Clinical Amalgam Flashcards
(69 cards)
1
Q
What is amalgam?
A
- An alloy of mercury with another metal or metals
2
Q
What are 3 examples of direct restorative materials?
A
- Amalgam
- Composite resin
- Glass ionomer & RMGI
3
Q
What are 4 examples of indirect restorative materials?
A
- Gold
- Other metals
- Ceramic
- Composite resin - Ceromeric
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
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
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)
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
8
Q
What may long term corrosion at the tooth restoration interface of amalgam result in?
A
- ‘ditching’ leading to replacement of repair
9
Q
Can local sensitivity reactions happen at amalgam restoration s?
A
- Yes
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
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)
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)
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)
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
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
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
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)
18
Q
What are the 2 possible cavity designs to treat interproximal caries?
A
- Self-retentive box preparation
- Proximo-occlusal preparation
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
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
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
22
Q
What are the disadvantages of a proximo-occlusal preparation?
A
- Destruction of tooth tissue for retention
- Increased risk of weakening the tooth
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)
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
25
What are the initial problems with using pins as added mechanical retention? (3 points)
- Stress in tooth around the pin
- Cracking of dentine
- Sensitivity of tooth due to temperature transference
26
What are the long term problems with using pins as added mechanical retention? (1 point)
- Filling can leak but will fall out because of the pin -> secondary caries which can progress further into the tooth because of the pain
27
What filling material should you never use pins with?
- Composite resins
28
What are examples of adhesive technology which can be used for additional retention? (3 points)
- 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
When finishing the cavity prior to a restoration what do you need to do? (4 points)
- Ensure all caries is removed
- Smooth and round internal line angles
- Check and finish cavo-surface angles
- Smooth cavity margins
30
What does moisture contamination do to restorative materials (especially composite)? (4 points)
- Reduces strength
- Increases creep
- Increases corrosion
- Increases porosity
31
What would you use for sealing dentine?(3 points)
- Cavity varnishes
- Normally with RMGIC
- Can use DBA but this complicates the process
32
What is microleakage?
- Passage of fluid and bacteria in micro gaps (10 microns) between restoration and tooth
33
What can microleakage cause? (3 points)
- Pulpal irritation and infection
- Discolouration
- Secondary Caries
34
Over time, what can lead to microleakage? (2 points)
- MEchanical loading and thermal stresses
35
What are 2 examples of matrices?
- KerrHawe Matrices
| - Omni-matrix
36
What are examples of uses of a matrix? (4 points)
- Recreate wall(s) of the cavity
- Allows creation of proximal form
- Allows adequate condensation
- Confines amalgam to the cavity
37
What properties should a matrix have? (4 points)
- Should be <0.5mm thick
- Smooth and strong
- Allow close adaptation especially at the cervical margin
- Allow good contact with adjacent tooth
38
What are wedges essential for?
- To produce adaptation of the matrix at the cervical margin buccal or lingual approach
39
What are 2 examples of wedges?
- Wizard wedges
| - Anatomical wedges
40
What are 4 uses for wedges when using amalgam?
- Temporary tooth separation
- Prevents excess amalgam gingivally
- Aids proximal wall contour
- Prevents movement of matrix band
41
What does the mixing time of amalgam affect? (4 points)
- Handling characteristics
- Working time
- Amalgam microstructure
- Restoration longevity
42
Is condensation pressure important?
- Yes, very important
| - Vertical and lateral pressure needed
43
What does condensation of amalgam do? (4 points)
- 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
What do you require to get optimal condensation of amalgam? (4 points)
- 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
What can inadequate condensation of amalgam lead to? (4 points)
- Lack of adaptation to cavity
- Poor bonding between layers
- Inadequate mercury expression and consequently removal during carving
- Inferior mechanical properties
46
Do you want to overfill the cavity when placing amalgam?
- Yes
47
There is a higher mercury content in the surface amalgam which needs to be removed. How can we do this? (3 points)
- Carving
- Burnishing
- Using high volume aspiration
48
When carving amalgam you want to recreate the anatomical contour. What do you want to recreate? (5 points)
- Marginal ridge
- Inter-proximal contact areas
- Fissure pattern
- Cusps and cuspal inclines
- Re-establishes occlusal contacts
49
What is the finishing of amalgam used to do?
- Only do it if required to adjust anatomical contour after the amalgam has set
50
What is meant by the term 'corrosion'?
- Detrimental change in the character of amalgam due to reactions in the mouth
51
What is corrosion of amalgam in the mouth associated with and what can this cause? (4 points)
- 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
What is meant by the term 'creep'?
- Slow internal stressing and deformation of amalgam under stress
53
What is incorporated into amalgam to reduce creep?
- Copper
54
What should reduced creep of amalgam maintain?
- Marginal integrity
55
What is essential to reduce creep in amalgam restorations?
- Correct cavo-surface angles
56
In which situations would you remove an amalgam restoration? (3 points)
- Secondary caries
- Bulk fractures
- Removal of an amalgam core within an extra-coronal restoration
57
When is the greatest amount of mercury released from an amalgam restoration?
- During the insertion and removal of amalgam restorations
During insertion
- Amount is proportional to the restorations free surface area
During removal
- Vapour + particles
58
How can you absorb mercury? (5 points)
- Vapour into lungs
- Contact with skin
- GIT
- Gingival and mucosa
- Dentine and pulp as metal ions (not a lot do this)
59
How much mercury is absorbed from a filling?
- Inorganic mercury vapour is released very slowly from an amalgam (about 0.5 microgrammes/surface/day)
60
What protection would you use to ensure mercury hygiene? (6 points)
- Dental dam
- High volume aspiration
- Amalgam traps - separaotrs
- Spillage kit
- Coreect disposal of waste amalgam
- Correct disposal of unused amalgam
61
Does dental amalgam produce delayed hypersensitivity contact reactions on the skin and mucous membranes?
- Yes
62
What can higher levels of mercury than found in dentistry cause to happen to the body? (6 points)
- Neuro-toxicity
- Kidney disfunction
- Reduced immunocompetence
- Effects on the oral and intestinal bacterial flora
- Effects on general health
- Foetal and birth defects
63
What is Black's classification?
- Classifications of a CAVITY
64
What is blacks class I cavity?
- Pit and fissure caries
65
What is blacks class II cavity?
- Approximal caries (posterior teeth)
66
What is blacks class III cavity?
- Approximal caries (anterior teeth)
67
What is blacks class IV cavity?
- Approximal caries involving incisal edge
68
What is blacks class V cavity?
- Caries affecting cervical surfaces
69
What is blacks class VI cavity?
- Caries affecting the cusp tips
