Let's say 600-200 BCE to narrow the time down.
How would Alexander the Great or one of his soldiers brush his teeth? What did they use? Did they even brush? Was there any toothpaste? Did men and women brush their teeth?
hi! there's lots of room for scholarly input on this topic, but FYI, there's a section in the FAQ on teeth brushing; while I don't notice responses for Ancient Greece specifically, you may find responses for neighbouring regions of interest