Cytotoxicity and estrogenicity of Invisalign appliances.
BACKGROUND
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.
Eliades
Theodore
T
Department of Orthodontics, School of Dentistry, Aristotle University of Thessaloniki, Thessaloniki, Greece. teliades@ath.forthnet.gr
Pratsinis
Harris
H
Athanasiou
Athanasios E
AE
Eliades
George
G
Kletsas
Dimitris
D
D000230:Adenocarcinoma / Q000473:pathology; D001559:Benzhydryl Compounds; D001943:Breast Neoplasms / Q000473:pathology; D045744:Cell Line, Tumor; D049109:Cell Proliferation / Q000187:drug effects; D002478:Cells, Cultured; D004396:Coloring Agents; D003764:Dental Materials / Q000494:pharmacology / Q000633:toxicity*; D052244:Endocrine Disruptors / Q000494:pharmacology; D004958:Estradiol / Q000494:pharmacology; D004968:Estrogens, Non-Steroidal / Q000494:pharmacology*; D005260:Female; D005347:Fibroblasts / Q000187:drug effects; D005881:Gingiva / Q000166:cytology / Q000187:drug effects*; D006801:Humans; D008422:Materials Testing; D016382:Orthodontic Appliance Design; D010636:Phenols / Q000494:pharmacology; D011960:Receptors, Estrogen / Q000819:agonists; D012965:Sodium Chloride; D013696:Temperature; D013778:Tetrazolium Salts; D013844:Thiazoles; D013997:Time Factors; D014087:Tooth Movement Techniques / Q000295:instrumentation*; D000098826:Bisphenol A Compounds
D001559:Benzhydryl Compounds; D004396:Coloring Agents; D003764:Dental Materials; D052244:Endocrine Disruptors; D004958:Estradiol; D004968:Estrogens, Non-Steroidal; D010636:Phenols; D011960:Receptors, Estrogen; D012965:Sodium Chloride; D013778:Tetrazolium Salts; D013844:Thiazoles; C022616:thiazolyl blue; C006780:bisphenol A; D000098826:Bisphenol A Compounds