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Mandibular right first molar

The largest mandibular tooth: five cusps on a broad crown and two well-separated roots, mesial and distal.

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FDI

46

Universal

30

Palmer

LR6

Roots

Two (mesial and distal)

Root canals

Usually three

Eruption

About 6–7 years

Form and anatomy

The crown is wider mesiodistally than buccolingually and has five cusps: three on the buccal side (mesiobuccal, distobuccal and distal) and two on the lingual side (mesiolingual and distolingual), which are slightly higher. The mesiobuccal and distobuccal grooves separate the buccal cusps, and a lingual groove runs between the lingual cusps. Two roots, mesial and distal, spring from a short root trunk and are well separated, which makes the furcation accessible to both disease and cleaning. The mesial root is broad buccolingually and curves distally, typically holding two canals; the distal root is straighter and holds one wide canal or, less often, two. In some populations a third, distolingual root (radix entomolaris) is common. As the first permanent tooth to erupt, it is often mistaken for a primary tooth by parents.

Function

Primary grinding tooth of the lower arch.

Clinical relevance

Among the teeth most often restored and treated endodontically. The mesial root typically carries two canals (mesiobuccal and mesiolingual); the distal root one, sometimes two.

Neighbouring teeth

Mesial neighbour

Mandibular right second premolar

Distal neighbour

Mandibular right second molar

Same tooth, other side

Mandibular left first molar

Opposing tooth

Maxillary right first molar

This text is a draft and has not yet been reviewed by a dental professional. Educational reference only, not for diagnosis or treatment.