The radio frequent (RF) safety of dental retainer wires during Magnetic Resonance Imaging at 7 tesla has been investigated using electromagnetic simulations and thermal measurements on a phantom model. In the Netherlands up to 40% of the younger adults have such a dental retainer wire, which at the moment is listed as a contraindication for 7 T head scans. The conclusion of this study for the safety of retainer wires is the following. Short wires up to 32 mm can be considered RF safe for a clinical 7 tesla MR head scan. Longer wires are not always RF safe. A solution to heating due to longer wires is to fully cover the wire with a non conductive spacer such as a silicone sports mouth guard to ensure RF safety. As a consequence of these findings, people with a retainer wire have the possibility of going into a 7 tesla MR scanner.