The first mandibular molar is the very first tooth that erupts among the permanent teeth. It is also the most significant mandibular molar tooth, and mesiodistally it has the largest crown.

The first mandibular molar presents with five cusps:

The lingual cusps are usually sharper than others. As this tooth contains a small distal cusp, it appears pentagonal, and it looks like the distal surface of the tooth has two angled surfaces. The buccolingual length of the distal surface is slightly smaller than the same length of the mesial surface.

Every cusp presents with a cusp apex, which is its highest point.

The height of the contour of the first mandibular molar is as follows:

Buccal - in the cervical third, close to the middle third;
Lingual - in the middle third, close to the occlusal third.

The first mandibular molar presents with two roots (mesial and distal). The distal root is more rounded, while the mesial root is flatter. The mesial root has two depressions, named the mesial and distal root depressions.

The first mandibular molars contain three root canals. Two root canals are located in the mesial root.

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First mandibular molar (part 1)