Twice a day I put five drops of this bitter in the container of my oral irrigator and rinse my gum lines. I hate to floss my teeth and I find this to be something I don't mind doing on a regular basis. The pulsing water cleans the space between my teeth, along the gum line and the soft tissues of the mouth. When you add grapefruit seed extract, the mouth bugs die in droves, leaving your breath fresh and your mouth/gums clean. The bacteria are mostly the cause of tooth decay, gum disease and even some heart disease, especially valves. The last dental cleaning I had was short, since there was very little plaque build-up.
Grapefruit seed extract is a very power antimicrobial, meaning it kills a very wide range of harmful bugs, including bacteria, parasites, mycoplasm, virus and fungus. In liquid form it is very important to follow the easy directions given by the manufacturer.
The extract is so strong that if you use too much you can give yourself a minor, short-lived chemical burn, so some reasonable care is needed. The extract comes from the seed of the grapefruit and not the juice or pulp; this makes it safe to use for everyone including those on heart/blood pressure medications.
While I use it for my mouth, it can be used for a lot of different things. If you travel and worry about the foreign water, put a few drops in it. If you get a nasty from strange water, mix some GSE, rinse your mouth and swallow -- it kills those troublesome bugs. Does a lot more, too.