Cytotoxicity of monomers, plasticizer and degradation by-products released from dental hard chairside reline resins.
OBJECTIVE
The aim of this study was to evaluate the cytotoxic effect of the monomers isobutyl methacrylate (IBMA) and 1,6-hexanediol dimethacrylate (1,6-HDMA), the plasticizer di-n-butyl phthalate (DBP), and the degradation by-products methacrylic acid (MA) and benzoic acid (BA) on L929 cells. Based on previous investigations on the release of these compounds from hard chairside reline resins, a range of concentrations (micromol/L) were selected for the cytotoxicity tests (IBMA, 5.49-1406.57; 1,6-HDMA, 1.22-39.32; DBP, 1.12-143.8; MA, 9.07-581; BA, 3.19-409).


METHODS
Cytotoxic effects were assessed using MTT and (3)H-thymidine assays after the cells had been exposed to the test compounds at the given concentrations for 24 h. Cytotoxicity was rated based on cell viability relative to controls (cells exposed to medium without test substances).


RESULTS
DNA synthesis activity was inhibited by all compounds. Mitochondrial dehydrogenase activity decreased in cells treated with monomers, plasticizer and MA by-product, whereas no cytotoxic effect was observed on contact with BA at the majority of concentrations tested. The ranges of suppression for (3)H-thymidine assay were: IBMA, 25-95%; 1,6-HDMA, 95-98%; DBP, 40-98%; MA, 97-99%; BA, 54-71%. For MTT assay, the ranges of suppression were: IBMA, 0-96%; 1,6-HDMA, 26-89%; DBP, 17-80%; MA, 52-66%; BA, 0-27%. The (3)H-thymidine assay was more sensitive than the MTT assay.


CONCLUSIONS
This study evaluated the cytotoxicity of a wide range of concentrations of monomers (IBMA and 1,6-HDMA), plasticizer (DBP) and degradation by-products (MA and BA), including those expected to be released from hard chairside reline resins. The differences observed in the cytotoxicity of these compounds, along with other properties, may assist the dental practitioners in the selection of reline materials with improved service life performance and low risk of adverse reactions in patients who wear relined dentures.
Chaves
Carolina de Andrade Lima
CA
UNESP - Univ Estadual Paulista, Araraquara Dental School, Department of Dental Materials and Prosthodontics, Rua Humaitá, 1680, Araraquara, CEP 14801-903, São Paulo, Brazil.
Machado
Ana Lucia
AL
Carlos
Iracilda Zeppone
IZ
Giampaolo
Eunice Teresinha
ET
Pavarina
Ana Cláudia
AC
Vergani
Carlos Eduardo
CE
D000818:Animals; D019817:Benzoic Acid / Q000633:toxicity*; D049109:Cell Proliferation / Q000187:drug effects; D002470:Cell Survival / Q000187:drug effects*; D004249:DNA Damage; D003822:Denture Liners / Q000009:adverse effects*; D003823:Denture Rebasing / Q000009:adverse effects; D003993:Dibutyl Phthalate / Q000633:toxicity; D004305:Dose-Response Relationship, Drug; D005347:Fibroblasts / Q000187:drug effects; D007739:L Cells; D008689:Methacrylates / Q000633:toxicity*; D051379:Mice; D033681:Mitochondrial Membrane Transport Proteins / Q000037:antagonists & inhibitors; D019384:Nucleic Acid Synthesis Inhibitors; D010968:Plasticizers / Q000633:toxicity*; D013778:Tetrazolium Salts / Q000378:metabolism; D013936:Thymidine / Q000378:metabolism
D008689:Methacrylates; D033681:Mitochondrial Membrane Transport Proteins; D019384:Nucleic Acid Synthesis Inhibitors; D010968:Plasticizers; D013778:Tetrazolium Salts; C008384:methacrylic acid; D003993:Dibutyl Phthalate; D019817:Benzoic Acid; D013936:Thymidine