Tooth Morphology

Question 1

How many adult and primary/deciduous human teeth are there?

Answer 1

Adult human teeth - 32 (including wisdom teeth)
Primary/deciduous teeth - 20

Question 2

How many teeth are in the maxilla and mandible for adult and primary/deciduous teeth?

Answer 2

Adult - 16 in the upper and lower arch
Primary/deciduous - 10 in upper and lower arch

Question 3

What are the main layers of teeth?

Answer 3

Enamel - the hard, highly mineralised outer shell of the tooth
Dentine - the middle layer, higher organic content
Pulp - the nervous and vascular structures at the centre of the tooth

Question 4

What is the name of the structures which support the teeth?

Answer 4

The periodontium

Question 5

What is the periodontium and its function?

Answer 5

The periodontium is the name given to the structures which support the teeth. This includes bone and periodontal ligaments between the bone and root.

Question 6

What are the 4 types of teeth and their functions?

Answer 6

Incisors (central and lateral) and canines - to cut and shear food preparatory to grinding
Premolars and molar - to chew and grind food

Question 7

What is the most common charting classification of teeth in the UK?

Answer 7

The Zsigmond charting classification

Question 8

How does the the Zsigmond charting classification work?

Answer 8

1. Mouth is split into 4 quadrants
2. Each tooth is numbered 1-8 from centreline going backwards
3. Quadrants divided into left and right from viewers perspective

Question 9

How many teeth are there of each type in an adult?

Answer 9

8 incisors
4 canines
8 premolars
12 molars

Question 10

What is a cusp?

Answer 10

An elevation (rounded or pointed) area of the crown of a tooth.

Question 11

What is a fissure?

Answer 11

A small groove found on the surface of a tooth.

Question 12

What is a pit?

Answer 12

A small sharp depression on the surface of a tooth.

Question 13

What is a fossa?

Answer 13

A small depression usually round or angular on the surface of a tooth.

Question 14

What is the contact area?

Answer 14

The point of contact between 2 teeth.

Question 15

What does interproximal mean?

Answer 15

The space between the proximal surfaces of adjoining teeth.

Question 16

What is the marginal ridge?

Answer 16

A slight elevation of the occlusal table at the mesial or distal surfaces of premolars and molars OR the lingual surfaces of incisors and canines.

Question 17

What is a lobe?

Answer 17

A separate division of tooth growth at calcification. In a central incisor there is usually three facial lobes visible. The fourth lobe is the cingulum. A cingulum is a ridge usually found at the back (palatal or lingual surface) of incisors and canines around the cervical area -the body of the tooth around neck where crown transitions to root.

Question 18

What are mamelons?

Answer 18

Rounded prominences usually seen on the incisal edges- there are usually 3- but with age, they tend to wear away.

Question 19

What are perikymata?

Answer 19

Essentially a series of growth lines analogous to that of a tree, usually present on the surface as ‘wavy curves or lines’- these tend to wear away with abrasion.

Question 20

What are embrasures?

Answer 20

The space in the interproximal area that opens up (from the contact area) labially, palatally/lingually. This space is usually triangular in shape.

Question 21

What are line angles?

Answer 21

This is the angle where 2 surfaces meet e.g. mesial/distal-facial.

Question 22

What is the general anatomy of the maxillary central incisor?

Answer 22

The central incisor has a wedge or spade shape. Mesial aspect is a straight line at 90
degrees to the incisal edge. The distal aspect is more rounded morphology. The front surface has a convex shape, whilst the back palatal surface has a convex shape. On the concave palatal surface there are well defined marginal ridges and cingulum.
In natural teeth, there will be mammelons, lobal form
(usually 3 in central incisors) etc. There is a single root will
slight distal inclination.

Question 23

What is the general anatomy of the lateral incisor in the maxilla?

Answer 23

The lateral incisors are smaller, but also have an acute
mesial angle and rounder distal angle to the incisal edge. The incisal edge slopes downwards to the disto-incisal junction. The palatal aspect is more concave compared to the central incisor and can house a pit known as foramen caecum incisivum. They have a single rounded root, which also has a slight distal inclination at the apex.

Question 24

What is the general anatomy of the maxillary canine?

Answer 24

They constitute a single cusp, which converges to a single point. The mesial slope is shorter than the distal slope They have a highly convex labial surface and a bulbous palatal
surface with a cingulum. They have a very long root.

Question 25

What is the general anatomy of the mandibular central incisor?

Answer 25

The smallest tooth in the permanent human dentition. The mesio-incisal and distoincisal angles are
acute/ 90 degrees, they have a relatively smooth lingual aspect with very few distinguishing features.
The labial surface has a slight convexity and lingual concavity. The single root has a slight distal
inclination.

Question 26

What is the general anatomy of the mandibular lateral incisor?

Answer 26

The lateral incisor is very similar to the central incisor, but with a few subtle differences. They are
slightly larger than the central incisor, it is fan shaped with a greater incisal edge length. The incisal edge also slightly slopes down from mesial to distal. The marginal ridges palatally are slightly more visible vs. central incisor. They have a single root.

Question 27

What is the general anatomy of the mandibular canine?

Answer 27

In contrast to the maxillary canine, the mandibular canine crown is smaller mesiodistally relative to the root. The distal aspect also curves around more than the mesial aspect. The cingulum is not as well defined as the maxillary. The mesial slope of the single cusp, similarly to the maxillary canine is shorter compared to the distal slope. There is a single root which can be bifurcated.

Question 28

What are the annotations for the primary teeth?

Answer 28

A - Central Incisors
B - Lateral Incisors
C - Canines
D - 1st Molars
E - 2nd Molars

Question 29

What are the number roots for the maxillary teeth?

Answer 29

Central Incisor 1 1 1 1
Lateral Incisor 1 1 1 1
Canine 1 1 1 1
1st Premolar 2 2 1 1
2nd Premolar 1 1 or 2 1 1
1st Molar 3 3 or 4 2 3
2nd Molar 3 (often fused) 3 2 2
3rd Molar 3 (often fused) (H. variable) 2 (H. variable)