mandibular premolars

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A brief anatomy of Mandibular Premolars

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Page 1: Mandibular Premolars
Page 2: Mandibular Premolars

Dr.Syed Sadatullah King Khalid University

Abha

Page 3: Mandibular Premolars

Buccal aspect From the buccal aspect a large well formed,

pointed buccal cusp is seen

The mesial outline is similar to the distal outline The mesiobuccal cusp ridge is shorter than the

distobuccal cusp ridge (similar to canines)

The mesial and distal slope of the buccal cusp sometimes show concavity

Dr.Syed Sadatullah King Khalid University

Abha

Page 4: Mandibular Premolars

Dr.Syed Sadatullah King Khalid University

Abha

Buccal aspect

Page 5: Mandibular Premolars

Lingual aspect

The crown tapers and inclines lingually

The lingual cusp is small, pointed and nonfunctional and in some specimens it is no longer than the cingulum of maxillary canine

Between the mesiobuccal and lingual lobe is the mesiolingual developmental groove

Dr.Syed Sadatullah King Khalid University

Abha

Page 6: Mandibular Premolars

Dr.Syed Sadatullah King Khalid University

Abha

Lingual aspect

Page 7: Mandibular Premolars

Mesial aspect The lingual inclination of the crown can be seen

from this aspect

The lingual cusp is approximately two thirds the size of the buccal cusp

The mesial marginal ridge has extreme lingual slope

Mesiolingual developmental groove is present between the mesial marginal ridge and the mesiolingual cusp ridge

The mesial and distal contact areas are in the middle third, the distal contact area being more wider.

Dr.Syed Sadatullah King Khalid University

Abha

Page 8: Mandibular Premolars

Dr.Syed Sadatullah King Khalid University

Abha

Mesial aspect

Page 9: Mandibular Premolars

Distal aspect

. Distal marginal ridge is higher and does not have the extreme lingual slope

The cervical line curvature is less curved

Dr.Syed Sadatullah King Khalid University

Abha

Distal aspect

Page 10: Mandibular Premolars

Occlusal aspect The crown converges sharply to the centre of the

lingual surface

The occlusal surface has two depressions; mesial and distal fossae

Most common form of mandibular 1st premolar shows a mesiolingual depression and mesiolingual developmental groove

Dr.Syed Sadatullah King Khalid University

Abha

Page 11: Mandibular Premolars

Dr.Syed Sadatullah King Khalid University

Abha

Occlusal aspect

Page 12: Mandibular Premolars

Root The mandibular 1st premolar has one root

The root is approximately (3-4mm)shorter than the root of mandibular canine but the outline bears a close resemblance to the canine

A deep developmental groove is seen on the mesial aspect on the root

On the distal aspect there is a shallow depression devoid of any developmental groove.

Dr.Syed Sadatullah King Khalid University

Abha

Page 13: Mandibular Premolars

Dr.Syed Sadatullah King Khalid University

Abha

1.0 0 6.5 7.5 5.0 7.0 14.0 8.5

Curvature of Cervical Line M D

LabiolingualDiameter atCervical Line

LabiolingualDiameter atCrest of Curvature

MesiodistalDiameter atCervical Line

MesiodistalDiameter atContact Area

RootLength

Crown Length

Average Dimensions in millimeters

Page 14: Mandibular Premolars

Dr.Syed Sadatullah King Khalid University

Abha

Mandibular Second Premolar

Mandibular 2nd premolar resembles the mandibular 1st premolar from the buccal aspect only

The crown assumes two common types. The first and more common type is the 3-cusp type and the second is the 2-cusp type

The two differ mainly in the occlusal design

Page 15: Mandibular Premolars

Buccal aspect The buccal cusp is shorter with the cusp slopes

presenting less degree of angulations

Lingual aspect There may be one or two lingual cusps –

mesiolingual and distolingual cusps

The cusp(s) are more developed than the lingual cusp of lower first premolar

A groove separates the two lingual cusps

Dr.Syed Sadatullah King Khalid University

Abha

Page 16: Mandibular Premolars

Dr.Syed Sadatullah Ibnsina National Medical College

Mesial and Distal aspects The crown and root are wider buccolingually

Unlike mandibular 1st premolar the marginal ridge is at right angle to the long axis of the tooth

More of occlusal surface is visible form the distal aspect because the distal marginal ridge is at lower level than the mesial marginal ridge

The contact areas both mesial and distal are broad and appear higher because of the short buccal cusp

Page 17: Mandibular Premolars

Occlusal aspect From the occlusal aspect the 3-cusp type appears

square and the 2-cusp type appears rounded.

3-cusp type: - each cusp is separated by deep developmental

grooves forming a “Y” shape in the centre

- the occlusal surface also includesa. central pitb. mesial developmental groovec. mesial triangular fossad. distal developmental groovee. distal triangular fossaf. lingual developmental grooveg. supplemental grooves

Dr.Syed Sadatullah King Khalid University

Abha

Page 18: Mandibular Premolars

Dr.Syed Sadatullah Ibnsina National Medical College

2-cusp type: - one buccal cusp and one well developed

lingual cusp is present

- a central groove travels in a mesiodistal direction

and end in mesial and distal fossa (forming ‘H’ shape)

Root

Mandibular 2nd premolar has a single root which is larger and longer than the root of mandibular 1st premolar

The root is usually wide with a blunt apex

Page 19: Mandibular Premolars

Dr.Syed Sadatullah King Khalid University

Abha

Buccal aspect Lingual aspect

Mesial aspect Distal aspect

Occlusal aspect

Mandibular Second Premolar