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Propriétés des gouttières Invisalign

Les gouttières quasi invisibles sont constituées d'un matériau thermoplastique stable *, qui a été approuvé pour un usage médical et spécialement développé pour le système Invisalign.

* Polyuréthane, un polymère ayant une masse moléculaire élevée et composé de méthylène diphényle d'isocyanate et le 1,6-hexanediol

Absence de cytotoxicité et d'oestrogénicité

Des études scientifiques ont montré que les gouttières Invisalign ne sont ni cytotoxiques (toxiques pour les cellules) ni ostrogéniques (favorisant e. a. le cancer du sein).

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 T, Pratsinis H, Athanasiou AE, Eliades G, Kletsas D.

Am J Orthod Dentofacial Orthop. 2009 Jul;136(1):100-3

Aucune libération de monomère ni d'autres sous-composants

D'autres études ont montré que les aligneurs ne libèrent dans la salive ni monomères (molécules réactives pouvant s'associer avec d'autres pour former des polymères) ni d'autres composants propres.

To investigate the short-term optical, chemical and morphological changes in Invisalign appliances. METHODS: One 'as-received' Invisalign aligner, one 'as-received' Invisalign aligner immersed in artificial saliva for 14 days and 10 Invisalign aligners worn by 10 randomly selected patients for 14 days were used. Fourier'transform infra-red microspectroscopy was used to characterise any molecular changes on the surfaces of the appliances, spectrophotometry was used to evaluate any changes in colour and transparency, scanning electron microscopy and energy dispersive X-ray microanalysis were used to examine the surface morphology and elemental composition of deposits on the surfaces of the aligners and gas chromatography-mass spectrometry was used to identify substances released from the aligners into the artificial saliva. RESULTS: Aligners worn for 14 days had microcracks, abraded and delaminated areas, localised calcified biofilm deposits and loss of transparency. Monomers and/or by-products were not released from the aligner suspended in artificial saliva for 14 days, which suggests that the material is chemically stable.

CONCLUSIONS: Further studies are required to evaluate how intra-oral conditions may influence the optical properties and chemical stability of the aligners.

Gracco A, Mazzoli A, Favoni O, Conti C, Ferraris P, Tosi G, Guarneri MP.

Aust Orthod J. 2009 May;25(1):34-40