There is no effect of doing a new crown nucleic acid after brushing your teeth. Doing new crown nucleic acid is mainly a pharyngeal swab and nasal swab examination, specimen collection in the posterior wall of the pharynx and nasal mucosa, the main collection is secretion. The teeth, gums and oral mucosa brushed will not affect the pharynx, so brushing and gargling have no effect. Before collecting nucleic acid, you need to eat a light diet and avoid spicy, stimulating and greasy food to avoid vomiting during the throat swab collection. After collecting nucleic acid need to wear a mask, good personal protection, to avoid cross infection. So there is no effect of brushing your teeth to do the new crown nucleic acid, you can brush your teeth before collection, and eating has no effect.