Choosing the Best Mouthwash

Q: Is one mouthwash the same as another in its action and effectiveness?

A: There have been several studies that address the efficacy of various mouthwashes, including those rinses containing sodium fluoride (NaF), stannous fluoride, chlorhexidine, phenolic, and quaternary ammonium. These studies show there is a difference in the ability of mouthwashes to kill germs.

Rinses that contain 0.05 percent NaF have been shown to be clinically significant in reducing cavities. In fact, children who use fluoride rinse in addition to brushing with fluoride toothpaste may have up to 40 percent fewer cavities than children who do not use a fluoride mouthrinse.

Adults can also benefit from rinsing with fluoride. Fluoride mostly changes the structure of enamel to make it stronger, but there is evidence that fluoride also affects the bacteria responsible for causing tooth decay. The exact mechanism of action is unknown, but it appears that fluoride inhibits enzymes which are important to the survival of these bacteria. Stannous fluoride is also active against bacteria. This ion (charged particle) is allowed inside the bacterial cell, affecting its ability to grow and metabolize.

For reducing plaque and gingivitis, mouthrinses containing chlorhexidine (e.g. Peridex, Perioguard) appear to be the most effective. Dr. Sebastian Ciancio, chairman of the Department of Periodontics at SUNY Dental School in Buffalo, did a survey of studies involving anti-plaque and anti-gingivitis products. In three long-term studies of chlorhexidine, Dr. Ciancio found that patients using this product showed a reduction in plaque by 55 percent and a reduction in gingivitis by 45 percent.

Chlorhexidine appears to kill bacteria by altering the permeability of the cell membrane of the bacteria. This alteration causes the bacterial cell to leak, which eventually kills the bacteria. Chlorhexidine mouthrinses are available by prescription only.

Phenolic compounds such as Listerine have also been shown to reduce plaque by about 28 percent and gingivitis by about 30 percent. Listerine also contains "essential oils." These compounds appear to kill bacteria by causing a disruption in their cell membrane.

Studies on quaternary ammonium compounds (Scope, Cepacol) seem to give mixed results. One study showed an average of 35 percent reduction in plaque with mixed effects on the gingival tissues. Another study showed only a 14 percent reduction in plaque and a 24 percent reduction in gingivitis. Cepacol may have some benefit in reducing symptoms of an oral yeast infection. The exact mechanism of action is unknown at this time.

As you can see, various mouthrinses do have different actions, some being more effective than others in reducing plaque and gingivitis. Mouthrinses should only be used as an adjunct to mechanical removal of plaque by daily brushing and flossing. If you have questions about which mouthrinse may be most helpful for you, consult me or visit your dentist.

References:

McCann, Daniel, "Mouthwashes: How effective are they?," The Journal of the American Dental Association, July 1993, 55-56.

Genco, Robert et al, Contemporary Periodontics, C.V. Mosby Company, 1990, pp. 167-8, 368.