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Mandibular right second molar

A four-cusped molar with two roots that are often closer together than those of the first molar.

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FDI

47

Universal

31

Palmer

LR7

Roots

Two, sometimes fused

Root canals

Usually three

Eruption

About 11–13 years

Form and anatomy

The crown is smaller and more rectangular than that of the first molar and usually has four cusps of nearly equal size: mesiobuccal, distobuccal, mesiolingual and distolingual. A buccal and a lingual groove cross the central groove at right angles, forming a characteristic cross-shaped (plus-sign) pattern that distinguishes it from the first molar. There is no distal cusp, and the crown is often slightly shorter. The two roots, mesial and distal, are closer together, more parallel and more inclined toward the distal than those of the first molar, and they sometimes fuse. When fused, the canals may form a C-shaped configuration, especially common in East Asian populations, which complicates cleaning and filling. The tooth erupts around age 12, which is why it is sometimes called the twelve-year molar.

Function

Grinding food.

Clinical relevance

Roots may converge or fuse; C-shaped canal configurations occur in some populations.

Neighbouring teeth

Mesial neighbour

Mandibular right first molar

Distal neighbour

Mandibular right third molar

Same tooth, other side

Mandibular left second molar

Opposing tooth

Maxillary right second molar

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