In Vitro Cytotoxicity of Four Light-Cured Orthodontic Resins

  • Dr Roberto Uomo, Department of Orthodontics, University of Naples “Federico II”., Italy
  • Dr Vincenzo D'Anto, University of Naples “Federico II”., Italy
  • Dr Gianrico Spagnuolo, Department of Orthodontics, University of Naples “Federico II”., Italy
  • Dr Paolo Manzo, University of Naples “Federico II”., Italy
  • Ing Luigi Ambrosio, Institute for Composite and Biomedical Materials - CNR, Italy
  • Dr Rosa Valletta, Department of Orthodontics, University of Naples “Federico II”., Italy

Aim: The purpose of this study was to evaluate the cytotoxic effect of commercially available light-cured orthodontic bonding resins.
Material and Methods: Four light-cured orthodontic resins, Spectrum (American Orthodontics, Sheboygan, USA), Greengloo (Ormco, Glendora, USA), Transbond and Transbond Plus (3M, Monrovia, USA), were tested in this study. Balb 3T3 cells were indirectly exposed to uncured and cured resin disks by the Transwell insert methodology. After 24 hours, morphological changes were observed by phase contrast microscopy and the inhibition of cell proliferation was assessed by evaluating alamar blue reduction. The results were expressed as the percentage of untreated cells and statistical analysis was performed by means of two-way ANOVA (p<0.05).
Results: After 24 hours of exposure to cured and uncured composite disks, Balb 3T3 cells appeared smaller, retracted and rounded. Tested materials showed different cytotoxic potencies (figure 1). Considering cured samples, the mean value of cell proliferation were 67,23 % for Spectrum, 15,41% for Greengloo, 58% for Transbond and 18,84% for Transbond plus. Moreover, a statistically significant difference was found between cured and uncured samples (p=0.018).
Discussion and Conclusions: This study suggests that orthodontic composites may exert a cytotoxic effect even when cured. Our results might be of clinical relevance since no-mix adhesives have an inhomogeneous polymerization pattern which can increase their toxic effect.