priciples of adhesion, acid etch and bonding agents

Question 1

how has adhesive material aided preventative and restorative dentistry?

Answer 1

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

Question 2

three approached to achieving attachment to tooth

Answer 2

micromechanical attachements
chemical adhesion to enamel/ dentine
complex

Question 3

what is an example of micromechanical?

Answer 3

acid etching

Question 4

what is etching?

Answer 4

introducing pits and imperfections to allow resin to flow into these

Question 5

what is chemical adhesion?

Answer 5

coupling agents bond to material and tooth (poly acids)

Question 6

what is an example of chemical adhesion?

Answer 6

glass polyalkenoates

Question 7

what is complex?

Answer 7

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

Question 8

how can good wetting be determined?

Answer 8

small angle… low wetting

large angle- high wetting

Question 9

who introduce acid etch for enamel margins?

Answer 9

Buonocore 1955

Question 10

what is the bond strength re acid etching?

Answer 10

20-25mpa

Question 11

how does acid etch work?

Answer 11

increased surface roughness

increases enamel surface energy

Question 12

how does etch increase enamel surface energy?

Answer 12

removes surface contaminants
increases wetting
facilitates micro mechanical retention

Question 13

what factors effect etching?

Answer 13

time 10-60 seconds
washing- 60 seconds
drying

Question 14

what is the purpose of drying?

Answer 14

enables hydrophobic rein to penetrate and attach

Question 15

what happens if etched for too long?

Answer 15

precipitation of calcium and phosphate

Question 16

what properties does the ideal dental adhesive have?

Answer 16

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

Question 17

what problems re. dentine bonding?

Answer 17

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

Question 18

what is a primer?

Answer 18

acid
dentine conditioner
alters surface appearance and removes smear layer

Question 19

what is the function of coupling agent?

Answer 19

component that does the sticking

Question 20

what does the sealer do?

Answer 20

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

Question 21

what are dentine conditioners?

Answer 21

materic
oxalic
phosphoric
nitric acids

Question 22

what is the reaction re etch and priming?

Answer 22

acid based reaction with hydroxyapatite- opens dentinal tubules

Question 23

what depth of deminerlisation?

Answer 23

up to 4 micron

Question 24

what do primers do?

Answer 24

bond hydrophobic composites to hydrophilic dentine

act as adhesive

Question 25

what is the general formula for primers?

Answer 25

M-R-X

Question 26

M=?

Answer 26

methacrylate group in resin matrix

Question 27

R=?

Answer 27

pacer that allows resin to move

Question 28

X=?

Answer 28

component that interacts with dentine

Question 29

what is a popular primer?

Answer 29

HEMA- hydroxyethylmethacrylate

Question 30

what are the negative effects of HEMA?

Answer 30

dermatological effects

Question 31

What are sealers?

Answer 31

resins

BISGMA & HEMA

Question 32

What effect longevity of bond?

Answer 32

acid opening of tubules risks nano leakage

dentine tubules etched greater than resin penetrates= leaves denatured dentine… bond eventually fails