Lower central incisors – #24 and #25
The two front teeth in the very middle of the lower jaw.
Roots
One root.
Canals
Usually one. A second canal turns up in about 22% of these teeth worldwide, from 2% in Nigeria to 45% in Syria.
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 6–7 years old, according to the ADA's eruption chart.
They replace the lower baby central incisors, which fall out at 6–7 years.
They bite against the upper central incisors.
Sources
Mashyakhy et al. 2022; Martins et al. 2023; Usha et al. 2021; American Dental Association 2012; Harris 2005. Full titles are on the About page.