Tooth morphology

Question 1

Permanent incisors

Answer 1

Chisel shape
Mesioincisal edge almost 90⁰
Distoincisal angle more rounded
Cervix of tooth curved
Upper roots rounded, lower roots oblong

Question 2

Permanent canines

Answer 2

Two incisal edges meeting at point (cusp) - can put a lot of pressure on it
Very long roots
-about 3x length of crown
-when developing roots extend very close to orbit

Question 3

Premolars

Answer 3

Two cusps of unequal size except on upper 5s (buccal largest)
Crushing/ grinding action
Have single root except upper 4s (2)
Uppers have oval crown outline
Lowers have round crown outline

Question 4

Permanent molars

Answer 4

Broad occlusal outline ('cube'-shaped)
Reduction in size from 6 to 7 to 8
Multiple cusps - reduction in number of cusps from 6 to 7
Lowers - rectangular with 2 roots
Uppers - rhomboid with 3 roots

Question 5

Compare morphology of primary teeth and permanent teeth

Answer 5

A, B, C same morphology as 1, 2, 3
E=small 6
D = nothing else (mix of premolar and molar morphology)
-has tubercle of Zuckerkandl on mesiobuccal aspect

Question 6

Crown and pulp primary vs permanent

Answer 6

Crown more bulbous in primary teeth, larger pulp chamber in primary teeth

Question 7

Colour of primary vs permanent teeth

Answer 7

Primary whiter - 92% CaHAP therefore more opaque than 96%

Question 8

Roots primary vs permanent teeth

Answer 8

Primary molars have flared roots to allow adult teeth to grow underneath

Question 9

Lower 1 vs 2

Answer 9

Sharper mesial corner in 1 than 2
Both have a cingulum
2 is fan shaped
Both have 1 root

Question 10

Compare lower and upper 3

Answer 10

Lower narrower than upper
Short edge mesial in both
No cingulum in both
1 root (3x length of crown)

Question 11

Lower 4 vs 5

Answer 11

4 has 2 cusps, 5 has 3 cusps
Both have 1 root, but 4’s root is smaller and shorter
Larger cusps buccal

Question 12

Lower 6 vs 7 vs 8

Answer 12

6 has 5 cusps (3 buccal), 7 and 8 have 4 even cusps
All have 2 roots
Lingual side more smooth and rounded than buccal for tongue groove on all
Buccal side more bulbous
Distal narrower than mesial

Question 13

Upper 1 vs upper 2

Answer 13

Both have 1 root, a cingulum and a square corner

2 smaller than 1

Question 14

Upper 4 vs 5

Answer 14

4 has 2 roots, 5 has 1
Both have 2 even cusps, buccal larger on 4
Canine fossa on 4, not 5

Question 15

Upper 6 vs 7 vs 8

Answer 15

6 has cusp of carabelli on mesiopalatal aspect
All have 4 cusps and 3 roots
8 is ‘trigon’ shaped and roots are often fused