Fluoride Varnish Surface Characterization: Wettability and Chemical Composition

Fluoride varnish is widely used in North America and Europe to reduce caries risk and remineralize enamel tooth structure. The aim of this study was to determine physico-chemical surface properties of five fluoride varnishes, which include the wettability and outermost layer chemical composition. 

Method: 

Five brands of fluoride varnish were used in this study: FluoroDose (PD), 3M Vanish (3M), Enamel Pro Varnish (EP) and Fluor Protector (FP). Samples were stored at room temperature and characterized with the following techniques: 1) Wettability was tested using a Contact Angle test (CA) [Ramé-hart Standard Goniometer Model 200]. Each specimen was mixed according to manufacturer’s instructions and applied in a thin coat to a glass slab. Each specimen was allowed to set for at least 4 hours, from which point the contact angle test was administered. Statistical analysis was conducted using one-way ANOVA, Tukey test p<0.05. 2) Surface chemical composition was carried out using X-ray Photoelectron Spectroscopy (XPS), [Kratos Axis Ultra system] and compared with the bulk composition as determined by Fourier Transform Infrared (FTIR) spectroscopy analysis [Thermo Scientific Nicolet 6700]. Each varnish was mixed as per the manufacturer’s instructions and applied to a glass slide in a thin coating. Each specimen (n=3) was tested immediately after application. 

Result: 

Contact angle testing shows that the wettability means are significantly different (p<0.05). FTIR results showed that FD, 3M and ED have a similar chemical composition, different from FP. XPS Atomic percentage of the samples is shown in the table below.

Conclusion: 

Fluoride concentration is very low on the surface due to a strong amount of hydrocarbon on sample surfaces.