Effects of honey consumption on enamel microhardness in normal versus xerostomic patients

The aim was to investigate the effect of honey on the microhardness of enamel in normal and xerostomic patients. Normal subjects and patients who were xerostomic after neck irradiation, wearing prosthetic appliances with slabs of human enamel inserted, were asked to consume a single teaspoonful of pure honey, pH 3.9. Measurements of the saliva pH were taken before, during and after a 5 min exposure to the honey. The pH of the honey-saliva mixtures decreased significantly from about 6 to 4 in both groups, returning to the baseline pH after the mixture was swallowed. The initial microhardness of the surface of the enamel slabs decreased significantly after consumption of a teaspoonful of the honey in the subjects with a regular saliva flow, whereas in the irradiated dry-mouth patients, no enamel microhardness decrease occurred. The supposed solubility-reducing factor present in honey which, according to the literature remains active in the absence of saliva, but will be inactivated by salivary enzymes, gives some support to the hypothesis that honey is less cariogenic in dry-mouth subjects. The absence of adequate controls in the present study prevents the investigation of how specific this effect is to honey.