After brushing your teeth, you should spit out the excess toothpaste but not rinse your mouth with water, in order to let the protective active ingredients take effect.

noli's read

The habit of not rinsing your mouth after brushing, often summarized by the phrase "spit, don't rinse," is solidly validated by research. Leading organizations such as the Union Française pour la Santé Bucco-Dentaire (UFSBD) and the FDI World Dental Federation actively support this practice (expert recommendations based on clinical observational data). Indeed, rinsing with water prematurely removes the protective active ingredients deposited on the enamel, which reduces their beneficial action against acid attacks. Clinical kinetic studies confirm that the concentration of these protective agents remains much higher in the mouth for up to 30 minutes after brushing if water is avoided. Conversely, the statement written on the visual suggesting "not to spit out" the toothpaste is a confusion or a clumsy choice of wording. It remains essential to spit out excess foam to avoid ingesting the product, a step necessary to prevent any discomfort or internal imbalance. The ideal approach for your routine is therefore to thoroughly spit out the excess, without ever adding water afterward.

the sources

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