Bonding

Question 1

what is the purpose in acid etching

Answer 1

removes cores of enamel prisms, creating pores for resin

Question 2

components of enamel

Answer 2

5% organic, 95% inorganic

Question 3

components of dentine

Answer 3

20% organic 70% inorganic 10%h2o

Question 4

etching of enamel vs dentine

Answer 4

enamel 20-30secs
dentine 15-20secs

dentine more organic

Question 5

what is smear layer

Answer 5

debris plugging dentine tubules
removed via acid conditioning to dissolve/solubilise plugs and expose tubules for resin pores

Question 6

what is critical surface energy

Answer 6

surface tension of liquid that will JUST SPREAD on solid surfaces

DBA increase surface energy of dentine allowing composite to stick

Question 7

what is the point in etch
what %

Answer 7

37% phosphoric acid
removes smear layer, opens dentine tubules, decalcifies upper layer

Question 8

what is the purpose and mechanism of primer/bond

Answer 8

resin penetrates dentine surface attaching to hydrophobic end of primer
Bis-GMA, HEMA
filler, camphorquinone

Question 9

what is the hybrid layer

Answer 9

micro mechanical bond between tubules and dentine collagen with resin

Question 10

issues with overetching

Answer 10

collagen collapse = no penetration