Anatomy and Features of Premolars

Sep 26, 2024

Lecture on Premolars

Overview

  • Premolars are intermediate teeth between canines and molars.
  • Named mesially to distally.
    • First Premolar: Closest to the canine.
    • Second Premolar: Closest to the molar.
  • First Premolar: More similar to canines, sharp for ripping.
  • Second Premolar: More flat, better for grinding.
  • Eruption age: Around 10-12 years.
  • Root development completes about 2.5 years after eruption.
  • Also known as bicuspids, but this is a misnomer since some have more than two cusps.

Maxillary First Premolar

  • Typically has two roots.
  • Roots bifurcate in middle or apical thirds.
  • Two cusps: Two pulp horns and two root canals.
  • Unique features:
    • Longer mesial cusp slope than distal cusp slope (exception to general rule).
    • Deep mesial crown concavity.

Buccal View

  • Resembles a canine.
  • Visible cusp: Buccal, lingual cusp is smaller and not visible.
  • Crown is slightly shorter than a canine.
  • Development from three lobes.

Lingual View

  • Lingual cusp smaller than buccal.
  • Both cusps visible from this view.

Mesial and Distal Views

  • Mesial marginal groove and prominent developmental depression.
  • Distal marginal ridge more cervical than mesial.

Occlusal View

  • Hexagonal shape.
  • Differentiation between cusp ridges and marginal ridges.
  • Contains mesial and distal triangular fossae.

Maxillary Second Premolar

  • More anatomical variation than the first premolar.
  • Less angular, more rounded.
  • Usually has one root, sometimes two roots.

Differences from First Premolar

  • Mesial cusp slope shorter than distal.
  • Buccal cusp and lingual cusp sizes are more similar.
  • More supplemental grooves, shorter central groove.

Mandibular First Premolar

  • Smallest premolar with narrowest and shortest roots.
  • Typically one root and one canal.
  • Most prominent triangular and transverse ridges.
  • Mesolingual developmental groove separates mesial marginal ridge from lingual cusp.

Buccal and Lingual Views

  • Lingual cusp very short.
  • Tapers lingually, allowing visibility of multiple surfaces from lingual view.

Occlusal View

  • Prominent transverse ridge separates mesial and distal pits.

Mandibular Second Premolar

  • May have three cusps: Not a true bicuspid.
  • Larger than first premolar, more molar-like.
  • Most likely premolar to have a central pit.

Buccal and Lingual Views

  • Shorter buccal cusp, taller lingual cusp.
  • Possible Y-shaped groove pattern in the three-cusp type.

Occlusal View

  • Y-shaped groove pattern for three-cusp type.
  • Crescent shape for two-cusp type.

Study Table

  • Differences between mesial and distal sides, especially regarding marginal grooves and depressions.

Conclusion

  • This lecture covered the anatomy and differentiation of premolars, focusing on identifying key features of each type.