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 a dults and then eight samples of saliva over a 20-min period while chew ing, in random order, 3 g of either Wrigley's Spearmint chewing-gum or gum-base at frequencies of 35, 50, 70, 90, or 130 chews/min. With bot h stimuli, flow rates peaked in the first minute of stimulation and th en fell with time, A repeated-measures analysis of variance showed tha t for both the gum and the gum-base, flow rates were independent of ch ewing 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 sali va was also independent of chewing frequency. The salivary sucrose con centration peaked during the second minute of chewing (mean +/- SE = 4 24.7 +/- 20.0 mM) and the concentration then fell progressively with t ime. 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 sho wed no change in filler content or a reduction in the average molecula r weight. The decrease in hardness of the chewed gum-base may have res ulted from improved mixing of heterogeneous phases and increased dispe rsion of plasticizing agents.