Tooth Anatomical Landmarks: Depressions and Concavities

Key Definitions

• Anatomical landmarks: Features on the tooth surface (elevations or depressions) aiding in function and identification.
• Depressions/Concavities: Specific types of anatomical landmarks discussed here.

Types of Depressions

Fossa

• Definition: Irregular depression or concavity on the crown's surface.
• Locations:
  • Anterior Teeth: Lingual surface (called lingual fossa).
  • Posterior Teeth: Occlusal surface (called triangular fossa or central fossa).
• Lingual Fossa:
  • Present on lingual surface of all anterior teeth.
  • Incisors have one; canines have two.
  • Typically, no grooves or pits, except maxillary lateral incisor (may have grooves and a pit).
• Triangular Fossa:
  • Present on occlusal surface of all premolars and molars.
  • Shape: Triangular (base towards marginal ridge, apex towards center).
  • Always two: One mesial and one distal.
  • Contains pits and grooves.
• Central Fossa:
  • Found on occlusal surface of all molars.
  • Each molar: One central fossa, containing pit and grooves.

Sulcus

• Definition: Linear concavity or depression on the crown.
• Locations:
  • Present in posterior teeth on occlusal surface.
  • Has a developmental groove at its base (e.g., central sulcus in maxillary 1st premolar).

Groove

• Definition: Sharply defined groove or line on tooth surface.
• Locations:
  • Present in posterior teeth, absent in anterior teeth (except maxillary lateral incisor).
  • Named according to their location.
  • Occlusal surface: Bottom of a sulcus or fossa (e.g., central groove in maxillary premolars).
  • Other surfaces: May be present without prominent depression (e.g., mesial marginal groove in maxillary 1st premolar).
• Types:
  • Developmental Grooves: Have specific names (e.g., mesio-buccal groove in mandibular 1st molar).
  • Supplemental Grooves: No specific names, vary by individual (common in maxillary 2nd premolar, mandibular 1st molar).

Pit

• Definition: Pinpoint depression on the crown's surface.
• Locations:
  • Junction of two or more grooves or terminus of a groove.
  • Seen in all posterior teeth, absent in anterior teeth (except maxillary lateral incisor).
  • Named according to location (e.g., mesial pit, distal pit in premolars and molars, central pit in molars).
  • Occlusal surface: Present in a fossa.
  • Other surfaces: May not be in prominent depression (e.g., buccal pit in mandibular molar).