Module 8 - Maxillary Premolars

General Features

• 2 per quadrant

• Succedaneous

• Assist in grinding, piercing and tearing food

• Maintain vertical dimension

• Esthetics and speech

• Pentagonal

• 2-3 cusps

• Shorter crown compared to anterior teeth

• Buccal rounded with vertical buccal ridge

• Buccal HOC at cervical third

• Lingual HOC at middle third

• Most have 1 root

What are the clinical considerations?

• Orthodontic extractions

• Instrumentation

Permanent Maxillary Premolars

• Erupt before mandibular premolars

• 1st premolar larger than 2nd

• Pentagonal from buccal/lingual

• Trapezoidal from proximal

• Wider buccolingually than mesiodistally

• 2 cusps

Root Features

• Shorter than canines

• Lingual and distal inclination

• Elliptical in cross section

Maxillary First Premolars (#5 & #12) - Overall Features

• Erupt between 10 and 11 years of age

• Replace primary 1st molars

• Comparison to maxillary 2nd premolars

  • Central groove longer

  • Appear bent mesially when viewed from occlusal

Root Features - Maxillary First Premolars

• Complete at 12-13 years

• Bifurcated

• Elliptical in cross section with sharp apices

• Buccal root larger

• Furcation midway

• Distinct mesial root concavity

• Two pulp horns and canals

Buccal View Features - Maxillary First Premolars

• Maxillary first premolar is the widest mesiodistally of all the premolars

• Mesial and distal contacts just cervical to junction of middle and occlusal third

• Mesial and distal outlines straight

• Imbrication lines and perykymata present on buccal surface

• Buccal cusp is sharp and located distal to long axis of tooth

• Mesial cusp slope longer than the distal

Lingual View Features - Maxillary First Premolars

• More rounded than buccal surface

• Smaller than buccal surface

• Lingual cusp shorter and less sharp than buccal surface

• Lingual cusp offset toward the mesial

• Mesial cusp slope shorter than distal

Proximal View Features: Mesial - Maxillary First Premolars

• Marginal Ridge

• Marginal groove

• Mesial Depression

• CEJ

Proximal View: Distal - Maxillary First Premolars

• Like mesial but does NOT have depression

• More occlusal surface shows

• Shallow distal marginal groove

• CEJ curvature on the distal is not as deep as the mesial

Occlusal View Features - Maxillary First Premolars

• Hexagonal

• Wider buccolingually than mesiodistally

• Buccal ridge

• Lingual is semicircular

• Lingual narrower than buccal

Maxillary Second Premolars (#4 & #13) - Overall Features

• Erupt between 10 to 12 years

• Resembles the first premolar, except the crown is less angular and more rounded

• More variations in anatomy compared to 1st premolar

Root Features - Maxillary Second Premolars

• Root completion between age 12 and 14

• Single root

• Root size about the same as maxillary first but longer

• Mesial concavity not as pronounced

• 2 pulp horns, single pulp canal

Buccal View Features - Maxillary Second Premolars

• Buccal cusp not as long nor as sharp as that of the maxillary first premolar

• Mesial and distal contacts are just cervical to the junction of the occlusal and middle thirds

Lingual View Features - Maxillary Second Premolars

• Similar to maxillary 1st premolar

  • Exception: lingual cusp is larger, almost the same height as the buccal cusp on a maxillary second premolar

• Less occlusal surface is seen from this view because crown is longer on the lingual

• Lingual cusp slightly toward the mesial

Proximal View Features - Maxillary Second Premolars

• No mesial development depression is present on the crown

• No mesial marginal groove

• Cusps closer to same size

Occlusal View Features - Maxillary Second Premolars

• More rounded overall

• Shorter central groove

• Central groove ends in mesial and distal pits

• More supplemental grooves