Although hydrogen peroxide isn't exactly a powerful antiseptic like alcohol or chloride compounds, its strength is in its oxidation. It releases oxygen in a burst that works to debride, or clear debris, very effectively. Toothbrushes can be stored or cleaned in a peroxide solution before and after brushing, and studies have found that peroxide is useful in keeping bacteria counts lower in dental office water lines used for oral rinsing [source: Linger, et al.].
Not only is hydrogen peroxide a proven weapon in the fight against bacteria, it's also been shown to fight gingivitis, or inflamed and bleeding gums. One study published by the National Institutes of Health found that when used as a mouth rinse, H2O2 prevents bacteria buildup and plaque, both contributors to gingivitis [source: Wennström and Lindhe]. This is also great news for bad breath: Better oral health means fresher breath, and the oxidizing action of hydrogen peroxide really enables it to get into the crooks and nooks of teeth, gums and the tongue where bacteria tend to hang out and multiply.
More tips for a healthy mouth follow.