Dental Anatomy: Permanent mandibular 1st premolar

Permanent mandibular 1st premolar:
?It is the smallest premolar in the human dentition. It resembles both the mandibular canine and the mandibular 2nd premolar in function and has some of the characteristics of each of them.
A. Characteristics that resemble those of the mandibular canine:
?The buccal cusp is long, sharp, and is the only occluding cusp.
?The bucco-lingual measurement is similar to that of the mandibular canine.
?The occlusal surface slopes sharply lingually in a cervical direction.
?The mesio-buccal cusp ridge is shorter than the disto-buccal cusp ridge.
?The outline form of the occlusal surface resembles the incisal aspect of the mandibular canine.
B. Characteristics that resemble those of the mandibular 2nd premolar:
?The mesial and distal contact areas are located at nearly the same level.
?The curvature of the cervical line mesially and distally is similar.
?It has more than one cusp.
?The length of the root of the mandibular 1st premolar is closer to the length of the root of the mandibular 2nd premolar.