Actual
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Principal Identifying Features
There are two cusps, one vestibular and one lingual, the vestibular being slightly larger than the lingual. The mesial slope of the vestibular cusp is shorter than the distal slope. As with the first premolar the lingual cusp is displaced mesially (more...), the general plan of the crown is flattened mesio-distally and the cusps sit directly above the root (more...).
Unlike the first upper premolar there is only one root which is flattened mesio-distally. There may be one or two root canals and two pulp horns. The root may have a bend distally at the apex and a more prominent groove on the distal side.
Chronology
| Initial calcification | 2-2.5 years |
| Crown completion | 6-7 years |
| Eruption into occlusion | 10-12 years |
| Root completion | 12-14 years |