L3- RC 2

Question 1

what is the inorganic part of the RC

Answer 1

filler particles

Question 2

why filler particles need to be added?

Answer 2

doesnt take part in the poly shrinkage so it reduces a lot of issues

Question 3

what are the issues in RC that can be solved by using filler

Answer 3

Reduces
- poly shrinkgae
exothermic reaction
-water absorption for non absorbing resins (not PMMA)
- thermal expansion

Increases strength and elastic modulus if the resin filler bonding is effective

Question 4

what happens to the RC that has no bonding between resin and filler when heat is applied to it

Answer 4

resin matrix will expand, causing gaps in filler resin interface.
The filler particles get loose and rattled. This weaken the RC

• therefore coupling agent is needed

Question 5

what properties increases with increainf filler content

Answer 5

flexural modulus - how much it can bend
flexural strength
hardness

Question 6

is it beneficial to have high or low SA:V ratio when it comes to filler loading

Answer 6

low because the filler particles are larger compared to resin. so you can load a lot which can make the most of the resin compared to smaller particles

• this was the traditional filler

Question 7

problems of using large particles as filler

Answer 7

wear and tear of the RC can happen which can expose the large particles at the surface of the restoration. This compromises the effectiveness of the RC

Question 8

what was microfine (homogenous) filler and what are the issues with its loading

Answer 8

its a filler with same type of smaller particles of 0.05 um.
This meant it has higher SA:V so the loading of the filler decreases which decreases the mechanical properties

Question 9

whats microfilled heterogenous filler

Answer 9

smaller particles are added to the filler containing larger particles. it is then prepolymerised and added tot he resin.

This overcomes the problems of using larger and smaller particles

Question 10

3 types of RCs

Answer 10

Universal -
Flowable -
Posterior composites

Question 11

properties of universal RC

Answer 11

• have a range of filler loading
• perform well most of the time
• but limited in aesthetic treatments

Question 12

properties of flowable

Answer 12

reduced filler content than normal
- easy to handle
-low viscosity
-high strength
but greater poly shrinkage

Question 13

properties of posterior compositis

Answer 13

used in molar area and this has high filler loading so it can provide high mechanical properties

Question 14

what happens to the visocity of the resin when filler is added to the resin

Answer 14

increases

Question 15

how can we reduce visocity of the resin when filler is added

Answer 15

reduce the visocity of the resin by using a visocity controller or reduce the amount of filler

Question 16

how can the RC being bonded to surfaces/walls correlates with poly shrinkage

Answer 16

when its bonded to the wall and undergoes shrinkage, it pulls on the RC from the wall. This causes stress on the RC, tissues and elastic modulus.

Question 17

consequences of shrinkage when RC is bonded to wall

Answer 17

detaching and cracking
cupsal fratcure
failure of RC
ingress of bacteria
irritation
necrosis

Question 18

does being bonded to more surfaces increase the stress caused by poly shrinkage

Answer 18

yes - more bonded, the shrinkage stress increase

Question 19

how can we prevent shrinkage stress

Answer 19

by layering the RC randomly