The maxillary first premolar

First Molar :)

The upper first premolar has Mesial Marginal Developmental Groove in its mesial aspect. It also has long central groove and no supplement groves on its occlusal surface.Also 80% of the upper premolars have 2 roots. However, the upper second premolar has no MMDG and many supplemental groves. Upper second premolar is more rounded and usually has one conical root.

The concavity that forms on the mesial aspect of maxillary first premolars is called the cuspid groove. It is the result of the first premolar having both a buccal and palatal root. The groove functions as an alignment guide for the maxillary cuspid as it descends into the mouth.

Well I don't know but I have 3 in my lower ones and my dentist said that was strange cause its usually 1 or 2