisphenol A-Glycidyl Methacrylate; C005044:hydroxyethyl methacrylate