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DMD2 sem 2 > Dental Luting cements > Flashcards

Dental Luting cements Flashcards

1
Q

What are the uses of dental cements?

A

Luting agent (short and long term cements)

Pulp protection or cavity sealing (Cavity varnish, liner, and base)

Filling (temporary or permanent)

Others (Root canal sealer, calcium hydroxide cement, and bite registration material)

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2
Q

What are the general requirements for luting cements?

A

Biocompatibility

Retention

High tensile strength, fracture toughness, fatigue strength

Good marginal seal

Low film thickness

Ease of use

Radiopacity

Aesthetics

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3
Q

What are the types of conventional cements?

A

Zinc phsophate cement

Zinc oxide-eugenol cement

Polycarboxylate cement

Glass Ionomer cement

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4
Q

What are the types of resin-base cements?

A

Resin cement

Resin modified glass ionomer cement

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5
Q

What is film thickness?

A

Thickness of film between 2 flat surfaces

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6
Q

What is the maximum allowable thickness?

A

25 µm

Low film thickness is preferred

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7
Q

What is zinc phosphate cement made up of?

A

Typically a powder/liquid system

Liquid is an acid (phosphoric acid), water, and aluminum phosphate

Powder is a base that is insoluble in oral fluid made up of zinc oxide and magnesium oxide

Acid-base reaction and micromechanical retention does the job.

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8
Q

What is the setting reaction for zinc phosphate cement?

A

Zinc aluminophosphate gel matrix is formed with unreacted zinc oxide dispersed in the matrix.

Reaction is exothermic adding water to it can accelerate it and losing water can lengthen time for setting.

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9
Q

How long is the working and setting time for zinc phosphate cement?

A

Working time is 3 - 6 minutes

Setting time is 5 - 9 minutes

This depends on manufacturer instruction.

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10
Q

How can setting time of zinc phosphate be made longer?

A

Reducing the powder/liquid ratio

Mixing on the cool glass slab

Mixing over a large area

Mixing cements in increments

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11
Q

How is zinc phosphate cement mixed?

A

3 steps:

First: Add small amount of powder into the liquid to achieve slow neutralization of the liquid and to control the reaction.

Second: Larger amount of powder is added to the liquid for further saturation of liquid to newly form zinc phsophate.

Finally: Small amount of powder is added again to control the optimum consistency

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12
Q

What are the ADA specifications for zinc phosphate cement?

A

Setting time at 37 degrees: 5 - 9 minutes

Minimum compressive strength: 75 MPa

Maximum film thickness: 25 µm (for luting prostheses)

Maximum solubility: 0.2% by weight

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13
Q

How are the following variables affected by Decreased powder/liquid ratio:

Compressive strength

Film thickness

Solubility

Initial acidity

Setting time

A

Compressive strength: Decreases

Film thickness: decrease

Solubility: Increases

Initial acidity: Increases

Setting time: Increases

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14
Q

How are the following variables affected by increased rate of powder incorporation:

Compressive strength

Film thickness

Solubility

Initial acidity

Setting time

A

Compressive strength: Decreases

Film thickness: increase

Solubility: Increases

Initial acidity: Increases

Setting time: decreases

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15
Q

How are the following variables affected by increased mixing temperature:

Compressive strength

Film thickness

Solubility

Initial acidity

Setting time

A

Compressive strength: Decreases

Film thickness: increase

Solubility: Increases

Initial acidity: Increases

Setting time: decreases

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16
Q

How are the following variables affected by water contamination:

Compressive strength

Film thickness

Solubility

Initial acidity

Setting time

A

Compressive strength: Decreases

Film thickness: increase

Solubility: Increases

Initial acidity: Increases

Setting time: decreases

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17
Q

What is the biocompatibility of zinc phosphate luting cement like?

A

Acid can penetrate into the dentinal tubule and irritate the pulp.

(pH of liquid is 2 and 3 minutes after mixing 4.2, 1 hour 6, 48 hours 7)

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18
Q

How can zinc phosphate be modified?

A

Stannous fluoride can be added but this leads to higher solubility and lower strength

Zinc silicophosphate is created from addign silicate. this leads to higher strength and lower solubility and fluoride can be released and this can create better translucency.

19
Q

What are zinc oxide-eugenol cements used for?

A

It has a lower strength than zinc phosphate cement.

Usually used as a temporary filling.

20
Q

What are the types of ZnO Eugenol cements?

A

Simple ZOE

Reinforced ZOE

EBA cement

21
Q

What is the composition of simple ZOE?

A

Powder:

ZnO

Rosin: Reduces the brittleness of the set cement

Zinc stearate: Plasticizer

Zinc acetate Improve strength

Liquid:

Eugenol and olive oil

22
Q

What is the setting reaction for zinc eugenol cement?

A

First reaction: ZnO + Eugenol -> Zn(OH)2

Second reaction: Zn(OH)2 + 2HE -> ZnE2 + H2O

23
Q

What does water do to the setting reaction of zinc eugenol?

A

It accelerates the reaction

Zinc eugenolate is easily hydrolized by moisture

24
Q

How is zinc oxide eugenol manipulated?

A

Paste/paste: Mix 2 equal pastes together until it obtains the homogenous colour

Powder/liquid: Usually 4/1 for maximum strength. Mix the large increment first. (Cool slab not required)

25
Q

What are the types of lutinc cements?

A

Type 1: Temporary luting cement

Type 2: Permanent cementation

Type 3: Temporary restoration

Type 4: Cavity liner

26
Q

What type of ZOE is IRM?

A

It is reinforced ZOE

27
Q

What is the compressive strength of IRM?

A

35 - 55 MPa

28
Q

What is the overall structure of composite resin cement?

A

Resin matrix + inorganic filler (silane coated)

29
Q

What is the general composition of composite resin cement?

A

Dimethacrylate oligomers (Bis-GMA, UDMA or TEGDMA)

Dimethacrylate monomers

Silica or glass fillers (20 - 75%)

HEMA, 4-META, TBB and MDP

30
Q

What is the setting reaction for composite resin cement?

A

Chemically activated, light activated, or dual activation polymerization

31
Q

What are the preparation style of composite resin cements?

A

Powder / liquid (Chemical light or dual cure)

2 paste system [base / catalyst] (Chemical, light, or dual cure)

Single paste (light cure)

32
Q

What kind of bonding system can be used for bondign?

A

Bonding with the tooth surface by enamel and dentin bonding systems

Bond with metal by using metal primer

Bond with ceramic restoration by treating surface of porcelain with silane coupling agent.

33
Q

How is bonding to tooth surface done?

A

Self adhesive

Self etch

Total etch

34
Q

How are self etch resin cements used?

A

1) Coat prep with self-etching primer
2) Scrub primer into preparation for 30 seconds starting with enamel and working toward dentin
3) Air dry
4) Load cement into pre-treated restoration and seat
5) Remove excess
6) Light-cure or self-cure

35
Q

What are the features of self adhesive resin cements?

A

Capsules or automixing syringes

No need for preconditioning tooth structure

Unique moisture tolerance

Little risk for preop hypersensitivity

Fluoride ion release

Monomer is phosphorylated methacrylate

36
Q

How are self adhesive cements applied?

A

They do not require any pretreatment of tooth surface and once cement is mixed it can be applied immediately.

37
Q

How does self-adhesive resin cement bond to tooth structure?

A

Multifunctional monomers with phosphoric acid groups demineralize and infiltrate the ename and dentine. Alkaline fillers are functional monomers and include 10-MDP and 4-MET

38
Q

What does silane coupling agent do?

A

It is bifunctional can bond to hydroxyl group on silica and the monomer of the resin cement

39
Q

What are metal primers?

A

A bifunctional compund. One end carries methacryl for resin bonding and the other end a mercapto group for bonding to precious metals

40
Q

How is G-CEM LinkForce applied?

A

Link 1: is a G-Multi primer which uses 3 different chemical bonding agents to ensure perfect adhesion in all situations to all substrates Silane adheres glass ceramics , hybrid ceramics, and composites, MOP adheres to zirconia, MDTP adhesion to precious metals

41
Q

How is G-CEM Linkforce applied?

A

1) Try in
2) Rinse thoroughly and dry
3) Etch with HF for lithium disilicate and fedspathic ceramics and leucite reinforced ceramics and sandblast zirconia, alumina, metal, composite, and hybrid ceramics
4) Rinse and dry
5) Clean with alcohol and dry
6) G multi primer apply and dry

42
Q

What is relyx unicem used for?

A

Indicated for the permanent cementation of:

All ceramic, composite or metal inlays, onlays, crowns, and bridges

Posts and screws

All-ceramic, composite or metal restorations to implant abutments

2- or 3-unit maryland bridges and 3-unit inlay/onlay bridges

43
Q

What is contained in the base paste and catalyst paste for relyx unicem?

A

Base:

Methacrylate monomers containing phosphoric acid groups

Methacrylate monomers

Silanated fillers

Initiator components

Stabilizers

Rheological additives

Catalyst:

Methacrylate monomers

Alkaline (basic) fillers

Silanated fillers

Initiator components

Stabilizers

Pigments rheological additives

DMD2 sem 2 (97 decks)

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