The yeast Saccharomyces cerevisiae is frequently used as a model organism in a range of basic biological research, mainly because it is easy to manipulate. In this study, the yeast strain Saccharomyces cerevisiae W303 was used to investigate the toxicity of metal ions obtained by elution of parts of the orthodontic appliance into the culture medium. The entire orthodontic appliance was used, consisting of two wire arches, twenty brackets, four bands and twenty ligatures, and the elution time was 14 days. The number of proliferated cells was measured using the LUNA-FLTM dual fluorescence cell counter, which can be used to monitor the type of cell growth in addition to viability. The vitality of the yeast was determined using AO/PI staining. The content and composition of the metal ions in the eluates was analysed using mass spectrometry with inductively coupled plasma. The isolation of the mitochondria and finally the proteins from the mitochondria is the next step after the growth of the yeast on substrates with eluted metal ions. The proteins obtained were analysed and identified using a high-resolution mass spectrometer in conjunction with liquid chromatography. The predominant metal ions in the substrate are iron, nickel, copper, chromium, aluminium and, in smaller quantities, cobalt, manganese, molybdenum and titanium. A total of 284 proteins were identified in this study, of which 199 proteins showed increased expression compared to the untreated sample, while 4 proteins showed decreased expression. 31 proteins were identified that were only expressed in the eluate of the 14-day treatment, while 50 proteins were only expressed in the control sample. In this work, the results of the metal ions eluted into the yeast medium could not be correlated with the identified and modified mitochondrial proteins isolated after treatment with such a medium.