Tooth Morphology

Question 1

Upper 1

Answer 1

Mesial surface parallel to long axis of tooth
Mesial angle right angle
Distal surface angled meaning edge of tooth is wider than the neck
Distal angle is more obtuse and rounded
Cingulum well marked and marginal ridges surround a deep fossa
Short bulky root, fairly circular in cross section
Labial surface convex at gingival third and flat towards the incisal edge

Question 2

Upper 2

Answer 2

Mesial angle very acute and sharp
Distal angle obtuse and rounded
Single root, compressed mesio-distally, distal groove normally the deepest
Low cingulum, and under developed marginal ridges enclose a shallow palatal fossa

Question 3

Compare upper 1 and upper 2

Answer 3

Upper 2 = thinner root, compressed mesio-distally rather than rounded
Upper 2 has a lower cingulum and loss developed marginal ridges so has a shallower palatal fossa
Mesial angel of 2 is more acute (sharp), distal angle is more obtuse (round)
Upper 2 has a smaller narrower crown

Question 4

Lower 1

Answer 4

Symmetrical crown
Mesial and distal angle both 90 degrees
Mesial and distal surfaces both parallel to long axis of the tooth
Crown is tilted lingually
Single root compressed mesio-distally (distal groove the deepest
Edge of cusp at right angle to labio-lingual axis

Question 5

Lower 2

Answer 5

Asymmetrical fan-shaped crown
Mesial and distal angle both 90 degrees
Mesial surface parallel to long axis of the tooth but distal surface diverges at a greater angle
Flattened root mesio-distally, distal groove the deepest
Edge of cusp is curved distally in a lingual direction
Crown is tilted lingually

Question 6

Compare upper and lower incisors

Answer 6

Uppers have broader crowns relative to height, lowers are narrower
Uppers have more palatal relief
Uppers have more circular root in cross section, lowers are much more compressed mesio-distally

Question 7

Upper 3

Answer 7

Longest and strongest root
Triangular crown
Mesial surface almost parallel to long axis of the tooth, distal surface is more obtuse
Mesial slop of incisal edge is shorter than distal
Labial surface is wider than palatal surface
Palatal ridge running down from cingulum splits palatal surface in mesio and distal palatal fossa
Root is triangular in cross section

Question 8

Difference between upper and lower 3

Answer 8

Similar but lower is smaller, with a shorter root
More symmetrical crown with less pronounced slopes
Rounded cingulum on lingual surface
Enamel extends further apically on lingual rather than labial surface
Crown tilted lingually
Upper has more palatal relief

Question 9

Right or left canine?

Answer 9

Mesial marginal ridge is more pronounced and medial slope is shorter than distal

Question 10

Compare upper and lower pre-molars

Answer 10

Crowns of uppers are more angular whilst crowns of lowers are more circular
In lowers the buccal cusp inclines lingually = buccal cusp more prominent than the lingual
Uppers are wider bucco-lingually whilst lowers are wider mesio-distally

Question 11

Upper 4

Answer 11

Mesial slope is longer and straighter than the distal
Central fissure may extend over the medial surface = canine groove
Canine fossa on medial surface continues into the roots
Palatal cusp lower and more central than buccal = asymmetrical
Crown is wider on buccal surface than palatal surface
2 roots

Question 12

Compare upper 4 and 5

Answer 12

Crown of 5 is smaller and rounder
Upper 5 = distal slope longer than mesial, upper 4 = medial slope is longer than distal 
Buccal cusp is short = more compressed
5 is single rooted but deeply grooved
No canine groove or fossa

Question 13

Lower 4

Answer 13

Smallest pre-molar
Dominating buccal cusp and small lingual cusp
Mesial slope shorter than distal
Canine groove on the medial surface
Single rooted, slightly compressed mesio-distally
Often has a disto-lingual accessory cusp that may eb as large as the lingual cusp

Question 14

Compare lower 4 and 5

Answer 14

5 is larger
Better developed lingual cusp and smaller buccal cusp in 5
5 = medial ridge is higher than the distal ridge
No canine fossa and groove
Both often have ditto-lingual accessory cusp

Question 15

Compare upper and lower molars

Answer 15

Uppers have 3-4 cusps whereas lowers have 4-5 cusps
Uppers are more rhomboid, lowers are mo re square
Uppers are more asymmetrical, lowers more symmetrical
Uppers have 3 roots, lowers have 2§

Question 16

Upper 6

Answer 16

Rhomboid shaped crown with 4 cusps sported by H shaped fissure
Mesio-palatal cusp is the largest
Tubercle of carabelli often present not he palatal surface of the mesio-palatal cusps
Distopalatal cusp is the smallest
3 roots - 2 buccal 1 palatal - palatal is longest and thickest

Question 17

Largest cusp on upper 6?

Answer 17

Mesio-palatal

Question 18

Smallest cusp on upper 6?

Answer 18

Disto-palatal

Question 19

Where is the Tubercle of Carabelli found?

Answer 19

Palatal surface of the mesio-palatal cusp

Question 20

What fissure connects the disto-buccal cusp and mesa-palatal cusp of the upper 6?

Answer 20

Oblique fissure

Question 21

3 types of upper 7

Answer 21

1. 4 cusp = similar to 6 but smaller
2. heart shaped = no disto-palatal cusp, T shaped fissure
3. Fusion of mesio-palatal and distal-buccal cusp (oblique fissure) = oval

Question 22

Roots of upper 7

Answer 22

3 roots, 2 buccal 1 palatal

Question 23

Upper 8

Answer 23

Most variable
Most common = similar to type 2 of 7 (heart shaped)
Roots often fused

Question 24

Lower 6

Answer 24

5 cusps = central fissure divides into buccal and lingual halves - and there is a distal cusp

Question 25

Lower 7

Answer 25

4 cusp separated by cross shaped fissure

Question 26

Lower 8

Answer 26

4 cusps

Reduction - becomes rounded rectangular or circular.