Composite

Question 1

15 factors which can go wrong when placing composite

Answer 1

• The wrong Patient - have high caries amount/risk
• The wrong tooth
• Isolation
• Removing the (restoration) caries
• Designing the cavity
• Managing the dentine/pulp complex
• Matrix application
• Contact point
• Etching
• Washing
• Drying
• Lining
• Primer application
• Wet & dry surfaces
• Bonding
• Placing & Handling material
• Curing
• Finishing and polishing
• Occlusal considerations
• Post operative advice

Question 2

6 factors we need to consider when placing composite

Answer 2

• tooth biology
• materials science
• interfaces
• marginal seal
• manipulation
• polymerisation

all interlined

Question 3

what will happen if caries remains at ADJ?

Answer 3

result in unsupported enamel and early breakdown of restoration margin (interstitial enamel failure) if micro-leakage occurs as marginal integrity is compromised

Question 4

why do we need a hybrid layer?

Answer 4

so resin can penetrate the freshly cut dentine

Question 5

what type of dentine is the poorest to bond to?

Answer 5

tertiary

• occluded tubules
• more mineralised/contaminated
• irregular tubules

when contracts/shrinks restoration more likely to fail

Question 6

things to consider when preparing dentine

Answer 6

• Removal of smear layer
• Creation of Hybrid layer
• Dentine physiology
• Peri/inter tubular
• Tubule size
• Tubule density
• Water content
• Water transport
• Sclerosis
• Intertubular dentine
• Dead tracts
• Tertiary dentine
• Restorative materials

Question 7

characteristics of older dentine

Answer 7

• fewer tubules
• more mineralised
• occluded tubules

Question 8

characteristics of deeper dentine

Answer 8

• water
• more mineralised
• more tubules

Question 9

basics of how resin bonds to dentine tubules

Answer 9

resin penetrated down tubules

strength from in-between network bonds composite to the solubilised dentine by a layer of resin

Question 10

characteristics of poor dentine for bonding

Answer 10

• smear layer modified
• solubilised surface
• water content
• resin modified GI

Question 11

how is adhesion allowed?

Answer 11

through mineral and ion exchange

Question 12

4 reasons for lining placement

Answer 12

• Effect on bonding
• Enamel contamination
• Protection of pulpal therapeutic agents
• Risks if microleakage occurs

Question 13

what is the purpose of a lining?

Answer 13

intermediary between poor quality dentine and enamel
- Turning it into good quality bonding material as can etch glass ionomer

Bonds to dentine in different way so can bond to tertiary dentine

Question 14

factors that can lead to secondary caries

Answer 14

• Dead tracts
• Secondary dentine
• Tertiary dentine
• Sclerosis
• Calcification

Question 15

what are the 5 commonest problems that can be encountered when preparing a dentine bond?

Answer 15

• cavity preparation (failure to remove all caries)
• bonding (successful? followed instructions?
• contacts (good contact with adj tooth after material contracts? food get stuck?)
• placement (cured?)
• countering contraction stresses (put pressure on rest of tooth on contraction)

Question 16

what is a bonding interface?

Answer 16

where restorative material meets tooth

Question 17

what is the best seal?

Answer 17

marginal

Question 18

what are factors to consider when optimising interfaces?

Answer 18

• Material properties
• Cavity design
• Matrices
• Manipulation
• Configuration factor
• polymerisation contraction stress

Question 19

what is the most important factor to consider when optimising interfaces?

Answer 19

configuration factor and polymerisation contraction stress

Question 20

configuration factor

Answer 20

Defined as the ratio of bonded to unbonded surfaces: Important for Composite restorations

Question 21

what does high configuration factor lead to?

Answer 21

increased polymerisation contraction stress

Question 22

what does low configuration factor lead to?

Answer 22

reduced polymerisation contraction stress

Question 23

what is plastic deformation?

Answer 23

polymerisation contraction shrinkage on the surface that is not bonded
- material shrinks

Question 24

do we want plastic deformation?

Answer 24

yes

Question 25

what is air inhibition?

Answer 25

when exposed to air only get a small amount of polymerisation due to oxygen inhibition

Question 26

plasticity

Answer 26

property of a material to undergo a non-reversible change of shape in response to an applied force (polymerisation)

Question 27

deformation

Answer 27

change in shape due to an applied force (polymerisation)

Question 28

factors that affect the nature of dentine

Answer 28

• type (1, 2, 3)
• intra/inter/peri tubular
• diamter
• density
• contents/mineralisation
• health/ diseased/ reactive

Question 29

what is the point of matrix?

Answer 29

way of rebuilding a missing wall of tooth

Question 30

how does a matrix work?

Answer 30

• Separates the tooth using periodontal membrane
• Composite bigger than need to be
• Shrinks and contacts maintained - nature of material not taken into account

Question 31

6 steps in clinical procedure

Answer 31

• Etch
• Prime - Etch and prime both done by phosphoric acid (10 on enamel; Another 10 seconds on dentine and enamel)
• Bond (Bonding agent hybrid layer)
• Placement
• Characterisation
• Finish (Shrink 1-2%)

Question 32

how to minimise contraction stress?

Answer 32

don’t want to bond 2 surfaces together so that they pull together so place in increments

Question 33

why do you place a small increment of floor of cavity only?

Answer 33

deformation area so bond good

- small bit of composite can deform before large placement

Question 34

what is important to check when curing?

Answer 34

have the right wavelength for the material - check

Minimum intensity required to adequately cure 1.5 to 2 mm of composite resin is between 280 and 300 mW/cm2

Question 35

what are 5 different curing regimes?

Answer 35

• Soft Start
• Ramp
• Pulse
• Boost
• Delayed curing

Question 36

when do you use high power curing?

Answer 36

for fast set

Question 37

when do you use low power curing?

Answer 37

for close to pulp

Question 38

when do you use soft start curing?

Answer 38

for polymerisation with reduced contraction stress

slow cure start and then increase in power

Question 39

what does uncured composite layers lead to?

Answer 39

pain

Question 40

what is the main reason for reduced shrinkage?

Answer 40

is decreased final conversion

Question 41

what determines shrinkage direction?

Answer 41

bonded surfaces and free surfaces

Question 42

when do composites shrink towards the light?

Answer 42

when bonding fails

Question 43

what is in composites that allows it to be light cured?

Answer 43

Camphorquinone exposed to light initiates polyermisation chain process

Question 44

what can be used to cover poor quality dentine?

Answer 44

resin modified glass ionomer

Question 45

what are the properties of flowable compoiste?

Answer 45

can shrink more than other composties

• relieves stress
• poorer bond strength

used as interface to relieve stress

Question 46

why do you need to cure after polishing and seal?

Answer 46

to prevent sticking feeling when patient leaves