The effects of chewing frequency and duration of gum chewing on salivary flow rate and sucrose concentration

On ten separate occasions, unstimulated saliva was collected from 12 adults and then eight samples of saliva over a 20-min period while chewing, in random order, 3 g of either Wrigleyʹs Spearmint chewing-gum or gum-base at frequencies of 35, 50, 70, 90, or 130 chews/min. With both stimuli, flow rates peaked in the first minute of stimulation and then fell with time. A repeated-measures analysis of variance showed that for both the gum and the gum-base, flow rates were independent of chewing frequency, except during the first minute with the chewing-gum. The gum elicited a significantly higher flow rate over the first 4 min of chewing, while the base elicited a significantly higher flow rate over the 8–20-min period of chewing. The sucrose concentration in saliva was also independent of chewing frequency. The salivary sucrose concentration peaked during the second minute of chewing (mean ± SE = 424.7 ± 20.0 mM) and the concentration then fell progressively with time. However, sucrose was still being released into saliva during the 15–20-min period of chewing (12.6 ± 0.8 mM). Gum-base which had been chewed without access to saliva was softer than unchewed base but showed no change in filler content or a reduction in the average molecular weight. The decrease in hardness of the chewed gum-base may have resulted from improved mixing of heterogeneous phases and increased dispersion of plasticizing agents.