Molars

Molar primary function

Mastication (grinding)

Molar other functions

Help maintain vertical dimension of the face, proper alignment, and support the cheeks

Molar facial-view dimension

MD is greater than occlusocervical

Buccal height of contour

Cervical third

Lingual height of contour

Middle third

Mesial contact

At the junction of the middle and occlusal thirds

Distal contact

Middle third

Distal marginal ridge

More cervical than the mesial marginal ridge

First molar roots

More divergent

Second molar roots

Less divergent with a longer root trunk

Maxillary molar roots

3 roots

Maxillary molar roots names

Mesiobuccal, distobuccal, and lingual

Mandibular molar roots

2 roots

Mandibular molar root names

Mesial and distal

Maxillary molar crown width

Wider buccolingually

Mandibular molar crown width

Wider mesiodistally

Maxillary molar occlusal outline

Rhomboid or square

Mandibular first molar occlusal outline

Pentagon

Mandibular second molar occlusal outline

Rectangle

Maxillary second molar 3-cusp outline

Heart-shaped

Mandibular first molar cusps

5 cusps

Mandibular first molar cusp names

Mesiobuccal, distobuccal, distal, mesiolingual, distolingual

Mandibular first molar buccal grooves

2: mesiobuccal and distobuccal

Mandibular first molar occlusal groove pattern

Zig-zag

Mandibular first molar roots

More divergent

Mandibular first molar cusp height order

Tallest to shortest: ML, DL, MB, DB, distal

Mandibular first molar smallest cusp

Distal cusp

Mandibular second molar cusps

4 cusps

Mandibular second molar cusp names

Mesiobuccal, distobuccal, mesiolingual, distolingual

Mandibular second molar buccal grooves

1 buccal groove

Mandibular second molar occlusal groove pattern

Plus sign (+)

Mandibular second molar roots

Closer together

Mandibular second molar cusp height order

Tallest to shortest: ML, DL, MB, DB

Mandibular second molar buccal cervical ridge

More prominent, especially on the mesiobuccal portion

Mandibular molar transverse ridges

Formed by the union of triangular ridges

Mesial transverse ridge

MB triangular ridge + ML triangular ridge

Distal transverse ridge

DB triangular ridge + DL triangular ridge

Mandibular distal cusp triangular ridge

Does not join another triangular ridge to form a transverse ridge

Maxillary first molar

Usually the largest tooth in the maxillary arch

Maxillary first molar major cusps

4 major cusps

Maxillary first molar Carabelli

Accessory cusp often associated with the mesiolingual cusp

Maxillary first molar lingual cusps

ML is much larger than DL

Maxillary first molar roots

More divergent

Maxillary second molar DL cusp

Smaller and may be absent

Maxillary second molar major cusps

Usually 4, but may have 3 if the DL cusp is absent

Maxillary second molar 3-cusp form

Heart-shaped

Maxillary second molar roots

Less divergent and have a longer root trunk

Maxillary molar oblique ridge

Connects the mesiolingual cusp to the distobuccal cusp

Oblique ridge formation

Triangular ridge of ML + distal cusp ridge of DB

Oblique ridge found on

Maxillary molars

Four-cusp maxillary molar fossae

4 fossae

Four-cusp maxillary molar fossae names

Central, distal oblique, mesial triangular, and distal triangular

Largest maxillary molar fossa

Central fossa

Second-largest maxillary molar fossa

Distal oblique fossa

Three-cusp maxillary molar fossae

3 fossae: mesial, central, and distal

Four-cusp maxillary molar grooves

Central, buccal, distal oblique, lingual, and transverse groove of the oblique ridge

Three-cusp maxillary molar grooves

Mainly buccal and central; distal oblique, lingual, and transverse oblique-ridge grooves are absent

Four-cusp maxillary molar transverse ridges

1

Four-cusp maxillary molar oblique ridges

1

Four-cusp maxillary molar triangular ridges

4

Maxillary molar lingual cusps

ML and DL are unequal, with DL much smaller or sometimes absent

Mandibular molar lingual cusps

ML and DL are closer to equal in size

Maxillary molar crown taper

Wider buccolingually

Mandibular molar crown taper

Wider mesiodistally

Maxillary first molar Universal number

#3 (right) and #14 (left)

Maxillary second molar Universal number

#2 (right) and #15 (left)

Mandibular first molar Universal number

#30 (right) and #19 (left)

Mandibular second molar Universal number

#31 (right) and #18 (left)

Maxillary molar MB root

Usually wider than the DB root

Maxillary molar largest major cusp

Mesiolingual cusp

Mandibular molar mesial root

Usually wider than the distal root

Third molars

Usually smaller than first and second molars

Third molar morphology

More variable, bulbous, smaller occlusal table, and more accessory grooves/fissures

Third molar roots

Often fused with a long root trunk

Maxillary third molar roots

Usually 3

Mandibular third molar roots

Usually 2

Third molar roots

May bend distally

Maxillary third molar occlusion

Can be the only maxillary tooth that contacts only one opposing tooth

Third molars eruption

May be partially erupted or covered by an operculum

To identify a maxillary molar

Look for 3 roots

To identify a mandibular molar

Look for 2 roots

To identify a mandibular first molar

5 cusps + zig-zag grooves + pentagon outline

To identify a mandibular second molar

4 cusps + plus-sign grooves + rectangle outline

To identify a maxillary first molar

4 major cusps + Carabelli + large DL cusp

To identify a maxillary second molar

Smaller DL cusp, possible 3-cusp/heart shape, less divergent roots

Oblique ridge clue

Maxillary molar

Transverse ridge clue

Mandibular molar

Two transverse ridges clue

Mandibular first molar

Plus-sign clue

Mandibular second molar

Zig-zag clue

Mandibular first molar

Pentagon clue

Mandibular first molar

Rectangle clue

Mandibular second molar

Heart-shaped clue

Maxillary second molar with 3 cusps

Carabelli clue

Maxillary first molar

Small or missing DL cusp clue

Maxillary second molar

Roots far apart clue

First molar

Roots closer together clue

Second molar