toothbrush is left to soak in the oregano oil/water until the next use and then the mixture is replaced with new? didn't know about oregano oil but would like to try. in the past, for lack of not knowing what else to use, would soak toothbrush in a very weak bleach/water mixture and would rinse in hot water and wash with antibacterial soap. woooohooooo, MH, you got to have something to say about this, even me being only a tad bit smarter today then i was yesterday knows this can not be any good.