Tooth 42 (FDI): mandibular right lateral incisor

The three numbers

About this tooth

Name

Mandibular right lateral incisor

Set

Adult (permanent)

Position

Lower arch, patient right (lower right, quadrant 4)

Erupts

7 to 8 years

Roots

1

Root canals

1

Crown surfaces

Mesial, distal, labial (facial), lingual and incisal.

Also written

#26 (Universal), 4.2 (FDI with a dot), lower right 2

Read on 23 October 2026. Sources: American Dental Association, Tooth development charts (primary and permanent); Number of roots and canals, from Ingle's Endodontics; Dental anatomy, citing Ash and Nelson, Wheeler's Dental Anatomy, Physiology and Occlusion. Ages and counts are usual figures, and teeth vary from person to person.

On the chart

Teeth next to it

• Toward the middle: 41 (mandibular right central incisor)
• Toward the back: 43 (mandibular right canine)
• Across the midline: 32 (mandibular left lateral incisor)
• In the other arch: 12 (maxillary right lateral incisor)

Convert any other tooth with the full chart.