The aim of this study was to determine whether Fluor Protector®, a fluoride varnish, applied to molars before orthodontic banding could prevent white spot formation. In the in vitro study 93 human premolars were used, divided in five different groups, representing different clinical situations. Each tooth was sliced in half, one as a control and the other as a test specimen. All tooth halves were stored in a demineralizing solution, in an attempt to induce white spot formation. In the in vivo study 104 molars (52 controls and 52 tests) of 28 orthodontic patients were involved. The ‘split-mouth technique’ was used. After evaluation of the results of both studies, it is evident that Fluor Protector® is very effective in the prevention of white spot formation under molar bands.