Residual Monomer Released After Polymerization of Orthodontic Adhesives

Methods: 120 bovine teeth were divided into 3 groups according to the adhesive system [Transbond XT light cure adhesive, Transbond LR Capsule (LR) and Light Bond Light Cure Adhesive Paste (LB)] and  each group divided into 2 sub groups according to light-curing procedure (LED, Halogen). All teeth were bonded with braces and then immersed in 75% ethanol-water solution at 37 ^oC for 10 second, 1 hour, 1 day, 1 week, 2 week and 1 month. Eluted monomers [Urethane Dimethacrylate (UDMA), Triethylene Glycol Dimethacrylate (TEGDMA), Bisphenol A Glycol Dimethacrylate (Bis-GMA)] were detected using HPLC.

Results: There were statistically significant differences of amount of TEGDMA and UDMA groups (p<0.05). There were no statistically significant differences of amount of BİSGMA and the other groups (p>0.05). The release of UDMA was statistically higher in LR group polymerized with halogen light unit compared to LR group polymerized with LED (p<0.05).

Conclusions: The release of monomers remains at a high level for a long time after polymerization. In this study leaching of residual monomers from LR groups were the lowest so it was recommended for bracket applications. LED unit was recommended for polymerization of orthodontic adhesives.