Comparison between Max. first and Max. second premolars

1. Premolar
comparison
Max. Premolars

2. Chronology Max. First Premolar Max. Second Premolar
First evidence of
calcification
1 12 to 1 34 2 to 2 12
Crown completed 5 to 6 y 6 to 7 y
Eruption 10 to 11 y 10 to 12 y
Root completion 12 to 13 y 12 to 14 y
Buccal Aspect
Geometric out line
Trapezoid
(with the smallest side at the
cervical line and the larger side
at the occlusal outline)
Trapezoid
Mesial out line
Concave
(starting from cervical line till
the M. contact area)
Slightly convex
(from cervix to the point
where it joins the mesial
slope of the buccal
cusp)

3. Buccal Aspect Max. First Premolar Max. Second Premolar
Distal outline
Less concave
(starting from cervical line till
D. contact area)
More convex
(than the mesial outline)
Contact areas
Mesial: just occlusal to the
middle of the middle third.
Distal: at the junction
between middle and occlusal
thirds.
Mesial: at the junction
between middle and
occlusal thirds.
Distal: just occlusal to the
middle of the middle third.
Buccal cusp
The buccal cusp tip is
displaced to a distal
direction.
The mesial slope is concave
and long.
The distal slope is convex
and shorter.
The tip is less pointed than
that of maxillary permanent
1st premolar and is
displaced to a mesial
direction.
Distal slope is longer than
the mesial slope.
The cervical line Convex root-wise Convex root-wise

4. Buccal Aspect Max. First Premolar Max. Second Premolar
Surface description
The buccal surface is generally
smooth and convex except for:
• The buccal ridge, which is a
well-developed middle labial
lobe.
• The shallow depressions on
either side of the ridge.
The buccal surface is
generally smooth and
convex except for:
• The buccal ridge; which is
a well-developed middle
labial lobe.
• The shallow depressions
on either side of the ridge.
Root
The buccal root outline
resembles that of the maxillary
canine but is shorter.
It is conical in form with convex
surface and pointed apex that
curved distally.
Single root which tends to
curve distally.
Longer than that of maxillary
permanent 1st premolar