Permanent Mandibular Molars Introduction Larger in all dimensions

Permanent Mandibular Molars

Introduction • Larger in all dimensions than premolars, except occluso-cervically • Four or five major cusps • Two lingual cusps about same size* • Two roots: mesial and distal

Introduction… • Wider M-D than F-L* • Rectangular/pentagonal occlusal outline • Rhomboidal proximal outline

Permanent Mandibular First Molar

General Characteristics • • First permanent tooth to erupt 6 th tooth from midline Universal #19 and #30 Largest, strongest tooth in mandibular arch

General characteristics… • Five cusps: MB, ML, DB, D (largest to smallest) • Two roots: mesial (larger) and distal • Pentagonal occlusal outline

Development Timeline: • • Initial calcification: at birth* Enamel completed: 2 1/2 - 3 years Eruption: 6 - 7 years Root completed: 9 - 10 years

Facial View • Buccal surface - largest surface of any tooth • Trapezoidal geometric form • Portions of all five cusps visible

Facial view, mesial outline: • Mesial HOC at junction of occlusal and middle thirds • Flat or slightly concave cervical to the HOC • Dip in CE line over bifurcation

Facial view, distal outline: • Distal HOC slightly more cervical than mesial, but still at junction of occlusal and middle thirds • Generally more convex than mesial

Facial view, occlusal portion: • Three cusps (MB, D) divided by two developmental grooves (MB and DB grooves) • Two facial pits: buccal and DB pits

• Buccogingival ridge running horizontally at cervical third area

Lingual View • Crown tapers towards lingual • Two lingual cusps separated by lingual groove (no pit) • Lingual cusps are taller and sharper than buccal cusps • Lingual HOC at middle third

Mesial View • Only two cusps visible (MB and ML) • Crown lingually inclined • Mesial marginal groove present

Mesial view. . . • CE line more occlusal on than buccal • Mesial contact area buccal to marginal groove, at junction of occlusal and middle thirds lingual

Distal View • Distal marginal groove present • Shorter O-C than mesial surface – See more of occlusal surface – Portions of all five cusps visible

Distal view. . . • Distal CE line almost flat • Distal contact area also buccal to distal marginal groove, usually in area of D cusp

Occlusal View • Pentagonal (5 -sided) • Tapers towards lingual (wider M-D towards facial) • Also tapers distally • Five cusps: MB, ML, DB, D • Buccogingival ridge visible

Occlusal view… • Five triangular ridges • No true transverse ridges(? ) • Three pits and three fossae: mesial, central, distal • Four primary developmental grooves: central, (mesio)buccal, lingual, distobuccal

Root Form • Two roots: mesial and distal • Root depressions on both roots • Mesial root wider than distal – Two pulp canals: MB and ML canals • Distal root usually one canal

Anomalies: • D cusp sometimes not prominent or missing • May exhibit three roots (MB, ML, D)

How To Tell Right From Left: • Broader mesial root • Presence of distal cusp • Wider F-L towards mesial (tapers to the distal)

Permanent Mandibular Second Molar

General Characteristics • • Arch position: 7 th from midline Universal #18 and #31 More symmetrical than first molar* Four cusps, less complex than first

Development Timeline: • • Initial calcification: 2 1/2 - 3 years Enamel completed: 7 - 8 years Eruption: 11 - 13 years Root completed: 14 - 15 years

Facial View • Shorter and narrower than first molar • Mesial and distal outlines similar to first • Two buccal cusps, similar in size, separated by buccal groove • Buccogingival ridge present

Lingual View • Two lingual cusps, similar in size, separated by lingual groove

Mesial View • • Similar to first molar Facial HOC at cervical third Lingual HOC at middle third Mesial contact area buccal to marginal groove

Distal View • No distal cusp • Less taper towards distal than first molar • Distal contact area centered F-L, in the middle third O-C

Occlusal View • Rectangular/pentagonal outline • More symmetrical and simple than first molar • Slightly more supplementary anatomy than first • MB bulge • Four cusps: MB, DB, ML, DL

Occlusal view… • Two transverse ridges • Three fossae and three pits: mesial, central, distal • Three primary developmental grooves: central, buccal, lingual (form a pattern)

Root Form • Similar to first, except closer together • Mesial broader than distal

How To Tell Second From First: • Four cusps on second, five on first • + groove pattern on second • Roots closer together on second • More supplemental anatomy on second

How To Tell Right From Left: • Broader mesial root • MB bulge • Distal contour more convex than mesial

Permanent Mandibular Third Molar

General Characteristics: • Arch position: 8 th from midline • Universal #17 and #32 • Extremely variable, but always M-D dimension wider than F-L

Development Timeline: • • Initial calcification: 8 - 10 years Enamel completed: 12 -16 years Eruption: 17 - 21 years Root completed: 18 - 25 years

Crown Form • Two basic types – Similar to 2 nd molar, 4 cusps – Similar to 1 st molar, 5 cusps • More secondary grooves • Shortest O-C of any mandibular tooth

Root Form • • Extremely variable Most commonly two-rooted Crown: root ratio closer to 1: 1 Roots almost as short as maxillary 3 rds

Anomalies: • Often congenitally missing or impacted

How To Distinguish Third Molar: • Shorter roots • Occlusal table has more secondary grooves • Narrower occlusal table • No distal contact wear facet

How To Tell Right From Left: • F-L dimension wider towards mesial • If two roots: mesial broader than distal • Distal more convex than mesial • No distal contact wear facet

Tooth ID

Project 2

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