American Journal of Orthodontics and Dentofacial Orthopedics
Original articleBisphenol A release from an orthodontic adhesive and its correlation with the degree of conversion on varying light-curing tip distances
Section snippets
Material and methods
A visible light-cured adhesive, Transbond XT, was used. From 138 premolar stainless steel brackets (3M Unitek), 120 were used to assess BPA release with HPLC, and 18 were used for estimating the DC with the FTIR spectrometer (Perkin-Elmer, Norwalk, Conn). BPA released and the DC values were assessed at 3 light-curing tip distances from the bracket: 0, 5, and 10 mm.
The varying distances of the curing tip were standardized by using a specially fabricated wooden box on which a yellow tile was
Results
Table I shows the mean concentrations of BPA released on days 1, 7, 21, and 35 at the 3 light-curing tip distances of 0, 5, and 10 mm. Table II, Table III, Table IV, Table V, Table VI, Table VII show the BPA release from days 1 to day 35 in the 3 groups and between the 3 groups. Greater amounts of BPA were observed at the 10-mm light-curing tip distance. There was a statistically significant increase in the mean release of BPA as the light-curing tip distance was increased (P <0.05). A
Discussion
Leaching of BPA was observed on day 1 even at the 0-mm light-curing tip distance; this substantiates the observation of Thompson et al14 that cured orthodontic adhesives are far from inert. Tip distances of 0 and 5 mm showed increases of BPA released up to day 21, after which the concentration showed a marginal decrease. At 10 mm, the day 1 release was not only greater, but this increased release remained more or less constant until day 35. This could be because of the depletions in the
Conclusions
Release of BPA was detected from Transbond XT with light-curing tip distances of 0, 5, and 10 mm, thus indicating that the cured composite is not inert. Increasing the light-curing tip distance caused a decrease in the DC, and this led to greater BPA release. The clinician should keep the light-curing tip as close to the adhesive as clinically possible.
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The authors report no commercial, proprietary, or financial interest in the products or companies described in this article.