clinical amalgam Flashcards
When to use amalgam
- moderate to large restorations
- posterior teeth
- core build ups
- NO chance of moisture control
whats core build up
the definitive restorations will be an indirect cast restoration such, as a crown or bridge retainer
core build up in the middle using amalgam
When not to use amalgam
- 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
Advantages
- 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
Disadvantages
- 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
why tooth discolouration?
corrosion products migrate into tooth surfaces that are porous
whats galvanic response
battery effect with 2 different amalgams – weird taste and feeling
whats retention form
o prevent loss of restoration in any direction
whats resistance form
o prevent loss of material due to distortion or fracture by masticatory forces
what do we need to keep in mind for retention form
o parallel or minimal undercut in occlusal direction
what is the minimum thickness of amalgam
1.5mm-2mm to prevent fracture of material
angle of occlusal floor to occlusal surface
should be parallel to occlusal surface with sufficient depth of the cavity to give adequate mechanical strength
angle between floor and axial wall
floor should be approx. 90degree to the axial wall otherwise filling might slide out of the cavity
whats self retentive box prep
just a small interproximal prep, does not touch the pits and fissures
very minimal
adv and disadv of self retentive box prep
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
adv and disadv of proximo occlusal prep
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
whats a amalgam pin
o pins are self tapping screws
o increased retention
where to place amalgam pin within a toot?
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
problems with pins
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
when can you never use a pin?
with composite
does adhesives help amaglam
no evidence
result of moisture contamination of amalgam
reduces strength
increases CREEP
increases corrosion
increases porosity
critical but not as much as in cr
why must we use matrices and wedges
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
what are some wedge examples
wizard, anatomical
what are some matrices
omni matrix
kerrhawe
what is the thickness of matrices
<0.5mm
mixing time of amalgam affects what properties?
handling, working time, microstructure, longevity
why is condensing the amalgam optimally important?
bond layers of amalgam together
adapts material to cavity walls
eliminates voids
expels excess mercury
method of condesing amalgam?
vertical and lateral pressure
overlapping axial strokes
small plugger
why overfill cavity
burnishing will remove
there is higher mercury content in surface amalgam that need to be removed
problems with amalgam
corrosion gamma 2
creep
ditching
old restorations need high volume and dental dam
remove in chunks
dispose properly
mercruy release
- mercury hygiene
dental dam
high volume aspiration
amalgam traps
spillage kit
correct disposal of waste amalgam
how can mercury enter body?
vapour can enter lungs
elemental mercury through lungs
methylated mercury through GIT
diffuse into dentine and pulp as ions
what is the health effects of mecury toxicity?
neuro
kidney disfunction
reduced immunocompetence
oral and bacterial disbiosis
foetal and birth defects
mission of minamata convention?
Protect human health and the environment from anthropogenic emissions and releases of mercury and mercury compounds
minamata convention dental amalgam policy?
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
