A characteristic feature of lingual surface of the mandibular first premolar is:
A characteristic of the lingual surface of the mandibular first premolar is the mesiolingual developmental groove. This groove acts as a line of demarcation between the mesiobuccal lobe and the lingual lobe and extends into the mesial fossa of the occlusal surface.
Rudimentary lingual cusp
Mesial marginal ridge
Mesiolingual developmental groove
Lingual triangular ridge