In a study done the NaF at different concentrations was found to inhibit the activity of salivary amylase activity. According to Burt (2003) the concentration was found to have the inhibitory effect at 50mM or above this concentration (p.72). As a matter of fact, this effect increased when more concentrated NaF was administered. In particular the study recorded a salivary amylase inhibitory rate of 7% to 11% for concentrations of between fifty and five hundred mM (Burt, 2003). However, it is worth noting that this study was done on assay mixtures incubated for a period of one to three hours.