Have We All Been Using Mouthwash at the Wrong Time?

Have We All Been Using Mouthwash at the Wrong Time?
Photo: Ju Jae-young, Shutterstock

Based on an unscientific survey of my husband, largest WhatsApp chat, and everyone I work with, 100% of respondents use mouthwash after brushing. But common wisdom might have many people using mouthwash at the wrong time. And it’s a lot of people: According to Statista, nearly 200 million Americans used mouthwash in 2020. But as it turns out, the best time to use mouthwash is before we brush.

Why do so many people use mouthwash after brushing?

Perhaps a dentist told you long ago to use mouthwash after brushing and you never questioned it again. Maybe rinsing after brushing gives you a feeling of unparalleled freshness and oral hygiene completion. You may have subconsciously learned it via the commercials peppering your Saturday morning cartoons as a child, or carry a vague idea that mouthwash needs to marinate, in a sense, to remain pure and undiluted by other liquids to do its best work. (Which is actually true.)

Why it’s more effective to use mouthwash before brushing

Dr. Anna Peterson recently challenged the conventional wisdom when she posted a viral TikTok video claiming it was best to use mouthwash directly after you eat or before you brush.

“Your toothpaste…has around 1450ppm (parts per million) fluoride…Your mouthwash has only 220ppm fluoride,” she began. “This is a much lower concentration and it’s not enough to protect your teeth from sugars that you eat and drink. So when you brush your teeth, and you rinse with mouthwash straight away — you just rinse off all the high concentration fluoride, for a very low concentration fluoride.”

In a follow-up video, Dr. Peterson explained how after we eat, the sugars in our food lower the PH in our mouth, making it acidic, and during this “acid attack, your teeth start to dissolve.” If we brush our teeth at that point, we brush the acid into our teeth, causing erosion. “To get your teeth out of this critical zone, use mouthwash.” Who knew?

Well, a lot of dentists knew, actually. In our research, we found supporting statements that mouthwash reduces the fluoride concentration of toothpaste made by the British Dental Journal, the NHS, and many American dental practice websites.

The difference between cosmetic and therapeutic mouthwash

We recently covered whether mouthwash was even necessary, and, unless specifically recommended or prescribed by your dentist, it’s actually not. (I don’t use it and haven’t gotten a cavity since my misspent, Skittles-chomping youth.) But you may enjoy that antiseptic clean feeling or want to give your teeth an extra layer of protection.

Cosmetic mouthrinses, according to the American Dental Association, “temporarily control bad breath,” while therapeutic mouthrinses have “active ingredients intended to help control or reduce conditions like bad breath, gingivitis, plaque, and tooth decay.”

Either way, in the words of the National Health Service of the United Kingdom, “Using a mouthwash that contains fluoride can help prevent tooth decay, but don’t use mouthwash (even a fluoride one) straight after brushing your teeth or it’ll wash away the concentrated fluoride in the toothpaste left on your teeth.”

We’ll leave you with this quote from Chicago’s Water Tower Dental Care: “If [using mouthwash] before brushing is similar to rinsing your dishes, after brushing is similar to soaking your dishes in diluted bleach water after they’re clean.” And who needs diluted bleach water on clean teeth?

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