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BDS2 CLINICAL Operative Dentistry > Composite > Flashcards

Flashcards in Composite Deck (45)
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1
Q

Why is longevity of a restoration important

A

we do not want to remove the restorations that we make as when we remove/replace a restoration we increase the risk of damaging the pulp and root canal as well as removing more healthy tooth tissue

2
Q

what is the most long lasting restoration

A

gold

3
Q

what are the 15 reasons a restoration can fail

A
 The wrong patient 
 The wrong tooth
 Isolation 
 Removing the caries 
 Designing the cavity
 Managing the dentine/pulp complex
 Matrix application
 Contact point
 Etching
 Washing
 Drying
 Lining
 Primer application 
 Wet and dry surfaces
 Bonding
 Placing and handling materials 
 Curing
 Finishing and polishing
 Occlusal considerations
 Post-operative advice
4
Q

how can the patient affect the longevity of a restoration

A

if a patient is at high risk of caries because of their diet and other factors then it is more likely that their restoration will fail

5
Q

what do we need to consider in terms of marginal integrity in regards to enamel

A

prism orientation

occlusion

6
Q

where should we avoid cavosurface margins

A

in areas of occlusal contact

7
Q

what will caries at the ADJ result in

A

unsupported enamel

early breakdown of restoration if micro leakage occurs

8
Q

what is microleakage

A

diffusion of the bacteria, oral fluids, ions and molecules into the tooth and the filling material interface

9
Q

why does poor enamel preparation allow micro leakage

A

. Poor enamel preparation results in rough surfaces and these rough surfaces have small cracks in them and these small cracks of unsupported enamel can later result in a fracture which can allow microleakage

10
Q

what does a white line around the edge of a restoration indicate

A

we are looking at early failure of the restoration as this indicates an enamel fracture.

11
Q

what does primary dentine consist of

A

fresh, open tubules

12
Q

what does tertiary dentine result in

A

irregular structure

not great to bond to

13
Q

what are factors that effect the bond

A
 Removal of smear layer
 Creation of hybrid layer
 Dentine physiology
 Peri/intertubular 
 Tubule size
 Tubule density
 Water content
 Water transport
14
Q

what is deeper dentine like

A

wetter
more mineralised
contains more tubules

15
Q

what is older dentine like

A

fewer tubules
more mineralised
occluded tubules

16
Q

what does poor dentine consist of

A
 Dead tracts
 Secondary dentine
 Tertiary dentine
 Sclerosis
 Calcification
17
Q

what is a lining for

A

When there is poor quality dentine we use resin modified glass ionomer which allows adhesion through ion exchange

18
Q

what does the lining protect

A

pulp

19
Q

what are the commonest issues when it comes to composite

A
cavity preparation 
bonding
contacts
placement
countering contraction stresses
20
Q

describe issues related to cavity prep

A

sometimes we have failed to remove all the caries and this can result in a poor bond

21
Q

describe issues related to contacts

A

If the tooth contracts then these contact points open up and the patient complains of food getting stuck between their teeth.

22
Q

describe issues relating to placement

A

sometimes not all the material will be cured.

23
Q

describe issues related to contraction stresses

A

if the material is successfully bonded to the tooth and shrinks slightly then this will put a lot of pressure on the rest of the tooth and restoration, the tooth will have tension

24
Q

what are the 2 biggest factors that need considered when preparing/fixing a filling

A

Configuration factor

Polymerization contraction stress

25
Q

what is the configuration factor defined as

A

the ratio of bonded to unbounded surfaces

26
Q

what does a high configuration result in

A

increased polymerization contraction stress

27
Q

what does a low configuration factor result in

A

reduced polymerization contraction stress

28
Q

what is polymerization contract shrinkage

A

movement of the material as there is a change in dimension of the material

29
Q

where do we want deformation to happen

A

surface that is not bonded

30
Q

what is the volumetric change dependent on

A

how much monomer make up the polymer

31
Q

what is plasticity

A

property of a material to undergo a non reversible change in shape in response to an applied force

32
Q

what is deformation

A

change in shape due to an applied force

33
Q

what happens if there is a poor bond in the base of the cavity

A

there is deformation is on the bonded surface and a gap appears
The gap fills with dentinal tubular fluid and when the patient is eating the forces will cause a change in shape and the dentinal fluid will move up and down causing sensitivity.

34
Q

what do we use to make better contacts for inter proximal restorations

A

matrixes

35
Q

how do matrices work

A

They separate the tooth using the periodontal membrane and so when the restoration shrinks the contact point is preserved

36
Q

what is the clinical procedure

A
  1. Etch – need to etch enamel surface
  2. Prime – need to prime dentine surface
  3. Bond
  4. Placement
  5. Characterization
  6. Finish
37
Q

where do we consider flowable composite

A

floor of the cavity to mediate contraction stresses on the interface to achieve optimal adaption to non load bearing margins

38
Q

how do we apply composite

A

in increments

39
Q

describe how we apply increments

A
  1. First increment – floor only. This is a reservoir for plastic deformation.
  2. The successive increments should touch as few surfaces as possible so that we don’t pull the walls to the center
  3. The final increments do not join enamel margins
40
Q

what is the minimum intensity required to adequately cure 1.5 to 2mm of composite resin

A

280 and 300 mW/cm2

41
Q

what are the curing regimes

A
soft start
ramp
pulse
boost
delayed curing
42
Q

what is the polymerization of all materials due to

A

halogen like emission spectrum

380-515nm

43
Q

what causes the polymerization

A

camphorquinone

44
Q

how does camphorquinone work

A

causes the polymerization as when exposed to a certain wave length it releases free radicals which initiate the polymerization process

45
Q

Removing a composite filling can be difficult due to how similar it looks to the natural tooth - what can be done to help differentiate?

A

if you etch the tooth and the filling - the restoration should be a diff color and the tooth chalky white which can therefore help the dentist differentiate and decide where to begin

  1. use air abrasion unit that uses aluminum oxide powder which can selectively remove composite and retain solid enamel