The effects of prolonged gum chewing on salivary flow rate and composition

OBJECTIVE: To determine the effect of gum chewing for 2 h on salivary flow rate and composition. DESIGN: Five male and five females each collected whole saliva at intervals over a 2 h period on three separate days, prior to which they collected unstimulated saliva for 5 min. For one 2 h session they continued to collect only unstimulated saliva while for the others one tablet of Wrigley's Extra peppermint- or fruit-flavoured (peach) gum was chewed continuously. Flow rates were calculated and the saliva was assayed for pH and for Na, K, Ca, Cl, inorganic P and protein concentrations. The data were subjected to repeated-measures ANOVA and Duncan tests. RESULTS: When only unstimulated saliva was collected, there was no significant change in salivary flow rate over the 2 h. With the chewing gums the flow rate increased initially and then, after 35-40 min, fell to similar plateau values which remained significantly higher than the initial unstimulated flow rate and significantly higher than the flow rate at the corresponding time intervals when only unstimulated saliva was collected. With both gums the salivary pH from 2 min to 2 h was significantly higher than that of unstimulated saliva. The changes in the salivary electrolyte and protein concentrations due to the flow rate increase elicited by the chewing gum were largely as expected from previous studies on parotid and submandibular saliva. CONCLUSION: During prolonged chewing gum use, both salivary flow rates and pH remained significantly above the values for unstimulated saliva.