Tooth Solubility

Question 1

what do teeth and bone consist of

Answer 1

calcium phosphate crystals held together by a mainly protein matrix

Question 2

is the proportion of mineral high in teeth or in bones

Answer 2

teeth

Question 3

in which component of the teeth is there a higher mineral content

Answer 3

enamel, at 95%

Question 4

what is the mineral component of teeth known as

Answer 4

hydroxyapatite

Question 5

what gives teeth and bone their rigidity

Answer 5

hydroxyapatite

Question 6

what can low pH drinks to teeth

Answer 6

it causes dissolution of the tooth enamel

Question 7

how does fluoride act (3)

Answer 7

• reduces enamel solubility at low pH
• inhibits bacterail metabolism of carbohydrates
• promotes enamel remineralisation by saliva

Question 8

why is calcium phosphate used in experiments that demonstrate tooth solubility

Answer 8

it is very similar to hydroxyapatite, and pure preparations of human enamel are hard to acquire

Question 9

what is an alternative hypothesis

Answer 9

this is what the researcher thinks is the cause of something, and is based on insufficient evidence that lends itself to further experimentation. it is the opposite of the null hypothesis

Question 10

describe the process of demineralisation of the teeth

Answer 10

the proteins in the saliva bind to the tooth surface, forming a layer called the pellicle. bacteria colonise this pellicle and cause the build up of plaque. when we consume sugar from our diet, the plaque bacteria breaks it down and produces acid, which pulls out the calcium and phosphate ions from our enamel and weakens it.

Question 11

what acids can be produced by oral bacteria

Answer 11

lactic acid
propiac acid
butyric acid
acetic acid

Question 12

is it true that the minerals within the saliva equilibrate with the minerals in our teeth

Answer 12

yes

Question 13

how does pretreatment with fluoride prevent dissolution of enamel

Answer 13

the fluoride ions replace the hydroxyl ions to form fluorapatite. in hydroxyapatite, the hydroxyl ions are very large and cause distortion of the crystal lattice, so these smaller fluoride ions fit the space better and reduce the demineralisation of enamel

Question 14

what is the relationship between pH and enamel

Answer 14

low pH leads to an increased dissolution in enamel

Question 15

how does calcium slow down dissolution of enamel

Answer 15

by preventing the forward reaction

Question 16

give an overview of hydroxyapatite

Answer 16

this is the mineral that makes up 98% of the tooth enamel. when there is a low pH, the calcium and phosphorus ions are drawn out from the hydroxyapatite, which is demineralisation which weakens the enamel

Question 17

what feature of saliva allows it to remineralise enamel

Answer 17

it contains calcium and phosphate ions which can be returned to the hydroxyapatite mineral within the enamel

Question 18

what are chelating agents

Answer 18

these clump together calcium ions

Question 20

what is a null hypothesis

Answer 20

this reflects a common view of something, and states that there is no significant difference between the two variables in a hypothesis
- it is the hypothesis that a researcher is trying to disprove

Question 21

what will happen to allens reagent if there is PO4 present

Answer 21

a blue colour will develop

Question 22

why is fluoride effective at reducing dental caries

Answer 22

it is incorporated into hydroxyapatite to form fluoroapatite, the hydroxide ions are replaced by the fluoride ions. since these ions are smaller than the hydroxide ions, they fit better into the crystal, rendering it more stable and therefore less soluble in acid

Question 23

what is erosion the direct effect of

Answer 23

acids from the diet on teeth

Question 24

what is an example of a chelating agent in drinks

Answer 24

citric acid in orange juice

Question 25

what is dissolution

Answer 25

the erosion

Question 26

how does an increase in the concentration of calcium or phosphate promote remineralisation

Answer 26

the increase in concentration causes the equilibrium to shift to the left, inhibiting solubilisation and promoting the remineralisation

Question 27

what increases the solubilisation of calcium phosphate

Answer 27

an increase in the hydrogen ion concentration