This is a question I am asked every so often by one of my hygienists. Lately more often. Most of the time when I am asked this question it turns out to be that the patient in question has a nose piercing. A nose piercing usually will appear on maxillary anterior radiographs as a wire with a small ball attached.
Sometimes wires seen above teeth on periapical radiographs can be due to other causes. Seeing a metal wire in what appears to be maxilary bone can also sometimes be a tell tale sign that a patient has previously either brokent their jaw or had maxillofacial bone surgery to reposition the jaw. Surgeons can leave the wires in place after a surgery and they show up on radiographs.