Blog

Memotain retainers are made of Nickel? What about patients who suffer from a Nickel allergy?

23 May 2019

Since the 1970s, orthodontists have been using nitinol (an alloy of nickel and titanium) for intra-oral treatment. Thanks to its outstanding biocompatibility and corrosion resistance, nitinol is the ideal material for meeting the highest demands in orthodontics.

Surface finish and coating are important factors that influence biocompatibility and corrosion resistance. They possess an extremely smooth surface and antibacterial properties.

The induction of an allergic reaction following the intra-oral application of nitinol can be virtually ruled out. Studies show that patients suffering from a “nickel allergy” did not display symptoms of an anaphylactic reaction following oral exposure to nitinol.

That is because the suspected “nickel allergy” is actually caused by an allergic response to nickel sulphide. Nickel sulphide can only originate if nickel reacts with sulphur.

This happens regularly when, for instance, the nickel in designer jewellery reacts with human sweat to form nickel sulphide. Fortunately, there are no sweat glands or other sources of sulphur in our oral cavity and hence there is no formation of nickel sulphide that can cause an allergic reaction.

Nitinol is thus a safe material which makes it suitable for its application in MEMOTAIN retainers. Nonetheless, there are isolated cases in medical literature that report about “nickel allergies” triggered by nickel in oral applications. Until now, there is no scientific explanation for these individual cases.