enamel and dentine caries chemistry

Question 1

Define dental caries

Answer 1

A localised chemical dissolution of tooth surface brought about by metabolism activity in a microbial deposit (dental biofilm) covering a tooth surface at any given time

Question 2

What is dental caries maintained by

Answer 2

Frequent dietary supply of fermentable carbohydrates

Question 3

Where does dental caries commonly form

Answer 3

Pits and grooves
fissures in the occlusal surface
approximate surfaces cereal to the contact point
along the gingival margin §

Question 4

What is enamel made up of

Answer 4

Calcium hydroxyapatite

Question 5

Describe the physical properties of enamel

Answer 5

1. Highly mineralised
2. Withstands both shearing and impact forces

Question 6

Describe the physical properties of dentine

Answer 6

1. Flexible and compressible
2. Poor abrasion resistance
3. Poor crack resistance

Question 7

What happens to enamel when is it exposed to acid

Answer 7

Enamel dissolution occurred

Question 8

What causes enamel dissolution

Answer 8

Overlyign plaque biofilm and the proproteolytic action of bacteria on the protein content of enamel

Question 9

What does acid dissolution enamel produce

Answer 9

irregular crystal outlines

Question 10

what does an initial caries lesion look like

Answer 10

A white spot lesion

Question 11

Describe a white spot lesion

Answer 11

Opaque white spots

Question 12

Why do white spot lesions have this appearance

Answer 12

As the sub surface enamel has become porous as result of the mineral being dissolved by the acid produced by plaque bacteria

Question 13

What happens as the porosity of a carious lesion increases

Answer 13

The lesion may take up a stain becoming a brown spot lesion
Will eventually cavities to expose dentine

Question 14

What can we do to non caveatted enamel caries lesions

Answer 14

We can arrest them

Question 15

What is tertiary dentine

Answer 15

An umbrella term used to describe all hard tissue deposited on the plural surface in response to an external stimulus

Question 16

Give examples of eternal stimuli that could stimulate the production of tertiary dentine

Answer 16

1. Caries
2. Attrition
3. Cavity prep
4. MIcro leakage
5. Trauma

Question 17

Give examples of tertiary dentine

Answer 17

1. Reactionary dentine
2. Reparative dentine

Question 18

What is reactionary dentine

Answer 18

Dentine forming in response to milder irritation resulting in dentine with an irregular appearance with fewer tubules

Question 19

What is reparative dentine

Answer 19

Dentine forming in repose to stronger stimuli by odontoblast like cells following the death of the original odontoblasts

Question 20

What can reparative dentine allow for

Answer 20

If plural exposure occurs can help with pulp exposure healing by forming a mineralised bridge

Question 21

What is sclerotic dentine

Answer 21

Tissue formed when dentinal tibias fill in as a repose to an external stimulus
appears transparent

Question 22

What happens to the pulp when a carious lesion forms

Answer 22

gets inflamed

Question 23

What causes the pulp to die

Answer 23

Bacterial infiltration of the dentine tubules and penetration of the pulp space with bacteria

Question 24

If we are treating a tooth with a deep carious lesion what should we do

Answer 24

Work under rubber dam to prevent salivary bacterial contamination

Question 25

Talk through how smooth surface caries spreads into dentine

Answer 25

1. Plaque layer forms on the enamel surface 2. Acid dissolution of enamel prisms increases porosity allowing acid attacks to advice through the enamel 3. Acid spreads also the enamel dentine junction laterally 4. dentinal tubules decrease in volume 5. enamel surface cavities plaque bacteria invades the lesion and penetrated the dental tubules 6. this is infected dentine

Question 26

Why should we restore teeth

Answer 26

1. Restore the function, form and aesthetics of the tooth 2. To protect the pulp dentine complex

Question 27

What should we take into consideration when determining what treatment option to go for

Answer 27

Patients caries risk and motivation

Question 28

How can we describe dentine

Answer 28

1. Hard 2. Firm 3. Leathery 4. Soft

Question 29

What is soft dentine

Answer 29

Dentine that deform with pressure and be faulty scooped with an excavator also known as caries infected dentine

Question 30

What is leathery dentine

Answer 30

Dentine that does not deform with an instrument but can still be easily lifted with an excavator also known as caries affected dentine

Question 31

What is firm dentine

Answer 31

Dentine that is physically resistant to hand excavation

Question 32

What is hard dentine

Answer 32

Sound dentine that creates a scratchy sound upon probing

Question 33

What do we mean by deep carious lesion

Answer 33

Radiographic evidence of caries reaching the inner third or quarter of the dentine still clear band of dentine between pulp and radiolucency

Question 34

What management lesions can we consider when treating Deep carious lesion

Answer 34

1. Non selective complete removal of caries 2. Selective removal of caries until we reach firm dentine 3. Selective removal of dentine to soft 4. Stepwise excavation

Question 35

What factors do we consider when deciding the treatment options for a Depp carious lesion

Answer 35

1. Lesion depth 2. Lesion activity 3. Patient motivation 4. Location of lesion

Question 36

What should we warn patient of when we treat a deep carious lesion

Answer 36

There is a chance that we explse the pulp which can lead to RXT or XLA We may opt to leave some affected non carious dentine behind

Question 37

What is stepwise excavation

Answer 37

Involves carious tissue removal in two stages stage 1: removal of caries but leaving a soft carious tissue over the pulp, placing decal and GIC State 2: review renter the lesion and further excavate in hopes tertiary dentine has been placed over the pulp. restore with permanent restoration we can opt to not re enter and just monitor for symptoms

Question 38

State the critical pH for enamel

Answer 38

5.5