Salivary fluoride concentration and plaque pH after using a fluoride-containing chewing gum

The aim was to study the salivary fluoride (F) concentration and plaque pH recovery on the chewing and the non-chewing side of the dentition during and after chewing 1 piece of chewing gum containing 0.25 mg F as NaF. Ten subjects refrained from toothbrushing for 3 days. On the fourth day, they rinsed for 1 min with 10 ml of a 10% sucrose solution. When plaque pH had reached a low value, they started to chew for either 5, 10, 15, 20, 30 or 45 min. Measurements of F concentration in saliva and of pH of approximal plaque were carried out at 2 contralateral sites for up to 60 min. In each individual, the chewing and non-chewing side were registered. Two to 3 times higher salivary F concentrations (expressed as area under the curve, AUC) were found on the chewing than on the non-chewing side (p < 0.05 or p < 0.01). The most pronounced recovery of plaque pH after the sucrose rinse was also registered for the chewing side, but the difference between the chewing and the non-chewing side was not so obvious as for the salivary F concentration. Significantly higher values of plaque pH (expressed as AUC) were found during prolonged chewing (p < 0.05 or p < 0.01), while only small numerical differences in salivary F concentration were noted between short and long chewing times. Thus, this study showed: (1) that the F concentrations in saliva after chewing a F-containing chewing gum were highest on the chewing side, and (2) that a prolonged chewing time increased the plaque pH recovery after a sucrose rinse, but had only a minor effect on the salivary F concentration.