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Part 3 > Bonding/Cements > Flashcards

Bonding/Cements Flashcards

1
Q

Who first reported on acid-etching of enamel? When?

A

Michael Buonocore 1960
- Phosphoric acid

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2
Q
  1. At its core, what are the two fundamental parts for adhesion to tooth structure?
  2. As a result, what is formed that micromechanically interlocks with hard tissue?
  3. What is the essential first step of all adhesion mechanisms?

(Phillip’s Science of Dental Materials, pg 259)

A
  1. Removing hydroxapatite to create micropores
  2. Infiltration of resin monomers into the micropores and subsequent polymerization
  3. Wetting - an adhesive needs to form intimate contact with the surface, spread over it, and penetrate by capillary attraction

As a result, “RESIN TAGS” are formed

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3
Q
  1. How can you increase the surface energy of dentin, enamel, and synthetic materials?
  2. What does this promote?
  3. To achieve strong bonding through the micromechanical interlocking mechanism, what must monomers adapt to?
A
  1. Roughening the surface
  2. Promotes wettability of the surface by adhesive monomers
  3. Adapt to enamel and fill enamel surface irregularities and/or infiltrate into a demineralized collagen network in dentin
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4
Q

What is the smear layer?

How big is it?

A

It is the layer of grinding debris and organic film that is left on the surface of enamel and dentin after mechanical cutting.

  1. Typically 1-2 µm thick, but it can get thicker based on the abrasives used
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5
Q

Michael Buonocore (1955) discovered that phosphoric acid does what and removes how many microns of enamel?

The etching exposes prisms of what?

Resin tags are how big?

A

Phosphoric acid removes the smear layer and about 10 microns of enamel.

Exposes prisms of enamel rods to create a honeycomb-like, high energy retentive surface

Resin tags: ~6 µm in diameter and 10-20 µm in length

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6
Q

Who’s work in 1979 led to wide acceptance of dentin etching? What concept did he introduce?

(He’s Japanese)

Nakabayashi 1984 revealed that hydrophilic resins can infiltrate what?
The structure formed is called what?

A

Fusayama - Total-etch concept with 37% phosphoric acid

Nakabayashi 1984 - Infiltrate acid-demineralized collagen fibers in etched dentin and form a layer of resin-infiltrated dentin
- Called “hybrid layer”

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7
Q

Hybrid layer structure (Nakabayashi 1984)

Forms very strong resin bonds through the development of an interpenetrating network of __ and ___, together with numerous micromechanical interlocks at the ___ layer interface.

This technique is known as?

A

1/2. Network of Polymer and Dentinal collagen
3. Resin-hybrid layer

  1. Etch-and-rinse technique
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8
Q

Unlike enamel, dentin is a __ tissue, consisting of 50 vol% of ___, 30 vol% of ___, and 20 vol% ___.

A
  1. Living tissue
  2. Hydroxyapatite (calcium phosphate)
  3. Organic material (type 1 collagen)
  4. Fluid
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9
Q

Acid etching removes ___ almost entirely from several microns of sound ___, exposing a microporous network of ___ suspended in ___.

A
  1. Hydroxyapatite
  2. Dentin
  3. Collagen
  4. Water
  5. Moist
  6. Hybrid layer
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10
Q

Whereas etched enamel must be completely dry to form a strong bond with hydrophobic adhesive resins, etched dentin must be ___ to form a ___.

If insufficient water is present, the collagen network will ___ and produce a relatively ___ layer that prevents resin infiltration and hybridization.

What happens if too much water?

A
  1. Moist
  2. Hybrid Layer
  3. Collapse
  4. Impermeable
  5. If too much water, resin infiltration cannot fully replace the water in the collagen network - future leakage.
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11
Q

What is required to maintain a hydrated collagen network while removing excess water?

The use of these above mentioned and adhesive creates resin ____.

A

Priming. If too dry, you get collagen network collapse. If too wet, resin infiltration cannot replace water in the network.

Resin macrotags and microtags.

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12
Q

Primers are solutions containing hydrophilic or hydrophobic functional monomers?

They are dissolved in what?

What’s a widely used primer? Why?

A
  1. Hydrophilic functional monomers, like HEMA.
  2. Acetone, ethanol, or water.
  3. HEMA (2-hydroxylethyl methacrylate) due to high hydrophilicity and solvent-like nature.
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13
Q

What six things are required for a successful dentin bonding system?

A
  1. Adequate removal of smear layer from enamel/dentin
  2. Maintenance of dentin collagen network
  3. Good wetting
  4. Efficient monomer diffusion/penetration
  5. Polymerization with tooth structure
  6. Copolymerization with resin composite matrix
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14
Q

What is the role of dentin bonding agents?

What’s the pH of etchants?

Why do primers have a wide pH range?

A

To fill the interfibrillar space of the collagen network, improve micromechanical bonding by optimal formation of resin tags

pH = 1 to 2

Primers: A primer can reach a pH low enough (1 to 2) to remove smear layers and etch dentin, hence a self-etching primer

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15
Q

Fourth gen Dentin Bonding
- How many steps?
- What’s an example?

A
  1. Three-Step (Etch, prime, bond)

Optibond Fl

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16
Q

Fifth Gen Dentin Bonding
- How many steps?
- Example?

While great for enamel bonding, why is fifth gen dentin bonding not great for dentin?

A
  1. Two steps (Etch, then prime and bond)
  2. Optibond Solo Plus
  3. By combining the primer and bond, you mix hydrophilic and ionic monomers. There isn’t a hydrophobic resin layer forming - so it is susceptible to water penetration.
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17
Q

Sixth Gen Dentin Bonding
- How many steps?
- Example?

Dentin bonding is superior to 4th and 5th, but what is the weakness?

A
  1. Two-step (Etch and prime, then bond)
  2. Clearfil SE bond

Weakness: Hybrid structure is more hydrophilic. That can increase degradation, and they have lower bond strength.

18
Q

Examples of Seventh Gen Dentin Bonding Systems (one-step)?

Difference between 7th and 8th gen?

What does 8th gen have to improve mechanical strength?

A

1.Clearfil S3 Bond

  1. Difference: 8th gen is considered universal adhesive - can be used as self-etch, total-etch, or selective etch
    - Contains nanofillers to improve thickness of hybrid layer and improve mechanical strength
19
Q

Describe the three types of initiators for dentin bonding systems

A
  1. Photoinitiator - a photosensitizer (like camphoroquinone) and initiator (teritary amine)
  2. Self-cure (through chemical initiator like benzoyl peroxide)
  3. Dual-cure
20
Q

Why are nanometer-sized silica particles added to adhesives? Why is there doubt if this can actually be successful?

What is the minimum bond strength necessary to provide successful bonding to dentin?

A
  1. Reinforce adhesive and produce higher bond strengths.
  2. Unknown if the fillers can penetrate the collagen networks (the space is 20 nm while filler particles may be 40 nm).
  3. 20 MPa
21
Q

Who developed the Bonding Agent classification system in 2003?

A

van Meerbeek

22
Q

Glass ionomer cements
- Three components

What’s in the acid pretreatment to clean the tooth and remove the smear layer?

A
  1. Powder (Ca, Al)
  2. Acid-soluble alumino-silicate glass
  3. Polyacrylic acid
  4. Polyalkenoic acid or polyacrylic acid?
23
Q

Difference between activator and initiator?

A

Activator - source of energy to activate an initiator and produce free radicals

Initiator - a free radical-forming chemical used to start the polymerization reactions. It becomes part of the final polymer component (hence, not a “catalyst”)

24
Q

What are three activators?

A
  1. Heat (thermal energy)
  2. Electron-donating chemical (e.g. benzoyl peroxide, tertiary amine) which forms a complex and reduces the necessary thermal energy
  3. Visible light (supplies energy via photosensitizer such as camphorquinone, and activated through blue light at 468 nm)
25
Q

C-Factor definition

To reduce stress at the restoration margin, do you want lower or greater C-factor?

A

Configuration ratio. Ratio between bonded surfaces to the non-bonded area.

Lower C-factor.

26
Q

What are the two components to a chemically activated resin (aka self cure)?

What happens when they are mixed?

What’s a disadvantage of chemically cured resins?

A
  1. Initiator - benzoyl peroxide
  2. Activator - Aromatic tertiary amine
  3. They release free radicals to initiate polymerization
  4. Aromatic amine accelerators oxidize and turn yellow with time
27
Q

Why is estrogenicity a concern with composites?

What’s an example?

A

Potential for synthetic chemicals to bind to estrogen receptors to cause reproductive alterations such as fetal and infant brain development.

Bisphenol-A (a precursor to bis-GMA) is an example

28
Q

What do inhibitors do? What’s their typical mechanism?

What’s an example for composite?

A

Provide increased working time and storage life by minimizing spontaneous polymerization, usually through free-radical scavenging mechanisms

Example: Butylated hydroxytoluene (BHT)

29
Q

What’s the oxygen-inhibited layer?

Why does this occur?

A

Surface of resin’s that is un-polymerized due to oxygen which inhibits the free-radical polymerization curing reaction

Reactivity of oxygen to a radical is much higher than that of a monomer

30
Q

What were Bowen 1962’s two main innovations to overcome the traditional problems of composite resins?

A
  1. bis-GMA (monomer that forms a cross-linked, durable matrix)
  2. Surface treatment using a silane bonding agent called a “coupling agent” to bond filler particles to resin matrix
31
Q

Four major components of composites and what they do

Bonus fifth component

A
  1. Polymer matrix - Highly cross-linked polymeric resin (like dimethacrylate monomers: bis-GMA and UDMA)
  2. Inorganic filler particles - glass, silica (like barium) - Reinforce the matrix, provide translucency, and control volume shrinkage
  3. Coupling agents (silane) to bond organic and inorganic phases
  4. Activator and initiator system (polymerize and cross-link the system into a hardened mass)
  5. Inhibitors
32
Q

Zinc polycarboxylate
- Powder
- Liquid
- Type of reaction

  • How does it chemically bond to teeth?
A

Powder: zinc oxide and magnesium oxide
Liquid: Polyacrylic acid, water

Acid-base reaction

Bonds to calcium ions on surface of enamel/dentin

33
Q

Glass ionomer
- Powder
- Liquid (4 components)

  • Reaction
  • How does it chemically bond to teeth?
A

Powder: Fluoroaluminosilicate glass
Liquid: Polyacrylic acid, carboxylic acid, water, tartaric acid (controls working time)

Acid-base reaction

Bonds to tooth by chelation of the carboxyl of polyacrylic acids with calcium

34
Q

Define dental amalgam

A

An alloy formed by reacting mercury with silver, copper, and tin.

35
Q

What kind of amalgam did you use?

What does copper do?
Zinc?

A

Dispersalloy Lathe-cut high copper admix alloy

Copper: Hardens and strengthens silver tin alloy

Zinc: deoxidizer to prevent other elements forming oxides

36
Q

What’s the high copper admix amalgam reaction?

A

Ag3Sn + AgCu + Hg -> Ag2Hg3 + Sn7-8Hg + unreacted Ag-Cu

Secondary rxn: Sn7-8Hg + unreacted Ag-Cu -> Cu6Sn5 + Ag2Hg3

37
Q

Are you concerned with creep for your amalgam?

A

No, I used a high copper amalgam alloy. Creep is when a solid material slowly deforms plastically under the influence of stresses. High copper amalgam has lower creep rates than other forms.

38
Q

How do composite coupling agents (silanes) work?

A

Silanes work by having a functional group (such as methoxy) hydroxylze and react with inorganic fillers

The other end has a methacrylate double bond to co-polymerize with the monomers.

39
Q

Glass Ionomer Reaction

How is fluoride released?

A
  1. Carboxylic acid with water leads to H3O.
  2. H3O attacks glass, releasing calcium and aluminum ions.
  3. Carboxylate polymer ions react with the metallic ions, forming a matrix, and gelating/setting. Initially, Ca ions are involved, but later aluminum ions are bound.

Fluoride: Released from glass matrix.

40
Q

What curing reactions occur in resin (light cure) modified glass ionomer?

A

Traditional acid-base glass ionomer cure and the free-radical methacrylate polymerization

Bonus: There’s a tri-cure which also adds light cure

41
Q

In terms of dentin bonding, what does “hybridization” refer to?

A

Infiltration of resin within the collagen scaffold. This results in a hybrid layer.

42
Q

What does 10-MDP stand for?

A

10-methacryloxyethyl-trimetllitic anhydride.

Part 3 (13 decks)

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