It is in the clinician’s interest to select the least hazardous devices and materials among the
many offered by manufacturers. The polymer chosen is important; some polymers have
been reported to be hazardous, and these are quite often used in direct contact with human
tissues. For protection, the clinician could test the material’s extract in water according to
an ISO standard, but the tests require sophisticated means and specific knowledge. Its simplified
version, however, can be successfully used, since it requires only the observation of
the aqueous solution of potassium permanganate, in which the polymer samples were
immersed. Initially purple, the solution discolors as the colored ions are reduced, while the
released ingredients are oxidized. The faster and more intense the discoloration, the higher
the amount of leached ingredients. World J Orthod 2003;4:157–161.
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