The first mandibular premolar contains two noticeable pits - the mesial and distal. Both pits can help to differentiate the first mandibular premolars from the canines. Also, these pits serve as the apexes of the mesial and distal fossae.

The first mandibular premolar also presents with the mesial triangular fossa and distal triangular fossa.

Similar to the maxillary premolars, the mesial and distal pits of the first mandibular premolars are located close to each other. Sometimes this characteristic results in only one central pit.

The first mandibular premolar presents with a short central groove. Also, several supplemental grooves can be found on the occlusal surface of the first mandibular premolar. They give a wrinkled appearance to the surface.

The mesiolingual groove of this tooth is unique as it begins in the mesial pit, crosses the mesial marginal ridge and terminates in the mesiolingual line angle.

Besides the central and mesiolingual grooves, the second maxillary premolar has the following grooves:

Mesiobuccal groove - goes from the mesial pit towards the buccal cusp;
Distobuccal groove - extends from the distal pit towards the buccal cusp;
Distolingual groove - goes from the distal pit towards the lingual cusp.

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First mandibular premolar (part 3)