(2) Sulcus. A sulcus (see figure 4-16) is an elongated depression (or valley)
on the surface of a tooth. It is formed by the inclines of adjacent cusps or ridges. The
sulcus has a developmental groove at the junction of its inclines (at the bottom).
Figure 4-16. Sulcus.
(3) Groove. A groove is a linear depression on the surface of a tooth.
Grooves are formed by the union of two lobes during the development of the crown. A
marginal groove is a depression running perpendicular to a marginal ridge. Facial and
lingual grooves are, simply, grooves on the facial and lingual surfaces of the teeth.
Grooves are indicated on the standard dental chart by means of dark lines. See figure
(4) Developmental groove. A developmental groove (see figure 4-17) is a
depression in the crown of a tooth that marks the boundary between separate lobes.
They are the junction lines between the inclined walls of a sulcus. These grooves
appear on facial, lingual, and occlusal surfaces.
Figure 4-17. Developmental grooves.