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

Maxillary second premolar

It has 5 surfaces:

Buccal

Lingual MesialDistal

occlusal

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

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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

A QESTION?

Upper 1st premolar .

Buccal aspect Lingual aspect

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Upper 1st premolar .

Mesial aspect Distal aspect

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Upper 1st premolar .

Occ. aspect

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Upper 1st premolar .

Buccal aspect Mesial aspect

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Upper 1st premolar .

Occ. aspect

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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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Upper 2nd premolar .

Bucc. aspect Mesial aspect

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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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Upper premolars.

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