[Aluminium release of glitter particles in removable orthodontic appliances]

In order to support children's compliance with orthodontic treatment, glitter particles containing aluminium (Al) are often embedded in the acrylic of removable appliances. When worn for up to 16 h daily for 2-3 years, it can be assumed that Al ions diffuse into saliva over time. The aim of this study was to investigate the release of Al ions from the acrylic using different orthodontic wires.

Test specimens (surface area 5.65 cm²) were prepared from orthodontic resin and various wires; half contained aluminium glitter particles. The test specimens were placed in Petri dishes containing 50 ml of corrosion medium (pH 2.3) according to DIN EN ISO 10271 at 37 °C for 7 days. Inductively coupled plasma mass spectrometry (ICP-MS) was used to quantify the specific ions in the corrosion solution.

Statistical analysis showed a significant difference in the concentration of Al ions between samples with and without glitter particles. Concentrations from samples with glitter reached up to 14,474 μg/l Al ions; samples without glitter contained on average 1260 μg/l. A small proportion of the Al ions may originate from the alloys of the wires.

It should be investigated whether the aluminium concentration can lead to health risks for humans. In view of the findings, orthodontists should not offer appliances containing glitter in order to minimize aluminium uptake with saliva. It needs to be clarified whether the conditions found in the oral cavity lead to the same results as under the abovementioned conditions. Legislation should be developed to limit the release of aluminium from orthodontic products.