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Fixed Prosth 3 Extras > Midterm > Flashcards

Midterm Flashcards

1
Q

What kind of bonding chemical bonding occurs between porcelain and zirconia?

A

None

Porcelain does however form chemical bonds with metals via the metal oxide layer

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2
Q

What kind of functional group is used in bonding chemistry for most dentistry?

A

Ester chemistry

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3
Q

What is the “mon” of all the “mer”s?

A

Methacrylate unit

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4
Q

___ monomers connects the polymer to something different.

___ monomers, like bis-gma is what forms the polymer

A

Functional monomers

Cross-linking monomers

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5
Q

In functional monomers one end is the methacrylate unit and the other performs a specific function (which joins organic to the inorganic). What does phosphate group bind to? What does silane bond to?

A

Metallic oxides

Glassy ceramics

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6
Q

The ____ group is the basis for acidic monomers and self-etch adhesives

A

Phosphate

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7
Q

MDP is an ____. It bonds to ___

A

Acidic monomer

Zirconia

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8
Q

Two viscous cross linking monomers are ___ and ___. A cross-linking monomer to reduce viscosity is ____

A

Bis-GMA
UDMA

TEGDMA

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9
Q

What causes initiation in a self initiating monomer?

A

Tertiary amine in a base paste

BPO chemical initiation in a catalyst paste

Combination of the two pastes produces free radicals that attack the carbon double bonds

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10
Q

What are found in photo initiated monomers?

A

Camphorquinone or other photo-initiator absorbs blue light, then reacts with amine activator to form free radicals

These free radicals then attack carbon double bonds

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11
Q

Inhibitors such as ___ and ___ are found in the catalyst paste of self-cure resins to prevent spontaneous polymerization and provide working time

A

BHT

MEHQ

(Oxygen is also a powerful inhibitor as it reacts with the radicals to form peroxyl formulations)

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12
Q

The tertiary amine eliminates the need for ___ to initiate free radical formation in self cure resins

A

Heat

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13
Q

Where does the free radical come from in self cure resins?

A

BPO

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14
Q

What are some other photoinitiators that are like camphorquinone?

A

Sulfinic acids

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15
Q

What kind of cure are adhesive cements, self adhesive cements, and esthetic cements?

A

Adhesive = self cure

Self adhesive = dual cure

Esthetic resin cement = either self or dual cure

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16
Q

True or false.. base paste can be used alone in a dual cure composite

A

True

Base paste can be used alone in light-cure mode or mixed with catalyst paste for dual cure mode

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17
Q

Incompatibility between bonding agents and dual cure composite resin formulations primarily occurs with ____ due to ____

A

Self etch adhesives

Acidic monomers

Can also occur with two-step etch and rinse adhesives when acidic amonomers are present in the un-polymerized oxygen inhibited layer

This can cause a problem with build-ups

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18
Q

The mechanism of failure of self etch adhesives and dual cure composite resin is due to two things which are…

A
  1. Neutralization of the tertiary amine co-initiators by acidic monomers (pH <3)
  2. H2O contamination of the adhesive/composite interface
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19
Q

Describe the H2O contamination mechanism of bonding agents with dual cure composites

A

During the time it takes for a complete cure in the deeper layers of the material, moisture from the dentin is osmotically pulled across the semi-permeable adhesive layer and into the uncurled composite resin at the interface.

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20
Q

How long should you acid etch for lithium disilicate, leucite ceramic, felspathic ceramic, and zirconia?

A

Lithium disilicate - 20s with 5% HF

Leucite ceramic - 60s with 5% HF

Feldspathic ceramic - 120 s with 9% HF

Zirconia - do not etch! Sand blast intaglio surface (AKA microetch)

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21
Q

Silane comes in two forms: ___ and ___ (acid activated)

A

Pre-hydrolyzed

Hydrolyzed

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22
Q

Silane bonds to ___

A

Glassy ceramics (AKA vitreous ceramics)

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23
Q

When should you bond zirconia?

A

Resistance and retention form in inadequate

Restorative material is thin

The restoration is a FPD

24
Q

Do not allow the indirect restoration to be disturbed during clean-up for full time of resin cement set. The only exception to theis is with ___

A

Adhesive resin cements

25
Q

What are two ways to bond to zirconia?

A

Tribochemical coating

APC protocol with MDP

26
Q

What is tribochemical?

A

Related to lubrication by chemical means

Caused by rubbing together mechanically

27
Q

Describe tribochemical silica coating

A

Air abrasion with silicon coated aluminum oxide particles

Leaves the SiO2 coating in zirconia so that it is receptive to silane treatment

28
Q

Describe the APC protocol of bonding to zirconia

A

A - air partial abrasion

P - primer application

C - cement with dual cure or self cure composite resin cement

29
Q

What are the two best types of cements to use for the APC protocol of zirconia bonding?

A

Adhesive or self-adhesive

30
Q

True or false… esthetic resin cements are best to be used with vitreous ceramics instead of crystalline

A

True

31
Q

True or false… self-adhesive resin cements are the least retentive of all resin cements and you should keep dentin moist during cementation

A

True

32
Q

True or false… it is acceptable to use RMGI such as relyX luting plus to bond zirconia

A

False

33
Q

Why should you place the MDP bond to zirconia before it is moved to the mouth?

A

Phospholipids in the saliva will bind to the zirconia and take up the places where MDP would bind to

34
Q

True or false… silane is not as stable in the presence of an acidic phosphate monomer

A

True

35
Q

Which type of zirconia bonding has poor late bond strength if subjected to hydrolysis however bonding is a more simple process

A

MDP

36
Q

True or false… moist dentin bonding will help the strength of the bond. When did this idea occur?

A

True

Fourth generation (where bond strength peaked

37
Q

What are MMPs?

A

Endogenous in dentin and throughout the body

Play an important role in tissue remodeling

Break down collagen and weakening of dentin bond

38
Q

MMPs can be inhibited by….

A

Chlorhexidine gluconate

Benzalkonium chloride

(Apply CHX or BAC directly to dentin prior to bonding or incorporate into bonding agents)

39
Q

True or false… phosphoric acid effectively cleans the contaminated surface of lithium disilicate and leucite glass

A

True

40
Q

How do you decontaminate zirconia?

A

Apply primer and wait 5 minutes BEFORE TRYING IN RESTORATION

Phosphoric acid can only be to clean the zirconia once it has already been primed with MDP

41
Q

What is ivoclean?

A

It can be used to decontaminate any ceramic surface in preparation for bonding

42
Q

What is the facial reduction for veneers?

A

0.5mm - 0.7mm

Increase slightly towards incisal

43
Q

What is the incisal reduction for maxillary or posterior?

A

2mm

44
Q

How many cavosurface margins with enamel are needed for posterior veneers? What about anterior?

A

Three

2 (at least opposing enamel mesial and distal)

45
Q

Can veneers be placed over existing restorations?

A

Yes, if existing restorations are in excellent condition, small in size, not discolored

46
Q

What is the purpose of the chamfer in the posterior veneer prep?

A

Gives more bulk of material near the cusp tip

47
Q

Why are minor shade changes not an indication for veneers?

A

Because you can bleach teeth to achieve minor shade changes

48
Q

What may happen in a no prep veneer?

A

It thickens the tooth which causes the lip to move the tooth back which then may lead to distalizing the condyle and impinge upon the retrodiscal tissue causing TMD issues

49
Q

What thickeners of veneer is necessary per 1 shade change?

A

0.2-0.3mm

50
Q

Although you want the margin to be 0.5 supragingival preclinically, where do you want it clinically?

A

0.5-1mm subgingival

51
Q

Why should you prescribe chlorhexidine to pts with veneer temps?

A

They cant floss in those areas

52
Q

What is the minimum occlusal clearance for ceramic prosthetics?

A

2mm

53
Q

True or false… if a ceramic onlay goes subgingival you shouldn’t do an ceramic onlay because it requires a rubber dam and excellent moisture control for bonding

A

True

54
Q

Why do temporaries for all ceramic onlays have to to be compatible with bis-gma?

A

Becuase it secured to the tooth with flowable and bonding agent

55
Q

True or false… a ceramic onlay is bonded not cemented

A

True. A full coverage (either milled or pressed) may be bonded or cemented

56
Q

When should you etch bond the temporary?

A

Only if there is little to no mechanical retention/resistance. If its necessary only spot etch a small area buccal and lingual

57
Q

When is a partial coverage ceramic indicated?

A

Not superior esthetics

Mesial and distal damage with buccal and lingual tooth structure remaining with enamel to bond to

Fixed Prosth 3 Extras (3 decks)

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