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BDS2 - DMS > Clinical Amalgam > Flashcards

Clinical Amalgam Flashcards

1
Q

What is amalgam?

A
  • An alloy of mercury with another metal or metals
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2
Q

What are 3 examples of direct restorative materials?

A
  • Amalgam
  • Composite resin
  • Glass ionomer & RMGI
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3
Q

What are 4 examples of indirect restorative materials?

A
  • Gold
  • Other metals
  • Ceramic
  • Composite resin - Ceromeric
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4
Q

What are possible indications for using amalgam as a resotra tive material? (2 points)

A
  • A direct restoration in moderate and large sized cavities in posterior teeth
  • Core build ups when the definitive restoration will be an indirect cast restoration such as a crown or bridge retainer
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5
Q

What are possible contraindications for using amalgam as a restorative material? (4 points)

A
  • IF aesthetics are paramount to the patient
  • The patient has a history of sensitivity to mercury or other amalgam components
  • Where the loss of tooth substance is such that a retentive cavity cannot be produced
  • Where excessive removal of sound tooth substance would be required to produce a retentive cavity
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6
Q

What are advantages of using amalgam? (9 points)

A
  • Durable
  • Good long term clinical performance
  • Long lasting if placed under ideal conditions (median survival 12-15 years)
  • Long-term resistance to surface corrosion
  • Shorter placement time than composite
  • Corrosion products may seal the tooth restoration interface
  • Radiopaque
  • Colour contrast (can be a good thing)
  • Economical (it is cheap - takes less time for you to place so not as expensive for you to place)
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7
Q

What are some disadvantages of amalgam? (5 points)

A
  • Poor aesthetic qualities
  • Does not bond easily to tooth surface
  • Thermal diffusivity high
  • Cavity preparation may require destruction of sound tooth tissue
  • Marginal breakdown
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8
Q

What may long term corrosion at the tooth restoration interface of amalgam result in?

A
  • ‘ditching’ leading to replacement of repair
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9
Q

Can local sensitivity reactions happen at amalgam restoration s?

A
  • Yes
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10
Q

Lichenoid lesions can occur at amalgam restorations. What are these and what would you do? (3 points)

A
  • Type IV hypersensitivity reactions
  • Remove amalgam and replace
  • Gold or composite
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11
Q

One disadvantage of using amalgam is that a galvanic response can occur. What does this mean?

A
  • Battery effect from 2 different amalgams more likely amalgam and a cast metal restoration (tingly effect in the mouth - rare)
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12
Q

One disadvantage of using amalgam is that it can cause tooth discolouration. How does it do this?

A
  • Corrosion products migrate into tooth surfaces which is porous -> darkened tooth
  • (not rare)
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13
Q

One disadvantage of using amalgam as a restorative material is that is can cause an amalgam tattoo. How does this happen?

A
  • Fine amalgam particles migrate into soft tissues
  • Not a problem - only problem potentially is the differential diagnosis - need to make sure it is definetly an amalgam tattoo and not something more serious
  • (can biopsy or use an x-ray, however x-ray is seldom helpful)
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14
Q

What advantageous properties has caused amalgam to be used for over 100 years? (6 points)

A
  • Quick and easy
  • Self hardening at mouth temp.
  • Can be used in load-bearing areas of the mouth
  • Good bulk strength and wear resistance
  • Usually placed at one visit
  • Economical
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15
Q

What is the caries restoration sequence? (8 points)

A
  • Caries risk, assessment and diagnosis
  • Likely material choice
  • Informed consent
  • Caries access and removal
  • Cavity design
  • Removal of deep caries
  • Cavity toilet
  • Restoration placement
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16
Q

What is meant by retention form?

A
  • Features that prevent the loss of the restoration in any direction
  • In an occlusal direction significant undercut is not required, parallel or minimal undercut is all that is necessary
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17
Q

What is meant by resistance form? (3 points -long)

A
  • Features that prevent loss of the material due to distortion or fracture from masticatory forces
  • Ideally the cavity floor should be approx. parallel to the occlusal surface with sufficient depth of the cavity to give adequate mechanical strength (approx. 1.5-2mm) (place a lining in the lower parts rather than taking tooth away in the upper parts)
  • The gingival floor of a proximal box should be approx. 90 degrees to the axial wall. IF it is greater than this -> a sloping inclined plane which makes the filling liable to slide out of the cavity (doesn’t slide out at any speed but will creep out)
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18
Q

What are the 2 possible cavity designs to treat interproximal caries?

A
  • Self-retentive box preparation

- Proximo-occlusal preparation

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19
Q

What are the advantages of a self-retentive box preparation? (3 points)

A
  • Less tooth tissue removed than with a proximo-occlusal restoration
  • Reduced amount of amalgam placed
  • Sound tooth tissue retained between proximal box and any occlusal cavity
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20
Q

What are the disadvantages of a self-retentive box preparation? (2 points)

A
  • Can be more technically demanding than a proximo-occlusal preparation
  • Further treatment of any pit and fissure caries may be required
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21
Q

What are the advantages of a proximo-occlusal preparation? (3 points)

A
  • (should be) very retentive
  • Also treats any caries in pits and fissures
  • Less or no opportunity for future caries in pits and fissures
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22
Q

What are the disadvantages of a proximo-occlusal preparation?

A
  • Destruction of tooth tissue for retention

- Increased risk of weakening the tooth

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23
Q

What additional mechanical retention can be added to a cavity? (2 points)

A
  • Include grooves or dimples within the cavity design

- Pin placement - titanium/stainless steel (pin use is controversial BUT used to increased retention is large)

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24
Q

When placing a pin for extra mechanical retention, what must you consider? (5 points)

A
  • Pins are self tapping screws
  • Place pin into dentine in the greatest bulk of the tooth
  • Never in enamel or at the
    ADJ
  • Avoid the pulp and periodontal ligament
  • Pack amalgam around the pin
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25
Q

What are the initial problems with using pins as added mechanical retention? (3 points)

A
  • Stress in tooth around the pin
  • Cracking of dentine
  • Sensitivity of tooth due to temperature transference
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26
Q

What are the long term problems with using pins as added mechanical retention? (1 point)

A
  • Filling can leak but will fall out because of the pin -> secondary caries which can progress further into the tooth because of the pain
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27
Q

What filling material should you never use pins with?

A
  • Composite resins
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28
Q

What are examples of adhesive technology which can be used for additional retention? (3 points)

A
  • Sealing + bonding restorations (resin) (must be dual curing bonding agent) e.g. scotchbond, prime&bond
  • Bonding - resin cement e.g. PANAVIA
  • Resin modified GIC e.g. Vitrebond
29
Q

When finishing the cavity prior to a restoration what do you need to do? (4 points)

A
  • Ensure all caries is removed
  • Smooth and round internal line angles
  • Check and finish cavo-surface angles
  • Smooth cavity margins
30
Q

What does moisture contamination do to restorative materials (especially composite)? (4 points)

A
  • Reduces strength
  • Increases creep
  • Increases corrosion
  • Increases porosity
31
Q

What would you use for sealing dentine?(3 points)

A
  • Cavity varnishes
  • Normally with RMGIC
  • Can use DBA but this complicates the process
32
Q

What is microleakage?

A
  • Passage of fluid and bacteria in micro gaps (10 microns) between restoration and tooth
33
Q

What can microleakage cause? (3 points)

A
  • Pulpal irritation and infection
  • Discolouration
  • Secondary Caries
34
Q

Over time, what can lead to microleakage? (2 points)

A
  • MEchanical loading and thermal stresses
35
Q

What are 2 examples of matrices?

A
  • KerrHawe Matrices

- Omni-matrix

36
Q

What are examples of uses of a matrix? (4 points)

A
  • Recreate wall(s) of the cavity
  • Allows creation of proximal form
  • Allows adequate condensation
  • Confines amalgam to the cavity
37
Q

What properties should a matrix have? (4 points)

A
  • Should be <0.5mm thick
  • Smooth and strong
  • Allow close adaptation especially at the cervical margin
  • Allow good contact with adjacent tooth
38
Q

What are wedges essential for?

A
  • To produce adaptation of the matrix at the cervical margin buccal or lingual approach
39
Q

What are 2 examples of wedges?

A
  • Wizard wedges

- Anatomical wedges

40
Q

What are 4 uses for wedges when using amalgam?

A
  • Temporary tooth separation
  • Prevents excess amalgam gingivally
  • Aids proximal wall contour
  • Prevents movement of matrix band
41
Q

What does the mixing time of amalgam affect? (4 points)

A
  • Handling characteristics
  • Working time
  • Amalgam microstructure
  • Restoration longevity
42
Q

Is condensation pressure important?

A
  • Yes, very important

- Vertical and lateral pressure needed

43
Q

What does condensation of amalgam do? (4 points)

A
  • Expels excess mercury bringing it to the surface where it can be carved off
  • Adapts material to cavity walls
  • Reduces layering (homogenous)
  • Eliminates voids
44
Q

What do you require to get optimal condensation of amalgam? (4 points)

A
  • Require correct size of instruments
  • Easier to control initial increment with a large plugger (smear into cavity, smaller plugger, overlapping axial strokes)
  • Lateral as well as axial condensation
  • Spherical alloys require less force for condensation
45
Q

What can inadequate condensation of amalgam lead to? (4 points)

A
  • Lack of adaptation to cavity
  • Poor bonding between layers
  • Inadequate mercury expression and consequently removal during carving
  • Inferior mechanical properties
46
Q

Do you want to overfill the cavity when placing amalgam?

A
  • Yes
47
Q

There is a higher mercury content in the surface amalgam which needs to be removed. How can we do this? (3 points)

A
  • Carving
  • Burnishing
  • Using high volume aspiration
48
Q

When carving amalgam you want to recreate the anatomical contour. What do you want to recreate? (5 points)

A
  • Marginal ridge
  • Inter-proximal contact areas
  • Fissure pattern
  • Cusps and cuspal inclines
  • Re-establishes occlusal contacts
49
Q

What is the finishing of amalgam used to do?

A
  • Only do it if required to adjust anatomical contour after the amalgam has set
50
Q

What is meant by the term ‘corrosion’?

A
  • Detrimental change in the character of amalgam due to reactions in the mouth
51
Q

What is corrosion of amalgam in the mouth associated with and what can this cause? (4 points)

A
  • Associated with gamma 2 phase
  • Can cause marginal breakdown with creep and ditching
  • Expansion of amalgam during corrosive process may assist in the development of a marginal seal
  • Most amalgam is now non-gamma 2, high copper, so less of a problem
52
Q

What is meant by the term ‘creep’?

A
  • Slow internal stressing and deformation of amalgam under stress
53
Q

What is incorporated into amalgam to reduce creep?

A
  • Copper
54
Q

What should reduced creep of amalgam maintain?

A
  • Marginal integrity
55
Q

What is essential to reduce creep in amalgam restorations?

A
  • Correct cavo-surface angles
56
Q

In which situations would you remove an amalgam restoration? (3 points)

A
  • Secondary caries
  • Bulk fractures
  • Removal of an amalgam core within an extra-coronal restoration
57
Q

When is the greatest amount of mercury released from an amalgam restoration?

A
  • During the insertion and removal of amalgam restorations

During insertion

  • Amount is proportional to the restorations free surface area

During removal

  • Vapour + particles
58
Q

How can you absorb mercury? (5 points)

A
  • Vapour into lungs
  • Contact with skin
  • GIT
  • Gingival and mucosa
  • Dentine and pulp as metal ions (not a lot do this)
59
Q

How much mercury is absorbed from a filling?

A
  • Inorganic mercury vapour is released very slowly from an amalgam (about 0.5 microgrammes/surface/day)
60
Q

What protection would you use to ensure mercury hygiene? (6 points)

A
  • Dental dam
  • High volume aspiration
  • Amalgam traps - separaotrs
  • Spillage kit
  • Coreect disposal of waste amalgam
  • Correct disposal of unused amalgam
61
Q

Does dental amalgam produce delayed hypersensitivity contact reactions on the skin and mucous membranes?

A
  • Yes
62
Q

What can higher levels of mercury than found in dentistry cause to happen to the body? (6 points)

A
  • Neuro-toxicity
  • Kidney disfunction
  • Reduced immunocompetence
  • Effects on the oral and intestinal bacterial flora
  • Effects on general health
  • Foetal and birth defects
63
Q

What is Black’s classification?

A
  • Classifications of a CAVITY
64
Q

What is blacks class I cavity?

A
  • Pit and fissure caries
65
Q

What is blacks class II cavity?

A
  • Approximal caries (posterior teeth)
66
Q

What is blacks class III cavity?

A
  • Approximal caries (anterior teeth)
67
Q

What is blacks class IV cavity?

A
  • Approximal caries involving incisal edge
68
Q

What is blacks class V cavity?

A
  • Caries affecting cervical surfaces
69
Q

What is blacks class VI cavity?

A
  • Caries affecting the cusp tips

BDS2 - DMS (14 decks)

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