title: Cytotoxicity of hard chairside reline resins: effect of microwave irradiation and water bath postpolymerization treatments.
abstract: OBJECTIVE
  To evaluate the influence of water bath and microwave postpolymerization treatments on the cytotoxicity of 6 hard reline acrylic resins.
  
  
  METHODS
  The materials tested were Tokuso Rebase Fast (TR), Ufi Gel Hard (UGH), Duraliner II (D), Kooliner (K), New Truliner (NT), and Light Liner (LL). LL resin was additionally tested with an air-barrier coating (LLABC). Nine disks of each material (10 x 1 mm) were made and divided into 3 groups: group 1 (no postpolymerization treatment); group 2 (postpolymerization in microwave oven); group 3 (postpolymerization in water bath at 55 degrees C for 10 minutes). L929 cells were cultured in 96-well plates and incubated for 24 hours in Eagle's medium. Eluates prepared from the disks or medium without disks (control) replaced the medium. Cytotoxicity was assessed by both dehydrogenase succinic activity (MTT) assay and incorporation of radioactive 3H-thymidine assay. Tests were carried out in quadruplicate and repeated twice. Differences between groups were determined by analysis of variance with Tukey multiple-comparison intervals (alpha = .05).
  
  
  RESULTS
  For MTT assay, the postpolymerization treatments had no effect on the cytotoxicity of all materials (P > .05). For 3H-thymidine assay, the postpolymerization treatments significantly decreased the cytotoxicity of UGH (P < .05). The cytotoxicity of K, NT, LL, and LLABC increased after microwave irradiation (P < .05). TR, NT, and LLABC showed an increase in cytotoxicity after water bath (P < .05).
  
  
  CONCLUSIONS
  When assessed by MTT assay, the cytotoxicity of the materials was not affected by postpolymerization treatments. 3H-Thymidine assay showed that the cytotoxicity of the resins was not improved by the postpolymerization treatments, with the exception of UGH.
authors.affiliation: Department of Dental Materials and Prosthodontics, São Paulo State University, Araraquara Dental School, Brazil.
authors.forename: Nara Hellen
authors.initials: NH
authors.lastname: Campanha
authors.forename: Ana Cláudia
authors.initials: AC
authors.lastname: Pavarina
authors.forename: Eunice Teresinha
authors.initials: ET
authors.lastname: Giampaolo
authors.forename: Ana Lucia
authors.initials: AL
authors.lastname: Machado
authors.forename: Iracilda Zeppone
authors.initials: IZ
authors.lastname: Carlos
authors.forename: Carlos Eduardo
authors.initials: CE
authors.lastname: Vergani
mesh_terms: D000180:Acrylic Resins / Q000737:chemistry / Q000528:radiation effects / Q000633:toxicity*; D000704:Analysis of Variance; D000818:Animals; D049109:Cell Proliferation / Q000187:drug effects; D004396:Coloring Agents / Q000378:metabolism; D003764:Dental Materials / Q000737:chemistry / Q000528:radiation effects / Q000633:toxicity*; D003822:Denture Liners / Q000009:adverse effects*; D003823:Denture Rebasing / Q000009:adverse effects*; D007739:L Cells / Q000187:drug effects; D008422:Materials Testing; D051379:Mice; D008872:Microwaves; D044367:Phase Transition; D013778:Tetrazolium Salts / Q000378:metabolism; D013844:Thiazoles / Q000378:metabolism; D014316:Tritium / Q000378:metabolism; D014867:Water
chemical_list: D000180:Acrylic Resins; D004396:Coloring Agents; D003764:Dental Materials; D013778:Tetrazolium Salts; D013844:Thiazoles; D014867:Water; D014316:Tritium; C022616:thiazolyl blue