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Using a mouthwash may have a beneficial effect on bad breath

The Dental Elf, 2012

Halitosis is an unpleasant odour that emanates from the oral cavity and can be serious enough to cause personal embarrassment.
 The prevalence of halitosis (bad breath or oral malodour) has been reported to be in the order of 50% although this has been questioned.
Although , nasal inflammation, diabetes mellitus and uraemia have also  suggested as causes.   The aim of this  review was to investigate the effect of mouthrinses on oral malodour in comparison with placebo⁄control mouthwash in studies with patients who used the mouthwash multiple times for a minimum follow-up period of more than 1 day.
 Randomized controlled trials (RCTs) or controlled clinical trials (CCTs)  where volatile sulphur compound measurements, organoleptic measurements and tongue coating were used as outcome variables were included.
12 RCTs were included ( 6 parallel, 6 cross over) .The risk of bias was low for seven trials, moderate for three and high for two.
In this review, nearly all mouthwashes with active ingredients had beneficial effects in reducing oral malodour in both short- and longer-term studies.
The most compelling evidence was provided for chlorhexidine mouthwashes, and those that contained a combination of cetyl pyridinum chloride and zinc provided the best evidence profile on oral malodour.
Little data with respect to tongue coating were available, and none of the studies showed a beneficial effect for this parameter.
 Interestingly,  only 3 of the studies included in the Cochrane review were subsequently included in this new review, which included 12 studies.  Three of the studies included in this new review were specifically excluded by the Cochrane reviewers and of the twelve included, only two were published after the Cochrane review.
Mouthrinses containing antibacterial agents such as chlorhexidine and cetylpyridinium chloride may play an important role in reducing the levels of halitosis-producing bacteria on the tongue, and chlorine dioxide and zinc containing mouthrinses can be effective in neutralisation of odouriferous sulphur compounds.  Well designed randomised controlled trials with a larger sample size, a longer intervention and follow-up period are still needed.
It is worth noting that athough the authors of the new review suggest long term benefits – the longest trial is still only 4 weeks!