Permanent Maxillary Molars Maxillary First Molar General Characteristics

Permanent Maxillary Molars

Maxillary First Molar

General Characteristics • Arch position: 6 th tooth from midline • Universal #3 and #14 • Mesially, contacts primary 2 nd molar and later 2 nd premolar • Largest tooth in maxillary arch • 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)

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

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 this view

Facial view, cervical line: • Oftentimes a Vshape 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* • 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 • M-D width as wide or wider lingually than facially*

Lingual view… • 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 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)

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

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

Occlusal view… • Transverse 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*

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

Root Form • Root trunk with trifurcation: – Lingual root: • Largest, longest • Wider M-D than F-L* – MB root • 2 nd 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: 7 th from midline Universal #2 and #15 Wider F-L than M-D Similar to 1 st, except smaller • Smaller DL cusp

Development Timeline: • • Initial calcification: 2 1/2 - 3 years Enamel completed: 7 - 8 years Eruption: 12 - 13 years Root completed: 14 - 16 years

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

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

Mesial and Distal Views • Similar to 1 st except shorter O-C • Facial HOC at cervical third • Lingual HOC at middle third

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 1 st • 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: 8 th 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 • 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 1 st and 2 nd, crown: root ratio closer to 1: 1 • Roots shorter than any other tooth (other than mandibular 3 rds)

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