The prevalence of oral malodour (halitosis) has been reported to be as high as 50% although the reliability of the data has been questioned. The majority of cases are now considered to have an oral cause with less than 10% having a non-oral cause. The major component of oral malodour (OM) are the volatile sulphur compounds (VSCs) and treatment appears to hinge on their reduction. This current review focuses on the use of mouthrinses to treat OM. A previous Cochrane review tackling the same question was published in 20081so this review could be viewed as an update as the same main databases were searched. One major difference between this review and the Cochrane review highlighted by the review authors is treatment times considered. The Cochrane review only considered treatment times of one week or greater whereas this current review considered treatment times of one day or more. This decision allowed the authors to include more trials, (12), compared with the Cochrane review, (five), as despite the passage of time only two studies included here were completed after the publication of the Cochrane review.

While the authors reported the assessment of risk of as low for seven of the included studies in the discussion, they indicate that if they had included allocation concealment (a key component of bias protection) only one of the studies would be considered to have a low risk of bias. While I agree that this may be a reporting issue rather than a study conduct it does form an important element of assessing potential bias.

Although the results of the review suggest beneficial effect from almost all of the mouthwashes with active ingredients in both the short- and long-term, the qualities of the studies mean that the evidence is not yet reliable enough to make informed decisions.

The authors also include a useful discussion of the main methods of assessing OM citing the recent paper assessing the relationship between organoleptic scores and the Halimeter® or gas chromatography, indicating that correlations between the three methods of breath measurement were high. However, it is clear from this and the previous Cochrane review that more high quality trials are needed to provide definitive answers to this problem. With this in mind it would be helpful to agree which standard assessment of OM should be used in studies in order to allow future systematic reviewers to combine trials from different research group more easily.

Practice point

  • There is limited evidence that mouth rinses with active ingredients (chlorhexidine and cetyl pyridinum chloride with zinc) may be effective in reducing oral malodour.