Aetiology of Dental Caries

Question 1

What are the cariogenic features of dental biofilm bacteria?

Answer 1

rapidly transport fermentable sugars when in competition with other plaque bacteria, and conversion of such sugars to acid

maintain sugar metabolism under extreme environmental conditions (low pH)

production of extracellular and intracellular polysaccharide

Question 2

What is the pathway of sugars to acid?

Answer 2

glycolysis-based pathway

Question 3

What sugars do bacteria convert to acid?

Answer 3

glucans and fructans

Question 4

What bacteria is shown and what is it notorious for?

Answer 4

s. mutans

extremely cariogenic

Question 5

What are the 3 cariogenic qualities?

Answer 5

ability to produce acid (acidogenicity)

ability to withstand acid

ability to adhere to teeth

Question 6

Can caries develop without S. mutans?

Answer 6

yes, but also high levels of S. mutans can be present without the development of caries

Question 7

What bacteria is important in lesion progression?

Answer 7

lactobacilli

Question 8

What bacteria is important in the caries initiation?

Answer 8

S. mutans

Question 9

Lactobacilli are the pioneer organisms in dentine caries, why is this (5 reasons)?

Answer 9

Question 10

When does lactobacilli become established?

Answer 10

there is a decrease in pH and S. mutans decreases

Question 11

What does the lactobacilli pioneer?

Answer 11

dorsum of tongue

Question 12

What type of bacteria are lactobacilli?

Answer 12

gram positive, non-spore forming rods

Question 13

What type of bacteria are Actinomyces?

Answer 13

gram-positive, non-spore forming filaments

Question 14

What is the fermentation equation of actinomyces?

Answer 14

glucose to lactic acid

Question 15

What bacteria have the ability to induce root caries?

Answer 15

A. viccosus

A. naeslundii

Question 16

What is the sign of early caries?

Answer 16

white spot lesions

Question 17

Can one bacteria be said to be the primary cause for root or enamel caries?

Answer 17

no

Question 18

What is the ecological plaque hypothesis?

Answer 18

caries becomes a consequence of changes in the natural balance of the resident microflora as a result of an alteration in the environment

Question 19

What are the aetiological variables causing caries susceptibility?

Answer 19

intrinsic and extrinsic factors to the tooth

Question 20

What are the intrinsic factors to the tooth?

Answer 20

enamel composition

enamel structure

tooth morphology

tooth position

Question 21

What are the extrinsic factors?

Answer 21

saliva
diet
use of fluoride
immunity

Question 22

What is the resting pH of plaque?

Answer 22

6.5 to 7

Question 23

How long does it take for plaque pH to fall to around 5 after rinsing mouth with sugar?

Answer 23

2-3 mins

Question 24

What curve is used to measure plaque pH and minutes after sucrose rinse?

Answer 24

stephens curve

Question 25

What does the speed of the pH drop indicate?

Answer 25

speed of sugar metabolism in plaque

Question 26

What acids can be made by bacteria?

Answer 26

mainly lactic acid also, aceitic acid, propionic acid

Question 27

What is the critical pH?

Answer 27

5.5

Question 28

What occurs at the critical pH?

Answer 28

acidogenic theory when the pH lower beyond 5.5, drives the dissolution of the calcium phosphate (hydroxy apatite), inhibit growth of beneficial bacteria and promote growth of acidogenic bacteria decrease pH further and promote carious lesion

Question 29

What dissolves at ph5.5?

Answer 29

enamel dissolves

Question 30

How does plaque store glucose as?

Answer 30

glycogen

Question 31

What increases the bulk of the plaque?

Answer 31

bacteria synthesising extracellular polymers from simpler sugars

Question 32

What breaks down sucrose into fructose/glucose?

Answer 32

glycosyltransferases

Question 33

What do bacteria do with the energy used from the breakdown of sucrose to glucose/fructose?

Answer 33

build polymers of glucose an fructose e.g glucan

Question 34

What does the polysaccharide allow?

Answer 34

sticky environment for the plaque organisms allows bacteria to form plaque on teeth

Question 35

What can plaque control methods target?

Answer 35

glucosyltransferases

Question 36

What type of diet do you find higher numbers of mutans?

Answer 36

sucrose rich diets

Question 37

What sugar creates bulkier plaque?

Answer 37

sucrose

Question 38

How does sucrose encourage dextran production in the plaque?

Answer 38

sucrose encourages dextran production in the plaque due to the energy released once the sucrose molecule is broken down into 2 monomers

Question 39

What sugars are non-cariogenic?

Answer 39

sweeteners (sugar alcohols)

Question 40

What sweetener is thought to prevent caries?

Answer 40

xylitol

Question 41

How does xylitol prevent caries?

Answer 41

affects bacterial growth and metabolism affects de and remineralisation reduced biofilm formation decreases the number of S. mutans

Question 42

What can remineralize enamel?

Answer 42

calcium or fluoride released form food

Question 43

If you are frequently eating sugar, what can be enhanced?

Answer 43

demineralisation enhanced

Question 44

What things can increase a babies chance of caries (dietary)?

Answer 44

sticky products sweetened dummies sweetened drinks in nursing bottles prolonged breast feeding