Atomic density of elements on the surface of orthodontic bands

The study was performed on new and used (from in vitro and in vivo experiments) orthodontic bands by using SEM-EDX technique. The bands were retrieved from earlier experiments: in vitro tests, in which the bands were incubated in a continuous flow system with various media: artificial saliva, lysozyme, orange juice and Coca Cola®. The bands were also retrieved from previously conducted in vivo tests on animals (pigs) and humans (patients). The micrographs of bands were presented as well as their chemical composition, reported in terms of atomic density. The bands that were used showed a significant contribution of oxygen as compared to brand new ones, and the contribution of Fe and Ni decreased, whereas the Cr contribution remained unchanged. The elements were inter-correlated. An antagonistic, statistically significant dependence was found between Fe and O, as well as between Fe and Cr. This could signify that that protective passivation layer of Cr2O3 was formed, which did not fully protect Ni and Fe from dissolution.