The second lower premolar 

The second lower premolar 

1. Chronology

Start of calcification: 27 to 30 months.

End of calcification: 6 to 7 years. 

Eruption: 10 to 12 years. 

End of apical calcification: 13 to 14 years.

2. Average measurements:

Total height: 22.5 mm.

Crown height: 8.5mm.

Coronal mesio-distal diameter: 7 mm.

Coronal vestibulolingual diameter: 8 mm.

3. Description

1. Vestibular face: 
2. The crown

• The general outline is roughly pentagonal like

for the canines and the 1st lower ^premolar . 

• It differs from the 1st lower ^premolar by: 

* a shorter and less acute cusp tip, 

*less inclined cusp slopes compared to 

 the horizontal 

*cusp slopes whose dimension is

 substantially equivalent. 

• The pattern of the vestibular face is similar to that of the 

1st lower ^premolar .

2. The root:

• It is similar to that of the 1st ^premolar with 

however a slight distal inclination

2. Lingual face:
3. The crown: 

• The lingual contour is voluminous. It is a little less high 

and a little less wide than the vestibular contour.

• In the most frequent cases, the 2nd ^premolar   presents 3

 cusps: 1 vestibular and 2 lingual, one of which 

mesiolingual which almost reaches the height of the cusp

 vestibular and occupies two thirds of the diameter 

mesiodistal from the lingual face, the distolingual cusp is

  low and occupies a third of the mesiodistal diameter of the 

lingual face, these 2 cusps are separated by a groove 

lingual.                                                                                                     

• In the case of a 2nd ^premolar with 2 cusps, the lingual cusp is approximately the same height as the vestibular cusp and there is no lingual groove. 

The lingual surface is a convex and regular surface 

2. The root:

• Its outline is similar to that of the 1st ^premolar with 

a slight distal tilt.

3. Mesial face: 
4. The crown:

• The general outline is inscribed in a trapezoid,
• The vestibular contour is less inclined towards 

the lingual face and the maximum convexity is found

 in the cervical third.

• The lingual contour remains regularly convex and the

 maximum convexity is found in the occlusal third.  

• The lingual part has a height almost 

equivalent to the vestibular cusp

• In the case of a 2nd ^premolar with 2 cusps, the lingual cusp is approximately the same height as the vestibular cusp.
• In the case of a 2nd ^premolar with 3 cusps, the disto-lingual cusp is not visible when observed from the mesial side.    

• The occlusal area has an orientation of advantage 

perpendicular to the coronoradicular axis of the tooth.

• The cervical line is barely convex towards

 the occlusal area

• The mesial surface is convex in the direction 

occlusocervical in the occlusal third. It is, rather 

concave in the middle third and in the cervical third.

2. The root:

• When observed from the mesial side, the root is

 identical to the root of the 1st ^premolar .

4. Distal face:
5. The crown

• For the 2nd ^premolar with 3 cusps, the cusp tip 

mesiolingual and the distolingual cusp tip are  

visible, the disto-lingual cusp is significantly smaller 

than the mesiolingual cusp.

• The marginal crest is located at a more cervical level, 
• The proximal contact zone is ovoid with a major axis 

vestibulo-lingual.

.

2. The root:

• The root is generally more convex than the side

 mesial

5. Occlusal face:  

• The general outline is rather square, especially when it comes to 

3-cusped premolar.

• The vestibular contour appearance is also “V” shaped.

 inverted, the top of the cusp being more central, 

the tooth appears more symmetrical.

• On 3-cusped premolars:

* The proximal walls are approximately parallel 

between them, half of the vestibular face is visible 

to observation by this face. 

* The vestibular cusp occupies 2/3 of the face 

occlusal, 

* The mesiolingual cusp is larger than the 

disto-lingual cusp

* The main intercuspal groove has a shape of 

“Y” whose arms are formed by the branches 

mesial and distal of the main mesiodistal groove 

and whose foot is represented by the lingual branch of the 

furrow which separates the mesiolingual and 

disto-lingual. 

• On 2-cusped premolars:

* The proximal walls may converge towards the lingual surface, but this 

convergence is always less than on the 1st ^premolar  .

* The vestibular cusp remains the most important

The second lower premolar 

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The second lower premolar