The incisors teeth (dentes incisivi; incisive or cutting teeth) are so named because they present a sharp cutting edge, adapted for biting the food. They are eight in number, and form the four front teeth in each dental arch.
The crown is directed vertically, is chisel-shaped, and is bevelled on its lingual surface to present a sharp horizontal cutting edge, which, before being subjected to attrition, presents three small prominent points separated by two slight notches. It is convex, smooth, and highly polished on its labial surface; concave on its lingual surface, where, in the teeth of the upper arch, it is frequently marked by an inverted V-shaped eminence, situated near the gum. This is known as the basal ridge or cingulum. The neck is constricted. The root is long, single, conical, transversely flattened, thicker in front than behind, and slightly grooved on either side in the longitudinal direction.
The upper incisors are larger and stronger than the lower, and are directed obliquely downward and forward. The central ones are larger than the lateral, and their roots are more rounded.
The lower incisors are smaller than the upper: the central ones are smaller than the lateral, and are the smallest of all the incisors. They are placed vertically and are somewhat bevelled in front, where they have been worn down by contact with the overlapping edge of the upper teeth. The cingulum is absent.