Tooth 84 (FDI): mandibular right primary first molar

The three numbers

About this tooth

Name

Mandibular right primary first molar

Set

Baby (primary)

Position

Lower arch, patient right (lower right, quadrant 8)

Erupts

14 to 18 months

Sheds

9 to 11 years

Roots

2

Root canals

3 or 4

Crown surfaces

Mesial, distal, buccal, lingual and occlusal.

Also written

Letter S (Universal), 8.4 (FDI with a dot), lower right D

Read on 23 October 2026. Sources: American Dental Association, Tooth development charts (primary and permanent); Salama and others, Anatomy of primary incisor and molar root canals, Pediatric Dentistry 1992; 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: 83 (mandibular right primary canine)
• Toward the back: 85 (mandibular right primary second molar)
• Across the midline: 74 (mandibular left primary first molar)
• In the other arch: 54 (maxillary right primary first molar)

Convert any other tooth with the full chart.