Luting agents

Question 1

How does size of filler particles affect the viscosity

Answer 1

Bigger - high viscosity
Smaller - lower viscosity

Question 2

What value should viscosity of luting agents be

Answer 2

Low and increases as it sets

Question 3

Are dental lutings agents cariostatic

Answer 3

Ideally yes
-fluoride releasing
-antibacterial

Question 4

What are the mechanical properties of dental luting agents

Answer 4

High compressive strength
-dentine around 275 MPa

High tensile strength

High hardness value (d-70k e-400k)

Young’s modulus similar to tooth (d-15GPa)

Question 5

What are the types of dental cement

Answer 5

Zinc phosphate
Zinc polycarboxylate

Question 6

What are the types of GI cement

Answer 6

Conventional
Resin modified

Question 7

What are the composite resin luting agents

Answer 7

Total etch with DBA
Self etch

Question 8

What are the contraindications of zinc phosphate cement

Answer 8

Low initial pH can cause pulpal irritation
Exothermic setting reaction
Brottle
Not cariostatic
Not adhesive to tooth of restoration

Question 9

What is the difference between zinc phosphate and zinc carboxylate

Answer 9

Zinc carboxylate contains polyacrylic acid as opposed to phosphoric

Question 10

Advantages of Zinc polycarboxylate

Answer 10

This material had the advantage of bonding to tooth surfaces in a similar way to glass ionomer cements​

There is less heat of reaction​

The pH is low to begin with but returns to neutral more quickly and longer chain acids do not penetrate dentine as easily​

Cheap​

Question 11

How does GI cement differ from GI filling material

Answer 11

Particle size is less than 20um to allow for suitable film thickness

Question 12

How does GI cement bond to the tooth

Answer 12

Ionic bonds with calcium and dentine
Hydrogen bonds with collagen and dentine

Question 13

Why can eugenol not be used for some temp fillings

Answer 13

Dont use eugonol when planning to use an RMGI cement in final restorationas it collapses the collagen fibres in dentine

Question 14

What are the disadv of Zinc polycarboxylate cement

Answer 14

Difficult to mix​

Difficult to manipulate​

Soluable in oral
environment at lower pH​

Opaque​

Lower elastic modulus
and compressive strength
than zinc phosphate

Question 15

What are the properties of GI cements

Answer 15

Clinically easy to use and durable cement​

Low shrinkage​

Long term stability​

Relatively insoluble once
fully set​

Aesthetically better than Zinc Phosphates​

Self adhesive to tooth substance​

Fluoride release​

Cheap

Question 16

How does RMGIC differ from GI

Answer 16

Glass particles size smaller
Contains a hyrophillic monomer

Question 17

What allows for dark curing

Answer 17

A secondary cure - redox reaction

Question 18

How does RMGIC properties differ from GI

Answer 18

Incorporation of Resin
-longer working time
-shorter setting time
-higher compressive and tensile strength
-higher bond strength
-decreased solubility

Question 19

What are the problems with RMGIC

Answer 19

HEMA is cytotoxic (monomer)
Hema expands in wet environment
No bond to indirect restoration

Question 20

When should RMGIC NOT be used

Answer 20

To cement a porcelain crown
Cement posts

Question 21

Which cure is better for comp luting agents

Answer 21

Light cure - increases properties by 25%

Question 22

How does indirect composite bond with comp luting agents

Answer 22

Composite bonds to composite​

Bond strength is lower to inlay/onlay/crown/veneer fitting surface than to new composite​

Bond is micromechanical to rough internal surface of indirect restoration​

Bond is also chemical to remaining C=C bonds on the fitting surface of the indirect restoration​

Use a dual curing cement as light penetration through the inlay will be poor

Question 23

What is needed to bond to porcelain

Answer 23

Surface wetting agent
-can treat with HF (hydrofluoric acid) to etch surface

Question 24

What is used alongside comp resin luting agents to bond porcelain

Answer 24

Silane coupling agent
-Hydroxyl groupdon silane molecule reacts with oxide groups on ceramic surface
-Other end of silane molecule has c=c bond which reacts with similary group on comp

Question 25

What is the composition of the silane coupling agent

Answer 25

Si(OH)3------------C(CH3)(CH2)

Question 26

What products are used to cement procelain

Answer 26

DBA Comp luting cement Silane Porcelain

Question 27

What is the function of silane in a direct comp restoration

Answer 27

Chemically bond filler particles to the resin matrix

Question 28

When can a composite luting agent be used with porcelain

Answer 28

When it is thin or very translucent (increase setting time to ensure cure)

Question 29

What comp luting agent can be used if porcelain is thick

Answer 29

Dual cured comp

Question 30

How is a metal surface roughened

Answer 30

Etching More commonly sandblasting

Question 31

How are precious metals roughened

Answer 31

NOT ETCH sandblasting

Question 32

How is bonding acheived with non-precious metal

Answer 32

Materials with carboxylic and phosphoric acid derived resin monomers MDP and 4-META These molecules have an acidic end and a C=C end The acidic end of the molecule reacts with the metal oxide and renders the surface hydrophobic

Question 33

What products are present to bond non-precious metal to tooth

Answer 33

DBA Comp luting resin Metal bonding agent Non-precious metal

Question 34

What comp luting resin MUST be used for metal

Answer 34

Dual cure as light will not penetrate metal

Question 35

How is bonding acheived with self-adhesive comp resin

Answer 35

Metal coupling agent in incorporated into the comp resin MDP

Question 36

What are the properties of MDP

Answer 36

This is an anaerobic self cured material​ Consistent results over many years​ Good film thickness​ Opaque​ Moisture sensitive​ Expensive

Question 37

What is panavia ex used for

Answer 37

Along with DBA to bond non-precious metal

Question 38

How do self-etching comp resin luting agents work

Answer 38

Attaches like a self etching primer (sort of)​ Acidic groups bind with calcium in hydroxyapatite forming a stabilising attachment between the tooth and the resin Ions from dissolution of filler neutralise the remaining acidic groups forming a chelate reinforced methacrylate network Limited removal of smear layer or significant infiltration into the tooth surface (only a couple of microns) Good bond strength to dentine

Question 39

What are the mechanical properties of self etching comp luting agents

Answer 39

Compressive strength Tensile strength Hardness Wear resistance

Question 40

Is etch required for self etching comp resin luting agents

Answer 40

Yes for enamel No for dentine

Question 41

When can self-etching comp luting agents not be used

Answer 41

If you cant use DBA and conventional resin cement Poor moisture control

Question 42

When using self etching comp resin luting agents what is needed for an indirect rest

Answer 42

Nothing else It will bond the indirect restoration directly to tooth

Question 43

What luting agent can be used for MCC

Answer 43

GIC

Question 44

What luting agent is used for metal post

Answer 44

GIC

Question 45

What luting agent is used for Fibre post

Answer 45

Dual cure comp and DBA

Question 46

What luting agent is used for gold

Answer 46

GIC

Question 47

What luting agent is used for a veneer

Answer 47

Light cure comp and DBA

Question 48

What luting agent is used for comp and porcelain inlay

Answer 48

Dual cure comp and DBA

Question 49

When are temp cements used

Answer 49

Made to cement temporary restorations in place whilepermanent restoration is fabricated.​ Soft for easy removal – (some do not set at all)​ Prep must be physically retentive or they will not work​ Can be used for trial lute of permanent restoration to allow assessment by patient or clinician

Question 50

When should eugenol not be used

Answer 50

to cement the provisional restoration where the permanent restoration will be cemented with a resin cement Any residual eugenol may interfere with the setting of a resin cement