The fluorides of CaF_2 and MgF_2 were deposited on Ti via e-beam evaporation technique to release fluorine in a controlled manner for orthodontic uses. The release of fluorine from the MgF_2 coating showed an initial burst, subsequently followed by a reduced release rate. Although the initial burst effect was reduced with heat treatment, severe cracks were generated on the surface. In contrast, the CaF_2 coating did not exhibit the initial burst effect in the as-deposited state, but showed a linear release profile over 21 days. This linear release of fluorine, along with the favorable cell viability, makes the CaF_2 coating a potential candidate material for fluorine releasing orthodontic bracket wire.
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