So today we brush our teeth (some people floss even though it has no benefit) and in the 19th century they would knock you out with primitive anesthetics and yank out the tooth, however what did they do in the Roman era? Did they ever develop a way to clean their teeth or did they let it be? Thanks in advance!
Yes! As to how widespread and effective dental hygiene would have been, I can't answer, but perhaps someone who studies ancient medicine or epidemiology could chime in. Individual teeth could be replaced with fake ones, and Aristotle (Mechanical Problems, 854 a) mentions tooth extraction by dentists.
Pliny the Elder (NH, 23.39) also wrote about remedies for oral hygiene. Olive oil, he writes, "if it be retained in the mouth [...] keeps the teeth white and strengthens loose ones."
Perhaps one of the most entertaining sources we have on ancient dental hygiene though, are several recipes for toothpaste purportedly written down by Scribonius Largus, a court physician to the emperor Claudius. According to Scribonius, one recipe, used by Octavia, the sister of Augustus, called for barley flour, vinegar, honey and salt cooked in a furnace till it was reduced to ash, before nard was added. A different recipe, purportedly used by Messalina, included a paste made from Chian mastic and deer antler that had been reduced to ash.