Monomer Release from Orthodontic Adhesives (Example: Transbond™ XT)

Objective: The aim of this work is the identification and the quantification of monomers released by a hydrophobic composite used in orthodontics, Transbond™ XT (3M).

Method: Samples (10 mm diameter, 1 mm thick) were prepared and polymerized with a 3M ESPE Elipar S10 LED lamp (power of 1200 mW/cm2, wavelength 430-480 nm) for 20 seconds. Each cured sample is immersed in 0.4 ml MilliQ water (ISO 10993-12 standard) contained in a glass tube for 24 hours at 37 ° C. The samples were then lyophilized. The analysis of the eluates composition was performed by GC-MS (gas chromatography - mass spectrometry).

Result: Peaks in the chromatogram correspond to mass spectra:

- Iodobenzene,

- Camphorquinone,

- Camphoric anhydride,

- Diethyl phthalate,

- Dimethyl benzocaine

- TEGDMA,

- Triphenyl stibine,

- Alkane.

The compounds found are mostly monomers or their derivatives, and additives. Camphorquinone is a photoinitiator and Dimethyl benzocaine a coinitiator. Qualitative analysis revealed the presence of monomers such as triethylene glycol dimethacrylate (TEGDMA). The triphenyl stibine is a toxic contaminant that may be genotoxic. No trace of BPA has been identified. This implies that the amount of BPA does not exceed the detection threshold, if present.

Conclusion: The probability of release of TEGDMA is strong, the use of composite without TEGDMA would be preferred. No trace of BPA has been identified in this orthodontic resin.