Questions and Answers
What is the geometric outline of the buccal aspect of the mandibular permanent second molar?
What is unique about the contact areas on the lingual aspect of the mandibular permanent second molar?
What is the shape of the occlusal aspect of the mandibular permanent second molar?
What is the characteristic of the roots of the mandibular permanent second molar?
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What is the characteristic of the mesial marginal ridge on the mesial aspect of the mandibular permanent second molar?
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What is unique about the distal aspect of the mandibular permanent second molar?
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How many triangular ridges are present on the occlusal aspect of the mandibular permanent second molar?
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What is the pattern formed by the developmental grooves on the occlusal aspect of the mandibular permanent second molar?
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Which statement is true regarding the cusps of the mandibular permanent third molar?
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Which aspect of the mandibular permanent third molar exhibits a distal conversion?
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What is the typical root morphology of the mandibular permanent third molar?
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Which characteristic best describes the occlusal surface of the mandibular permanent third molar?
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What percentage of mandibular permanent third molars have a cusp count that is NOT 4 or 5?
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Study Notes
Mandibular Permanent Second Molar
- Has five surfaces and two roots
Buccal Aspect
- Geometric outline: Trapezoid with small uneven side located cervically
- Only one buccal developmental groove, separating the mesiobuccal and distobuccal cusps, which are almost equal in size
- Buccal developmental groove may end in a buccal pit
- Roots are closer and nearly parallel with more pointed apex than the 1st molar
Lingual Aspect
- Crown and root converge lingually but to a slight degree
- Mesiodistal calibration at the cervix lingually is greater than that of the 1st molar
- Contact areas mesially and distally on the crown are more noticeable from lingual aspect and may be at slightly lower level especially in the distal area, than those of the 1st molar
Mesial Aspect
- Cervical ridge buccally on the crown is less pronounced
- Occlusal surface may be more constricted buccolingually
- Geometric outline: Rhomboidal with lingual inclination
- Mesial root apex is pointed, and it is longer than the distal root
- Mesial marginal ridge (MMR) is concave
- Mesial root is only visible
- Longitudinal depression on the mesial surface of mesial root
Distal Aspect
- Similar to that of the 1st molar except for the absence of a distal cusp and a distobuccal groove
- Distal marginal ridge (DMR) is concave but less angular than MMR
- Distal root is narrower than mesial root, so both roots are seen
Occlusal Aspect
- Geometric outline: Rectangular shape
- Disto-Lingual convergence
- Mesio-Distally is larger than bucco-lingually
- Anatomical landmarks:
- Elevations: Four cusps with 4 triangular ridges (mesial cusps are larger than distal cusps)
- Mesial and distal marginal ridge
- Depression:
- One major central fossae with central pit
- Two minor fossae (mesial and distal triangular fossae)
- Developmental grooves: form a typical cross pattern
- Supplemental grooves radiate from developmental grooves
Mandibular Permanent Third Molar
- 50% have 4 cusps, 40% have 5 cusps, and 10% have more or less than 4-5 cusps
Buccal Aspect
- Buccal surface is very convex
- Two Short roots (Mesial and Distal) may be fused in all or part of their length
- Roots are more inclined distally than 1st and 2nd molars
Lingual Aspect
- Lingual cusps are longer than the buccal cusps
- Mesiolingual is larger than the distolingual
Mesial Aspect
- Buccal cusp tips are closer to the lingual cusp tips giving a small occlusal table
Distal Aspect
- There is a distal conversion
- Distal root is narrower than mesial root, so both roots are seen
Occlusal Aspect
- Geometric outline: Rectangular or oval
- There are numerous supplemental grooves and pits give a wrinkled (irregular) appearance
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Description
This quiz covers the anatomical features of the Mandibular Permanent Second Molar, including its surfaces, roots, and cusps.
