Upper wisdom teeth – #16 and #1
The last teeth at the very back of the upper jaw.
Roots
Usually three, but wisdom teeth vary more than any other tooth. In a scan study of 196 upper wisdom teeth, 64% had three roots, 24% one, 8% two and 4% four.
Canals
Most often three. Published reports range from one canal to six.
These are typical counts from scan studies. Teeth vary, and only an X-ray or scan shows what a particular tooth has.
When they come in
Usually at 17–21 years old, according to the ADA's eruption chart.
No baby teeth come before them: adult molars come in behind the baby teeth.
They bite against the lower wisdom teeth.
Sources
Olczyk et al. 2024; Jain et et al. 2017; American Dental Association 2012; Harris 2005. Full titles are on the About page.