4-15. MAXILLARY FIRST MOLAR
The maxillary first molar (see figure 4-25) is the largest tooth in the mouth. It
develops from four lobes and is often called the "six year molar" because of the age at
which it erupts.
a. Facial Surface. The facial surface is convex in all directions. A groove (the
facial groove) passes vertically from the middle of this surface, between the two facial
cusps, and onto the occlusal surface. The mesiofacial cusp is higher and wider than is
the distofacial cusp.
b. Lingual Surface. The lingual surface is more convex and smaller in area
than the facial surface. The mesiolingual cusp is larger than the distolingual cusp. An
oblique groove, the lingual portion of the distolingual groove, passes from the lingual
surface between the two lingual cusps and onto the occlusal surface. A fifth
(supplemental) cusp, which develops from the fifth lobe, is present on the mesiolingual
surface. This cusp, when present, is called the cusp of Carabelli.
c. Mesial Surface. The mesial surface is nearly flat in all directions. The
contact area is located at the junction of the middle and occlusal thirds on the facial third
of this surface.
Figure 4-25. Maxillary right first molar.