Composite Resin

Question 1

Enamel bonding is _______ and _______.
Dentin bonding is _______ and _______.

Answer 1

Enamel = reliable & predictable
Dentin = not as reliable & predictable

Question 2

Describe enamel bonding.

Answer 2

• Acid etching transforms the smooth low energy enamel surface into an irregular surface, with increased surface free energy and wettablity
• The increased wettability allows fluid-based resin to easily spread into the irregularities and become mechanically interlocked following polymerization

Question 3

Enamel bonding can generate up to _____ MPa of shear bond strength, when conducted without moisture contamination.

Answer 3

20 MPa

Question 4

Describe dentin bonding compared to enamel bonding.

Answer 4

equally as strong as enamel bonding but not as reliable and predictable

Question 5

composition of dentin vs enamel that results in less reliable and predictable bonding

Answer 5

Dentin has a HIGHER WATER COMPOSITION than enamel, which reduces the effectiveness of acid etching.

Question 6

structure arrangement of dentin vs enamel that results in less reliable and predictable bonding

Answer 6

Enamel rods are arranged in parallel and have a regular pattern that is easily etched.
Dentin tubules are composed of a disorganized organic matrix of collagen.

Question 7

tubule arrangement of dentin that results in less reliable and predictable bonding

Answer 7

dentinal tubules become larger in diameter and more numerous near the pulp, this results in decreased bond strength closer to the pulp due to the interference of dentinal fluid

Question 8

smear layer of dentin that results in less reliable and predictable bonding

Answer 8

the smear layer will plug the dentinal tubule orifices to form a smear plug

Question 9

smear layer of dentin that results in less reliable and predictable bonding

Answer 9

the smear layer will plug the dentinal tubule orifices to form a smear plug, which will decrease dentinal permeability by up to 90%, the smear layer is composed of the shavings of hydroxyapatite and collagen generated during tooth preparation

Question 10

content of acid etch

Answer 10

30-40% phosphoric acid (commonly 37%)

Question 11

how to acid etch

Answer 11

apply for 15 seconds, rinse with water for 10 seconds

Question 12

What does acid etch do?

Answer 12

• dissolves the smear layer and cleans the surface debris
• exposes the collagen layer in dentin, widening the dentinal tubules

Question 13

When is GLUMA applied?

Answer 13

After etching, the surface must be gently air-dried and left moist. GLUMA can be applied to re-wet the tooth.

Question 14

appearance of enamel after etching, and why

Answer 14

chalky white appearance due to the creation of microporosity

Question 15

content of primer

Answer 15

HEMA, an amphiphilic resin monomer wetting agent and solvent (common solvents are acetone, ethanol, and water)

Question 16

purpose of primer

Answer 16

infiltrate the enamel prisms and dentinal tubules to prevent collagen collapse and allow for better adhesion

Question 17

After application, this step must be gently air-dried to evaporate the solvent and leaving only the monomers.

Answer 17

primer

Question 18

________ can result in an allergic reaction called contact dermatitis when it contacts bare skin.

Answer 18

Primer

Question 19

allergic reaction that primer can cause when it contacts bare skin

Answer 19

contact dermatitis

Question 20

content of bond/adhesive

Answer 20

bis-GMA monomers

Question 21

Bond/adhesive chemically bonds to the primer below and composite resin above through _________ bonds.

Answer 21

methylmethacrylate (MMA) bonds

Question 22

After application, this step is gently air dried to evaporate the solvent and light cured.

Answer 22

bond or adhesive

Question 23

layer of micro-mechanical retention between the resin and irregular tooth surface

Answer 23

hybrid layer

Question 24

the resin that is polymerized after penetration into the exposed dentinal tubules

Answer 24

resin tags

Question 25

main contributors to composite resin retention

Answer 25

micro-mechanical bond created by the hybrid layer followed by the chemical bond between the primer, adhesive, and composite

Question 26

4th generation etch and rinse systems

Answer 26

3-step process with each etch, primer, and adhesive as individual steps

Question 27

5th generation etch and rinse systems

Answer 27

2-step process in which etch is followed by a primer and adhesive product combined into a single step

Question 28

technique in which etchant is applied selectively to enamel to potentially reduce post-operative sensitivity while maintaining a strong enamel bond

Answer 28

selective etch technique

Question 29

Properties of a self-etch system and its implications:

Answer 29

Combines the acid etch with another step, the acid etchant is less potent because it is not rinsed after application Implications: - smear layer is not removed, a carbide bur is recommended for preparation to minimize smear layer formation - less post-op sensitivity - weaker enamel bond

Question 30

6th generation etch and rinse systems

Answer 30

2 step process which combines acid etch and primer into a single step followed by adhesive

Question 31

7th generation etch and rinse systems

Answer 31

combines acid etch, primer, and adhesive into a single step

Question 32

defined as a material that is composed of two or more constituent parts

Answer 32

composite

Question 33

Composition of composite (3):

Answer 33

Resin matrix- organic, highly viscous pre-polymer, proceeds to polymerize into a solid form when cured (bis-GMA) Filler particles- small RO particles of silica and powdered ceramic glass which ranges in different shapes and sizes Coupling agent- coats filler particles to promote adhesion between the fillers and resin-matrix (silane)

Question 34

Leaching of _________ can happen with uncured resin and through the wearing of composite.

Answer 34

bisphenol-A (BPA)

Question 35

Composite resins can be categorized by filler characteristics. Larger fillers = Higher filler content =

Answer 35

Larger fillers = more strength, low polishability and high wear into a rougher surface Higher filler loading = lower matrix content which results in less water absorption

Question 36

Name the composite resin type: - conventional composites that are no longer used - 80% filler - 8um particle size - high strength, low polishability, fast wearing of resin matrix to increase roughness overtime

Answer 36

macrofill

Question 37

Name the composite resin type: - 40% filler - 0.04um particle size - weak, better polish/ear resistance due to higher matrix composition, can flex under pressure

Answer 37

microfill

Question 38

Name the composite resin type: - 80% filler - 1um particle size

Answer 38

hybrid

Question 39

Name the composite resin type: - 0.005-0.01um particle size - small particles can group together with each other to form larger particles, resulting in a full range of filler sizes

Answer 39

nanofill

Question 40

Name the composite resin type: - incorporates nano-sized and larger particles

Answer 40

nanohybrid

Question 41

Composite resins can be categorized based on their viscosity (2):

Answer 41

Flowable composite- various composites with minimum filler amount, lower wear resistance Packable composite- composites with high filler amount, very viscous, handles like amalgam

Question 42

Composites can be categorized based on their method of polymerization (3):

Answer 42

Self-cure or chemical cure Light cure Dual cure

Question 43

a two-paste system which must be mixed in equal parts to initiate the polymerization reaction, have a limited working time of around 2 minutes

Answer 43

self-cure or chemical cure composites

Question 44

Two-paste system of self-cure composites:

Answer 44

Base paste- composed of composite and tertiary amine (activator) Catalyst paste- composite and benzoyl peroxide (initiator)

Question 45

a single paste system which does not involve mixing and requires a 468 nm blue visible light to initiate the polymerization reaction

Answer 45

light cure composite

Question 46

light required to cure composite and the photoinitiator

Answer 46

468nm blue light / camphorquinone

Question 47

composite resin combining elements of self-cure and light cure, useful for large build-ups which allow a light curing of the surface and a chemical reaction to cure the deeper material

Answer 47

dual cure composite

Question 48

initiator for self-cure vs light cure vs dual cure composite

Answer 48

Self-cure = benzoyl peroxide Light cure = camphorquinone Dual cure = both

Question 49

How does polymerization shrinkage occur?

Answer 49

During the polymerization reaction, free radicals break the carbon double bond in a bis-GMA monomer to form a single bond with an adjacent monomer. The side group will cross-link by sharing electrons via a covalent bond to create strong cured material. The continuous recruitment of monomers results in a decrease in resin volume and subsequent shrinkage.

Question 50

common range of polymerization shrinkage of composite resins

Answer 50

2-3%

Question 51

used to represent the expected polymerization shrinkage, determined by the proportion of bound to unbound surfaces of the composite resin restoration

Answer 51

configuration (C) factor

Question 52

high vs low C factor

Answer 52

Higher C-factor = high chance for shrinkage, micro-leakage, and post-op sensitivity To minimize shrinkage, smaller increments of 2mm can be cured for a larger restoration.