dental materials 25 ( 2 0 0 9 ) 376–382 available at www.sciencedirect.com journal homepage: www.intl.elsevierhealth.com/journals/dema Characterization and in vitro estrogenicity of orthodontic adhesive particulates produced by simulated debonding C. Gioka a , T. Eliades a,* , S. Zinelis b , H. Pratsinis c , A.E. Athanasiou a , G. Eliades b , D. Kletsas c a Department of Orthodontics, School of Dentistry, Aristotle University of Thessaloniki, Greece b Department of Biomaterials, School of Dentistry, University of Athens, Greece c Laboratory for Cell Proliferation and Aging, Institute of Biology, “Demokritos” National Center for Scientific Research, Athens, Greece article info Article history: Received 6 April 2008 Received in revised form 22 July 2008 Accepted 18 August 2008 Keywords: Orthodontic adhesive FT-IR spectroscopy SEM EDS Estrogenicity Particulates abstract Objective. To investigate the structure and composition of ground orthodontic adhesive par- ticulates produced under simulated clinical conditions and assess their estrogenic action in vitro. Materials and methods. A chemically cured and a light-cured adhesive were included in the study. Specimens were prepared by simulating bonding procedures, covering the bracket base surface with cellulose films to detach the full set material. The adhesives prepared under this method were grounded in glass chambers with an 8-fluted tungsten carbide on a high-speed handpiece; a new bur and different chamber was used for each adhesive sample and grindings were performed on different days to avoid contamination of the room. The adhesive particulates produced were subjected to FT-IR spectroscopy for the molecular char- acterization of particles; scanning electron microscopy for the morphologic condition and structure; and X-ray microanalysis for the elemental composition of the particles. Amounts of the ground adhesives were immersed in saline for 1 month at 37 ◦ C. Eluents from solution of the two adhesives were added to media of an estrogen-responsive cell line derived from human breast adenocarcinoma (MCF-7), to assess the estrogenicity. Positive (estradiol and bisphenol-A) and negative (saline) controls were used; all assays were repeated four times and the results were averaged. Estrogenicity data were analyzed with one-way ANOVA and the Tukey test at the .05 level of significance. Results. The study of the composition of particles revealed compounds related to monomers with no major differences noted. Significant structural alterations were observed between the materials studied, with the chemically cured adhesive having larger particles. The ground samples contained Si, Na and Al apparently deriving from fillers, whereas large Ba fillers were identified only in the chemically cured group, whereas no distinct molecu- lar variation was noted between the set material and its corresponding particulate form. Both chemically cured and light-cured adhesives exhibited an estrogenic action through induction of the proliferation rate of MCF-7 cells (160% and 128%, respectively, compared to control). Significance. Apart from the potentially hazardous action of adhesive particulate aerosol produced by grinding, composite resin particulates may act as endocrinological disruptors. © 2008 Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved. ∗ Corresponding author at: Department of Orthodontics, School of Dentistry, Aristotle University of Thessaloniki, Theodore Eliades 57, Agnoston Hiroon, Nea Ionia 14231, Greece. E-mail address: teliades@ath.forthnet.gr (T. Eliades). 0109-5641/$ – see front matter © 2008 Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved. doi:10.1016/j.dental.2008.08.010