Patient-friendly definition from the DentistsDirectory.org dental glossary.
Incisors are the eight front teeth — four in the upper arch and four in the lower — positioned at the very front of the mouth. They have a flat, chisel-shaped crown with a thin cutting edge, designed to bite into and cut food. Humans have two types of incisors in each arch: the two central incisors in the middle (the largest and most visible front teeth) and the two lateral incisors on either side of them (slightly smaller and narrower).
Incisors cut food as the first stage of chewing — when you bite into an apple or a sandwich, it is the incisors doing the work. They also play a pivotal role in speech. The precise position of the upper front teeth and their relationship with the lower lip and tongue determine the production of many sounds, including f, v, th, s, and z. Missing or severely malpositioned incisors can cause noticeable speech changes. The lower incisors support and guide the tongue during swallowing.
The lower central incisors are typically the first permanent teeth to erupt, around age 6–7, and the upper central incisors follow shortly after. Because incisors are highly visible, their aesthetics matter significantly — chips, discolouration, crowding, spacing, and alignment are all reasons patients seek cosmetic treatment. Incisors have a single root, making their root canals among the simplest in the mouth. Because they bear direct frontal impact, trauma from falls and sports injuries — including fracture, luxation, and avulsion — is common.