d. Distal Surface. The distal surface is smaller in area and much more convex
than is the mesial surface. The contact area is located at the junction of the incisal and
e. Incisal Edge. The incisal edge consists of two sloping narrow surfaces
forming a curved angle at the tip of the cusp. The distal slope is about twice the length
of the mesial slope. The tip of the cusp is located at the junction of the mesial third and
the middle third of the crown.
f. Root. The root is flattened mesiodistally and the apical portion is usually
inclined distally. It is shorter than the root of the maxillary cuspid.
4-21. MANDIBULAR FIRST BICUSPID
The mandibular first bicuspid (figure 4-31) is the smallest tooth in the bicuspid
group. It possesses characteristics of all bicuspids but it differs greatly in form,
particularly when compared to upper bicuspids.
a. Facial Surface. The facial surface is symmetrical in outline and more convex
in all directions than are the upper bicuspids, giving the crown a form resembling an
inverted bell. The two developmental grooves and the facial axial ridge are usually
prominent. The facial cusp is long and sharp.
Figure 4-31. Mandibular right first bicuspid.