Pre-Molars
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1st Maxillary Pre |
2nd Maxillary Pre |
1st Mandibular Pre |
2nd Mandibular Pre 3-cusp |
2nd Mandibular Pre 2-cusp |
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|
Tilt |
lingually |
lingually |
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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 |
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Root Shape |
Narrow lingually |
Same |
Narrow lingually |
Lingual not as narrow due to two cusps |
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Contacts |
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Root Ratio |
Longer than 1st. Highest root:crown of any max tooth. |
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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. |
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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. |
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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. |
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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. |
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Transverse Ridges |
Yes |
NONE |
Yes |
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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.