Resembles the mand. first premolar -buccal aspect only

Assumes 2 common forms:

3 cusp type- angular 2 cusp type- more

roundedThe single root of

second premolar is larger and longer than the first premolar

Occlusal outline square in 3-cusp type, round in 2-cusp typeM and D profiles are parallelOcclusal table square or circularWith 2-cusp type, there are M and D triangular fossaeWith 3-cusp type, there is central fossa at junction of central and lingual sulci

3-cusp type Y- most common,

H- found in 2-cusp typeU- found in 2-cusp typeTwo pits- found in 2-cusp type

Buccal Aspect

Shorter buccal cusp than first premolar Mesiobuccal cusp ridge and distobuccal

cusp ridge less degree angulation Contact areas both broad ,appear

higher bec. Of short buccal cusp Root is broader mesiodistally than first

premolar Similar in this aspect-both first and

second premolar

Buccal Aspect

Lingual Aspect Variation from the

crown portion of of the first premolar:

Lingual lobes are dev. Making the cusps longer

Less of occlusal surface maybe seen from this aspect , part of the buccal portion of the occlusal surface maybe seen

In 3 cusp type lingual devt. brings about the greatest variation between the two teeth –there are mesiolingual -the larger and more longer one in most cases and a distolingual cusp

There is a groove between them extending a very short distance on the lingual surface and usually centered over the root

In the two cusp type,the lingual cusp development attains equal height with the three cusp. The two cusp type has no groove but it shows a devt. Depression distolingually where the lingual cusp ridge joins the distal marginal ridge

The lingual surface of the crown of all mand. Second premolars is smooth and spheroidalnhaving a bulbous form above the constricted cervical portion

Mesial Aspect

Crown and root are wider buccolingually

Marginal ridge is at right angles to the long axis of the tooth

Less of the occlusal surface maybe seen

Distal aspect The same with the

mesial aspect except more of the occlusal surface maybe seen

Crown of all posterior teeth are tipped distally to the long axis of the roots so that when the crowns of all post. Teeth are tipped distally to the long axis of the roots

Occlusal aspect

3 cusp type appear square lingual to the buccal cusp ridges when highly dev.

Has 3 cusp that are distinct: Buccal cusp largest Mesiolingual cusp distolingual cusp Each cusp has well formed triangular

ridges separated by a deep dev.grooves The groove form a Y on the occlusal

surface

Round or 2 cusp type- Outline of the crown is rounded

lingual to the buccal cusp ridges Lingual convergence of mesial and

distal sides Mesiolingual and disto lingual line

angles are rounded There is one well developed lingual

cusp directly opposite the buccal cusp in a lingual direction

Ten typical specimen

Central dev. Groove on the occlusal surface travels in a mesiodistal direction

2 cusp type appears round lingual to the buccal cusp ridges

Root extremely long Root dwarfed Malformed root developmental groove on buccal surface

Contact areas on crown high and constricted

Crown oversize; developmental groove buccally on root

Root oversize. Root malformed and of extra length Root very long with blunt apex; extreme

curvature at apical third Crown and root oversized; developmental

groove buccally on root Crown narrow buccolingually; very little

curvature buccally and lingually.