The in vitro cytotoxicity of eluates from dentin bonding resins and their effect on tyrosine phosphorylation of L929 cells.
OBJECTIVE
The aim of this study was to examine the relationship between the monomers eluted from dentin-bonding systems and their cytotoxicities, and to investigate the biochemical effect of the monomers on tyrosine phosphorylation, especially relating to the cell growth activity, of L929 cells in vitro.


METHODS
The primers, uncured or cured adhesives (3M and Kuraray) were tested to determine the cytotoxicity of confluent L929 cells cultured by Eagle's MEM medium supplemented with 10% FCS. The area of cells affected by the eluted monomers were evaluated with an image analyzer and the concentrations of monomers eluted into the medium were measured with high performance liquid chromatography (HPLC) after 24h incubation. The protein composition of the stimulated cells was compared by sodium dodecyl sulfate-polyacrylamide gel electrophoresis and tyrosine phosphorylation was detected by Western blot.


RESULTS
The primer and uncured adhesives revealed variable cytotoxicities. 2-hydroxyethyl-methacrylate (HEMA) was the major component eluted from uncured primers and adhesives. Small amounts of triethylene glycol dimethacrylate (TEGDMA) were also detected from the uncured adhesives. The cytotoxicities of the adhesives decreased as photo activation time increased. The amount of monomers eluted from the cured adhesives was almost undetectable and did not reach a sufficient concentration to suppress cell viability or cell growth. The cytotoxicities of the primers and adhesives correlated well with the amounts of either HEMA or TEGDMA eluted. Moreover, a high concentration of HEMA (4 mg/ml medium) affected intracellular tyrosine phosphorylation, which is related to cellular activities.


CONCLUSIONS
Although the monomers present in dentin bonding resins are cytotoxic to L929 cells, the amount from cured bonding resin is very small and does not provide a cytotoxic dose. This data does however suggest that clinical exposure to the uncured primers and adhesives of dentin bonding resins should be minimized.
Kaga
M
M
Department of Pediatric Dentistry, School of Dentistry, Hokkaido University, Kita 13 Nishi 7, Kitaku, Sapporo 060-8586, Japan. kaga@den.hokudai.ac.jp
Noda
M
M
Ferracane
J L
JL
Nakamura
W
W
Oguchi
H
H
Sano
H
H
D000269:Adhesives / Q000633:toxicity; D000704:Analysis of Variance; D000818:Animals; D015153:Blotting, Western; D002452:Cell Count; D002455:Cell Division / Q000187:drug effects; D002460:Cell Line; D002470:Cell Survival / Q000187:drug effects; D002851:Chromatography, High Pressure Liquid; D003188:Composite Resins / Q000633:toxicity; D017220:Dentin-Bonding Agents / Q000633:toxicity*; D004591:Electrophoresis, Polyacrylamide Gel; D005347:Fibroblasts / Q000187:drug effects*; D007091:Image Processing, Computer-Assisted; D008027:Light; D008422:Materials Testing; D008689:Methacrylates / Q000633:toxicity; D051379:Mice; D010766:Phosphorylation; D011092:Polyethylene Glycols / Q000633:toxicity; D011109:Polymethacrylic Acids / Q000633:toxicity; D017027:Protein Tyrosine Phosphatases / Q000032:analysis / Q000187:drug effects*; D019279:Resin Cements / Q000633:toxicity; D012867:Skin / Q000166:cytology / Q000187:drug effects*; D014443:Tyrosine / Q000032:analysis / Q000187:drug effects*
D000269:Adhesives; C112274:Clearfil Liner Bond 2; C084544:Clearfil Linerbond System; D003188:Composite Resins; D017220:Dentin-Bonding Agents; D008689:Methacrylates; D011109:Polymethacrylic Acids; D019279:Resin Cements; C084018:Scotchbond Multi-Purpose; C020946:triethylene glycol dimethacrylate; D011092:Polyethylene Glycols; D014443:Tyrosine; C005044:hydroxyethyl methacrylate; D017027:Protein Tyrosine Phosphatases