Fluoride coatings on orthodontic wire for controlled release of fluorine ion

Abstract

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, CaF(2) and MgF(2), were coated on Ti via the electron-beam evaporation method. The fluorine was released rapidly from the as-deposited MgF(2) coating within a short period(,) and then the release rate slowed down. When the MgF(2) 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 CaF(2) coating, fluorine was released linearly for the entire period, without an initial burst. In the heat-treated CaF(2) coatings the trend was similarly observed. The linear fluorine release from the CaF(2) 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 CaF(2), are suggested to be potentially useful in the field of orthodontic Ti-based wire.