The second upper premolar

The second upper premolar

1. Timeline:

• Start of calcification: 24-27 months
• End of coronary calcification: 6-7 years
• Eruption: 10-12 years
• End of apical calcification: 12-14 years

2. Average measurement:

• Total height = 22.5 mm
• Crown height = 08.5 mm
• Coronal mesial-distal diameter = 7mm
• Coronal vestibulo-lingual diameter = 9mm

3. Description
   1. Vestibular face
4. The crown

• Its similarity to the upper 1st premolar is

 obvious but it is smaller.

• The cusp tip is less

sharper than the upper 1st ^premolar .

• The mesial cusp slope is shorter than the 

distal slope.  

• The proximal angles are less prominent and  

give the appearance of “narrow shoulders.” 

• The vestibular lobes are less pronounced and 

depressions are rare.

2. The root:

• The ^2nd premolar generally has only one 

Root.

• It is a little longer and a little narrower than

 that of the 1st ^premolar .

2. Palatal face:
3. The crown

• Palatal contour is substantially superimposable on the vestibular contour (the palatal cusp is almost equivalent to the vestibular cusp). 
• The mesial offset of the cusp tip is less significant than on the 1st ^premolar .

2. The root:

• It is generally unique 
• It sometimes has two apices

3. Mesial face
4. The crown

• The 2nd ^premolar is generally similar to the 1st ^premolar . 
• The vestibular outline resembles that of the 1st ^premolar . 

Convexity is generally more regular; maximum convexity is between the junction of the cervical 1/3 and the medial 1/3 or in the medial 1/3

• The palatal cusp has the same value as the vestibular cusp.
• The palatal contour is regularly convex, the maximum convexity is located in the middle 1/3
• The occlusal contour observed by the mesial face is perfectly centered on the root trunk. 
• The lingual cusp is approximately the same height as the vestibular cusp.
• The mesial marginal groove is absent,
• The cervical line is more or less irregular

2. The root
3. Distal face

b. The root:

• It is generally unique
• It is crossed by a vertical depression 

median over its entire height

3.4 Distal face:

1. The crown  :

• The two cusps are of height 

equivalent, the marginal ridge is located at 

a more cervical level and it is oblique.

• The contact area is of larger surface area 

important.

• The distal face appears more convex.

2. The root:

• It presents a vertical depression 

less marked than on the mesial side 

5. Occlusal face
6. The crown

• The 2nd premolar has an ovoid outline.
• The median prominence, which corresponds to the 

tip of the V, is located exactly opposite 

of the cusp tip: it is the edge

 vestibular.

• The mesial and distal corners are rounded. 
• The palatal contour is convex.

• The two cusps are substantially of volume 

equal

• The tip of the palatal cusp is less offset

towards the mesial contour than on the first premolar.

• The marginal ridges are relatively short

• The central groove has a mesio-distal dimension 

less large.

• Numerous accessory furrows radiate from the 

central furrow

• These accessory furrows are always more numerous and 

deeper on the ^1st premolar 

4. Endodontic anatomy:

The pulp chamber is also wider in the vestibulo-lingual direction than in the mesio-distal direction.

Usually, this tooth has only one root and one canal, but sometimes this single canal divides in the apical third and ends, through 2 canals, in 2 foramina.

4.1. Vertical cuts:

Vestibulo-lingual sense

The pulp chamber: 

The pulp horns are identical to those of the 1st ^premolar   . The cameral contour narrows as it approaches the cervical line.

Root canals:

The root cavity is conical towards the apex. The whole is wider than a 1st premolar canal ^.   The apex is more widely open.

4.2. Horizontal sections: 

The outline of the pulp cavity is superimposable on the general outline of the pulp cavity of the canine or the 1st premolar 

In 15% of cases this tooth has 2 distinct roots, each with a canal.

5. SITUATION IN THE MOUTH:

5.1. Vestibulo-lingual direction : The vestibular face of the crown is vertical. The lingual cusp descends slightly lower than the vestibular cusp. The root is inclined on the lingual side (approximately 17° from the vertical). 

5.2. Mesio-distal direction : Crown and root direction parallel to that of the upper first premolar. 

The second upper premolar

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The second upper premolar