Fluoride coatings on orthodontic wire for controlled release of fluorine ion

The purpose of this study was to develop a new method of releasing fluorine in a controlled manner for applications in the field of orthodontic Ti‐based wire, namely the coating of fluorides on Ti. Thin films of two fluoride compounds, CaF2 and MgF2, were coated on Ti via the electron‐beam evaporation method. The fluorine was released rapidly from the as‐deposited MgF2 coating within a short period, and then the release rate slowed down. When the MgF2 coating was heat treated, this initial burst effect was decreased, but a significant amount of cracks were generated. On the other hand, in the case of the as‐deposited CaF2 coating, fluorine was released linearly for the entire period, without an initial burst. In the heat‐treated CaF2 coatings the trend was similarly observed. The linear fluorine release from the CaF2 coatings, even in the as‐deposited state, was attributed to the high degree of crystallinity of the coatings. A preliminary cell test showed favorable cell viability on both the fluoride coatings. Given their sustained and controlled fluorine release, these fluoride coatings, particularly CaF2, are suggested to be potentially useful in the field of orthodontic Ti‐based wire. © 2005 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2005