TOOTH MORPHOLOGY

PERMANENT DENTITION

PERMANENT MOLARS

• 12 molars

• 1st at 6 years old

• non-succedaneus

• Formed from 5 lobes (II,III can be from 4)

• 3 major cusps (max) 4th lobe forms minor cusp

• 5th lobe forms supplementary cusp:

• Max – DL

• Man – D

• Functional just – Carabelli – Max I molar

MAXILLARY 1 MOLAR

• Largest in the arch

• Broad MD and BL

Facial View

• 4 cup• DB – sharper and longer

• B developmental groove

divides 2 B cusps

• Cervical line – curved toward occlusal

• M outline – straight from

cervical to M contact

• Contact – middle & occlusal thirds• D – outline = convex,

contact – center of the middle third

• Only lingual cusps can be seen• ML cusp longer & larger• Wide MD & BL• M outline – straight, D - more convex• L developmental groove from L becomes D

oblique groove = DL developmental groove

Lingual view

• Carabelli = tubercle, separated by ML groove from ML cusp

• 3 roots can be seen from L• Roots twice long than crown• L root longer• THE MORE POSTERIOR • - SMALLER TEETH• - ROOTHS CLOSER TO CENTER LINE OF TOOTH

Mesial view

• View profile of Carabelli

• L crest – center of the mid third &

• B crest – cervical third

• Cervical line is slightly convex M

Distal view

• Crown tapered D

• Cervical line straighter

• D surface of the crown is convex with concavity at the root trunk

• D marginal ridge – shorter, seen on occlusion

• DB root – narrowest of all three

• Crown wide M and L• 4 functional cusps, one – non• DL cusp – major (minor on II,III)• Center fossa – major, • B development groove – from central

development pit• M & D triangular – minor• Oblique ridge – ML cusp tip to DB cusp tip

Occlusal view

Grooves

• Facial

• Central M, D

• DL (oblique)

• ML groove (cusp Carabelli)

• M marginal

• D Marginal

Maxillary 2nd MolarFacial view

• Shorter cervicoocclusally and narrower MD than 1st molar

• B roots – same length, closer together

• DB root has no curvature• MB root – greater

curvature toward D at apex

Lingual view

• No cusp of Carabelli

• DL cusp is smaller than 1st molar

Mesial view

• Crown is shorter but BL similar to 1st molar

• Roots closer together

Distal view

• DB cusp – smaller

• More MB cusp can be seen

Occlusal view

• MD diameter – smaller

• BL diameter – similar

• More supplemental grooves and pits

Maxillary 3rd molar

• Varies shape, size• Crown shorter, fused roots• Occlusal outline heart-shaped• DL cusp poorly formed• Tendency to be impacted

Maxillary roots

• Trifurcation• Palatal root – longest, DB – shortest• All 3 roots visible from B view• 2 B roots incline D, and D root

straighter and curved M at the end• A deep developmental groove runs

between the bifurcation and cervical line

Characteristics of Maxillary roots

• Shorter to posterior

• Less divided to posterior

• More varied in shape, size, directions

Pulp cavity of Maxillary molar

• Pulp chamber, 3 main canals

• 1st molar can have 4 canals (2 in the MB root)

• Some 3rd molars can have 4 root canals

• One pulp for each cusp (4 in all)