Permanent Maxillary Molars

Maxillary First Molar

General Characteristics Arch position: 6th tooth from midline Universal #3 and #14 Mesially, contacts primary 2nd molar and later 2nd premolar Largest tooth in maxillary arch Largest crown in mouth Least variable in anatomic form among max molars

General form: Three roots: L, MB, DB Slightly wider F-L than M-D Trapezoidal geometric form F/L and proximal views Occlusal view: rhomboidal geometric form (described as 5-sided) mesial facial

Development Timeline: Initial calcification: at birth* Enamel completed: 3 - 4 years Eruption: 6 - 7 years Root completed: 9 - 10 years

Facial view, mesial outline: Mesial HOC at junction of occlusal and middle thirds Outline relatively flat cervical to mesial HOC M-D > O-C dimension

Facial view, distal outline: Distal HOC at middle third Entire distal outline convex Disto-occlusal angle more rounded than mesio-occlusal angle Distal surface visible from facial view (rhomboidal effect)

Facial view, cervical line: Oftentimes a V-shape dip CE line pointing towards buccal bifurcation

Facial view, occlusal portion: MB and DB cusps separated by buccal groove MB cusp wider, DB cusp tip sharper* (sharpest of 4 cusps) ML cusp visible between MB and DB cusps

More facial… Buccal groove usually ends midway O-C in a buccal pit Bucco-gingival ridge runs horizontally, more prominent towards mesial Facial HOC at cervical third

Lingual View DLG separates larger ML cusp from smaller DL cusp DLG oftentimes terminates in lingual pit Lingual groove midway M-D M-D width as wide or wider lingually than facially*

Lingual view… Cusp of Carabelli* Lingual HOC at middle third Georg Carabelli court dentist to Austrian emperor (1842 A.D.) Cusp of Carabelli* Lingual surface of ML cusp Varies in size: non-existent to prominent Lingual HOC at middle third Lingual root depression*

Mesial view, facial outline: Buccal HOC at cervical third (bucco-gingival ridge) Facial surface fairly flat from HOC to cusp tip

Mesial view, lingual outline: Lingual HOC at middle third Overall convex curvature Palatal root apex is lingual to the crown

Mesial view, occlusal outline: Only MB and ML cusps visible Mesial marginal groove usually present, midway of marginal ridge Mesial contact area situated buccal to mesial groove, at junction of occlusal and middle thirds

Distal View More of occlusal surfaces visible All four cusp tips visible Distal marginal groove usually present, midway of marginal ridge Pronounced distal cervical crown/root concavity*

Distal view… More of facial surface visible, but less of lingual surface (rhomboidal form) Distal contact area located midway F-L, more cervical than mesial contact (middle third) Mesial view

Occlusal View Rhomboidal geometric form 5-sided (pentagonal) Acute MB and DL corners Obtuse DB and ML corners 5-sided (pentagonal) Largest F-L dimension of any tooth*

Occlusal view… F-L and M-D dimensions more nearly similar* M-D width as wide or wider lingually than facially* Four major cusps: ML, MB, DB, DL (largest to smallest) Cusp triangle: MB, DB, ML (trigon)

Occlusal view… Transverse ridge Oblique ridge Triangular ridges of MB and ML cusps Oblique ridge Triangular ridges of DB and ML cusps (distal cusp ridge?) About same height as the marginal ridges* Mesial 2/3 looks like max premolar

Occlusal view… Three pits: mesial, central, distal Three primary developmental grooves: central, buccal, distolingual Four fossae: mesial, central, distal, distolingual

Root Form Root trunk with trifurcation: Lingual root: Largest, longest Wider M-D than F-L* MB root 2nd largest Apex in line with MB cusp tip* DB root Smallest of three

Root form... DB root area may have pronounced cervical concavity* MB and DB root forms look like “plier handles” MB root could have two pulp canals (70% possibility) Root depression, lingual surface of lingual root

How To Tell Right From Left: Distolingual groove Cusp of Carabelli on ML cusp Broader MB root than DB root MB prominence of facial surface

Maxillary Second Molar

General Characteristics Arch position: 7th from midline Universal #2 and #15 Wider F-L than M-D Similar to 1st, except smaller Smaller DL cusp

Development Timeline: Initial calcification: 2½ - 3 years Enamel completed: 7 - 8 years Eruption: 12 - 13 years Root completed: 14 - 16 years

Facial View Narrower M-D than 1st MB cusp larger than DB M-D > O-C dimension MB cusp larger than DB Buccal groove more distally located than 1st MB root tip in line with buccal groove*

Lingual View Smaller DL cusp than 1st Lingual groove more distally located No Cusp of Carabelli

Mesial and Distal Views Similar to 1st except shorter O-C Facial HOC at cervical third Lingual HOC at middle third Mesial HOC at junction of occlusal-middle Distal HOC slightly more cervical

Occlusal View Narrower M-D than F-L Tapers lingually Two major crown forms: - Rhomboidal - Heart-shaped (diminished DL cusp)

Root Form MB and DB roots closer than 1st MB apex in line with buccal groove* No lingual root depression

How To Tell First From Second: Occlusal view of first less rhomboidal than second Cusp of Carabelli only on first M-D and F-L dimensions more similar with first, narrower M-D with second*

First from second... MB root apex in line with MB cusp tip with first, in line with buccal groove with second*

Maxillary Third Molar

General Characteristics Arch position: 8th from midline Universal #1 and #16 No distal contact area Only maxillary tooth that has single opposing tooth* Smallest of all molars - shortest O-C dimension of any tooth*

Development Timeline: Initial calcification: 7 - 9 years Enamel completed: 12 - 16 years Eruption: 17 - 21 years Root completed: 18 - 25 years

Crown Form Most variable of maxillary posteriors Heart-shape most common Diminished or absent DL cusp 3-cusp form (L, MB, DB cusps) Still wider F-L than M-D Occlusal table more constricted No distal contact wear facet

Root Form Three roots, partially or fully fused Roots much shorter than 1st and 2nd, crown:root ratio closer to 1:1 Roots shorter than any other tooth (other than mandibular 3rds)

How To Distinguish a Third: Shorter root: Crown to root ratio nearly 1:1* Roots usually fused More supplemental occlusal grooves* Heart-shape occlusal outline, narrower occlusal table

How To Tell Right From Left: MB root larger than DB root MB prominence of facial surface DLG, if present Contact area wear facet only on mesial

TOOTH ID

That’s All, Folks!