CE: The agent

Question 1

Host (tooth surface)

Answer 1

age (deciduous teeth more susceptible to demineralization), fluoride presence, root surface exposure, saliva flow rate & buffering capacity
- Higher chance if low in nutrients (magnesium & Vit D) necessary for healthy tooth development

Question 2

Substrate (food)

Answer 2

Oral clearance, oral hygiene, eating frequency, food detergency, consumption of carbohydrates, carcinogenicity of consumed carbs
- When not actively removed, consumed more frequently, more sugars (sucrose containing) and sticky food à higher risk of caries

Question 3

Oral bacteria

Answer 3

Development of caries depends on microbial load, plaque composition & acidogenicity & aciduricity, oral hygiene, fluoride presence in plaque

Question 4

Time

Answer 4

Shift in microflora occur over short period, significant amount of time needed for
demineralization à white-spot or carious lesions – acid production doesn’t instantly cause decay,
early stages of remineralization can restore enamel

Question 5

Biofilm

Answer 5

bacteria collect on edge of gums in cream-colored mass = plaque

Question 6

Formation of an acellular layer

Answer 6

acquired pellicle= salivary glycoproteins, phosphoproteins, and lipids but NO bacteria – forms almost immediately on naked
enamel surface

Question 7

Initial attachment

Answer 7

free-floating early colonizers (Strep. sanguinis) normally inhabits
mouth and form initial attachment to pellicle by weak and reversible van der Waals forces – if bacteria not removed, anchor themselves w/ adhesive structures

Question 8

Irreversible attachment

Answer 8

bacteria unable to attach to pellicle begin to adhere to 1st layer of colonizers via specific adhesion-receptor interactions – bacteria replicate and form
microcolonies embedded in ECM

Question 9

Early maturation

Answer 9

increased dental plaque complexity due to allogenic factors (O2 consumption w/n plaque creating anaerobic zones) – cell division and recruitment of new bacteria & increase bacteria population

Question 10

Later maturation

Answer 10

microbial diversity continues to increase, while rates of cell division decreases – constant turnover of cells but overall composition remains roughly the same & thick 3D layer of dental plaque biofilm

Question 11

Dispersion

Answer 11

enzymes that degrade biofilm & bacteria detach themselves from biofilm (sometimes in response to deleterious environ conditions in order to spread/colonize new
surfaces

Question 12

Sugar metabolism

Answer 12

Extracellular invertase cleaves energy rich bonds btw glucose & fructose & bacterial cell transports sucrose across cell mem & cleaves bond via intracellular invertase & extracellular glycosyltransferases polymerize glucose molecule
while liberating fructose molecule so its free to enter bacterial cell & extracellular fructosyltransferases polymerize fructose while glucose molecule liberated to be freely
Intervention: taken up by cell & salivary amylase cleave polysaccharides

Question 13

Acid production

Answer 13

Convert glucose, fructose, and sucrose into acids via glycolysis (main
energy generating pathway in all bacteria)
- Additional intermediate steps for S. mutans (ability to metabolize pyruvate further
à more energy & acid byproducts) – when excess sugars available, favor lactate dehydrogenase & lactic acid (btw meals metabolize energy reserve & produce
formic & acetic acid instead)

Question 14

Etiology in Health & Disease

Answer 14

mature dental plaque= highly complex community of microbes, population varies person to person & btw diff sites in oral cavity (800 distinct oral species) healthy person has 50-100 diff species @ 1time

Question 15

Ecological plaque hypothesis

Answer 15

• Low pH: acid sensitive bacteria die but aciduric bacteria will thrive & disruption in natural balance, increasing demineralization
• pH neutral: acid-sensitive bacteria thrive and acid production decreases & increase remineralization

Question 16

Shift in plaque ecology caused by acid formed from fermentation of sugars causes what?

Answer 16

low pH (lower 5.5) where plaque community stable

Question 17

Plaque below 4.5

Answer 17

catastrophe for plaque microflora that normally inhabit healthy mouth, increase in S. mutans & Lactobacilli

Question 18

Biofilm

Answer 18

an aggregate of microorganisms in which cells adhere to each other and/or to solid substrate exposed to an aqueous surface

Question 19

What holds biofilm together?

Answer 19

Extracellular polysaccharides produced by oral bacteria hold biofilm together & triggers changes to make is hard to remove over time

Question 20

What adheres to biofilm to tooth surfaces and how?

Answer 20

Streptococci are Gram+ form chains & constitute large portion of lactic acid when
excess sugars available – adheres to biofilm on tooth surface by converting sucrose into adhesive dextran polysaccharide by dextransucrase (caries can still occur w/o this strand)

Question 21

What is extremely aciduric (endure very acidic conditions) do not significantly contribute to caries but frequently isolated from caries lesions due to ability to survive low pH?

Answer 21

Lactobacilli Gram+ rods present in plaque in small #s

Question 22

Biofilm disease that results in localized destruction of tooth tissues by acid is by

Answer 22

dropping below 5.5 pH demineralizes tooth enamel, early stages are
reversible b/c natural process of remineralization – enough mineralization lost so that soft organic matrix left behind disintegrates causing a cavity

Question 23

Infectious disease that is transmissible BUT one does not ‘catch’ caries

Answer 23

First enters the body when baby passes through birth canal – caused by shift in oral microflora to caries-causing
bacterial types in response to a shift to an acidic pH by metabolism of sugars

Question 24

Decay begins on the surface of teeth by

Answer 24

bacterial growing on food particles that lodge btw teeth

causing destruction

Question 25

Acid and germ are necessary for decay, carbohydrate retention & acidogenic bacteriaterial

Answer 25

linked fluoride to caries reduction & high surfer consumption was linked to caries but only in an environment where oral bacterial were present

Question 26

_______ is safe & effective in preventing dental decay in both children & adults

Answer 26

Fluoridation of community water supplies