Mouthwash does wash away the concentrated fluoride left on your teeth from brushing, especially when used immediately afterward. The main purpose of brushing with fluoride toothpaste is to coat the enamel with a high concentration of the mineral. Rinsing with any liquid, including mouthwash or water, immediately dilutes this protective layer and reduces its effectiveness.
The Role of Topical Fluoride in Dental Health
Fluoride is a naturally occurring mineral that strengthens the outer surface of your teeth, known as enamel. Enamel is constantly exposed to acids produced by bacteria, which cause demineralization where minerals are lost. Topical fluoride enhances the natural repair process known as remineralization. When fluoride is present, it encourages the enamel to absorb mineral ions to repair microscopic damage and form fluorapatite. This substance is significantly more resistant to acid attacks than the original enamel.
The Impact of Immediate Rinsing
The effectiveness of fluoride is strongly dependent on its concentration and how long it remains in contact with the tooth surface. Toothpaste is formulated to deliver a high dose of fluoride, typically between 1,350 and 1,500 parts per million (ppm), in a thick paste that clings to the teeth. After brushing, a thin film of this highly concentrated fluoride remains on the enamel. Rinsing with a large volume of liquid physically washes away and dilutes this residual film. Studies confirm that rinsing immediately significantly lowers the concentration of fluoride available for the remineralization process.
Distinguishing Mouthwash Types and Their Effects
Mouthwashes can be broadly categorized as non-fluoride (cosmetic) or fluoride (therapeutic).
Non-Fluoride Mouthwash
Non-fluoride washes are the main culprits for washing away the fluoride applied by brushing. These washes primarily contain ingredients for breath freshening and plaque reduction, but they contain no fluoride to replace the concentration they remove. Using a non-fluoride rinse immediately after brushing has been shown to reduce the anticaries protection provided by the toothpaste.
Fluoride Mouthwash
Therapeutic fluoride mouthwashes contain fluoride, but typically at a much lower concentration than toothpaste, often around 225 ppm for an over-the-counter daily rinse. Even though they contain the mineral, using a lower-concentration rinse immediately after brushing still dilutes the much higher concentration left by the toothpaste. This action replaces a highly potent, concentrated dose with a much weaker one.
Recommended Oral Hygiene Sequencing
To maximize the benefits of the fluoride in your toothpaste, the correct sequence involves a simple adjustment to your post-brushing routine. After brushing with a fluoride toothpaste, you should spit out the excess foam and paste. It is recommended that you avoid rinsing with water or mouthwash immediately afterward. This non-rinsing method allows the high-concentration fluoride residue to remain on the tooth surface for a longer period, continuing to strengthen the enamel. If you wish to use a mouthwash, it should be done at a separate time of day, such as mid-day or after lunch.