priciples of adhesion, acid etch and bonding agents Flashcards Preview

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Flashcards in priciples of adhesion, acid etch and bonding agents Deck (32):
1

how has adhesive material aided preventative and restorative dentistry?

seals vulnerable pits and fissures
allows conservation of tooth tissue
reduced microleakage

2

three approached to achieving attachment to tooth

micromechanical attachements
chemical adhesion to enamel/ dentine
complex

3

what is an example of micromechanical?

acid etching

4

what is etching?

introducing pits and imperfections to allow resin to flow into these

5

what is chemical adhesion?

coupling agents bond to material and tooth (poly acids)

6

what is an example of chemical adhesion?

glass polyalkenoates

7

what is complex?

wetting, penetration and formation of bound material and restorative substrate interface

8

how can good wetting be determined?

small angle... low wetting
large angle- high wetting

9

who introduce acid etch for enamel margins?

Buonocore 1955

10

what is the bond strength re acid etching?

20-25mpa

11

how does acid etch work?

increased surface roughness
increases enamel surface energy

12

how does etch increase enamel surface energy?

removes surface contaminants
increases wetting
facilitates micro mechanical retention

13

what factors effect etching?

time 10-60 seconds
washing- 60 seconds
drying

14

what is the purpose of drying?

enables hydrophobic rein to penetrate and attach

15

what happens if etched for too long?

precipitation of calcium and phosphate

16

what properties does the ideal dental adhesive have?

high bond strength
immediate and durable bond
reliable bond
prevent bacterial ingress

17

what problems re. dentine bonding?

dentine is hydrophilic
vital
consist of inorganic and organic material
covered by smear layer

18

what is a primer?

acid
dentine conditioner
alters surface appearance and removes smear layer

19

what is the function of coupling agent?

component that does the sticking

20

what does the sealer do?

flows into dentinal tubules
seals dentine with surface layer rich in methacrylate
ensures bonding to resin

21

what are dentine conditioners?

materic
oxalic
phosphoric
nitric acids

22

what is the reaction re etch and priming?

acid based reaction with hydroxyapatite- opens dentinal tubules

23

what depth of deminerlisation?

up to 4 micron

24

what do primers do?

bond hydrophobic composites to hydrophilic dentine
act as adhesive

25

what is the general formula for primers?

M-R-X

26

M=?

methacrylate group in resin matrix

27

R=?

pacer that allows resin to move

28

X=?

component that interacts with dentine

29

what is a popular primer?

HEMA- hydroxyethylmethacrylate

30

what are the negative effects of HEMA?

dermatological effects

31

What are sealers?

resins
BISGMA & HEMA

32

What effect longevity of bond?

acid opening of tubules risks nano leakage
dentine tubules etched greater than resin penetrates= leaves denatured dentine... bond eventually fails