Here is the reply from my dentist:
The brackets are clear and made from sapphire. The wire components will change throughout the treatment. Andras would be happy to discuss the materials with you at ecah stage and fit a suitable material should you have a preference or any allergies.
I have added a link below with information regarding the braces:
I wouldn't be concerned by sapphire and ceramics. But I think the wire could be in titanium as there is a product named titanium wire on the page.
I know titanium is more bio-compatible than nickel which mean titanium is less toxic than nickel. Anything foreign, implanted in the body will have a level of toxicity. The idea is to find the less toxic option or manageable one.
I think titanium might not be such a problem on the chemical side but the problem would be with the galvanic currents I mentioned and I would asked your orthodontist if they have non metal wired that can be used instead of a metal wire.
The quote below states that 2 different metal in the mouth can lead to electric current 100 to 1000 times stronger than the naturally occurring one in the brain. This can happen from only amalgams as amalgam are made with more than one metal.
Braces will clearly make it worst.