Clinical Amalgam

Question 1

What are the direct restorative materials?

Answer 1

Amalgam, composite resin, glass ionomer and RMGI

Question 2

What are the indirect restorative materials?

Answer 2

Gold, other metals, ceramic

Question 3

What are the contra-indications for amalgam?

Answer 3

Aesthetics, sensitivity to mercury, loss of tooth substance does not allow for retentive cavity, excessive removal of tooth substance would be required

Question 4

What are the indications for amalgam use?

Answer 4

Direct restoration in moderate and large sized cavities in posterior teeth

Question 5

What are the advantages of amalgam?

Answer 5

Durable, good long-term clinical performance, long lasting, resistance to surface corrosion, shorter placement time, radiopaque, economical

Question 6

What are the disadvantages of amalgam?

Answer 6

Poor aesthetic qualities
Does not bond easily to tooth substance
Poor thermal diffusivity
Cavity preparation requires destruction of sound tissue
Marginal breakdown
Local sensitivity
Lichenoid lesions

Question 7

What is the retention form of the cavity design?

Answer 7

Features that prevent the loss of the restoration in any direction

Question 8

What is the resistance form of the cavity design?

Answer 8

Features that prevent the loss of the material due to distortion or fracture by masticatory forces

Question 9

How is a resistance form made?

Answer 9

Cavity floor parallel to occlusal surface with sufficient depth of the cavity to give adequate mechanical strength

Question 10

On what type of cavity would amalgam be acceptable for?

Answer 10

Moderate to large occlusal cavities

Question 11

What are the cavity designs for interproximal caries

Answer 11

Self-retentive box preparation, proximo-occlusal preparation

Question 12

What is a self-retentive box preparation?

Answer 12

Small undercuts made on buccal and lingual walls

Question 13

What are the advantages of self-retentive box preparation?

Answer 13

Less tooth tissue removed, reduced amount of amalgam, sound tissue retained between proximal box and occlusal cavity

Question 14

What are the disadvantages of self-retentive box preparation?

Answer 14

More technically demanding than proximo-occlusal preparation, further treatment of any pit and fissure caries may be required

Question 15

What is a proximo-occlusal preparation?

Answer 15

Take out the fissure as well as interproximal caries

Question 16

What are the advantages of proximo-occlusal preparation?

Answer 16

Retentive, also treats pit and fissure caries, less or no opportunities for future caries in pits and fissures

Question 17

What are the disadvantages of proximo-occlusal preparation?

Answer 17

Destruction of tooth tissue, increased risk of weakening the tooth

Question 18

What sort of initial retention factors can you include?

Answer 18

Grooves or dimples within cavity design, pin placement

Question 19

How do you place a retentive pin?

Answer 19

Self-tapping screws, place into dentine, avoid pulp enamel and ADJ, pack amalgam around pin

Question 20

What are the initial problems with pins?

Answer 20

Stress in tooth, cracking dentine, sensitivity of tooth due to temperature transference

Question 21

What are the long-term problems with pins?

Answer 21

Filling can leak but will not fall out due to pin so secondary caries caused which can go deeper into tooth

Question 22

How do you finish an amalgam cavity?

Answer 22

Ensure all caries is removed, smooth and round internal line angles, check and finish cavo-surface angles, smooth cavity margins

Question 23

What is the effect of moisture contamination

Answer 23

Reduces strength, increases creep, increases corrosion, increases porosity, critical but not as bad as composite restorations

Question 24

What do you seal dentine with?

Answer 24

Cavity varnishes, RMGIC, use DBA sometimes

Question 25

What is microleakage?

Answer 25

Passage of fluid and bacteria in micro gaps between restoration and tooth

Question 26

What does microleakage cause?

Answer 26

Pulpal irritation, discolouration, secondary caries

Question 27

How can microleakage occur?

Answer 27

Due to mechanical loading and thermal stresses

Question 28

What is the purpose of a matrix?

Answer 28

Recreate cavity walls, allows creation of proximal form, allows adequate condensation, confines amalgam to the cavity, should be less than 0.5mm thick, smooth and strong, allow close adaption at cervical margin, allow good contact with adjacent tooth

Question 29

What do wedges do?

Answer 29

Produce adaptation of matrix at cervical margin, prevents excess amalgam gingivally, aids proximal wall contour, prevents movement of matrix band

Question 30

What does mixing time affect?

Answer 30

Handling characteristics, working time, amalgam microstructure, restoration longevity

Question 31

What does condensation do?

Answer 31

Expels excess mercury bringing it to the surface, adapts material to cavity walls, reduces layering, eliminates voids

Question 32

What does using a large plugger allow?

Answer 32

Controlling initial increment

Question 33

What does inadequate condensation do?

Answer 33

Lack of adaption to cavity, poor bonding between layers, inadequate mercury expression and removal, inferior mechanical properties

Question 34

How do you remove mercury from surface amalgam

Answer 34

Carving, burnishing, using high volume aspiration

Question 35

What does carving do?

Answer 35

Recreates anatomical contour

Question 36

What does finishing do?

Answer 36

Adjust anatomical contour after amalgam set

Question 37

What can corrosion cause?

Answer 37

Marginal breakdown with creep and ditching

Question 38

What is creep?

Answer 38

Slow internal stressing and deformation of amalgam under stress

Question 39

Which type of alloys do not exhibit as much creep?

Answer 39

High copper

Question 40

What do you need to remove amalgam restorations

Answer 40

Dental dam, high volume aspiration, minimal cutting, selective cutting, hand instruments

Question 41

When is the greatest amount of mercury released?

Answer 41

During insertion and removal of amalgam restorations

Question 42

During insertions what is the amount of amalgam proportional to?

Answer 42

The restorations free surface area

Question 43

Where can mercury absorption occur?

Answer 43

Vapour into lungs, contact with skin, GI tract, gingiva and mucosa

Question 44

What can mercury toxicity cause?

Answer 44

Neuro-toxicity, kidney dysfunction, reduced immunocompetence, effect on oral and intestinal bacterial flora, effects on general health, foetal and birth effects

Question 45

What does the Minamata convention aim to do?

Answer 45

phase down dental amalgam

Question 46

What is the consequences of the Minamata convention?

Answer 46

Aim for prevention minimize amalgam use promote mercury-free alternatives promote research of mercury-free materials encourage education of mercury-free alternatives, discouraging insurance policies favoring amalgam, encourage insurance policies favoring amalgam alternatives, only encapsulated amalgam promote good environmental practices

Question 47

Which groups of people should amalgam not be used on?

Answer 47

Children under 15, pregnant women, breastfeeding women

Question 48

What is the SDCEP guidance regarding amalgam use?

Answer 48

No justification for removal of sound amalgam restorations except in patients with allergies

Question 49

What are the main limitations for alternative amalgam placement

Answer 49

Lack of cooperation, inadequate moisture control

Question 50

What is Class 1 Caries?

Answer 50

Pit and fissure

Question 51

What is Class 2 Caries?

Answer 51

Approximal caries for posterior teeth

Question 52

What is Class 3 caries?

Answer 52

Approximal caries for anterior teeth

Question 53

What is Class IV caries?

Answer 53

Approximal caries involving incisal angle

Question 54

What is Class V caries?

Answer 54

Cervical surfaces

Question 55

What is class VI caries?

Answer 55

Affecting cusp tips

Question 56

What is dental amalgam made of?

Answer 56

Its an alloy of mercury, tin, copper, and silver. The mercury is a liquid that mixes with the other metals which are powdered.