Upper central incisors – #9 and #8
The two front teeth in the very middle of the upper jaw.
Roots
One root.
Canals
One canal. In a scan study of 100 of these teeth, every one had a single canal, and pooled Asian studies found a single canal in over 97% of upper front teeth.
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 7–8 years old, according to the ADA's eruption chart.
They replace the upper baby central incisors, which fall out at 6–7 years.
They bite against the lower central incisors.
Sources
Jain et al. 2017; Usha et al. 2021; American Dental Association 2012; Harris 2005. Full titles are on the About page.