title: Light-cured or chemically cured orthodontic adhesive resins? A selection based on the degree of cure, monomer leaching, and cytotoxicity.
abstract: OBJECTIVE
  The purpose of this study was to estimate the degree of cure and monomer leaching of a light-cured and a chemically cured (no-mix) adhesive and to assess their biologic properties.
  
  
  METHODS
  The degree of cure of adhesive specimens prepared with a procedure identical to the clinical bonding process was assessed by infrared spectroscopy. The adhesives were then immersed in normal saline solution for 2 months, and the residual monomer leached from the adhesives was quantitatively and qualitatively analyzed by liquid chromatography. The effect of the immersion media on human gingival fibroblasts' viability and proliferation was also evaluated with the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) and deoxyribonucleic acid (DNA) synthesis assays, respectively. The results were analyzed by analysis of variance and Tukey test (alpha = .05).
  
  
  RESULTS
  No difference was found between the 2 adhesives with respect to their degree of cure and the amount of triethylene glycol dimethacrylate released; no diglycidyl dimethacrylate monomer was detected in the eluent. However, significant qualitative changes in the composition of the substances eluted from the 2 adhesives were observed.
  
  
  CONCLUSIONS
  Whereas no cytotoxic effect was shown for either immersion media, a moderate reduction in the DNA synthesis was obtained by both adhesives, implying a minor cytostatic effect. Further research is required to assess the long-term biologic properties of adhesives, including potential estrogenic action.
authors.affiliation: Experimental Orthodontics, School of Dentistry, Bonn University, Germany.
authors.forename: Christiana
authors.initials: C
authors.lastname: Gioka
authors.forename: Christoph
authors.initials: C
authors.lastname: Bourauel
authors.forename: Anastasia
authors.initials: A
authors.lastname: Hiskia
authors.forename: Dimitris
authors.initials: D
authors.lastname: Kletsas
authors.forename: Theodore
authors.initials: T
authors.lastname: Eliades
authors.forename: George
authors.initials: G
authors.lastname: Eliades
mesh_terms: D000704:Analysis of Variance; D017438:Bisphenol A-Glycidyl Methacrylate / Q000032:analysis; D049109:Cell Proliferation / Q000187:drug effects; D002470:Cell Survival / Q000187:drug effects; D002478:Cells, Cultured; D002851:Chromatography, High Pressure Liquid; D004247:DNA / Q000096:biosynthesis; D005347:Fibroblasts / Q000187:drug effects; D005881:Gingiva / Q000166:cytology / Q000187:drug effects; D006244:Hardness; D006801:Humans; D015394:Molecular Structure; D016910:Orthodontic Brackets; D044367:Phase Transition; D011092:Polyethylene Glycols / Q000032:analysis; D011109:Polymethacrylic Acids / Q000032:analysis; D019279:Resin Cements / Q000737:chemistry* / Q000633:toxicity*; D018709:Statistics, Nonparametric; D013674:Technology, Dental / Q000379:methods
chemical_list: D011109:Polymethacrylic Acids; C090340:Reliance resin cement; C097531:Rely a Bond system; D019279:Resin Cements; C020946:triethylene glycol dimethacrylate; D011092:Polyethylene Glycols; D017438:Bisphenol A-Glycidyl Methacrylate; D004247:DNA