Module Four: Posterior Teeth – Premolars (Vocabulary Flashcards)

Vocabulary flashcards covering key terms related to maxillary and mandibular premolars, their anatomy, eruption, root morphology, and occlusal features based on the notes.

Premolar

A tooth located between the canine and molars; typically erupts anterior to permanent molars and has cusps for tearing/grinding.

Lobes of development

Crown-forming units; premolars typically develop from four lobes (three facial, one lingual); mandibular second premolar can have a 3-cusp variant from five lobes.

Facial cusp

The cusp on the buccal (facial) side of a premolar.

Lingual cusp

The cusp on the tongue (lingual) side of a premolar.

Afunctional cusp

A cusp that does not participate in occlusion.

Proximal root concavities

Concavities on the proximal surfaces of premolar roots, common even when a root is not bifurcated.

Root bifurcation

The splitting of a tooth root into two roots; more common in maxillary first premolars (about 60%).

Mesial marginal groove

A groove crossing from the occlusal surface onto the mesial surface along the mesial marginal ridge (notably on maxillary first premolars).

Mesial developmental depression

A slight depression around the CEJ on the mesial aspect of premolar roots (noted on some premolars).

Height of Contour (HOC)

The crest of curvature on a crown surface; in maxillary first premolars, located at the M-D junction of the middle and occlusal third on the mesial, facial at the cervical third, and lingual at the middle third.

Maxillary first premolar (universal numbers)

Teeth numbered 5 and 12 in the Universal system.

Maxillary first premolar eruption

Typically erupts around 10–11 years of age.

Maxillary first premolar root completion

Root completion usually by 12–13 years.

Maxillary first premolar cusp relationship

Buccal cusp longer than the lingual cusp.

Maxillary first premolar root count

Usually has two roots (buccal and lingual); may have a single root with two canals; mesial and distal root grooves may be present.

Maxillary first premolar facial surface

Face resembles a canine but the crown is shorter and narrower; buccal cusp tip is distal to the midline.

Maxillary first premolar mesial marginal groove

Mesial marginal groove crosses from the occlusal onto the mesial surface.

Maxillary second premolar (universal numbers)

Teeth numbered 4 and 13 in the Universal system.

Maxillary second premolar eruption

Typically erupts around 10–12 years.

Maxillary second premolar root completion

Root completion typically by 12–14 years.

Maxillary second premolar root

Has a single root with one pulp canal; longitudinal grooves run mesially and distally on the root.

Maxillary second premolar cusp morphology

Cusp tips more equal in length and more rounded; FA/LI cusps converge toward the middle; generally shallower occlusal anatomy with more supplemental grooves.

Mandibular first premolar (universal numbers)

Teeth numbered 21 and 28 in the Universal system.

Mandibular first premolar eruption

Typically erupts around 10–12 years.

Mandibular first premolar root completion

Root completion around 12–13 years.

Mandibular first premolar cusp dominance

Buccal cusp is dominant; lingual cusp is nonfunctioning in occlusion.

Mandibular first premolar occlusal pits

Occlusal surface usually has two pits (mesial and distal); mesial lingual developmental groove extends onto the lingual surface.

Mandibular first premolar root grooves

Grooves on the mesial and distal aspects of the root.

Mandibular second premolar (universal numbers)

Teeth numbered 20 and 29 in the Universal system.

Mandibular second premolar eruption

Typically erupts around 11–12 years.

Mandibular second premolar root completion

Root completion typically by 13–14 years.

Mandibular second premolar shape

Larger than the first premolar; often boxier and more molar-like in appearance.

Mandibular second premolar buccal vs lingual cusps

Buccal cusp shorter; lingual cusp(s) also developed; root is generally longer than the first premolar.

Mandibular second premolar variations

Two-cusp form (from four lobes) or three-cusp form (from five lobes); if three-cusp, the mesial lingual cusp is larger than the distal lingual cusp.

Mandibular second premolar pulp anatomy

Single root with one pulp chamber; two pulp horns in each cusp for the 2-cusp type; two lingual pulp canals in the 3-cusp type.

Mandibular second premolar occlusal groove patterns

Two-cusp type can have a H or U groove pattern; three-cusp type forms a Y groove pattern (mesial lingual groove forms the tail of the Y).