Caries Causation

Question 1

Primary causal factor of dental caries?

Answer 1

Plaque

Question 2

Plaque biofilm is the necessary and sufficient cause of dental caries.

Answer 2

False, it is not sufficient to cause dental caries but it is necessary.

Question 3

Dental caries is a non-communicable __________ disease.

Answer 3

Bacteria-related

Question 4

The responsible bacteria, and other micro-organisms, are located in a biofilm - ___________ - which adheres to tooth surfaces.

Answer 4

Dental plaque

Question 5

When plaque bacteria are exposed to refined carbohydrates, especially ______, in the human diet, sucrose is ____________ by particular bacterial species.

Answer 5

Sucrose; fermented to acid

Question 6

The acid is ______ against the tooth surface by the plaque biofilm and _____ through the enamel layer into dentine resulting in dissolution of the tooth mineral.

Answer 6

Trapped; diffuses

Question 7

The Stephan curve describes ________ in plaque following exposure to sucrose or glucose.

Answer 7

pH changes

Question 8

Describe the pH levels after exposure to glucose.

Answer 8

Plaque pH falls quickly following exposure to glucose and will rise back to its original value after 20 minutes or so, unless exposure continues.

Question 9

What happens to enamel in sustained pH fall?

Answer 9

Enamel decalcification occurs.

Question 10

What happens when pH returns to around 6?

Answer 10

Enamel calcification occurs; the decalcified enamel remineralises

Question 11

What is this?

Answer 11

Stephan curve

Question 12

Describe this graph/result

Answer 12

Duplicate curves of pH changes in plaque as measured by a microelectrode built into an extracted tooth on 2 days showing that the curves are reasonably reproducible.

Question 13

Describe this curve

Answer 13

Effect of plaque pH of the local application of drops of 0.5% sugar solutions at 2-min intervals - note the marked response to low concentrations of sugar and the prolonged fall.

The sugar did not reach the tongue so that saliva flow was not stimulated - this result may, therefore, differ from the changes during normal eating when saliva flow is stimulated and the saliva probably reaches the plaque, but may resemble the changes in plaque when saliva cannot easily reach it as in fissures and inaccessible contact points.

Question 14

Describe this figure

Answer 14

Effect of sugar rinse on the pH of plaque of different ages measured by microelectrodes built into an extracted tooth.

With the older plaques, the pH fall begins during the sugar rinse, reaches lower pH values and returns more slowly than with the 1-day-old plaque.

Mature 5-day plaque has the greater cariogenic potential. The pH dropped immediately rinsing commenced and remain depressed.

Question 15

Which sites do carious lesions occur at?

Answer 15

Occurs at sites where mature plaque remains undisturbed - in fissure pits, between teeth on approximal surfaces, and along gingival margins.

Question 16

Organic acids (the sucrose fermentation products) dissolve dental mineral in enamel (and at a later stage in dentine) known as _____, which is crystalline __________.

Answer 16

Apatite; calcium phosphate

Question 17

When fermentation is complete following a _____ sucrose exposure ____________________________, saliva neutralises the acid and remineralisation occurs - salivary calcium and phosphate precipitate back into the enamel. There is no _____ of mineral.

Answer 17

Brief; and in the absence of another exposure; no net loss of mineral

Question 18

Multiple cycles of _______ and ________ occur throughout the day associated with exposures to sucrose.

Answer 18

Demineralisation; remineralisation;

Question 19

The process of demineralisation and remineralisation is considered physiological and normal if?

Answer 19

If there is no net loss of tooth mineral

Question 20

When sucrose exposure is sustained ___________, the balance between demineralisation and remineralisation is tipped in favour of demineralisation with consequent net loss of mineral.

Answer 20

During which acid conditions persist

Question 21

When sustained acid conditions persists, macroscopic signs of enamel demineralisation (_______) emerge and indicate the disease of dental caries has initiated.

Answer 21

White spot lesions

Question 22

White spot lesion is not the disease - it is merely a?

Answer 22

Merely a manifestation of the disease

Question 23

How to identify white spot or a cavity?

Answer 23

Caries lesion

Question 24

When can we claim that caries is in remission?

Answer 24

Only when all white spot lesions have arrested and when the incidence of new lesions is zero.

Question 25

Explain this model

Answer 25

Mouth is represented by the pink circle. The black circle represents the environment.

Risk of caries depends on what is shoveled into the mouth and how individuals manage their plaque control. Importantly, what individuals do depends mainly on their social circumstances and peer group pressure.

This helps to explain the wide variation in caries experience (DMFS) across individuals and social groups.

Question 26

Epidemiological studies show that tooth loss due to dental caries far outweighs tooth loss due to periodontal disease.

Answer 26

True

Question 27

Withdrawal of all measures of oral hygiene in 12 healthy persons with clinically normal gingivae resulted in?

Answer 27

Gross accumulations of soft debris and the development of marginal gingivitis in all subjects.

Question 28

The time necessary to develop gingivitis varied from?

Answer 28

10 to 21 days

Question 29

This is an example of?

Answer 29

Clean teeth

Question 30

Describe this electron micrograph

Answer 30

Shows a scratch on a recently cleaned enamel surface - note bacterial colonies at the base of the scratch withstood the cleaning process

Question 31

What’s happening in this EM?

Answer 31

Bacterial colonies at the base of the scratch quickly multiplied and spilled out over the previously clean surface.

Question 32

Describe this electron micrograph

Answer 32

Other species adhere in succession - cocci are not the original colonisers

Question 33

Describe this electron micrograph

Answer 33

Cocci became sandwitched between the next layer

Question 34

Describe this image

Answer 34

Thick plaque covering the maxillary central incisors has been present for weeks.

Question 35

List the plaque index

Answer 35

Score 0 Clean surface - no visible plaque

Score 1 - no visible plaque but it can be wiped off the tooth surface with a periodontal probe

Score 2 Visible plaque - will appear after 24 hours following careful toothbrushing

Score 3 Thick visible plaque has been present for days or weeks

Question 36

Describe the calculation of the Plaque Index (PII)

Answer 36

Each tooth is scored on the 0-3 scale. The PII is the mean of the tooth scores.

This index score, by itself, is not very useful - it is difficult to interpret, for example, a score of 0.5??

It is more meaningful to report the percentage of teeth or tooth surfaces scored 0, 1, 2, or 3.

Similarly for the Gingival Index (GI)

Question 37

Describe this image

Answer 37

There is no sign of inflammation along the gingival margins of 11 and 21. Gingival Index Code 0

Question 38

Describe this image

Answer 38

Marginal inflammation on 11 and 21. Gingival Index Code 1 or 2??

Question 39

Describe this image

Answer 39

The gingiva bleeds on gentle probing, therefore Code 2

Question 40

Describe this image

Answer 40

The teeth in the previous slide have been brushed, but the gingivitis remains. Dentists/hygienists know if teeth have been just cleaned prior to a dental visit

Question 41

Describe this image

Answer 41

gingival Index Code 3 - the gingiva bleed spontaneously when inspected with sharp eyes.

Question 42

Concurrent bacteriological examinations showed what in the Lo