The primary ingredient in a relatively new class of mouthwashes with clinical-sounding names such as TheraBreath, Oxyfresh, CloSYS and ProFresh is sodium chlorite, also known as stabilized chlorine dioxide. These rinses claim to freshen breath for up to six hours. But one independent study found that sodium chlorite rinses actually worked for anywhere from four to 42 minutes.
The products change the chemical composition of odiferous gases so they no longer smell. However, the underlying bacteria remain potent and continue producing odors.
Some mouthwashes have attempted to go further. SmartMouth uses sodium chlorite mixed with zinc chloride. The zinc ions find the bacteria that produce rancid gases, then block amino-acid receptor sites so the bacteria cannot produce gas. Another brand, Biotene, contains two enzymes that break down the biofilm and put the mouth bacteria into a healthy balance.
Even the most effective products, however, will not help people with extremely bad oral hygiene.