Anatomical features of a permanent mandibular central incisor

1. Dr. Ramil B. Simsuangco
Oral Anatomy Professor
College of Dentistry
Manila Central University

2. Permanent Mandibular Incisors
 Develops from 4 primary centers of formation (lobes); 3
labial lobe and 1 lingual lobe
 SMALLER IN ALL DIMENSION compared to maxillary incisors
 Central incisor is smaller than Lateral incisor, which is
reverse in maxilla
 Incisal surfaces shows a labial inclination when occlusion
is normal; while incisal surfaces of maxillary incisors has
lingual inclination.
This arrangement makes the incisal planes of the max.
and mand. Incisors parallel with each other, fitting together
during incising action

3. MANDIBULAR CENTRAL INCISOR
 Smallest tooth in the dental arch
 It presents the characteristic of
being BILATERALLY SYMMETRICAL
 Crown has more than half the MD
dimension of the max. incisors, but
labiolingual diameter is only about
1mm.
 Single root is very narrow MD but the
root and crown are wide
labiolingually.

4. LABIAL ASPECT
 Crown outline is trapezoidal
 Crown outline is regular and tapering evenly to a sharp MI and DI
angle
 Incisal ridge is straight and is approximately at a right angle to the
root axis line.
 CONTACT AREAS:
 Mesial- in the incisal 3rd, very near the incisal angle
 Distal- in the incisal 3rd, but cervical to the level of the mesial contact
area
 Labial surface is smooth with flattened surface at the incisal 3rd, more convex
middle 3rd and narrows down to the convexity of the root at the cervical
portion
 Mesial and Distal root outlines are straight with the M and D outlines of the
crown
 Root terminates in a small pointed taper, in most cases curving distally

6. Lingual Aspect
 Crown outline is trapezoidal
 Smooth with very slight
concavity
 Marginal ridges are more
prominent near the incisal
edges
 No developmental lines mark
the cingulum

8. MESIAL ASPECT
 Crown is triangular
 Incisal ridge is rounded or worn flat and its center is usually
lingual to the center of the root (RAL)
 Curvature of CEJ is marked, curving approximately 1/3 the length
of the crown
 Mesial surface of crown is convex and smooth at the incisal 3rd and
is broad and flat at the middle 3rd
 Mesial surface of root is flat just below the CEJ
 Root diameter is uniform through the cervical 3rd and part of the
middle 3rd, tapering rapidly to the apical 3rd to either a blunt
rounded or pointed apex.
 Most roots have a broad developmental depression for most of its
root length, depressions mostly deeper at the junction of middle
and apical 3rd

10. DISTAL ASPECT
 Same as the mesial except CEJ
curves less than 1 mm than
mesial,
 developmental depression may
be more marked, with deeper
and more well defined
developmental groove at the
center

11. INCISAL ASPECT
 Illustrates bilateral symmetry, mesial half is almost
identical with the distal half
 Incisal edge is almost at right angles to the line bisecting
the crown labiolingually (serves as identification)
 Labiolingual diameter is always greater than mesiodistal
width
 Labial surface of crown is wider MD than the lingual
surface
 Labial surface of crown at the incisal 3rd has tendency
towards concavity
 More of the labial surface may be seen than the lingual
surface