Despite widespread use of mouthwashes, breath mints, sprays, chewing gums and mechanical tongue cleaning, research is inconclusive about which method is most effective at attacking bad breath, investigators conclude in a new review of clinical studies.

“From the results of some low-powered trials, tongue cleaning, scraping and brushing do appear to have some benefit at reducing halitosis, and the effects appear to be short lived,” said co-investigator Zbys Fedorowicz, a periodontist at the Ministry of Health in Bahrain. “But we were unable to find any reliable evidence confirming any benefits of using tongue-scraping over mouthwash, or vice versa, at reducing halitosis.”

The review appears in the most recent issue of The Cochrane Library, a publication of The Cochrane Collaboration, an international organization that evaluates medical research. Systematic reviews draw evidence-based conclusions about medical practice after considering both the content and quality of existing medical trials on a topic.

The review was conducted by a team from the Bahrain Branch of the UK Cochrane Center based at the Ministry of Health in Bahrain. Dr. Fedorowicz is also the director of the UK Cochrane Center in Bahrain.

Halitosis, a general term used to describe any disagreeable breath odor, usually originates from the gums and from the furrows on the surface of the tongue. Odor is caused by accumulated bacteria created by the decay of food particles and other debris in the mouth. The decay and debris produce volatile sulfur compounds - or VSC - that can cause “bad breath.”

“Halitosis is ubiquitous, and in the developed world is considered a very private personal yet very public issue associated with personal hygiene and body image,” said Dr. Fedorowicz. “In parts of the developing world there is an increased awareness of dental hygiene, and attention to oral malodor is also considered an increasingly important part of personal grooming.”

Currently, there are no standard and accepted methods for treating the odor associated with halitosis. Mouthwashes, mints, gums and sprays provide a competing and temporary smell that masks the odor. Some mouth rinses have ingredients that can neutralize the odor or the bacteria that produce it.

Odor-causing bacteria can also be reduced through improving oral hygiene and by tongue cleaning, including brushing or scraping of the tongue to dislodge trapped food, cells and bacteria from the taste buds. A variety of mechanical tongue scrapers and tongue cleaners are commercially available.

Although Fedorowicz said tongue brushing scraping and cleaning “have been in and out of vogue with no apparent clear guidance from the dental profession,” the review authors all recommend periodic use of a brush.

The investigators wanted to compare mechanical cleaning versus mouthwashes, but they were not able to find statistically valid studies. However, they did identify two eligible trials comparing different methods of tongue scraping or cleaning involving 40 adults.

Researchers in one trial reported a 42 percent reduction in volatile sulfur compounds with tongue cleaning, 40 percent with tongue scraping and 33 percent with the tooth brushing. “Reduced VSC levels persisted longer with the tongue cleaner than the toothbrush and could not be detected for more than 30 minutes after the intervention in any of the groups,” the Cochrane review team said.

Researchers in the second trial reported a 75 percent reduction of VSC levels after use of the tongue scraper and 45 percent with the toothbrush.

Wayne T. Wozniak, director of guidelines and standards development at the American Dental Association, said, “The most important finding from this review is that cleaning the tongue with either a tongue scraper or toothbrush is of some benefit in reducing breath odor for a very short time.

However, Wozniak cited the small size of the total study population in the review as a problem. “In addition, effectiveness was measured by reduction in volatile sulfur levels, which would not be sufficient for consideration for the ADA Seal of Acceptance. Therefore, evidence for tongue cleaners being more effective than tooth brushing in treating halitosis is very weak, and further well-controlled clinical trials are needed.”

TL Outhouse, R Al-Alawi, Z Fedorowicz, JV Keenan. Tongue scraping for treating halitosis. The Cochrane Database of Systematic Reviews 2006, Issue 2.

www.cochrane.org