Could three be the lucky number for a healthy mouth?
Good oral hygiene is linked to a reduced risk of serious conditions, including Alzheimer’s disease and rheumatoid arthritis.
And while Americans are mostly taught to brush once in the morning and once at night — for two minutes each time, followed by flossing in the evening — maintaining pearly whites looks a bit different on the other side of the globe.
In South Korea, a 1980s Korean Dental Association campaign advocated for the “3-3-3 rule,” i.e., cleaning teeth thrice daily, three minutes after eating for a period of three minutes.
The campaign caught on. According to the Korean Herald, brushing in the middle of the day is so common that there are “toothbrushing-friendly” subway stations, cafes and malls. Some highway rest areas have toothbrush vending machines, while some department stores feature built-in mouthwash dispensers in their restrooms.
In 2016, more than 100 elementary, middle, and high schools in Seoul installed designated toothbrushing stations.
Do these extra mouth measures pay off, and should Americans adopt the midday brush en masse?
Maybe. One 2017 study found that those who brushed their teeth after lunch had a lower risk of gum disease than those who did not.
But a celebrity dentist says not so fast.
“Although it does have its benefits, I am not totally in love with this method,” Dr. Daniel Naysan, D.D.S., owner and founder of Bedford Dental Group in Beverly Hills, told The Post.
“In one sense, Korean culture makes oral hygiene a daily habit, reduces plaque exposure and encourages thorough brushing, but the exact timing is not necessarily ideal.”
Naysan notes that brushing immediately after meals can be detrimental, as acidic foods and drinks like citrus, soda or wine briefly soften the enamel surface of the teeth.
“Brushing hard during that window can actually wear down the enamel because you are scrubbing a temporarily weakened surface. That’s why dentists in the US recommend waiting 30-60 minutes after eating before brushing your teeth.”
While devotion to oral hygiene is critical, he said three times a day does not beat two, calling the lunchtime cleaning “not necessary.”
Similarly, three minutes of brushing may not be superior to two.
“Two minutes is absolutely enough time if you are brushing properly. Three minutes isn’t harmful, but it’s not automatically better,” said Naysan.
He added that extended, aggressive cleaning with hard-bristled brushes can actually wear down enamel over time — a condition called toothbrush abrasion — causing teeth to appear browner, thinner, and more brittle, especially around the gumline.
Even worse, overly aggressive brushing can irritate the gums to the point that they begin to pull back from the teeth, which is where the phrase “long in the tooth” comes from.
Naysan pointed out that there are a few situations in which three minutes of brushing could be called for: if you have braces, heavy plaque buildup, and/or a high risk of cavities or gum disease.
Ultimately, he stresses the need for an effective electric toothbrush, daily flossing, and twice-a-year cleanings.
As a nation, though, the US seems more inclined to skimp on scrubbing: Surveys show the average American forgets to brush their teeth five times per week, and when we do manage to make it to the sink, we only average 37 seconds — well below Naysan’s professional recommendation of a full two minutes.
