Wikipedia says on tooth brushing:

Teeth-cleaning twigs have long been used throughout human history. As long ago as 3000 B.C., the ancient Egyptians constructed crude toothbrushes from twigs and leaves to clean their teeth.

We even started using the tooth brush as we know it quite a while ago.

Modern-day tooth brushing as a regular habit became prevalent in Europe from the end of the 17th century. The first mass-produced toothbrush was developed in England in 1780 by William Addis.

Although some took a bit longer.

In the United States, although toothbrushes were available at the end of the 19th century, the practice did not become widespread until after the Second World War, when US soldiers continued the tooth brushing that had been required during their military service.

Aren't the yanks always making fun of the English for having fucked up teeth?