Resto Flashcards
Remember***
<6% copper
Low copper amalgam
> 9%-30% copper
can almost completely eliminate the gamma 2 phase
no need to polish
High copper amalgam
Important Properties of Amalgam
- Dimensional Change
- Creep
- Tarnish & Corrosion
- Trituration
contraction or expansion of a material
Dimensional change
Increase expansiom of amalgam is related to
- Increase mercury
- Short trituration time
- Decrease condensation pressure
- Increase particle size
- Moisture contamination
gradual , time dependent dimensional change due to constant stress
Creep
chemical rxn between amalgam & local environment
Tarnish & Corrosion
formation of oxides
atoms disintegrates resulting to weakening of the metal
Corrosion
thin layer of corrosion at the top of the restoration . loss of luster of the amalgam
Tarnish
Corrosion byproduct of amalgam has what adv.
Tin sulfide
it improves the sealing properties of the amalgam to prevent secondary caries
dull, rough & grainy surface
low strength
Undertriturated
shiny
wet
homogenous
optimal strength
Properly triturated
wet sticky appearance
moderate strength
Overtriturated
Which do your prefer over or under triturated?
Overtriturated
What is the procedure in which the amalgam is rubbed using the first finger & thumb
Mullimg
Most common cause of amalgam chipping during carving
Carving after time has elapsed
when there is ditching of amalgam restoration when it is indicated for replacement
0.5mm depth of ditch to make it more homogenous mixture
Proper way of carving the amalgam
Resting sharp instrument on the cusp while carving
Distance of margin of M& D wall to proximal surface must not be less tham
Premolars: 1.6mm
Molars: 2mm
Marginal ridge of restoration must be of the
Same Level of Adjacent Tooth
Most diff. tooth to adapt a matrix band
Max. 1st PM mesial due to developmental depression
Why is matrix band extended occlusally when restoring class II cavities
Overfilling
Diff. Type of Wedge
- Single Wedge
- Double Wedge
- Wedge Wedging
- Piggyback
gingival recession
Piggyback wedging
Hand Instruments Classification
Classification
Cutting
Non- cutting
Basic Parts
Handle
Shank
Working end
4 unit formula
Width
Angle cutting
Length
Angle degrees
3 unit formula
WLA
Width
Length
Angle
omitted in 3 unit formula because in this formula the cutting edge angle is immediately 90* or perpendicular to the blade
Cutting Edge Angle
