We observed and quantified the structural changes of the enamel of human teeth under the influence of some commonly consumed soda pops of pH 4 to pH 5. In order to observe the onset of structural changes, we developed a device allowing a fast exchange of the liquid medium covering the sample in a scanning force microscope during image acquisition. The average material loss in two soda pops containing sugar as well as in a diet beverage was roughly 0.1 nm s(-1). The samples were initially smooth and finely grained and changed to being rougher and exhibited a coarsely grained surface after about 15 min.