Composite Flashcards

Question

how can composite be classified based on its handling

Answer 1

can be condensable syringable flowable

Answer 2

‘amalgam feeling’ – it is more viscous and is used for packing the cavity in a similar way to amalgam. Has a greater porosity.

Answer 3

good adaption, less porosities, easy to apply

Answer 4

lower filler content, more shrinkage, difficult to apply, place for them with fibre ribbons.

Answer 5

light cured | self cured

Answer 6

if we only used a large filler particle we would run out of space and we would not be able to fill up the volume but if we put more of the smaller ones then we can get more filler particles per unit volume than if we restricted ourselves to the larger one

Answer 7

• Improved mechanical properties o Strength o Hardness o Rigidity • Improved aesthetics – it is the glass that reflects the light and is what is responsible for the tooth like appearance • Increased abrasion resistance – the filler particles make it less easy to break the surface of the composite surface • Lower thermal expansion (still not perfect) • Lower polymerization shrinkage (still a problem) • Less heat of polymerization (but not negligible) • Some radiopaque

Answer 8

``` self curing (two pastes) UV activation (obsolete, one paste) light curing (blue light 440 nm, one paste) ```

Answer 9

cured in the mouth

Answer 10

cured outside the mouth

Answer 11

Consists of benzoyl peroxide + aromatic tertiary amine which react to create the free radicals and start the polymerization reaction

Answer 12

Blue light source activates the camphorquinone to create free radicals which breaks the resin C=C and start the polymerization reaction

Answer 13

was a box which had an ordinary halogen white light and a filter which would only allow the blue light to pass through.

Answer 14

500nm - out of the camphorquinone absorption range

Answer 15

Ideally the light source should focus on the optimum wave light. LED is efficient as there is an overlap but its peak is the same as camphorquinone but for the old style halogen LCU it’s peak is well beyond that of camphorquinone showing that it is not as efficient as the LED for curing the composite.

Answer 16

* Extended working time as it is on demand set * Less finishing * Immediate finishing * Less waste * High filler levels (not mixing two pastes) * Less porosity (not mixing two pastes) – porosity is not a good thing as it is more vulnerable to fracture

Answer 17

close to the surface and this means that the composite resin nearest the surface sets the most readily and becomes hard as there is more polymerization at the surface and the molecules are harder and heavier

Answer 18

where the hardness of the material is half of that of the surface – this is typically around 2mm and this is why we use increments when building a restoration

Answer 19

underpolymerised base | leads to early failure

Answer 20

cure depth of up to 6mm

Answer 21

they have lucerin initiator as well as camphorquinone

Answer 22

UV | means we need to use poly wave curing light technology

Answer 23

* Can curing light be positioned the same as in a lab test? * Can optical rod be placed adjacent to tooth/composite * Does all blue light illuminate material? * Will composite polymerize (cure) fully? * What impact does ‘stray’ blue light have on tissue

Answer 24

``` light/material mismatch premature polymerization from dental lights optimistic depth of cure values recommended setting times too short polymerisation shrinkage ```

Answer 25

when you polymerase the reaction is an exothermic one - potential pulp damage divergent light beam modern devices are brighter/more intense illumination of patient's soft tissue causing thermal trauma

Answer 26

5.5 degrees

Answer 27

ocular damage