Characteristics of 1st Mandibular Premolars

Mandibular Premolars

Teeth that vary in shape more than maxillary premolars.

1st mandibular Premolar Lobes

Developed from 4 lobes, similar to maxillary premolars.

2nd mandibular Premolar Lobes

Typically developed from 5 lobes.

Size Comparison of mandibular 1st premolars

1st premolars are generally smaller than 2nd.

Lingual Inclination of mandibular premolars

Lingual inclination of lingual surface can make access more difficult

Eruption Age of mandibular 1st premolars

between 10-12 years.

Root Completion Age of mandibular 1st premolars

Root completion occurs at 12-13 years.

Tooth Outline of mandibular 1st premolars

Outline is nearly symmetrical, resembling a canine.

Buccal Cusp of mandibular 1st premolars

Large, pointed cusp slightly mesial to tooth axis.

Buccal Ridge of mandibular 1st premolars

Prominent ridge present on the buccal surface.

Root Structure of mandibular 1st premolars

Usually single root; occasionally bifurcated.

Root Apex of mandibular 1st premolars

Characterized by a sharp root apex.

Cusp Ridge Length of mandibular 1st premolars

Mesial cusp ridge shorter than distal cusp ridge.

Mesial and Distal Outline

Mesial: slightly concave

Distal: Convex, shorter and rounder

Contact Areas of mandibular 1st premolars

Contacts at occlusal and middle thirds junction with distal being mesial more cervical

Imbrication Lines of mandibular 1st premolars

Usually absent on mandibular premolars.

Enamel Surface of mandibular 1st premolars

Buccal surface smooth with few developmental lines.

Lingual Cusp Size of mandibular 1st premolars

Lingual cusp smaller than the buccal cusp.

Non-functional Lingual Cusp of mandibular 1st premolars

Small height and width; does not occlude.

Occlusal Surface Visibility of mandibular 1st premolars

Most of occlusal surface is visible.

Cusp Tip Alignment of mandibular 1st premolars

Cusp tip aligns with buccal triangular ridge.

Mesiolingual Groove of mandibular 1st premolars

can be seen separating marginal ridge from lingual cusp.

Crown Tip Orientation of mandibular 1st premolars

Crown tip is oriented lingually.

Buccal Cusp Tip aligment of mandibular 1st premolars

Centered over the root.

Buccal Triangular Ridge of mandibular 1st premolars

Slopes at a 45-degree angle.

Marginal Ridge of mandibular 1st premolars

Nearly parallel to buccal triangular ridge so greater amount of occlusal surface is visible

Distal View of mandibular 1st premolars

Similar to mesial view but less steep and no groove

Occlusal view profile of mandibular 1st premolars

Diamond-shaped profile with two cusps.

Buccal triangular ridge of mandibular 1st premolars

Longer than Lingual triangular ridge

Central Groove of mandibular 1st premolars

Indistinct central groove present on occlusal surface.

Transverse Ridge of mandibular 1st premolars

Distinct ridge separates mesial and distal fossae.

Fossa Characteristics of mandibular 1st premolars

Distal fossa larger and deeper than mesial.

Snake Eyes Restoration of mandibular 1st premolars

Class I restorations resemble snake eyes in fossae.