The Korea Dental Health Association has long promoted the ‘333 brushing rule’—brushing three times a day for three minutes within three minutes after meals—as the golden rule for oral health. However, recent discussions among experts suggest this may not always be correct. In particular, studies indicate that brushing immediately after eating might actually be harmful to dental health.
According to the medical community on the 23rd, the environment inside the mouth turns acidic immediately after a meal. This effect is intensified when consuming acidic foods such as carbohydrates, oranges, or vinegar. Brushing at this time can weaken the enamel, the hard protective layer of the tooth surface, leading to potential tooth damage. Enamel needs time to re-harden.
Experts recommend waiting at least 30 to 60 minutes after a meal for the tooth surface to recover from the acidic environment. Particularly with high-acid foods like orange juice or coffee, brushing after about an hour is safer. Research from the American Academy of Dentistry shows that brushing within 20 minutes of drinking a carbonated beverage causes more damage to the tooth surface compared to brushing 30 minutes to an hour later.
Experts suggest lowering oral acidity first instead of brushing immediately after eating. Rinsing the mouth with warm water or green tea can help. A dental expert noted, “The long-standing ‘333 rule’ was beneficial for developing brushing habits but is not an absolute standard for every situation.” They added, “Waiting at least 30 minutes after meals before brushing is safer, and using a soft toothbrush with gentle pressure for thorough cleaning is advisable.”
Netizens responded with comments like “This would be difficult for busy office workers to adhere to” and “Using an interdental brush to clean between teeth is more important.”