4. Maxillary 2nd
Premolars
•The maxillary 2nd
premolar has two cusps (facial & lingual)
of nearly equal size and height
•Shorter mesial cuspal ridges
•This tooth typically has one root with 2 pulp canals.
•The facial ridge is not as prominent as that of the maxillary
1st
premolar.
•When compared to the maxillary 1st
premolar, this tooth will
usually present with more supplemental occlusal anatomy.
5. Chronology
Maxillary first premolar
• Appearance of enamel
organ: 7m.i.u.
• First evidence of
calcification:1.5-1.75yr
• Enamel completed:5-6yr
• Eruption:10-11yr
• Root completed:12-13yr
Maxillary second premolar
Appearance of enamel organ:
8m.i.u.
• First evidence of
calcification:
• 2- 2.25yr
• Enamel completed:6-7yr
• Eruption:10-12yr
• Root completed:12-14yr
7. Geometric outline of the crown
• Buccal and lingual surfaces have
trapezoid outline.
The smallest of the
uneven sides is cervically.
8. Facial Outlines and surface anatomy of the crown
4 5
B cusp is long and pointed B cusp is short and less pointed
M slope is longer than D M slope is shorter than D
Mesial contact A is in the M1/3
while distally more occlusal.
Mesial contact A is in O1/3 while
distally more cervically.
M
D D M
Cervical line curved root wise. Cervical line less curved.
9. 4 5
M
D D M
Prominent B ridge
Distally located cusp tip
Less prominent B ridge
Mesially located cusp tip
Narrow cervical portion. Wider cervical portion.
Short root. Longer root.
10. Facial Aspect
Maxillary 1st
Premolar Maxillary 2nd
Premolar
Shape is trapezoidal Trapezoidal or Oval
Cusp tip is pointed or sharp Rounded
Mesial slope is longer Mesial slope is shorter
Cusp tip is towards distal side Cusp tip is towards mesial side
M D
11. Mesial Proximal contact area
is at middle1/3rd
more
cervically and distal is more
occlusally
Both proximal contact areas
are at middle 1/3rd
occlusally
high
Outline on the mesial side is
convex up to mesial contact
area and distal outline is
almost straight
Outline is convex
Cervical line is convex and
crest of curvature is at distal
side
It is evenly convex
Buccal ridge is more
prominent
Less prominent
Apex of lingual root is seen Single root is seen pointing
distally
M D
12. Lingual outline and surface anatomy of the crown
The L cusp is shorter
by 1 mm than the B
cusp.
The L and B cusps are
nearly of same height.
80% has 2 roots with L
root is shorter than B
root and its apex is
pointed.
Rare to has 2 roots
In case of two roots the L root
is shorter and its apex is
more blunt.
4
5
13. Lingual Aspect
Max. 1st
Premolar Max. 2nd
Premolar
Lingual cusp is 1mm shorter
than buccal cusp
Same level
Cusp ridges of lingual cusp are
high
Not high
Mesial and distal cusp ridges
meet at an angle of 90
degrees
They form an oval shape
Cervically thinner thicker
D M
14. Mesial aspect
B cusp is longer than L cusp
by 1mm
4
The cusps are nearly at the
same level.
5
Mesial DG and canine
fossa.
The crown surface is smooth
and convex while the root has
shallow developmental
depression.
15. 4 5
Contact area:
At the middle third (OC
dimension) and slightly
buccal to the midline (BL
dimension)
At the occlusal third (OC
dimension) and slightly
buccal to the midline (BL
dimension)
MMR at the junction of M1/3
&O1/3
MMR positioned more
occlusal.
16. Mesial Aspect
Max. 1st
Premolar Max 2nd
Premolar
Trapezoidal in shape Trapezoidal
Both cusp tips are sharp Facial sharper than lingual
slightly
Mesial marginal dev. Groove is
seen
not seen
Canine fossa seen Not seen
17. Max. 1st
Premolar Max 2nd
Premolar
Triangular ridges are steep Not steep
2 roots Single root
Dev depression extends to
cervical line
Does not exted to cervical line
Contact area is 1mm above
mesial marginal ridge and
more facially
1mm cervical to mesial
marginal ridge
18. Distal aspect
4
5
DMR more occlusal than MMR DMR more cervical than MMR
CA occlusally positioned and
more buccally than MCA.
Smooth and convex surface except
for a small flat area cervical to
contact area.
CA cervically positioned and
more buccally than MCA.
Smooth and convex surface.
19. Root trunk is long as
the bifurcation is near
apical 1/3
Surface is smooth and
convex except shallower DD
on the root trunk than
mesially.
5
4
One root and if 2 the
bifurcation will be more
apically.
Surface is smooth and
convex except deeper DD
in the middle of the root
than mesially.
20. Distal Aspect
Max. 1st
Premolar Max 2nd
Premolar
Cervical line curvature is less It shows even convexity
Distal development
depression not prominent
It is prominent
2 roots Single rooted
22. Long Central DG
M and D triangular fossae.
M developmental groove
5
4
Shorter Central DG.
Not present.
M and D triangular fossae.
23. Occlusal Aspect
Max 1st
Premolar Max. 2nd
Premolar
Facial Cusp tip- Distal side
Lingual-Mesial side
Cusp tip mesially placed
Triangular ridges meet
slightly lingually
Meet lingually
Mesial cusp ridge forms
acute and distal cusp ridge
form 90degree angle with
marginal ridges
They form obtuse angle
with marginal ridges
Hexagonal Oval
M D
24. Mesial and distal
triangular fossa distance is
more
Less
Length of cental groove is
more
Less
Supplementary grooves not
seen
Seen giving it a wrinkled
appearance
Mesiofacial and disto facial
line angles are prominent
Not prominent
M D
31. Why it is upper 4 ?
The only premolar
only premolar with 2 roots
2 roots.
There is mesial marginal groove
mesial marginal groove.
The hexagonal
hexagonal outline of the occ.
occ.
Aspect.
The lingual cusp
lingual cusp is shorter
shorter than the
buccal Cusp
buccal Cusp.
31
33. Why it is upper 5???
There is no mesial marginal groove
is no mesial marginal groove.
Less angular
Less angular occ. Outline “oval
oval”.
Both
Both lingual and bucc. Cusps
Cusps at the
same level
same level.
Wrinkled appearance of occ. aspect as
many supplemental grooves.
Single root
Single root.
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