engleski

Kinetics of monomer and bisphenol-A release from an orthodontic adhesive

AIM: To evaluate the kinetics of Bis-GMA, TEGDMA and bisphenol-A (BPA) release from an orthodontic adhesive system. METHODS: Ten samples of Transbond XT adhesive (3M Unitek, USA) combined with the Transbond XT primer (3M Unitek, USA) were produced under a metallic bracket in a simulation of the clinical procedure and illuminated for 20 seconds. The samples were placed in a glass tube containing 6 mL of distilled water and stored in a thermal chamber at 37° C. After 6 hours, the solution was removed and stored, while 6 mL of fresh distilled water was added to the tube. This process was repeated 12, 24, 36 hours, as well as 2, 3, 4, 7, 9, 11, 14, 21 and 28 days after polymerization. The solutions were analysed for the presence of Bis-GMA, TEGDMA and BPA using high-performance liquid chromatography on a Thermo Separation Products (Spectra System, USA) system equipped with a UV/VIS detector. The experiment was repeated 6 times. RESULTS: TEGDMA showed the highest release rate, peaking at 1337.01 µg/g of adhesive. Its release increased significantly during the first 4 days (p≤0.043), thus reaching a plateau. The release of Bis-GMA increased significantly between all consecutive testing times (p≤0.03), with a maximum of 132.44 µg/g of adhesive on the 28th day. Similarly, a significant increase in the release of BPA was found throughout the testing period (p<0.001) and its maximal release was 283.58 µg/g of adhesive. CONCLUSION: TEGDMA is released at a high rate during the early days after polymerization of the Transbond XT adhesive system. Bis-GMA and BPA have a lower and slower release rate that is, however, likely to be continued in the long term.

monomers ; bisphenol A ; orthodontic adhesive

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