Arthur Jeske DMD, PhD; James Zahrowski DMD, MS, PharmD
There is no strong evidence that any topical therapy is effective to relieve the symptoms of dry mouth.
In adults with xerostomia, which topical therapy (saliva substitute or stimulant) compared to placebo or another topical therapy is effective to relieve the symptoms of dry mouth?
The authors conducted a systematic review of the literature by using searches of seven electronic databases for articles published from 1950 to October 2011. Two or more reviewers followed a clear protocol and independently searched for studies, assessed bias and heterogeneity, and extracted data. They included randomized clinical trials comparing topical treatment for xerostomia to placebo or another treatment. Trials included different dosages or frequencies of treatment. The reviewers included crossover studies if allocation was random and eight hours elapsed between treatment phases. They excluded trials if a comparison was made to a systemic pharmacological intervention. They did not restrict participants based on the cause of xerostomia. Topical interventions included saliva substitutes (sprays, gels, oils, or liquids) or saliva stimulants (lozenges, gums, or pastes). The authors measured primary outcomes (day or nighttime dryness, speech or swallowing difficulty) from a visual analogue scale (VAS). Secondary outcomes were comprised of salivary flow, quality of life, patient satisfaction, and oral health assessment.
Thirty-six randomized controlled trials (1,597 participants) met inclusion criteria: two trials compared saliva stimulants to placebo, nine trials compared saliva substitutes to placebo, five trials compared saliva stimulants to substitutes, 18 trials compared two or more saliva substitutes, and two trials compared two or more saliva stimulants. In a meta-analysis of two trials, oxygenated glycerol triester (OGT) saliva substitute spray shows evidence of effectiveness when compared to an electrolyte spray (standard mean difference 0.77, 95% CI 0.38-1.15), which corresponds to a mean difference of 2 points on the 10-point VAS. Both integrated mouth-care systems (e.g., toothpaste, gel, mouthwash) and oral reservoir devices showed promising results but lacked sufficient evidence to recommend their use. The reviewers found an association between chewing gum and increased saliva production in the majority of participants with residual capacity, and they found chewing gum and saliva substitutes to be equally effective. Patients generally preferred gum compared to sprays.
There is no strong evidence to identify effective topical treatments for dry mouth, although OGT spray appears to be more effective than an aqueous electrolyte spray. Chewing gums appear to increase saliva production, but there is no evidence that chewing gum is effective for managing dry mouth.
Source of Funding:
University of Manchester, UK; Manchester Academic Sciences Centre, UK; Department of Health, Cochrane Incentive Scheme 2010, UK; British Orthodontic Society, UK.
Importance and Context:
The prevalence of persistent dry mouth is quite high, estimated at 20 percent of the general population and up to 50 percent of the elderly.(1,2) Dry mouth impacts quality of life, with people withdrawing from social situations due to impaired taste, eating, and speech functions. The symptoms of dry mouth may be related to hyposalivation, but symptoms also may exist with normal salivary secretion. The causes of decreased salivary flow are likely to be multifactorial, such as medications, dehydration, salivary gland dysfunction due to disease, or radiation treatment. Many topical treatments are available to treat dry mouth symptoms; however, effective management of dry mouth is difficult. Saliva substitutes provide moisture but need to be reapplied frequently. Saliva stimulants may provide more moisture during the day in a more socially acceptable way.
Strengths and Weaknesses of the Systematic Review:
This high quality systematic review included a comprehensive search strategy of multiple electronic databases as well as hand-searching reference lists for possible study inclusion. The authors clearly defined their inclusion and exclusion criteria. Trial authors were contacted for additional information. The review authors made no mention of how conflict of two reviewers was resolved, nor did they describe the inclusion of non-English articles, although they state that there were no language restrictions. They conducted standard assessments for bias and heterogeneity. Due to the range of interventions, comparisons, and outcome measures, meta-analysis was usually not possible. The meta-analysis of OGT vs. electrolyte spray was based on only two trials and showed high heterogeneity, so the results should be interpreted with caution.
Strengths and Weaknesses of the Evidence:
Trials used different scales and point systems to evaluate xerostomia relief. Many of the trials were small and had insufficient numbers of participants to determine statistical differences for treatment outcomes. The limited evidence consisted of 17 trials that were at high risk of bias, 18 trials of unclear bias, and only one trial that was at low risk of bias. Well-designed, adequately powered randomized controlled trials (conducted and reported according to CONSORT guidelines) are needed to provide evidence of effectiveness for topical interventions for xerostomia. Trials should evaluate whether treatments are palatable and effective, not only for the short-term but also the long-term effect on the quality of life.
Implications for Dental Practice:
Symptoms of dry mouth may or may not denote decreased salivary flow. A true lack of saliva can cause a more frequent occurrence of caries and a dysfunction to taste, eating, or speech. Chewing sugar-free gum may elicit more saliva in patients with a secretory reserve. Although an OGT spray may be more effective than an electrolyte spray, this review concluded there is a lack of strong evidence that any topical intervention effectively relieves the symptoms of dry mouth. Without an evidence-based recommendation, perhaps the patient’s medical and dental history, the therapy’s cost and effectiveness, along with the patient’s preference and ability to use the delivery form should be evaluated before considering a topical intervention to manage dry mouth symptoms.
1. Villa A, Abati S. Risk factors and symptoms associated with xerostomia: a cross-sectional study. Australian Dental Journal; 56(3):290-5.
2. Orellana MF, Lagravere MO, Boychuk DG, Major PW, Flores-Mir C. Prevalence of xerostomia in population-based samples: a systematic review. Journal of Public Health Dentistry 2006; 66(2):152-8.