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.
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.