Upper lateral incisors – #10 and #7
The narrower front teeth on either side of the upper central incisors.
Roots
One root.
Canals
One canal in 98% of a scan study of 85 of these teeth; the rest had two canals that join before the tip of the root.
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 8–9 years old, according to the ADA's eruption chart.
They replace the upper baby lateral incisors, which fall out at 7–8 years.
They bite against the lower lateral incisors.
Sources
Jain et al. 2017; Usha et al. 2021; American Dental Association 2012; Harris 2005. Full titles are on the About page.