This document provides information about the mandibular first premolar tooth, including its location and function in shearing and masticating food. It describes the tooth's development timeline, characteristics resembling the mandibular canine and second premolar, distinctive features like its single root and lingual inclination, and variations that can occur. Measurements, aspects of the tooth like its buccal, lingual, mesial, and distal sides are examined in detail.

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DR. DIVYAB
Department of Oral Pathology
& Microbiology
SRM DentalCollege,
Ramapuram,Chennai, India
MANDIBULAR FIRST PREMOLAR

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LOCATION

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FUNCTION
 Shearing of food with canines
 Mastication of food complementing with molars
 Support corners of mouth

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Nomenclature
 FDI
 Universal
 Zsigmondy

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Predecessor tooth
 Primary mandibular I molar

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Chronology
 I evidence of calcification – 1.5 to 2 years
 Crown completion – 5 to 6 years
 Eruption – 10 to 12 years
 Root completion – 12 to 13 years

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DEVELOPMENT
 4 lobes
1
2
3
4

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Measurements

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Characteristics resembling mandibular canine
 Buccal cusp is long and sharp and is the only occluding cusp.
 Buccolingual measurement - similar
 Occlusal surface slopes sharply lingually in a cervical direction.
 Mesiobuccal cusp ridge is shorter than the distobuccal cusp
ridge.
 Outline form of the occlusal aspect resembles the outline form of
the incisal aspect of the canine

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Characteristics resembling second mandibular premolar
 Outline of crown and root from the buccal aspect resembles that
of the second premolar.
 Curvatures of the cervical line mesially and distally are similar.

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Characteristic features of Mandibular I Premolar
 Single root
 Marked lingual inclination
 Lingual cusp smaller than buccal cusp
 More occlusally located distal contact area
 Root concavities found on mesial surface of root
 Endodontist enigma

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BUCCAL ASPECT
Slight concavity
Slightly mesial
Buccal ridge
Distal curvature

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Lingual Aspect
 Lingual taper
 Lingual cusp is short, less developed
 Most of the occlusal surface seen
 Mesiolingual developmental groove
 Grooves in mesial aspect of root
 Mesial marginal ridge shorter, lower than
distal marginal ridge
Pointed tip

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MESIAL ASPECT
 Crown – overhang above root trunk
 Mesiolingual developmental groove
 Occlusal surface
 Mesial surface of the root - shallow groove

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DISTAL ASPECT
 Distal marginal ridge - right angles
 No developmental groove

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OCCLUSAL ASPECT
 Middle buccal lobe - major bulk of the tooth crown.
 Buccal ridge - prominent.
 Mesiobuccal and distobuccal line angles are prominent, although
rounded.
 Broad distal contact areas
 Crown converges - triangular in form
 Marginal ridges - well developed.
 Lingual cusp is small

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OCCLUSAL ASPECT
 Diamond shaped
 Cusps
 Cusp Ridges – 4
 Triangular ridge – 2
 Marginal ridge – 2
 Fossa -2
 Groove - 5

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VARIATIONS
Crown oversized
Diminutive
Unusual formation of lingual cusp
Long lingual cusp
No lingual cusp
Very long curved root
VARIATIONS
VARIATIONS

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Clinical considerations
 Mesial, distal pits
 Periodontal problems
 Difficulty in instrumentation
 Dens evaginatus