Tooth Morphology

Question 1

What is the cheek side of the tooth?

Answer 1

Buccal

Question 2

What is the opposite to the cheek side of the tooth?

Answer 2

Palatal if upper

Lingual if lower

Question 3

What is the orientation of the teeth towards the front of the head?

Answer 3

Mesial

Question 4

What is the orientation of the teeth towards the back of the head?

Answer 4

Distal

Question 5

What is cingulum?

Answer 5

Portion of the teeth that forms a convex protuberance at the cervical third of the anatomic crown

Question 6

What distinguishes an upper/lower incisor?

Answer 6

Uppers have roughly rectangular labial surface

Lowers have triangular or fan shaped labial surface

Question 7

For upper incisors how do you determine whether its central/lateral?

Answer 7

1st is larger

2nd is small/narrow

Question 8

For upper incisors how do you determine whether its R/L of mouth?

Answer 8

Mesial profile of crown is in straight line with root, distal side flares

Junction of mesial and incisal edge is sharp, distal is rounded

Cingulum is skewed distally

Question 9

For lower incisors how do you identify whether its 1st/2nd?

Answer 9

1st is smaller and crown is almost symmetrical

2nd is larger and crown shows more pronounced distal flare

Question 10

For lower incisors how do you determine left or right?

Answer 10

Mesial profile of crown is in straight line with root, distal side flares

Junction of mesial and incisal edge is sharp, distal is rounded

Cingulum skewed distally

Question 11

How do you distinguish an upper or lower canine?

Answer 11

• Crown shape - upper canine has stout crown with broad-diamond shaped surface and pointed cusp - lower canine has high, narrower crown with less pointed cusp
• Crown-root - Upper canine has crown set in straight line with root, lower is at an angle
• Level of ACJ - upper has ACJ at same level on labial and lingual sides
  Lower has enamel extending further apically on labial side

Question 12

How do you determine left or right?

Answer 12

• Mesial slope is shorter
• Mesial profile of crown is straighter and in line with root, distal side bulges out into a marked convexity and forms angle
• Cingulum skewed distally

Question 13

How do you determine whether upper/lower premolar?

Answer 13

Shape of occlusal surface - upper oval, lower round

Crown-root angle - Upper straight line, lower curved buccal

Question 14

For an upper premolar, how do you determine whether its first or second?

Answer 14

Upper 1st has larger cusps, buccal larger than lingual
Upper 1st has marked concavity “canine fossa” on mesial surface

Upper 2nd has smaller cusps than 1st
Upper 2nd has flat mesial surface

Upper 1st sometimes has 2 roots
Upper 2nd usually has one

Question 15

For upper premolar how do you determine orientation in mouth?

Answer 15

Proximal surfaces - upper 1st has concavity (CANINE FOSSA) on mesial surface, upper 2nd has flat mesial surface/convex distal surface

Lingual (palatal) cusp - both upper premolars show mesial displacement of lingual cusp, though this is less marked in second premolar

Question 16

For lower premolars how can you distinguish 1st/2nd?

Answer 16

Lower 1st premolar has large buccal cusp and very small lingual cusp

Lower 2nd has one or two cusps more closely approximating the buccal cusp in height

Question 17

For lower premolars how can you distinguish left or right orientation?

Answer 17

Lower 1st has flattened area on mesio-lingual aspect and often fissure running from mesial pit over on to this surface
Lingual cusp is often displaced slightly distally

Lower 2nd has mesial displacement of single lingual cusp, or if 2 cusps, mesial is larger

Question 18

How can you distinguish upper or lower molar?

Answer 18

Upper have 3 or 4 cusps with 3 roots

Lower has 4 or 5 cusps with 2 roots

Question 19

How can you distinguish upper 1st molar?

Answer 19

Has 4 cusps
Occlusal surface rhomboidal
Roots are long, well-shaped and separated

Question 20

How can you distinguish upper 2nd molar?

Answer 20

Varying degrees of reduction of disto-lingual cusp, which can either be slightly reduced/reduced/absent

Occlusal surface usually compressed mesiodistally, or may be triangular

Roots are shorter. more irregular, may be partly fused

Question 21

How can you distinguish upper 3rd molar?

Answer 21

Shows greater degree of reduction of disto-lingual cusp, which may be considerably reduced/absent

May be compressed/triangular

Shorter roots, more irregular, or completely fused

Question 22

How can you distinguish lower 1st molar?

Answer 22

Usually has 5 cusps
Crown regular and well shaped
Roots are long, well-shaped and well-separated

Question 23

How can you distinguish lower 2nd molar?

Answer 23

Usually 4 cusps
Crown regular
Roots are shorter, more irregular and partly fused

Question 24

How can you distinguish lower 3rd molar?

Answer 24

May have 3-6 cusps
Crown usually irregular
Roots shorter, more irregular, could be completely fused

Question 25

How do you identify primary incisors?

Answer 25

Same as permanent incisors

Question 26

How do you identify primary canines?

Answer 26

Often very difficult to identify as point of cusps may be placed centrally, or skewed mesially or distally

Question 27

How do you identify primary molars?

Answer 27

1st molars unlike any permanent tooth | 2nd primary molars same morphology as 1st permanent molars, with 4 cusps in maxilla and 5 in mandible

Question 28

How do you identify upper/lower and left/right in 1st primary molars?

Answer 28

Upper - quadrilateral in shape, wider buccolingually Lower - compressed buccolingually and longer mesodistally Molar tubercle is always found at mesiobuccal corner of cervical margin

Question 29

How do you identify 2nd primary molar orientation?

Answer 29

Same as for 1st molar in permanent dentition

Question 30

When do primary teeth begin mineralisation?

Answer 30

4-6 months

Question 31

Which primary teeth are the first to erupt and when?

Answer 31

Central incisors (A) - 6-7 months

Question 32

Which primary teeth are second to erupt and when?

Answer 32

Central incisors (B) - 7-8 months

Question 33

Which primary teeth are third to erupt and when?

Answer 33

1st molars (D) - 12 months

Question 34

Which primary teeth are fourth to erupt and when

Answer 34

Canines (C) - 18 months

Question 35

Which primary teeth are last to erupt and when?

Answer 35

2nd molars (E) - 24 months

Question 36

In what order do the permanent dentition erupt?

Answer 36

``` First molars - 6y Central incisors - 7y Laterals - 8y Canines - 9y Premolars - 10y Second molar -12y Third molars - 18y ```

Question 37

When do the permanent teeth begin mineralisation?

Answer 37

``` First molars - at birth Anteriors - 3-5 months (upper laterals 11 months) Premolars - 2y 2nd molars - 3y 3rd molars - 9y ```