"Padres, cepíllense los dientes antes de dormir."
The speaker is giving their parents a plural formal command in the Spanish sentence "Padres, cepíllense los dientes antes de dormir," telling them to brush their teeth before bed.
Utilizing the reflexive pronoun "se" in conjunction with the verb "cepillar" highlights the action's return to the subjects, thereby underscoring the significance of personal hygiene. The tone of the sentence is responsible and caring, encouraging a good habit in the family setting.