Quick google shows that as the metal of a partial would touch the skin, the metal has to be hypoallergenic. That means gold, platinum, or austenitic surgical stainless steel (both 316L and 316LVM, Lowcarbon or no rust, Vacuum melted, higher Molybdenum content), so if it's not gold-colored, I'll go with not magnetic.

Hopefully others can chip in on what metals and techniques are used for medical implants (and other objects that touch tissue).

Either way, finding out the material used would help greatly, which would lead you back to your dental provider.