DMS summary - restorative materials

Question 1

What is etchant also known as

Answer 1

dentine conditioner

Question 2

What is in etchant

Answer 2

34% phosphoric acid

Question 3

What are the functions of etchant

Answer 3

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

Question 4

What type of molecule does a primer contain

Answer 4

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

Question 5

What is an example of a bifunctional molecule used in primers

Answer 5

HEMA

Question 6

What is adhesive made of

Answer 6

a mixture of resins

usually bis-GMA or HEMA

Question 7

What is the function of adhesive

Answer 7

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

Question 8

What is the brand name for primer in GDH

Answer 8

Prime and Bond NT

Question 9

What are the constituents of composite resin

Answer 9

resin
glass filler particle
camphorquinone
silane coupling agent
low weight methacrylate

Question 10

What is the function of the resin in composite

Answer 10

Allow for composite to be moulded

Facilitates the cross linking

Question 11

What is an example of a resin used in composite

Answer 11

bisGMA

Question 12

What is the function of glass filler particle in the composite

Answer 12

Gives strength and hardness

More filler = stronger but also more viscous

Question 13

What is an example of a glass filler particle

Answer 13

quartz

Question 14

What is the function of camphorquinone in composite

Answer 14

Allows for light activation (blue light)

Initiates the free radical addition polymerisation reaction

Question 15

What is the function of the silane coupling agent

Answer 15

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

Question 16

What is the function of low weight methacrylates

Answer 16

Adjusts viscosity and reactivity

Question 17

What are different types of composite

Answer 17

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

Question 18

What are good properties of composite

Answer 18

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

Question 19

What are the not so good properties of composite

Answer 19

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

Question 20

When is composite useful

Answer 20

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

Question 21

What is composite not so useful for

Answer 21

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

Question 22

What does amalgam consist of

Answer 22

powder & liquid

Question 23

What is the constituents of amalgam powder

Answer 23

intermetallic compound (silver+tin)
copper
zinc
mercury

Question 24

What is the formula for intermetallic compound

Answer 24

Ag3Sn

Question 25

What is the function of the intermetallic compound in amalgam powder

Answer 25

it reacts with mercury

Question 26

What is the function of copper in amalgam powder

Answer 26

increases strength and hardness

Question 27

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

Answer 27

scavanger

Question 28

What is the function of mercury in amalgam powder

Answer 28

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

Question 29

What type of amalgams is mercury seen in the powder

Answer 29

pre-amalgamated

Question 30

What is the function of mercury in the liquid

Answer 30

Triple distilled to ensure purity

Question 31

What are different types of amalgam

Answer 31

lathe cut, spherical and admixed | copper enriched

Question 32

What is the setting reaction for amalgam

Answer 32

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

Question 33

What does Ag3Sn provide amalgam with

Answer 33

strength + corrosion resistance

Question 34

What does Ag2Hg3 provide amalgam with

Answer 34

corrosion resistance

Question 35

What does Sn7Hg9 provide amalgam with

Answer 35

weak and poor corrosion resistance

Question 36

What are good properties of amalgam

Answer 36

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

Question 37

What are not so good properties in amalgam

Answer 37

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)

Question 38

How may amalgams strength be reduced

Answer 38

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

Question 39

What is amalgam useful for

Answer 39

Useful for large cavities especially posteriorly were loads are high

Question 40

What is amalgam not so useful for

Answer 40

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

Question 41

Who is amalgam contraindicated in

Answer 41

Deciduous teeth Under 15s Pregnant women Breastfeeding women