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FRP - Crowns/Bridges/Wear/TMD/SDA/IMPLANTS > Dental materials - Luting cements > Flashcards

Dental materials - Luting cements Flashcards

1
Q

Properties of luting agents

A 
Viscocity and film thickness
radiopaque
ease of use
marginal seal
aesthetics
solubility
cariostatic
biocompatible 
Mechanical properties
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2
Q

Viscocity

A

Low to allow seating of restoration - dependant on filler particle size (<25micrometers)

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3
Q

ease of use

A

good setting and working time. Also easy to mix.

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4
Q

Radiolucent

A

Able to see marginal breakdown and easily identified on Rg

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5
Q

Marginal seal

A

Ideally bond to tooth - permenant and impeneatrable bond

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6
Q

Aesthetic

A

Not shine through tooth, non staining and variable translucency

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7
Q

Solubility

A

LOW

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8
Q

Cariostatic

A

Fluoride releasing and bacteriostatic

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9
Q

Biocompatible

A

No damaging pH, acceptable thermal reaction or conductivity.

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10
Q

Mechanical props

A

High compressive, tensile strength
High hardness
YM similar to tooth - 15GPa

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11
Q

Cement - ZInc Phosphate

A

Powder:
Zinc Oxide - reactive agent
Magnesium dioxide - white colour/> compressive strength
Other oxides - alumina, silica - greater physical properties and varied translucency

Liquid:
aqueous solution of phosphoric acid
Oxides - buffer solution eg aluminium - consistency
Zinc oxide - slower setting reaction

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12
Q

Reaction of zinc phosphate

A
  1. Acid base 2. Hydration

Aluminium oxide - prevents crystallisation leading to amorphous glassy matrix of acid salt surrounding unreacted ZnO powder. Insoluble but porous.This contains free water from setting reaction. Material matures and binds to water giving less porous material.

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13
Q

Issues with Zn Phosphate cement

A

Low initial pH 2 - Damage pulp, Exothermic setting reaction, Not adhesive to tooth or restoration, brittle, opaque, Npt cariostatic and final set takes 24hr

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14
Q

Zinc Polycarboxylate - Adv

A

Polyacrylic acid

BONDS TO TOOTH SURFACE, reduced heat of reaction, low pH quickly increases to neutral. Cheap.

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15
Q

Zinc Polycarboxylate - dis

A

Difficult to mix and manipulate.soluble in low pH environment, lower modulus and compressive strength that Zn Phos

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16
Q

Glass ionomer cements - Constituents

A

Acid - Liquid: Polyacrylic acid or tartaric acid

Base - Powder: Silica, alumina, aluminium fluoride, aluminium phosphate, calcium fluoride, sodium fluoride.
>silica means more translucent

17
Q

GI - Setting reaction stages

A

Dissolution - acid in solution, H ions attack the glass particles causing the release of ions (Ca, Al, Na, F), leaves silica gel around glass particles.

Gelation - initial setting stage. Due to bivalent Ca ions crosslinking with polyacid by chelation with carboxyl groups. Formation of Calcium Polyacrylate.

Hardening - Trivalent Aluminium ions crosslinking causing an increasing in strength. Aluminium polyacrylate formation - takes 30mins to a week.

18
Q

Difference between GI cement and luting cement

A

Smaller filler particle size - <20micrometers

19
Q

How does GI bond to tooth

A

Ion exchange with calcium in enamel and dentine
Hydrogen bonding with collagen in dentine

NO bond to restoration - needs to be sandblasted for mechanical retention.

20
Q

GI cement properties

A

low shrinkage, long term stability, insoluble once set, aesthetics good, self adhesive to tooth substance, fluoride release, cheap.

21
Q

RMGI - contains HEMA, considerations of this.

Setting reaction?

A

HEMA is highly hydrophillic and can be cytotoxic if left uncured
Same acid base reaction but light curing causes polymerisation of HEMA and copolymers, some can have secondary REDOX reaction.

22
Q

Improved properties of RMGI over GI

A

Command set, shorter setting time, longer working time, greater compressive and tensile strength, greater bond to tooth. reduced solubility.

23
Q

Composite luting cement properties - use with DBA

A

Dual or light cured, better aesthetics, better mech properties
Eg. NX3

24
Q

How to bond to direct composite

eg. Inlay

A

Composite can bond to composite.
Micromechanical - inlay rough internal surface
C=C chemical bond
Dual bond - can’t light cure thoroughly
Tooth->DBA->Composite Luting Cement->Resin Inlay

25
Q

Bonding to Porcelain

A

Porcelain = Brittle so needs to be bonded to tooth, prevent #
Treated porcelain with Hydrofluoric acid - etch surface
Gives rough retentive surface.
SUrface wetting agent required - Silane Coupling agent (SCA)
Tooth->DBA->Composite LC->SCA->Porcelain

26
Q

What is a silane coupling agent

A

Works like a DBA - Porcelain surface and oxide groups bond and C=C reacts with composite resin luting agent.

27
Q

Bonding to Metal?

A

Metal needs to be treated - sandblasted to roughen surface. Etching or more likely sandblasting

28
Q

Bonding to NPM

A

Materials with carboxylic/phosphoric acid derivatived resin monomers. Eg. MDP
Acidic and and C=C end
Acidic - metal oxide, renders surface hydrophobic.
(Metal Bonding Agent)

29
Q

Bonding to Precious metal

A

Change composition to allow oxide formation eg. increaswe copper content and heat to 400 degrees

30
Q

Explain self Adhesive composite resins

A

metal coupling agent incorporated into resin. Eg. MDP used in Panavia
Tooth->DBA->SEcomp(Panavia)->NPM

31
Q

Explain self etching composite resins

A

Eg. RelyX - Composite resin with incorporated DBA

MOISTURE CONTROL

32
Q 
Examples of acceptable bonging agents for materials
MCC
Metal Post
Fibre Post
Veneer
Adhesive bridge
Zirconia crown
Composite resin
Porcelain inlay
Gold restoration
A 
MCC - GIC, RMGIC  can use Composite
Metal Post - GIC, 
FIbre Post - Dual cure composite and DBA
Veneer - Light cure composite and DBA
Adhesive bridge - anaerobic cure composite
Zirconia Crown - GIC/RMGIC
Composite resin - Dual cure comp, self adhesive comp
Porcelain inlay - dual cure comp
Gold restoration - GIC/RMGIC

FRP - Crowns/Bridges/Wear/TMD/SDA/IMPLANTS (8 decks)

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