Tooth decay or dental caries is damage to teeth caused by bacterial action on carbohydrates in the mouth. The presences of carbohydrates—especially simple carbohydrates—encourages the growth of certain bacteria in the mouth. As it grows and reproduces, it creates byproducts, including acid. This acid is mixed with other compounds, which together compose dental plaque. If left in place, this acidic plaque will begin to break down the teeth, and will also turn into tartar, which is more difficult to remove. If the acidic substance is left in place, it will slowly cause the area it is in contact with to break down, creating an indentation. This provides some protection for the bacteria, so it will continue to reproduce and generate acid unless removed, resulting in a dental cavity. Preventative methods include the use of dental floss and brushing the teeth, to remove much of the acidic plaque and some bacteria. Mouthwash (which usually contains alcohol) is often used to destroy some of this bacteria, though some others use hydrogen peroxide (very diluted, usually to 1%) or colloidal silver.