Masking products such as mouthrinses/mouthwashes are not, and antimicrobial ingredients in oral healthcare products are only temporary effective in reducing micro-organisms or their substrates.
Good short-term results were reported with chlorhexidine. Triclosan seems less effective, essential oils and cetylpyridinium chloride are only effective up to 2 or 3 h. Metal ions and oxidizing agents, such as hydrogen peroxide, chlorine dioxide and iminium are active in neutralizing volatile sulphur-containing compounds. Zinc seems to be an effective safe metal at concentrations of at least 1%.
The effectiveness of active ingredients in oral healthcare products is dependent on their concentration and above a certain concentration the ingredients can have unpleasant side effects. (1)
Antimicrobial mouthrinses are generally considered safe and effective in reducing plaque and gingivitis, and should be part of a comprehensive oral health care regimen that includes brushing, flossing and rinsing to prevent or minimize periodontal disease. (2)
One concern with the regular use of alcohol-containing mouthwash was oral cancer, and the occurrence of oral cancers is not supported by epidemiological evidence. (3)
One of the major drawbacks of mouthwashes containing products such as chlorhexidine is the occurrence of stains on long term use. (4)
So, the final verdict?
Sources:
(2) Lemos CA Jr, Villoria GE. Reviewed evidence about the safety of the daily use of alcohol-based mouthrinses. Braz Oral Res. 2008;22 Suppl 1:24-31.
(3) La Vecchia C. Mouthwash and oral cancer risk: an update. Oral Oncol. 2009 Mar;45(3):198-200. Epub 2008 Oct 25.
(4) Adams D, Addy M. Mouthrinses. Adv Dent Res. 1994 Jul;8(2):291-301.