Crown of Mandibular First Molar Anatomy

Questions and Answers

Circular

Trapezoidal (correct)

Triangular

Rectangular

Distolingual cusp

Mesiobuccal cusp

Distobuccal cusp

Mesiolingual cusp (correct)

Distally from the cervical line to the apex

Mesially from the cervical line to the apical third, then distally to the apex

Mesially from the cervical line to the middle third, then distally to the apex (correct)

The mesial root does not curve

3 mm Signup and view all the answers

Regular on the buccal aspect, irregular on the lingual aspect Signup and view all the answers

They are longer lingually than buccally Signup and view all the answers

Study Notes

The crown is roughly trapezoidal in shape
All five cusps are visible from the buccal aspect
The mesiobuccal, distobuccal, and distal cusps are relatively flat
The mesial outline of the crown is concave at the cervical third, then convex at the contact area
The distal outline of the crown is straight above the cervical line, then convex at the distal contact
The surface of the buccal portion of the crown is smoothly convex

The cervical line is regular
The point of bifurcation of the two roots is approximately 3 mm below the cervical line
The mesial root curves mesially from a point shortly below the cervical line, then distally to the tapered apex
The distal root is less curved, with some curvature possible at its apical third
The apex is usually more pointed than that of the mesial root

The two lingual cusps are pointed and separated by the lingual groove
The mesiolingual cusp is the widest mesiodistally, with its cusp tip higher than the distolingual cusp
The cervical line lingually is irregular
The roots of the mandibular first molar appear 1 mm longer lingually than buccally