The effect of gum chewing on xerostomia and salivary flow rate in elderly and medically compromised subjects: A systematic review and meta-analysis

Abstract

Abstract Background Xerostomia negatively affects quality of life. Symptoms include oral dryness; thirst; difficulty speaking, chewing, and swallowing food; oral discomfort; mouth soft tissue soreness and infections; and rampant tooth decay. The objective of this systematic review and meta-analysis was to investigate if gum chewing is an intervention that results in objective improvements in salivary flow rates and subjective relief from xerostomia. Methods We searched electronic databases including Medline, Scopus, Cochrane, Google Scholar and the citations of review papers (last searched 15/11/22). The study populations were elderly people with xerostomia (> 60 years old, any gender, and any severity of xerostomia), and medically compromised people with xerostomia. The intervention of interest was gum chewing. Comparisons included gum chewing vs. no gum chewing. The outcomes included salivary flow rate, self-reported xerostomia, and thirst. All settings and study designs were in scope. We conducted a meta-analysis on studies where measurements of unstimulated whole salivary flow rate for both a gum chewing, and no gum chewing intervention (daily chewing of gum for two weeks or longer) were reported. We assessed risk of bias using Cochrane’s Risk of Bias tool (version 1). Results Five thousand and sixty-two studies were screened and 0.44% (n = 24) met the inclusion criteria for the systematic review. Eight of the 24 papers had a high overall risk of bias. Of the 24 papers selected for the systematic review, 23.08% (n = 6) met the criteria to be included in the meta-analysis which confirmed a significant overall effect of gum on saliva flow outcomes compared to control (SMD = 0.44, 95% CI: 0.22–0.66; p = 0.00008; I2 = 46.53%). Conclusions Chewing gum can increase unstimulated salivary flow rate in elderly and medically compromised people with xerostomia. Increasing the number of days over which gum is chewed increases the improvement in the rate of salivation. Gum chewing is linked with improvements in self-reported levels of xerostomia (although it is noted that in five of the studies reviewed, no effects were detected). Future studies should eliminate sources of bias, standardise methods to measure salivary flow rate, and use a common instrument to measure subjective relief from xerostomia. Study registration: PROSPERO CRD42021254485.