EvoraPro Oral Probiotic contains harmless bacteria that compete with and replace the oral bacteria that cause gum disease and tooth decay. They are supplied as small mints which are taken once each day with no refrigeration needed. The mint is allowed to dissolve slowly in the mouth...not swallowed whole or chewed. A side effect of the mints is low dose hydrogen peroxide (which also helps fight gum disease). The hydrogen peroxide also slowly whitens stained or darkened teeth. Minimum time use to notice oral effects are three months. Longer term use is recommended.