Permanent Mandibular Molars

Introduction Larger than the premolars in all dimensions, 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 6th tooth from midline Universal #19 and #30 Largest, strongest tooth in mandibular arch

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

Development Timeline: Initial calcification: at birth* Enamel completed: 2½ - 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 from this view

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, in the middle third but close to the junction of occlusal and middle thirds Generally more convex than mesial

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

Occlusal outline... 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 Facial HOC at cervical third Lingual HOC at middle third

Mesial view... CE line more occlusal on lingual than buccal ~ 1 mm Root length of lingual > buccal length Mesial contact area buccal to marginal groove, at junction of occlusal and middle thirds

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, DL, DB, D Bucco-gingival ridge visible Occlusal table shifted lingually – see more of buccal surface

Occlusal view… Five triangular ridges No true transverse ridges(?) Three pits and three fossae: mesial, central, distal Four primary developmental grooves: central, mesiobuccal, 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: 7th from midline Universal #18 and #31 More symmetrical than first molar* Four cusps, less complex than first

Development Timeline: Initial calcification: 2½ - 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, more similar in size, separated by buccal groove Buccogingival ridge present

Lingual View Two lingual cusps, similar in size, separated by lingual groove Mesial HOC at junction of occlusal and middle third Distal HOC at middle third

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* Less lingual taper than first 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

Incline planes:

Permanent Mandibular Third Molar

General Characteristics: Arch position: 8th 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 More secondary grooves Similar to 2nd molar, 4 cusps Similar to 1st 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 3rds

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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