8/26: Lecture 2 - Adhesives and Bonding

Question 1

What is the purpose of beveling?

Answer 1

reduce microleakage at cervical and ascending walls in class 2

Question 2

What does beveling expose?

Answer 2

ENDS of enamel rods = reveals prismatic enamel = etches better

Question 3

What is the purpose of bevelling for axiopulpal?

Answer 3

Resistance by distributing stress

Question 4

Where do you bevel?

Answer 4

in ENAMEL, NOT in deep preps where a bevel would remove all enamel or where gingival floor is on cementum/dentin

Question 5

When should you NOT bevel?

Answer 5

in class 3 if heavy centric contact to margin

Question 6

Where is a flare in a class 2 composite prep?

Answer 6

• Buccal flared > 100
• Lingual Flared > 90
  Buccal contact can remain in many cases
  Slight flare occlusal of prep

Question 7

Where is a flare in a class 2 amalgam prep?

Answer 7

both exit angles are 90 degrees (need S curve on buccal to achieve)
- NEED to break buccal contact

Question 8

Should you have a gingival bevel for amalgam?

Answer 8

NO

Question 9

Where is a flare in a class 3 composite prep?

Answer 9

• Internal Labial flare
• Gingival flare to exit at 90 degrees
• Labial wall flare of 100 degrees at cavosurface = exposes ends of enamel rods

Question 10

What is the purpose of etch?

Answer 10

Increases surface wetting by increasing surface area available for bonding

Question 11

What is surface wetting?

Answer 11

ability of liquid to maintain intermolecular contact with a solid surface

Question 12

Etching
__________ free energy to _______ the surface tension of bonding material

Answer 12

raises; exceed

Question 13

What spaces does etching produce?

Answer 13

Spaces where bond agent resin can penetrate and form resin tags

Question 14

What layer does etching remove?

Answer 14

Smear layer

Question 15

What is a smear layer?

Answer 15

Mixture of tooth debris, saliva, blood cells, bacteria and does NOT accept bond well

Question 16

How do you use etch?

Answer 16

Place for 15 seconds, rinse for 10

Question 17

What is primer?

Answer 17

hydrophilic (allows for binding to moist dentin and wetting of surface) monomers (like ethanol/water, acetone) to draw bond agent in

Question 18

Is bond hydrophobic or hydrophilic?

Answer 18

Hydrophobic

Question 19

What kind of binding does bond use?

Answer 19

micro-mechanical binding to interlock into surface irregularities

Question 20

How does bond bind to enamel?

Answer 20

interlocking with enamel rods

Question 21

How does bond bind to dentin?

Answer 21

interlocking with dentin collagen, which depends on MMPs

Question 22

What is bond more predictable with?

Answer 22

Predictable with enamel (especially incisal and middle 3rd) but less with dentin as the bond strengths vary due to heterogeneity (very organic)

Question 23

What system is etch separate frmo bond agent?

Answer 23

Etch and rinse (total etch)

Question 24

What are the types of etch and rinse systems?

Answer 24

Primer and bond can be separate (3 step) or together (2 step)

Question 25

What are pros of the etch and rinse system?

Answer 25

larger hybrid layer, adhesive can penetrate further, more predictable, stronger bond because enamel is adequately prepared

Question 26

What is the hybrid layer?

Answer 26

micromechanical interlocking of demineralized intertubular collagen and resin, good for bonding to dentin

Question 27

How is the hybrid layer formed?

Answer 27

by etching, washing, primer, adhesive (resin), light cure

Question 28

What does overetching lead to?

Answer 28

Unprotected layer = underfilled restoration

Question 29

What does overdrying lead to?

Answer 29

Collagen collapse = lower bond strength

Question 30

What does underdrying lead to?

Answer 30

collagen is too wet = blister spaces where primer and adhesive separate

Question 31

What etch doesn't have a separate etch step?

Answer 31

Self-etch

Question 32

Describe the self etch system

Answer 32

Acid is apart of the primer (2 step) or primer/bond (1 step: all-in-one)

Question 33

What is a con of self etch?

Answer 33

will NOT etch unprepared enamel, collagen degradation over time, lower bond strength

Question 34

What layer of the tooth does selective etch etch?

Answer 34

only etch the enamel NOT the dentin

Question 35

What layer of the tooth does complete etch etch?

Answer 35

enamel AND dentin

Question 36

What etch systems can universal adhesives be used with?

Answer 36

can be used with total etch, self-etch, and selective-etch We use!!!!

Question 37

What is the game changer for universal adhesives?

Answer 37

10-MDP

Question 38

What does 10-MDP allow for?

Answer 38

Bonding to many surfaces

Question 39

Describe the chemical reaction of universal adhesives

Answer 39

Monomer (phosphate ester) chemically interacts via ionic bonding to calcium in hydroxyapatite

Question 40

What is the function of adhesive?

Answer 40

resin tags (macro and micro) interlock into surface irregularities

Question 41

What are the steps of a composite restoration?

Answer 41

1. Etch for 20 seconds to enamel and 15 to dentin or selective etch 2. Wash for 10 seconds and dry enamel and dentin lightly (moist) 3. Apply primer (not with adhesive universal) 4. Apply adhesive 5. Light cure (470 nm) = initiate 6. Place composite

Question 42

When should you re-etch?

Answer 42

if tooth gets contaminated with saliva, re-etch for 10 seconds, rinse and dry, until frosted ename

Question 43

Should you etch longer for fluoridated teeth?

Answer 43

YES because more resistant to acids

Question 44

How do you repair old composites?

Answer 44

roughen old composite with diamond bur, etch, wash, dry, bond, thin, cure, and add new composite

Question 45

What is the shape of type 1 enamel rods? from dissolution of what?

Answer 45

honeycomb; enamel rod cores

Question 46

What is the shape of type 2 enamel rods? from dissolution of what?

Answer 46

cobblestone; enamel rod peripheries

Question 47

Where are type I and type II enamel found?

Answer 47

In occlusal and middle thirds of teeth

Question 48

What enamel gives the BEST bond?

Answer 48

Type 1 and 2

Question 49

What kind of enamel tags does cervical enamel have?

Answer 49

Shorter and fewer

Question 50

What do shorter and fewer enamel tags create?

Answer 50

Less prism delineation

Question 51

What MPa does using adhesive result in?

Answer 51

20-25MPa

Question 52

What kind of MPa bond strength does perpendicular enamel have?

Answer 52

25 MPa

Question 53

Where is perpendicular enamel found?

Answer 53

ENDS of rods - at cavosurface margin of class 1 prep and bevels of class 2 preps

Question 54

What kind of MPa bond strength does parallel enamel have?

Answer 54

7-10 MPa bond strength

Question 55

Where is parallel enamel found?

Answer 55

SIDES of rods - in internal walls of occlusal preps and in gingival floor of box in Class 2 prep

Question 56

Is dentin more/less predictable with bonding?

Answer 56

LESS because its heterogenous

Question 57

Where do odontoblastic processes extend to?

Answer 57

Tubules

Question 58

Where is peritubular dentin?

Answer 58

Directly around tubule

Question 59

Is peritubular dentin organic or inorganic?

Answer 59

INorganic

Question 60

Where is intertubular dentin?

Answer 60

Between tubules

Question 61

Is intertubular dentin organic or inorganic?

Answer 61

ORGANIC

Question 62

What is intertubular dentin rich with?

Answer 62

Collagen = allows for bonding

Question 63

What are factors affecting bond to dentin?

Answer 63

Cavity depth, caries, moist/dry