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Pre-Molars

 

1st Maxillary Pre

2nd Maxillary Pre

1st Mandibular Pre

2nd Mandibular Pre

3-cusp

2nd Mandibular Pre

2-cusp

Tilt

   

lingually

 

lingually

Ligual cusp

Shorter than buccal. Bend toward mesial.

Shorter but almost same heigt as buccal. Bends mesially.

Shorter than buccal.

Shorter than buccal. Distolingual shorter than mesiolingual.

Shorter than buccal

Height of contour

Buccal: junct middle &cervical 3rd.

Lingual: middle 3rd.

Same

Buccal: apical 3rd.

Lingual: middle 3rd.

Buccal: junct apical & mid 3rd.

Lingual: middle 3rd.

Buccal: junct apical & mid 3rd.

Lingual: middle 3rd.

CEJ

Mesial & lingual more occlusal.

Same

Greater convexity on mesial.

Greater convexity on mesial.

Greater convexity on mesial.

# Roots

Two (buccal longer). Bifurcates in apical 1/3rd to 1/2th.

One

One

One

One

Root Curvature

Distal bend

Distal bend

     

Root Shape

Narrow lingually

Same

Narrow lingually

Lingual not as narrow due to two cusps

 

Contacts

         

Root Ratio

 

Longer than 1st. Highest root:crown of any max tooth.

     

Root depressions

Both mesial and distal.

Prominent on mesial.

Both on mesial & distal.

Prominent on distal.

Both mesial & distal in middle/apical 3rd.

Only on distal in middle 3rd. NONE on mesial.

Only on distal in middle 3rd. NONE on mesial.

Buccal Cusp

Tip sharp and slightly distal

Tip obtuse and slightly mesial.

Centered over root.

   

Cusp ridges/cusp tip distance

Buccal and lingual cusp tips well within confines on root contour.

Buccal and ligual tips are close.

Mesial: meet marginal ridge at acute angle.

Distal: Meet marginal ridge at 90 degrees.

   

Occlusal outline

Mesial straighter or concave. Distal is longer & round.

 

 

 

More symmetrical

Diamond.

Mesial: flat/slight curve.

Distal: more convex. Distal side bulkier, mesial pushed inward. Buccal crest of curvature is slightly mesial. Lingual is slightly distal.

Round/Oval

Occlusal table is square.

RoundOval. More bulk on mesial than distal.

Occlusal Groove pattern

H

H

H

Y

H

Developmental Grooves

Central longer than 2nd. Hence pits are closer to marginal ridges.

 

Run B.L. from mesial and distal fossae.

No central groove.

 

Fossae

   

Two. Mesial is smaller. Distal larger & deeper.

Three. Central is most lingual & closer to distal. Distal is small.

2. Mesial is smaller. Distal larger & deeper.

Transverse Ridges

   

Yes

NONE

Yes

Grooviness depth

Deeper but less grooves

Grooveier but less deep.

Deeper but less grooves

Grooveier but less deep

Grooveier but less deep

Special Notes:

Mesial marginal ridges are occlusal to the distal except for Mandibular 1st pre-molar.

Mesiolingual groove exists on Mandibular 1st Pre-molar.

Mesial concavity under the contact exists on the max 1st pre-molar.

Mesial groove on max 1st pre-molar. Sometimes distal groove. Rarely grooves on 2nd max pre-molar.