Etiquette of Brushing Teeth

The Prophet (SAWA) said, 'Brush your teeth in a horizontal manner and not in a vertical manner.

Prophet (SAWA) used to brush in a horizontal manner whenever he brushed his teeth, and that he would brush his teeth thrice every night: once before going to bed, once when he would wake up for his night worship, and once before going out to perform the dawn prayer. He used to brush with twigs of Arak (a thorny kind of tree) which the archangel Gabriel had told him to do.

Imam al-Baqir (AS) said, 'Verily brushing one's teeth at dawn before performing the ablution is part of recommended prophetic practice.