umehany

1
MORPHOLOGY OF PERMANENT MAXILLARY Central INCISORS

• DR. UME HANI
• LECTURER- DEPARTMENT OF ORAL BIOLOGY
• DIKIOHS DUHS

2
LECTURE Outline

• Anterior Landmarks
• Terms of Orientation
• Class Traits
• Chronology
• Morphology
• Labial View
• Lingual View
• Mesial View
• Distal View
• Incisal View
• Questions

3
ANTERIOR LANDMARKS

• Developmental Lobes- primary center of formation,
  growth and calcification present during the crown
  development

4
Mamelons

• Mamelons- rounded projections on the incisal
  ridge of newly erupted incisors

5
Marginal ridges

• Marginal ridges- rounded elevations that form the
  mesial and distal borders on the lingual surface
  of anterior teeth

6
cingulum

• Cingulum- is the lingual lobe of an anterior
  tooth. It makes up the bulk of the cervical third
  of the lingual surface

7
Lingual fossa

• Lingual Fossa- an irregular depression or
  concavity on the lingual surface of incisors

8
Incisal edge

• Incisal edge/Incisal ridge- incisal ridge is the
  part of the crown that makes up the entire
  incisal rounded portion. An incisal edge refers
  to an angle formed by two flat surfaces merging.

9
CREST OF CURVATURE

• Crest of curvature- also known as the height of
  contour, is the greatest amount of a curve, or
  greatest convexity or bulge. The height of
  contour on the facial or lingual surfaces of the
  crown is where this greatest bulge would be
  touched by a tangent line drawn parallel to the
  root axis line.

10
CONTACT AREAS

• The proximal height of contour on the mesial and
  distal surfaces touching the adjacent tooth of
  same arch

11
TERMS OF ORIENTATION
cervico-facial
labiolingual
mesio-distal
12
CLASS TRAITS

1. The facial surface of all anterior teeth forms
   from three labial lobes the mesial, middle, and
   distal lobes, remember that a fourth (lingual)
   lobe forms the lingual bulge called a cingulum
   (314)
2. The incisal two-thirds of the crowns appear
   flattened or compressed facio-lingually,
   providing a long horizontal biting edge
3. Distinct and rounded protuberances termed
   mamelons representing developmental lobes
   surmount the incisal margins of all newly erupted
   incisors
4. The marginal ridges of all incisors are located
   on the mesial and distal borders of the lingual
   surfaces

13
CHRONOLOGY OF MAXILLARY CENTRAL INCISOR
14
MORPHOLOGY

• The maxillary central incisors are two in number,
  centered in the maxilla, one on either side of
  the median line, with the mesial surface of each
  in contact with the mesial surface of the other
• FDI system tooth numbers 11,21. Universal system
  tooth numbers 8,9
• The maxillary central incisor is the widest
  mesio-distally of any of the anterior teeth
• Labial surface of the crown is usually convex
• Lingually the surface form of the maxillary
  central incisor is more irregular and concave
  below the cingulum

15
LABIAL VIEW

• Cervico-incisal length (10-11 mm) is greater than
  the mesiodistal width (8-9 mm)
• Crown outline as seen from the facial aspect is
  trapezoidal in shape
• Crown width at contact area is greater than at
  cervix

16
LABIAL VIEW

• Mesioincisal line angle is straight (90 degrees)
  and distoincisal line angle is rounded
• Incisal edge is relatively straight
• Mesial crown outline is more straight than he
  distal
• Cervical outline of crown is slightly concave
  incisally (semicircle)

M
D
17
LABIAL VIEW

• Facial surface may show some evidence of shallow
  vertical developmental depression delineating
  lobe structure
• Facial surface is relatively flat (only slightly
  convex) in its incisal 2/3rd
• Facial surface may show horizontal ridges at the
  cervical one-third representing differing rates
  of enamel formation during normal growth patterns
• Outline of root is cone shaped with a relatively
  blunt apex usually located slightly distal to
  center line of tooth, the root is usually 2 or 3
  mm longer than the crown

18
LABIAL VIEW

• Mesial contact area is incisal third of crown
• Distal contact area is located at the junction of
  incisal and middle third

M
D
19
LINGUAL VIEW

• The lingual surface appears the same trapezoidal
  in shape
• A well-developed convexity- the cingulum is
  present in cervical ½ of crown
• Mesially and distally confluent with the cingulum
  are the marginal ridges. Between the marginal
  ridges, below the cingulum, a shallow concavity
  is present called the lingual fossa
• Cervical outline is more concave towards the
  incisal (not a semicircle)

20
MESIAL VIEW

• Crown outline is triangular with apex at incisal
  and base at cervix
• The incisal ridge of the crown is on a line with
  the center of the root (faciolingually)
• The incisal edge is lined up with the height of
  curvature of the cervical line and the apex of
  the root
• Labially and lingually, immediately coronal to
  the cervical line are the crests of curvature of
  these surfaces

21
MESIAL VIEW

• The facial outline of the crown from the crest of
  the facial cervical ridge to the incisal ridge is
  relatively flat (shows very little convexity)
• The lingual outline of the crown is said to have
  an S shaped contour, denoting the convexities
  over the cingulum and linguo-incisal ridge
• The root surface is relatively smoothly convex,
  blunt end and centered

22
DISTAL VIEW

• Crown outline is triangular with apex at incisal
  and base at cervix
• Incisal ridge and apex of the root are in line
  with each other along the long axis of the tooth
• Note that the convexity of the outline of the
  cingulum begins approximately halfway between the
  incisal ridge and the cervical line on the
  lingual
• The curvature of the cervical line outlining the
  CEJ is less in extent on the distal than on the
  mesial surfaces
• The distal root surface has no developmental root
  depression and is relatively smoothly convex

23
INCISAL VIEW

• Mesiodistal width is greater than labiolingual
  diameter
• From this aspect, the labial face of the crown is
  relatively broad and flat in comparison with the
  lingual surface
• The outline of the lingual portion tapers
  lingually toward the cingulum
• The mesiolabial and distolabial line angles are
  prominent from the incisal aspect. From this way
  theres more bulk on the mesial half of the crown
  than distal

24
QUESTIONS?