clinical amalgam

Question 1

When to use amalgam

Answer 1

• moderate to large restorations
• posterior teeth
• core build ups
• NO chance of moisture control

Question 2

whats core build up

Answer 2

the definitive restorations will be an indirect cast restoration such, as a crown or bridge retainer

core build up in the middle using amalgam

Question 3

When not to use amalgam

Answer 3

• small pit and fissure caries
• aesthetics of high importance like anterior
• sensitivity to mercury
• retentive cavity shape cannot be produced due to loss of tooth structure
• excessive removal of sound substance needed to produce a retentive cavity

Question 4

Advantages

Answer 4

• durable
• quick easy cheap
• good long term
• long lasting 12-15 years
• resistance to surface corrosion
• load bearing
• shorter placement time than composite
• corrosion products may seal the tooth restoration
• radiopaque so can see clearly on xray
• biofilms prefer composite over amalgam so may be less carious than cr

Question 5

Disadvantages

Answer 5

• poor aesthetics
• does not bond to tooth
• thermal properties poor
• destruction of sound tooth structure
• marginal breakdown
• CREEP
• lichenoid lesions
• galvanic response
• tooth discoloration
• amalgam tattoo
• mercury toxicity

Question 6

why tooth discolouration?

Answer 6

 corrosion products migrate into tooth surfaces that are porous

Question 7

whats galvanic response

Answer 7

 battery effect with 2 different amalgams – weird taste and feeling

Question 8

whats retention form

Answer 8

o prevent loss of restoration in any direction

Question 9

whats resistance form

Answer 9

o prevent loss of material due to distortion or fracture by masticatory forces

Question 10

what do we need to keep in mind for retention form

Answer 10

o parallel or minimal undercut in occlusal direction

Question 11

what is the minimum thickness of amalgam

Answer 11

1.5mm-2mm to prevent fracture of material

Question 12

angle of occlusal floor to occlusal surface

Answer 12

should be parallel to occlusal surface with sufficient depth of the cavity to give adequate mechanical strength

Question 13

angle between floor and axial wall

Answer 13

floor should be approx. 90degree to the axial wall otherwise filling might slide out of the cavity

Question 14

whats self retentive box prep

Answer 14

just a small interproximal prep, does not touch the pits and fissures

very minimal

Question 15

adv and disadv of self retentive box prep

Answer 15

advantages
 less tooth tissue removed
 reduced amount of amalgam placed
 sound tooth tissue retained between proximal box and any occlusal cavity

disadvantages
 technically demanding
 need to treat pit and fissure caries separately

Question 16

adv and disadv of proximo occlusal prep

Answer 16

adv
 very retentive
 treats pits and fissure caries too
 no opportunity for future caries in pits and fissures

disadv
 destruction of sound tooth
 increasing risk of weakening the tooth

Question 17

whats a amalgam pin

Answer 17

o pins are self tapping screws
o increased retention

Question 18

where to place amalgam pin within a toot?

Answer 18

o place pin into dentine in the greatest bulk of the tooth
o never in enamel or at the ADJ
o avoid pulp and PDL
o pack amalgam around pin

Question 19

problems with pins

Answer 19

stress in tooth around the pin
cracking of dentine
sensitivtiy of tooth due to transferance

filling may leak but cannot fall out due to pin, secondary caries progressing underneath the pin, deeper into the tooth because of the pin

Question 20

when can you never use a pin?

Answer 20

with composite

Question 21

does adhesives help amaglam

Answer 21

no evidence

Question 22

result of moisture contamination of amalgam

Answer 22

 reduces strength
 increases CREEP
 increases corrosion
 increases porosity
 critical but not as much as in cr

Question 23

why must we use matrices and wedges

Answer 23

 recreate walls
 allows condensation
 confines amalgam
 CLOSE adaption especially at cervical margins to prevent overhangs
 good contact with adjacent tooth
 prevents movement of matrix band
 aids proximal wall contour
 prevents excess amalgam gingivally

Question 24

what are some wedge examples

Answer 24

wizard, anatomical

Question 25

what are some matrices

Answer 25

omni matrix
kerrhawe

Question 26

what is the thickness of matrices

Answer 26

<0.5mm

Question 27

mixing time of amalgam affects what properties?

Answer 27

handling, working time, microstructure, longevity

Question 28

why is condensing the amalgam optimally important?

Answer 28

 bond layers of amalgam together
 adapts material to cavity walls
 eliminates voids
 expels excess mercury

Question 29

method of condesing amalgam?

Answer 29

 vertical and lateral pressure
 overlapping axial strokes
 small plugger

Question 30

why overfill cavity

Answer 30

 burnishing will remove
 there is higher mercury content in surface amalgam that need to be removed

Question 31

problems with amalgam

Answer 31

corrosion gamma 2
creep
ditching
old restorations need high volume and dental dam
remove in chunks
dispose properly
mercruy release

Question 32

• mercury hygiene

Answer 32

 dental dam
 high volume aspiration
 amalgam traps
 spillage kit
 correct disposal of waste amalgam

Question 33

how can mercury enter body?

Answer 33

 vapour can enter lungs
 elemental mercury through lungs
 methylated mercury through GIT
 diffuse into dentine and pulp as ions

Question 34

what is the health effects of mecury toxicity?

Answer 34

neuro
kidney disfunction
reduced immunocompetence
oral and bacterial disbiosis
foetal and birth defects

Question 35

mission of minamata convention?

Answer 35

Protect human health and the environment from anthropogenic emissions and releases of mercury and mercury compounds

Question 36

minamata convention dental amalgam policy?

Answer 36

phase DOWN not phase out

• encapsulated amalgam
• amalgam separation, all amalgam separators must retain at least 95% of amalgam particles
• all amalgam waste collected by an authorised waste management establishment
• silver amalgam not used in
   children under 15
   pregnant
   breastfeeding
   unless there is specific reason for its use like moisture control or lack of cooperation