It is essential to brush your teeth at least twice a day (particularly in the morning and evening) to maintain good oral hygiene, and it is ineffective to think that a single brushing performed the night before can continue to protect the teeth the next day.

noli's read

The recommendation to brush teeth twice a day is the central pillar of oral hygiene, validated by the Union Française pour la Santé Bucco-Dentaire (UFSBD) (expert opinion). A meta-analysis by Kumar et al. demonstrates that people who brush their teeth less than twice a day have an increased risk of cavities of nearly 50% (meta-analysis). Biologically, the idea of relying on the previous day's brushing does not hold up: the Oral Health Foundation notes that plaque reforms continuously and that acids attack the enamel after every intake of food (expert opinion). To be completely thorough, a scientific review by Attin and Hornecker highlights that a single brushing, if it were absolutely perfect and meticulous, could theoretically suffice to disrupt the bacterial biofilm (consensus review). However, as plaque removal at home is rarely flawless, these same researchers agree that the rule of twice-daily brushing remains essential to compensate for the imperfections of daily brushing (consensus review).

the sources

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