Ch. 17 - Permanent Premolars

What are the general features of permanent posterior teeth?

Marginal ridges, cusps, developmental grooves, height of contour, contact area, CEJ, roots, furcation, occlusal table, fossa, and pits.

What is the occlusal table?

The occlusal surface bordered by the marginal ridges.

Where are marginal ridges located?

On the distal and mesial surfaces of the occlusal surface.

What are cusp ridges?

Cusp ridges are the ridges that descend from the cusp tips toward the central part of the occlusal table.

What is a transverse ridge?

The joining of two triangular ridges crossing the occlusal table transversely from labial to lingual.

What is the central fossa?

A shallow and wide depression on the occlusal table located at the convergence of the cusp ridges.

What are occlusal pits?

The deepest parts of the fossae where two or more grooves meet.

What are developmental grooves?

Also known as primary grooves, they are found on the occlusal table and mark the junction among developmental lobes.

What is the central groove?

The most prominent developmental groove that travels mesiodistally and separates the occlusal table buccolingually.

What is the height of contour for the buccal surface of posterior teeth?

The cervical third.

What is the contact area of posterior teeth compared to anterior teeth?

The contact area is wider in posterior teeth.

What does CEJ stand for?

Cementoenamel junction.

What is furcation in relation to posterior teeth?

The area between two or more root branches before they divide.

What are the two types of permanent premolars?

First premolar and second premolar.

What is the function of permanent premolars?

To assist molars in grinding food during mastication and to assist canines in piercing and tearing food.

What is the crown outline of maxillary premolars from the buccal view?

Pentagonal shape with a prominent centrally placed vertical buccal ridge.

What is unique about the maxillary first premolar's root?

Most have a bifurcated root with two root branches: one buccal and one palatal.

What is the cervical cross-section shape of the root of maxillary premolars?

Kidney bean shaped.

What are the specific overall features of the maxillary first premolars?

Crown has an angular shape with sharp outlines, two sharply defined cusps, and a bifurcated root.

What is the eruption age for maxillary first premolars?

Between 10 and 11 years of age.

What is the occlusal view shape of maxillary first premolars?

Somewhat hexagonal, wider buccolingually than mesiodistally.

What distinguishes the maxillary second premolars from the first?

The crown is less angular and more rounded with more variations in occlusal surface anatomy.

What is the eruption age for maxillary second premolars?

Between 10 and 12 years of age.

What is the significance of the mesial developmental depression on maxillary first premolars?

It is located cervical to the contact area and is a distinguishing feature.

What are the boundaries of the mesial triangular fossa?

Mesial marginal ridge, transverse ridge, and the mesial cusp of the two cusps.

What are triangular grooves?

Grooves that descend from the cusp tips toward the central part of the occlusal table.

What is the clinical consideration regarding the maxillary sinus?

The roots may penetrate the sinus due to accidental trauma or during an extraction.

What is the general feature of permanent mandibular premolars compared to maxillary premolars?

Mandibular premolars do not resemble each other as much as maxillary premolars.

What is the size comparison between the first and second mandibular premolars?

The mandibular first premolar is smaller than the mandibular second premolar.

What is the typical eruption age for permanent mandibular first premolars?

Between 10 and 12 years old.

What is the typical root completion age for permanent mandibular first premolars?

Between 12 and 13 years old.

What is a distinctive feature of the buccal outline of mandibular premolars?

The buccal outline shows a strong lingual inclination from the proximal view.

What is the shape of the cross-section of mandibular premolars?

Oval (ovoid or egg-shaped) or elliptical.

What clinical consideration is important regarding the apices of mandibular premolars?

The apices are in close proximity to the mental foramen, requiring x-rays before extraction.

What is the primary functional cusp of the permanent mandibular first premolar?

The buccal cusp.

What is the shape of the occlusal view of the permanent mandibular first premolar?

Diamond-shaped with a notch at the mesial outline.

What distinguishes the pulp cavity of the permanent mandibular first premolar?

It has 2 pulp horns and 1 canal.

What are the two types of permanent mandibular second premolars?

3 cusp type (tricuspidate) and 2 cusp type (bicuspitate).

What is the eruption age for permanent mandibular second premolars?

Between 11 and 12 years old.

What is the root completion age for permanent mandibular second premolars?

Between 13 and 14 years old.

What is a notable feature of the buccal cusp of the permanent mandibular second premolar?

It has a short buccal cusp with more rounded slopes.

What is the occlusal view shape of the permanent mandibular second premolar?

Nearly square.

What is the difference in the pulp cavity between the 2-cusp and 3-cusp types of the permanent mandibular second premolar?

The 3-cusp type has 3 pointed pulp horns, while the 2-cusp type has 2 pulp horns.

What is the mesial marginal ridge orientation of the permanent mandibular second premolar?

Perpendicular to the long axis of the tooth.

What developmental feature is present in the lingual view of the 3-cusp type of permanent mandibular second premolar?

A lingual groove located between the cusps extending onto the lingual surface.

What is a clinical consideration for Class I amalgam restorations in mandibular first premolars?

They may appear like snack eyes.

What is the feature of the occlusal table components in the 3-cusp type of permanent mandibular second premolar?

The cusps are separated by two developmental grooves forming a distinct y-shaped groove pattern.

What is the difference in the distal marginal ridge between the mesial and distal views of the permanent mandibular first premolar?

The distal marginal ridge is more developed and unbroken by deep developmental grooves.

What is the significance of the mesial contact area on the buccal surface of the mandibular first premolar?

It is located just cervical to the junction of the occlusal and mesial thirds.

What is the characteristic of the lingual cusp of the permanent mandibular first premolar?

It is small and nonfunctioning.

What is the occlusal table component of the 2-cusp type of permanent mandibular second premolar?

The central groove travels in a mesiodistal direction.

What is the clinical consideration for partial anodontia related to mandibular premolars?

They are commonly involved in partial anodontia and can be congenitally missing.

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