Efficacy of saliva substitutes and stimulants in the treatment of dry mouth

Aims: To evaluate the efficacy of saliva substitutes and stimulants compared to placebo in improving findings of dry mouth not caused by Sjӧgren's. 

Methods and Results: Four databases were searched (PubMed, Web of Science, Cochrane Library, and EMBASE) through March 2018. Only randomized controlled trials (RCT) using placebo interventions with dry mouth patients were included. Outcomes included salivary flow and self-reported patient improvement. The Cochrane Collaboration's tool for assessing risk of bias was used. A total of 348 references were reviewed, resulting in 7 RCTs with 257 dry mouth patients with 5 studies at high risk of bias, 1 unclear and 1 low risk being included. Topical spray of 1% malic acid increased unstimulated (Difference in Means [DM] = 0.096, 95% CI = 0.092-0.100; P < 0.001) and stimulated (DM = 0.203, 95% CI = 0.106-0.300; P < 0.001) salivary flow in 2 studies. Patients using 1% malic acid topical spray were 5.4 times more likely to report improvement compared to placebo (95% CI = 2.634-11.091; P < 0.001) in 2 studies. No significant improvements were found with other products when compared to placebo. 

Conclusion: Use of 1% malic acid topical spray seems to improve dry mouth compared to placebo. Quality of the evidence was low due to risk of bias and imprecision.