Cytotoxicity and estrogenicity of Invisalign appliances
Received 26 January 2009; received in revised form 23 February 2009; accepted 4 March 2009.
Introduction
Our purpose was to study the in-vitro cytotoxic and estrogenic properties of Invisalign appliances (Align Technology, Santa Clara, Calif).
Methods
Three sets, each consisting of a maxillary and a mandibular appliance, of as-received aligners were immersed in normal saline solution for 2 months. Samples of eluents were diluted to 3 concentrations (5%, 10%, and 20% vol/vol) and tested for cytotoxicity on human gingival fibroblasts and estrogenicity by measuring their effect on the proliferation of the estrogen-responsive MCF-7 breast cancer cells. All assays were repeated 4 times for each maxillary and mandibular set, and the results were analyzed with 2-way analysis of variance (ANOVA) with appliance and concentration serving as predictors at the .05 level of significance; differences among groups were investigated with the Tukey test.
Results
There was no evidence of cytotoxicity on human gingival fibroblasts and no stimulation of proliferation of the MCF-7 cell line at any concentration, indicating no estrogenicity of aligner eluents.
Conclusions
The use of Invisalign appliances did not seem to induce estrogenic effects under the conditions of this experiment.
aAssociate professor, Department of Orthodontics, School of Dentistry, Aristotle University of Thessaloniki, Thessaloniki, Greece
bAssistant researcher, Laboratory of Cell Proliferation and Ageing, National Center for Scientific Research “Demokritos,” Athens, Greece
cProfessor and director, Department of Orthodontics, School of Dentistry, Aristotle University of Thessaloniki, Greece
dProfessor and director, Department of Biomaterials, School of Dentistry, University of Athens, Athens, Greece
eDirector, Laboratory of Cell Proliferation and Ageing, Institute of Biology, National Center for Scientific Research “Demokritos”, Athens, Greece
ABSTRACT