Brushing your teeth: why is it important to wait 30 minutes after meals ?

Brossage des dents : pourquoi faut-il attendre 30 minutes après les repas ?

Il est recommandé de se brosser les dents au moins deux fois par jour, durant deux minutes. Néanmoins, un autre conseil est moins connu du grand public : attendre 30 minutes avant de se brosser les dents après un repas. 

It is often recommended to wait half an hour before brushing your teeth after a meal. This is due to the acidity of certain foods and drinks, the effects of which on enamel can be exacerbated by brushing.

Indeed, the acid contained in food or drinks attacks tooth enamel. More precisely, it erodes the enamel and the layer just below it, the dentin. And brushing can intensify this process. "With brushing, you can really push the acid deep into the enamel and dentin", explained in 2012 at New York Times DR Howard R. Gamble, then president of the dental academy.

A study, which the New York Times then reported, showed a loss of dentin when brushing within 20 minutes after drinking diet soda. Wear was significantly less when brushing took place 30 to 60 minutes after drinking. "So, in order to protect the dentin surface, at least 30 minutes should elapse for brushing your teeth after an acid attack", concluded the authors.

Dr Vera Tang, assistant professor at NYU College of dentistry, confirmed this recently, in April 2023, on the American website Self. This time it was about coffee. Here again, the specialist advised waiting half an hour before brushing your teeth after drinking coffee, explaining that the action of the toothbrush just after coffee pushed the acid into the pores of the teeth.

Soda, coffee… wine, vinaigrette sauce, fruits and fruit juices, soft drinks, tomatoes, ketchup, sweets, sweet desserts are also acidic foods and drinks.

The protective effect of saliva for teeth

Concretely, what happens during these thirty minutes ? Foods and drinks lower the pH of the mouth, making it more acidic. Brushing your teeth when the pH is acidic will cause erosion that is harmful to enamel and dentin. But gradually, under the effect of saliva, the PH rises, you can then brush your teeth without fear, after at least 30 minutes.

Saliva has many protective properties for teeth. In addition to regulating the pH of the mouth , "the mineral ions contained in saliva contribute to the remineralization of enamel. Thus, saliva can help repair the damage caused by acid attacks", underlines the French Union for Oral Health.

But half an hour is a long time. And you may not have time to wait 30 minutes before brushing your teeth. Dr. Never, star dentist on social networks, gives the following advice:

Rinse your mouth with clean water immediately to raise the pH of the mouth Chew sugar-free gum to stimulate saliva production and therefore raise the pH of the mouth

What rules for brushing your teeth properly ?

The French Union for Oral Health (UFSBD) recommends brushing your teeth twice a day, morning and evening, for 2 minutes with a fluoridated toothpaste, which protects against cavities. For effective brushing, the BROS method is popular:

B to brush the upper and lower teeth separately R for roller or make a rotating movement to brush teeth and gums from pink to white O for oblique. We tilt the brush at 45° on the gum S to follow a path to be sure to go around all the teeth, including the top

L’UFSBD also recommends using dental floss every evening.