Anatomical Landmarks of Teeth

General Information

• Anatomical landmarks are surface features on the tooth.
• They can be elevations or depressions.
• These landmarks help in tooth functions and identification.
• Focus on landmarks showing convexity or elevation.

Types of Elevations

Cusp

• Elevation on the crown portion.
• Part of occlusal surface.
• Represents developmental lobes.
• Present on molars, premolars, and canines.
• Number of Cusps:
  • Canines: 1
  • Premolars: 2 (except mandibular 2nd premolar which may have 2 or 3)
  • Maxillary and mandibular 1st molars: 5
  • 2nd molars: 4
• Naming:
  • Based on location (e.g., lingual cusp, buccal cusp).
  • Molars: mesio-buccal, disto-buccal, mesio-lingual, disto-lingual.
• Shape: 4-sided pyramid with 4 ridges from cusp tip:
  • 2 cuspal ridges (mesial and distal)
  • 1 ridge to cervical line (buccal or lingual)
  • 1 triangular ridge towards occlusal center

Cingulum

• Mound or elevation on the cervical third of the lingual surface of anterior teeth.
• Formed by the lingual developmental lobe.
• Seen in all maxillary and mandibular incisors, and all canines.
• Always on the lingual surface and limited to the cervical third.
• Largest in maxillary canine.

Ridges

• Linear elevations on the tooth.
• Named by location, shape, or direction.

Types of Ridges

1. Labial/Buccal Ridge

   • Present on all canines and premolars.
   • Runs on the facial surface from cusp tip to cervical line.
   • Called labial ridge in canines and buccal ridge in premolars.

2. Lingual Ridge

   • Seen in canines and premolars.
   • Runs on the lingual surface.
   • Canines: from cusp tip to cingulum, splits lingual fossa.
   • Premolars: from lingual cusp tip to cervical line.

3. Incisal Ridge

   • Present in all incisors.
   • Runs mesio-distally on the incisal surface.
   • With use, becomes sharp and is called 'incisal edge'.

4. Cuspal Ridge

   • Present in all teeth with cusps (molars, premolars, and canines).
   • Runs from cusp tip in proximal direction.
   • Each cusp has 2 cuspal ridges (mesial and distal).

5. Marginal Ridge

   • Present in all teeth.
   • Runs on proximal borders.
   • Each tooth has 2 (mesial and distal).
   • In anterior teeth: on lingual surface.
   • In posterior teeth: on occlusal surface.

6. Cervical Ridge

   • Seen in all molars.
   • Runs mesiodistally in cervical third of buccal surface.
   • More prominent in deciduous molars than permanent.

7. Triangular Ridge

   • Present in all premolars and molars.
   • Runs from cusp tip towards occlusal center.
   • Named according to originating cusp (e.g., buccal or lingual triangular ridge).

8. Transverse Ridge

   • Seen in all premolars and molars.
   • Formed by 2 triangular ridges.
   • Crosses occlusal surface transversely in bucco-lingual direction.

9. Oblique Ridge

   • Present on all maxillary molars.
   • Formed by triangular ridge of disto-buccal cusp and distal ridge of mesio-lingual cusp.
   • Crosses occlusal surface obliquely.

Mamelons

• 3 protuberances on the incisal surface of newly erupted permanent incisors.
• Formed by 3 developmental lobes (mesial, labial, distal).
• Present in all permanent incisors, not in deciduous incisors.
• Disappear with continuous use, making the incisal ridge straight.
• Used to differentiate permanent from deciduous incisors in children.