Mandibular first molars

• The mandibular first molars have five cusps and two roots
• From the buccal side, three cusps can be seen (mesiobuccal, distobuccal, distal); the presence of the distal cusp can be used to determine the tooth orientation
• The distobuccal cusp is smaller than the mesiobuccal
• The facial outline has a trapezoidal outline; the mesial outline is concave until the contact area, and the distal outline is straight until the contact area
• The cervical outline is straight with some dipping into the root bifurcation
• Two developmental grooves are visible at the mesiobuccal and distobuccal cusps
• Occlusally there are five triangular ridges (one for each cusp) and mesial and distal marginal ridges
• Occlusally there is one major central fossa and pit, with two minor mesial and distal triangular fossae
• The central groove zigzags across the mesiodistal dimension
• There are mesiobuccal, distobuccal, and lingual developmental grooves