Lower canines – #22 and #27
The pointed teeth at the corners of the lower front teeth.
Roots
Usually one. About 2% have a second root worldwide, rising to 7% in Spain.
Canals
Usually one. About 8% have a second canal worldwide, from under 1% in Nigeria to 18% in Uruguay.
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 9–10 years old, according to the ADA's eruption chart.
They replace the lower baby canines, which fall out at 9–12 years.
They bite against the upper canines.
Sources
Martins et al. 2024; Mashyakhy et al. 2022; American Dental Association 2012; Harris 2005. Full titles are on the About page.