Cytotoxicity of denture base resins: effect of water bath and microwave postpolymerization heat treatments.
OBJECTIVE
This study compared the effect of two postpolymerization heat treatments on the cytotoxicity of three denture base resins on L929 cells using 3H-thymidine incorporation and MTT assays.


METHODS
Sample disks of Lucitone 550, QC 20, and Acron MC resins were fabricated under aseptic conditions and stored in distilled water at 37 degrees C for 48 hours. Specimens were then divided into three groups: (1) heat treated in microwave oven for 3 minutes at 500 W; (2) heat treated in water bath at 55 degrees C for 60 minutes; and (3) no heat treatment. Eluates were prepared by placing three disks into a sterile glass vial with 9 mL of Eagle's medium and incubating at 37 degrees C for 24 hours. The cytotoxic effect from the eluates was evaluated using the 3H-thymidine incorporation and MTT assays, which reflect DNA synthesis levels and cell metabolism, respectively.


RESULTS
The components leached from the resins were cytotoxic to L929 cells when 3H-thymidine incorporation assay was employed. In contrast, eluates from all resins revealed noncytotoxic effects as measured by MTT assay. For both MTT assay and 3H-thymidine incorporation, the heat treatments did not decrease the cytotoxicity of the materials tested.


CONCLUSIONS
Resins were graded by 3H-thymidine incorporation assay as slightly cytotoxic and by MTT assay as noncytotoxic. Cytotoxicity of the denture base materials was not influenced by microwave or water bath heat treatment.
Jorge
Janaina Habib
JH
Department of Dental Materials and Prosthodontics, São Paulo State University, Araraquara Dental School, São Paulo, Brazil.
Giampaolo
Eunice Teresinha
ET
Vergani
Carlos Eduardo
CE
Machado
Ana Lúcia
AL
Pavarina
Ana Cláudia
AC
Carlos
Iracilda Zeppone
IZ
D000180:Acrylic Resins / Q000633:toxicity*; D000704:Analysis of Variance; D000818:Animals; D004396:Coloring Agents / Q000378:metabolism; D003819:Denture Bases / Q000009:adverse effects*; D006358:Hot Temperature; D007739:L Cells / Q000187:drug effects; D051379:Mice; D008809:Mice, Inbred C3H; D008872:Microwaves; D015394:Molecular Structure; D044367:Phase Transition; D013778:Tetrazolium Salts / Q000378:metabolism; D014316:Tritium / Q000378:metabolism; D014867:Water
D000180:Acrylic Resins; D004396:Coloring Agents; C488492:QC 20 (denture base resin); D013778:Tetrazolium Salts; C042207:4-anisyltetrazolium blue; D014867:Water; D014316:Tritium; C075051:Acron MC; C040291:Lucitone