Dental Materials - Bonding systems

Question 1

How can you increase viscosity of etching agent?

Answer 1

addition of fine particles of colloidal silica

Question 2

Would you rather use an etching gel or liquid?

Answer 2

gel

Question 3

What is a pure chemical - liquid or gel etchant?

Answer 3

liquid

Question 4

What penetrates the enamel to a greater depth, liquid or gel etchant?

Answer 4

liquid

Question 5

What is an example of an etchant gel?

Answer 5

Scotchbond etchant (3M) (35% phosphoric acid gel)

Question 6

Once the acid is placed where you want, what should you do?

Answer 6

gently agitate, removing the contaminated etch, adding new uncontaminated etch to the enamel

enhance efficacy

Question 7

What is applied after the etch is applied?

Answer 7

bonding material (adhesive)

resin

Question 8

What are the properties of bonding materials?

Answer 8

low viscosity dilute dimethacrylate resin system

Question 9

What is the most Commonly used bonding material?

Answer 9

bis-GMA diluted with TEGDMA

Question 10

What happens to the resin monomer when cured?

Answer 10

is then polymerised to form a solid polymer

Question 11

Dentin is heterogeneous, what does this mean?

Answer 11

organic phase (10% water) and inorganic phase

Question 12

What is the problem with dentin?

Answer 12

large water component…

• always wet
• surface is difficult to clean
• frequently contaminated with debris from the cutting process (smear layer)

Question 13

What is the smear layer?

Answer 13

frequently contaminated with debris from the cutting process

Question 14

What are the steps to bonding dentin? (long)

Answer 14

Question 15

What are the 3 steps in bonding dentin? (short)

Answer 15

1. priming
2. coupling agent
3. sealer

Question 16

What is the coupling agent?

Answer 16

impregnation of the dentine by a water-miscible fluid or one which will substitute for water

Question 17

Is the smear layer boded to the dentin?

Answer 17

no

Question 18

What are acids used to remove the smear layer?

Answer 18

phosphoric acid
nitric acid
maleic acid
citric acid
EDTA

Question 19

Is the surface of dentin hydrophobic or hydrophilic and is the resin hydrophobic or hydrophilic?

Answer 19

dentin - hydrophilic
resin - hydrophobic

= PROBLEM

Question 20

What chemical connects the resin and dentin together?

Answer 20

amphiphilic

polar water end attached to a non-polar insoluble hydrocarbon chain

Question 21

In bonding agents you have a ‘glue’ and what else?

Answer 21

a carrier

Question 22

What is the role of a carrier in a bonding agent?

Answer 22

hydrophilic chemicals which rapidly pass through the conditioned dentine carrying the coupling agent with them

Question 23

Where does the carrier in bonding agents infiltrate into?

Answer 23

dentinal tubules

Question 24

What are the common carriers in bonding agents?

Answer 24

alcohol (ethanol or butanol)

acetone

Question 25

What is the primary objective in the priming stage?

Answer 25

hybridisation

Question 26

What is the hybridisation during the priming stage?

Answer 26

infiltration of the partly demineralised dentine with the conditioning agent is known as hybridisation

forms the hybrid layer

Question 27

What happens if you fail to achieve the hybrid layer?

Answer 27

results in voids leading to microleakage in the long term

Question 28

What is WET bonding?

Answer 28

care must be take not to over-dry the dentine or the collagen becomes desiccated and the scaffold of collagen collapses

Question 29

What happens if the dentine is dried too much?

Answer 29

the scaffold of collagen collapses

Question 30

How do you evaporate residual solvent?

Answer 30

light air from 3 in 1

Question 31

Why is it important to keep the area dry (bonding agents)?

Answer 31

they are hydrophobic

maximise bond strengths