Upper first molars – #14 and #3

Roots

Three roots: two on the cheek side (mesiobuccal and distobuccal) and one toward the palate (palatal). In a worldwide study, fewer than 1 in 200 had either a single root with one canal or four roots.

Canals

Usually four. Older textbooks say three, but scans find a second canal in the mesiobuccal root (called MB2) in about 64–74% of these teeth, and anywhere from 48% to 98% depending on the country studied.

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.

No baby teeth come before them: adult molars come in behind the baby teeth.

They bite against the lower first molars.

Sources

Morris et al. 2023; Martins et al. 2024; Jo et al. 2016; Barbhai et al. 2022; Martins et al. 2018; Wu et al. 2026; American Dental Association 2012; Harris 2005. Full titles are on the About page.