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Flashcards in Midterm Deck (57):
1

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

None

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

2

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

Ester chemistry

3

What is the “mon” of all the “mer”s?

Methacrylate unit

4

___ monomers connects the polymer to something different.

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

Functional monomers

Cross-linking monomers

5

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?

Metallic oxides

Glassy ceramics

6

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

Phosphate

7

MDP is an ____. It bonds to ___

Acidic monomer

Zirconia

8

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

Bis-GMA
UDMA

TEGDMA

9

What causes initiation in a self initiating monomer?

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

10

What are found in photo initiated monomers?

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

11

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

BHT

MEHQ

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

12

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

Heat

13

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

BPO

14

What are some other photoinitiators that are like camphorquinone?

Sulfinic acids

15

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

Adhesive = self cure

Self adhesive = dual cure

Esthetic resin cement = either self or dual cure

16

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

True

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

17

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

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

18

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

1. Neutralization of the tertiary amine co-initiators by acidic monomers (pH <3)

2. H2O contamination of the adhesive/composite interface

19

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

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.

20

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

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)

21

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

Pre-hydrolyzed

Hydrolyzed

22

Silane bonds to ___

Glassy ceramics (AKA vitreous ceramics)

23

When should you bond zirconia?

Resistance and retention form in inadequate

Restorative material is thin

The restoration is a FPD

24

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 ___

Adhesive resin cements

25

What are two ways to bond to zirconia?

Tribochemical coating

APC protocol with MDP

26

What is tribochemical?

Related to lubrication by chemical means

Caused by rubbing together mechanically

27

Describe tribochemical silica coating

Air abrasion with silicon coated aluminum oxide particles

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

28

Describe the APC protocol of bonding to zirconia

A - air partial abrasion

P - primer application

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

29

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

Adhesive or self-adhesive

30

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

True

31

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

True

32

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

False

33

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

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

34

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

True

35

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

MDP

36

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

True

Fourth generation (where bond strength peaked

37

What are MMPs?

Endogenous in dentin and throughout the body

Play an important role in tissue remodeling

Break down collagen and weakening of dentin bond

38

MMPs can be inhibited by....

Chlorhexidine gluconate

Benzalkonium chloride

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

39

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

True

40

How do you decontaminate zirconia?

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

What is ivoclean?

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

42

What is the facial reduction for veneers?

0.5mm - 0.7mm

Increase slightly towards incisal

43

What is the incisal reduction for maxillary or posterior?

2mm

44

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

Three

2 (at least opposing enamel mesial and distal)

45

Can veneers be placed over existing restorations?

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

46

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

Gives more bulk of material near the cusp tip

47

Why are minor shade changes not an indication for veneers?

Because you can bleach teeth to achieve minor shade changes

48

What may happen in a no prep veneer?

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

What thickeners of veneer is necessary per 1 shade change?

0.2-0.3mm

50

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

0.5-1mm subgingival

51

Why should you prescribe chlorhexidine to pts with veneer temps?

They cant floss in those areas

52

What is the minimum occlusal clearance for ceramic prosthetics?

2mm

53

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

True

54

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

Becuase it secured to the tooth with flowable and bonding agent

55

True or false... a ceramic onlay is bonded not cemented

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

56

When should you etch bond the temporary?

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

57

When is a partial coverage ceramic indicated?

Not superior esthetics

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