It is recommended to brush your teeth before breakfast, or to wait at least 30 minutes after the meal if you prefer to do so afterward, in order to protect the surface of the teeth from the acidity of food.

noli's read

The idea of waiting after a meal to brush your teeth is a standard recommendation, widely shared by institutions such as the American Dental Association (ADA) (expert opinion). The explanation is based on the fact that acids from breakfast (coffee, fruit juice) temporarily soften the protective surface of the teeth. Brushing your teeth immediately after eating could risk accelerating the wear of this outer layer, whereas waiting 30 minutes allows saliva to naturally neutralize the acidity. Nevertheless, research provides compelling nuances. A 2020 meta-analysis revealed that while the protective effect of waiting is measurable on animal enamel, the difference in wear between immediate and delayed brushing is statistically much less pronounced on human enamel in real-world conditions. This work instead shows that the regular use of a strengthening and protective toothpaste remains the most decisive factor. Thus, observing this delay is an excellent routine habit, but simply rinsing your mouth with water after a meal is a fully validated alternative if you are short on time.

the sources

No named source held this one up — that absence is part of the verdict.