Questions and Answers
At what age is the root of the mandibular second premolar completed?
What is the most common type of mandibular second premolar?
What is a characteristic of the buccal cusp of the mandibular second premolar compared to the first premolar?
What is a characteristic of the crown of the mandibular second premolar compared to the first premolar?
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What is a characteristic of the cervical line of the mandibular second premolar compared to the first premolar?
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What is a characteristic of the root of the mandibular second premolar compared to the lower four?
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What is a characteristic of the lingual cusp or cusps of the mandibular second premolar compared to the lower four?
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What is the characteristic of the root apex of the mandibular second premolar?
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What is characteristic of the b-Two-cusp type mandibular second premolar?
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What is the shape of the occlusal outline in a three-cusp type lower mandibular second premolar?
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What can be seen in the mesial and distal fossae of the b-Two-cusp type mandibular second premolar?
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What is the characteristic of the lingual cusp in the two-cusp type lower mandibular second premolar?
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What is a characteristic of the pulp cavity of the permanent mandibular second premolar?
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What is the direction of the long mesial groove in a three-cusp type lower mandibular second premolar?
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What is true about the apical foramen of the permanent mandibular second premolar?
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How many developmental grooves are present on the occlusal surface of a three-cusp type lower mandibular second premolar?
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What is an anomaly of the mandibular premolars?
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What is the characteristic of the root apex of the lower mandibular second premolar from the mesial aspect?
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What is dens evaginatus?
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What can be seen from the distal aspect of the lower mandibular second premolar?
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What can be seen in the cervical cross-section of the mandibular second premolar?
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What is the characteristic of the lingual portion of the root of the lower mandibular second premolar?
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What is the difference in the lingual cusps of the lower mandibular second premolar from the distal aspect?
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What is a characteristic of the mandibular second premolar compared to the mandibular first premolar?
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Study Notes
Mandibular Second Premolar
- Erupts between 11-12 years, with roots completed between 13-14 years.
Buccal Aspect
- Resembles mandibular first premolar, but with differences:
- Buccal cusp is shorter
- Contact areas are broader and appear higher due to short buccal cusp
- Mesio-buccal and disto-buccal cusp ridges are less steep, more rounded
- Crown is shorter overall, wider in cervical third than mandibular first premolar
- Buccal ridge is not well developed
- Cervical line is less curved
- Root is broader mesiodistally, with a more blunt apex
Lingual Aspect
- Lingual cusp(s) are well developed, longer than those of mandibular first premolar
- In the three-cusp type:
- Mesiolingual cusp is larger and longer than the distolingual cusp
- Short lingual groove extends occlusolingually between the two cusps
- In the two-cusp type, the lingual cusp is smaller, with no developmental groove
- Lingual portion of the root is smoothly convex for most of its length
Mesial Aspect
- Crown and root are wider buccolingually compared to mandibular first premolar
- Buccal cusp is shorter
- Lingual cusp is more developed
- Root is longer, with a more blunt apex
Distal Aspect
- Similar to mesial aspect, except:
- Most of the occlusal surface can be seen from this aspect
- Distal marginal ridge is lower than the mesial marginal ridge
- Disto-lingual cusp is usually smaller and shorter than the mesio-lingual cusp (three-cusp type)
Occlusal Aspect
- Three-cusp type:
- Occlusal outline is square in shape
- Three cusps are well developed, with the buccal cusp being the largest
- Central fossa has a central pit, with three developmental grooves radiating from it
- Mesial and distal grooves extend to the marginal ridges
- Two-cusp type:
- Occlusal surface is rounded in shape, lingual to the buccal cusp ridges
- Mesiolingual and distolingual line angles are rounded
- Central developmental groove ends in the center of the mesial and distal fossae
- Mesial and distal fossae are roughly circular depressions with supplemental grooves
Pulp Cavity
- A. Buccolingual Section:
- Mandibular second premolar has a larger crown and root than the first premolar
- Pulp horns are more prominent, with the lingual pulp horn present more often
- Pulp chambers gently taper into the pulp canal
- Apical foramen may appear to exit at the apex
- B. Mesiodistal Section:
- Similar to mandibular first premolar, but with slightly larger overall dimensions
- Pulp horns are prominent, and the pulp chamber and root canal gently taper toward the apex
- Apical foramen appears to exit at the tip of the root in most cases
- C. Cervical Cross Section:
- Root outline is rectangular, oval, or triangular in shape
Anomalous Mandibular Premolars
- Mandibular first premolar with three distinct, separate roots
- Mandibular second premolar with a C-shaped root canal system
- Macrodontia of mandibular second premolar
- Dens evaginatus (outgrowth on the crown of a tooth)
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Description
Eruption and root completion timeline of mandibular second premolar, its resemblance to mandibular first premolar, and its types.
