Nerd moment

Oral-B toothbrush: they pride themselves on the round head brussels because dentist use round silicone attachment to clean your teeth. Nerd moment: Can anyone in the world ? please show me where in your mouth is there a round tooth. Oral-B commercial actually uses a pearl to represent a tooth & shows the Brussels wrapping around it. I'm lookin for a round tooth in my mouth. Plz help me ???