Questions and Answers
What is the shape of the crown of the mandibular first molar?
Which cusp is the widest mesiodistally on the lingual aspect?
How does the mesial root of the mandibular first molar curve?
What is the approximate distance between the cervical line and the point of bifurcation of the two roots?
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Which of the following accurately describes the cervical line of the mandibular first molar?
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How do the roots of the mandibular first molar appear from the lingual aspect compared to the buccal aspect?
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Study Notes
Crown of Mandibular First Molar
- 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
Cusp Portions and Developmental Groove
- The cusp portions have a developmental groove between them
Cervical Line and Root Formation
- 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
Lingual Aspect
- 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
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Description
This quiz covers the shape, outline, and surface features of the crown of a mandibular first molar. Learn about the visible cusps, curvature, and convexity of the buccal portion.