Dr.Syed Sadatullah King Khalid University
Abha
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
Dr.Syed Sadatullah King Khalid University
Abha
Buccal aspect
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
Dr.Syed Sadatullah King Khalid University
Abha
Lingual aspect
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
Dr.Syed Sadatullah King Khalid University
Abha
Mesial aspect
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
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
Dr.Syed Sadatullah King Khalid University
Abha
Occlusal aspect
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
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
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
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
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
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
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
Dr.Syed Sadatullah King Khalid University
Abha
Buccal aspect Lingual aspect
Mesial aspect Distal aspect
Occlusal aspect
Mandibular Second Premolar