Biomaterials/Adhesives Review

Question 1

What part of the tooth has predictable bonding?

Answer 1

Enamel

Question 2

_______% phosphoric acid is most effective for enamel retention

Answer 2

30-40%

Question 3

What does etching enamel remove?

Answer 3

10 um enamel

Question 4

How long should etch be placed on enamel for?

Answer 4

15 sec prior to rinsing

Question 5

What does etching create?

Answer 5

Porous layer 5-50 microns deep

Question 6

Why should you rinse after etching?

Answer 6

For 10 sec to remove acid and leave enamel surface clean for bonding

Question 7

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

Answer 7

raises; exceed

Question 8

What is the function of the spaces that etch produces?

Answer 8

spaces where resin can penetrate to form
resin tags

Question 9

Where is mechanical interlocking formed in etch?

Answer 9

Between polymerized resin and porosities in etched enamel

Question 10

What do you apply after etching?

Answer 10

Bond agent resin (low viscosity)

Question 11

Where does bond agent resin flow into after being applied?

Answer 11

Microporosities

Question 12

What does bond agent polymerize into?

Answer 12

Micromechanical bond

Question 13

Describe the bond strength of the incisal and middle third of enamel

Answer 13

Predictable and strong

Question 14

Describe the bond strength of the cervical enamel

Answer 14

• Less strong
• Shorter and fewer enamel tags
• Due to presence of prismless enamel

Question 15

What is the bond strength of perpendicular enamel (enamel rods)?

Answer 15

25 MPa

Question 16

What is the bond strength of parallel enamel (sides of rods)?

Answer 16

7-10 MPa

Question 17

Why is dentin challenging to bond?

Answer 17

Bond strengths vary

Question 18

Where in dentin has higher bond strength?

Answer 18

Superficial dentin more than deeper (close to pulp)

Question 19

Why does superficial dentin have higher bond strength than pulpal?

Answer 19

The deeper dentin has more and larger dentinal tubules. This increases the amount of water and reduces the amount of collagen the adhesive is able to interact with and create micromechanical retention.

Question 20

What does dentin bonding require intertubular dentin to do?

Answer 20

create hybrid layer in collagenous matrix

Question 21

What are the types of bond systems?

Answer 21

Etch and rinse (total etch)
Self-etch

Question 22

How does etch and rinse system work?

Answer 22

Etch is separate from bond agent
Primer and bond can be separate (3 step - etchant, primer, bond agent) or together (2 step - etchant, primer and bond agent combined)

Question 23

What are the advantages of the etch and rinse system?

Answer 23

• More predictable, stronger bond
• Enamel adequately prepared

Question 24

What are the disadvantages of the etch and rinse system?

Answer 24

• Collagen collapse is possible (user error due to overdrying)
• Etched zone is often deeper than hybrid layer
• Exposed demineralized, collagen fibrils
• Post operative sensitivity

Question 25

What is the self-etch system?

Answer 25

No phosphoric acid etch step Acid part of the primer or primer/bond agent

Question 26

What is the 2 step self etch?

Answer 26

* Acidic primer * Bonding agents * Acidic primer partially dissolves smear layer, allows penetration of bond resin

Question 27

What is the 1 step- all in one?

Answer 27

Most variable/least predictable * Acidic primer and bond resin, one silution * Many require mixing

Question 28

What are advantages of self-etch?

Answer 28

- No separate etch: overdried demineralized collagen not a problem - Etched zone and hybrid layer comparable width; however, some exposed collagen - Low post operative sensitivity - Time efficient

Question 29

What are disadvantages of self-etch?

Answer 29

- Not compatible with self-cure, dual cure composite * Acidic monomers, low pH, kills the basic amine activator - Will not etch unprepared enamel

Question 30

How is the bond strength of self etch primer systems?

Answer 30

Long term bond strength is questionable

Question 31

How is the bond strength of self etch adhesives?

Answer 31

- Lower bond strength - Long term breakdown * Collagen degradation over time

Question 32

What is selective etch?

Answer 32

only etch the enamel, NOT dentin

Question 33

What is complete etch?

Answer 33

Eetch enamel and dentin

Question 34

Where can universal adhesives be used?

Answer 34

In total etch, self etch, or selective etch

Question 35

What is the game changer for universal adhesives?

Answer 35

10-MDP