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Figure 4-23.—Vertical and horizontal overlap | Up
Dental Volume 1 - Dentist training manual for military dentists | Next
MAXILLARY CUSPIDS |
Figure 4-27.—Surfaces of a maxillary central incisor.
Lingual Surface—The lingual surface (fig. 4-28)
is quite similar to the facial surface in outline except that
it is slightly smaller in all dimensions. At the mesial and
distal margins there are marginal ridges. Occasionally
there is a cingulum at the junction of the lingual surface
with the cervical line. Sometimes a deep pit, the lingual
pit, is found in conjunction with a cingulum.
Root Surface—As with all anterior teeth, the root
of the maxillary central incisor is single. This root is
from one and one-fourth to one and one-half times the
length of the crown. Usually, the apex of the root is
inclined slightly distally.
MAXILLARY LATERAL INCISORS
The maxillary lateral incisor (tooth #7 or #IO),
illustrated in figure 4-29, is much like the maxillary
central incisor, except in size: it is shorter, narrower,
and thinner.
Figure 4-28.—Features of a lingual surface of maxillary
central incisor.
Figure 4-29.—Surfaces of a maxillary lateral incisor.
Facial Surface—The developmental grooves on
the facial surface are not so evident as those of the
central incisor. Of more significance, however, is the
distoincisal angle, which is well-rounded with this
curvature continuing to the cervical line.
The
mesiofacial angle is nearly straight to the cervical line.
Lingual Surface—The shape of the lingual
surface varies with the individual. In some persons it is
markedly concave, almost spoon-like in appearance,
and in others, it is flat. The lingual surface is almost the
same as the facial surface.
Root Surface—The root is conical (cone-shaped)
but somewhat flattened mesiodistally.
MANDIBULAR CENTRAL INCISORS
The mandibular central incisor (tooth #24 or #25)
is illustrated in figure 4-30. These are the first
permanent teeth to erupt, replacing deciduous teeth,
and are the smallest teeth in either arch.
Facial Surfaces—The facial surface of the
mandibular central incisor is widest at the incisal edge.
Both the mesial and the distal surfaces join the incisal
surface at almost a 90° angle. Although these two
surfaces are nearly parallel at the incisal edge, they
converge toward the cervical margin.
The
developmental grooves may or may not be present.
When present, they appear as very faint furrows.
4-16
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