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BDS3 OSCE > DMS summary - restorative materials > Flashcards

DMS summary - restorative materials Flashcards

1
Q

What is etchant also known as

A

dentine conditioner

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2
Q

What is in etchant

A

34% phosphoric acid

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3
Q

What are the functions of etchant

A

Removes smear layer
Opens dentine tubules
Decalcifies the uppermost layer of dentine
Exposes collagen network for penetration

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4
Q

What type of molecule does a primer contain

A

Bifunctional molecule that has a hydrophilic and hydrophobic end to connect the hydrophilic tooth to the hydrophobic resin.

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5
Q

What is an example of a bifunctional molecule used in primers

A

HEMA

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6
Q

What is adhesive made of

A

a mixture of resins

usually bis-GMA or HEMA

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7
Q

What is the function of adhesive

A

it is a resin which penetrates into the surface of dentine and will attach to the hydrophobic part of the primer. This then allows the composite to bond

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8
Q

What is the brand name for primer in GDH

A

Prime and Bond NT

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9
Q

What are the constituents of composite resin

A 
resin
glass filler particle
camphorquinone
silane coupling agent
low weight methacrylate
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10
Q

What is the function of the resin in composite

A

Allow for composite to be moulded

Facilitates the cross linking

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11
Q

What is an example of a resin used in composite

A

bisGMA

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12
Q

What is the function of glass filler particle in the composite

A

Gives strength and hardness

More filler = stronger but also more viscous

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13
Q

What is an example of a glass filler particle

A

quartz

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14
Q

What is the function of camphorquinone in composite

A

Allows for light activation (blue light)

Initiates the free radical addition polymerisation reaction

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15
Q

What is the function of the silane coupling agent

A

Allows for good bond between filler particle and resin as water adheres to glass so stops the two from coming together nicely

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16
Q

What is the function of low weight methacrylates

A

Adjusts viscosity and reactivity

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17
Q

What are different types of composite

A

Glass filler types - fine, microfilled, hybrid (both)
Curing method
Area of use
Handling characteristics

18
Q

What are good properties of composite

A

its generally strong (not as strong as amalgam though except for in tensile strength)
good aesthetics
low thermal conductivity (less than amalgam)
command set
bonds to tooth so allows for more conservative preparations

19
Q

What are the not so good properties of composite

A

Shrinkage is an issue for composite (due to polymerisation)
High thermal coefficient - a gap forming between tooth and material is dependant on bond strength
Technique sensitive - requires good moisture control

20
Q

When is composite useful

A

Restorations - especially when not large
Anterior restorations
Veneers
Temporary restorations (especially when wanting to preserve aesthetics)

21
Q

What is composite not so useful for

A

You have restorations very near the gingival margin or subgingivally, will be difficult to get moisture control
Very large restorations will experience more polymerisation shrinkage - increments are important
Also not available on NHS for posterior restorations

22
Q

What does amalgam consist of

A

powder & liquid

23
Q

What is the constituents of amalgam powder

A

intermetallic compound (silver+tin)
copper
zinc
mercury

24
Q

What is the formula for intermetallic compound

A

Ag3Sn

25
Q

What is the function of the intermetallic compound in amalgam powder

A

it reacts with mercury

26
Q

What is the function of copper in amalgam powder

A

increases strength and hardness

27
Q

What is the function of zinc (if present in amalgam powder)

A

scavanger

28
Q

What is the function of mercury in amalgam powder

A

Found in pre-amalgamated alloys to allow for a quicker reaction

29
Q

What type of amalgams is mercury seen in the powder

A

pre-amalgamated

30
Q

What is the function of mercury in the liquid

A

Triple distilled to ensure purity

31
Q

What are different types of amalgam

A

lathe cut, spherical and admixed

copper enriched

32
Q

What is the setting reaction for amalgam

A

Ag3Sn (γ) + Hg –> Ag3Sn (γ) + Ag2Hg3 (γ1) + Sn7Hg9 (γ2)

33
Q

What does Ag3Sn provide amalgam with

A

strength + corrosion resistance

34
Q

What does Ag2Hg3 provide amalgam with

A

corrosion resistance

35
Q

What does Sn7Hg9 provide amalgam with

A

weak and poor corrosion resistance

36
Q

What are good properties of amalgam

A

strong (poorer when initially setting)
high abrasion resistance (v hard)
lowest failure rate

37
Q

What are not so good properties in amalgam

A

Prone to creep - makes it protrude at margins and prone to fracture
High thermal conductivity - requires a liner
Doesn’t bond to tooth - requires more tooth prep
Prone to corrosion - weakens tooth at margins (but is reduced by copper enriched alloys)

38
Q

How may amalgams strength be reduced

A 
Undermixed
Too much mercury after condensation
Too low condensation pressure
Slow rate of packing so increments dont bond
Corrosion
39
Q

What is amalgam useful for

A

Useful for large cavities especially posteriorly were loads are high

40
Q

What is amalgam not so useful for

A

small cavities (would need to extend prep) and for anterior restorations

41
Q

Who is amalgam contraindicated in

A

Deciduous teeth
Under 15s
Pregnant women
Breastfeeding women

BDS3 OSCE (65 decks)

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