Recent data indicate that salivary stimulation by chewing sugarless gum after snacks or meals can reduce the acidogenic potential of foods significantly. The purpose of this study was to determine the optimal initiation time and duration of post-snack salivary stimulation to obtain the maximum benefits of chewing sorbitol gum on reducing the acidogenic potential of starch-containing snacks. An indwelling plaque pH telemetry system was used on five adults in a randomized block design with four starch-containing snacks--pretzels, potato chips, granola bars, and corn chips. Results indicated that salivary stimulation caused by chewing sorbitol gum initiated after 5 min rather than waiting 15 min significantly reduced the acidogenic challenge induced by the snack foods. This study indicates that when the recommendation to chew sugarless gum following food ingestion is used as an adjunct in caries prevention, it should start within 5 min after food ingestion--the sooner the gum chewing is initiated the better--and should continue for at least 15 min to obtain the maximum benefits.