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.