upper second premolar
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MAXILLARY SECOND PREMOLARS
Assistant Professor of Oral BiologyFaculty of Dentistry
Mansoura University
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.
ChronologyMaxillary 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 premolarAppearance of enamel organ:
8m.i.u.• First evidence of
calcification:• 2- 2.25yr
• Enamel completed:6-7yr
• Eruption:10-12yr
• Root completed:12-14yr
Geometric outline of the crown
• Buccal and lingual surfaces have trapezoid outline.
The smallest of the uneven sides is cervically.
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.
MD D M
Cervical line curved root wise.
Cervical line less curved.
4 5MD D M
Prominent B ridge
Distally located cusp tip
Less prominent B ridge
Mesially located cusp tipNarrow cervical portion. Wider cervical portion.
Short root. Longer root.
Facial AspectMaxillary 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
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
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 rootsIn case of two roots the L root is shorter and its apex is more blunt.
4 5
Lingual AspectMax. 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
Mesial aspect
B cusp is longer than L cusp by 1mm
4
The cusps are nearly at the same level.
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Mesial DG and canine fossa.
The crown surface is smooth and convex while the root has shallow developmental depression.
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.
Mesial AspectMax. 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
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
Distal aspect4
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.
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.
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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.
Distal AspectMax. 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
MD MD
Occlusal aspect54
It’s hexagonal
It’s oval
B & L triangular ridges.
M & D marginal ridges
B & L triangular ridges.Thicker M & D MRs
Long Central DG
M and D triangular fossae.
M developmental groove
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Shorter Central DG.
Not present.
M and D triangular fossae.
Occlusal AspectMax 1st Premolar Max. 2nd Premolar
Facial Cusp tip- Distal sideLingual-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
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
Why it is upper 4 ?
The only premolar only premolar with 2 roots2 roots. There is mesial marginal groovemesial marginal groove.The hexagonal hexagonal outline of the occ. occ.
Aspect.The lingual cusp lingual cusp is shortershorter than the
buccal Cuspbuccal Cusp.
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Why it is upper 5??? There is no mesial marginal grooveis no mesial marginal groove.
Less angular Less angular occ. Outline “ovaloval”.Both Both lingual and bucc. Cusps Cusps at the
same levelsame level.Wrinkled appearance of occ. aspect as
many supplemental grooves.Single rootSingle root.
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