Orally applied metal alloys can cause undesirable physical effects. A distinction needs to be made in this respect between local and systemic reactions and toxic and immunological reactions. A case is presented which illustrates this problem. In this case, the application of orthodontic appliances was probably the trigger for an exacerbation of nickel allergy. The oral exposure to nickel resulted in hand eczema. The patient was also exposed to nickel by single-unit fixed dental prostheses, a removable dental prosthesis, and food, as a result of which removal of the orthodontic appliances did not result in complete healing. Therefore, the single-unit fixed dental prostheses also had to be removed and food had to be prepared henceforward in nickel free pans.