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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.
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Full transcript