W2: Amalgam + GI Lining Flashcards
Dif btw GI liner and base
liner= 0.5 mm
base= thicker, use when larger defects when want to replace dentine
When do you line/base?
to protect pulp
deep cavity
Pulp protection under amalgam and metal indirect restorations
* Deep cavities with or without pulp exposure
(pulp protection, dentine replacement)
* Restoration of endodontically treated teeth
(prevention of micro leakage, dentine replacement, blockage of undercuts)
objective of liner/base
protect pulp
How would you lime an amalgam vs composite filling?
sand which
liner under amalgam
has to be uunder to make resistance form
Is flowable composite a liner?
No, they are not material of choice, no benifits
Can any GIC be used as liner/base?
Yes
Do we use Eugenol?
No not when subsequent filling will be donw
Why use GIC?
When dentinal tubules are exposed what do we do?
seal them on pulpal and axial, no need gingival
Diff btw sealing mod/deep cavity
What geometry are we trying to preserve when lining?
create horizontal pulpal, vert axial wall
What are the diff btw CC and DC
removes smear layer, need to rinse thorough, can use either, main diff is just time exposure
Why dycal applicator?
small, can pick relevant amt of GIC and place it where we want it…apply on pulpal wall like a drawing, may need 2nd transfer for axial wall.
for MOD, need 3rd trsfr for remaining axial wall.
yellow, so we can see, easy to control. removable by spoon b4 it sets.
If unset, easy to remove excess, don’t wait for it to set.
If you use RGIC or GIC lining base, and there is excess what tip should you follow?
remove with spoon, dont light cure yet
If you have deep gingival class 2, what resto can you do?
sandwhich
GIC base,
comp/amalgam on top
2 options
open/close sandwhich
- open: GIC base covers ging. margin, GI exposed to oral cavity, do it when cavity is really gingival, amalgam no need to elevate.
- closed: enamel remaining, so you want to bond to enamel, GI is inside more
GIC base must be below…
contact
Defects in GI restoration could occure….
- shows contact defect of proximal contact
Is Open/close sandwhich technique used for A/comp?
composites
secondary caries always occur
at interface of material and tooth
what recc if GIC in proximal?
use them below contact
What are the recommendations
- Use GIC as liner/base in deep cavities with a therapeutic agent under
all direct and indirect restorations - Use GIC as liner on pulpal and axial walls under amalgam restorations
- Do not use a eugenol-based material under resin-based materials
(RMGI, adhesive and CR); eugenol adversely affects polymerisation
anything that contains eugenol DO NOT USE IT WITH
resin based material
Is amalgam still used?
less than 1%
IN SIM will be used for class 2
Amalgam composition
water and liquid
Composition of Amalgam
> 12% Copper
How to we reduce amalgam corroson?
Gamma 2 phase is
- weak phase, amalgam susceptible to corrosion (bad thing in OC bc water present)
Types of alloys
- lathe- harder to condense than composite, gotta pack it, need time to develop strength, cant polish str8 away gotta do it tmr or next week, apparently better proximal contact
- spherical- early strength
- admixed= contains diff particle shapes,
Adv/Disadv of amalgam….
good
- less technique compared by comp (comp guided by extent of caries)
Indications for amalgam
occ prox cavity
class II
cusp replacement (stronger than comp)
Clinically relevant properties:
- strength= cant compress it
edge strength (could fracture so you gotta maintain 90 degrees cavo surface) - better wear resistance compared to composite
Negatives of amalgam
- thermal: thats why need liner/base
- corrosion: oxidising of metal atoms in water/air. now we use high copper amalgam (so gamma 2 phase reduced=lower corrosion).. but still bad
- creep= edges.margin of resto goes out and up, if you probe, can detect gap btw resto and tooth. no 2ndary caries= no need to replace
What must you consider to prevent fracture?
CS angle
You found a creep but Why should you not replace amalgams?
unless no caries. dont take it out bc you’d have to drill more teeth. Just polish it.
There is always a minute gap in amalgams, what will this mean?
liner for amalgam vs composite
amalgam= place liner, no need matrix.
composite= need matrix to provide contact and confine material (NEED BURNISHING bc tofflemire is not contoured)
Mixing process for A
mixing for recc times, we use capsules in SIM
once mixed, place in dappen dish in A carrier/gun
Where should you fill A? Describe process
Fill in proximal box first
If MOD, distal box first bc its more difficult to reach
- place 1 increment in proximal box
- use condensor (flat ended or serrated) to press particles of metal alloy together, press p. hard.
condense vert and laterally bc if you do it only vertical there could be voids laterally.
-
Why condensate A?
particles close, no porosity
excess gone
- place 1 increment in proximal box
- use condensor (flat ended or serrated) to press particles of metal alloy together, press p. hard.
condense vert and laterally bc if you do it only vertical there could be voids laterally. - precarve burnishing= initial shape to resto while it is soft
- use explorer to define marginal ridge ASAP (MR is weakest point)
- remove matrix once Proximals done. BECAREFUL bc you could fracture
- unscrew slowly remove matrix with hands, in oblique manner
- carve
- remove rubber dam and adj occ
- post carve burnish, shiny
- floss check IP
Why define MR asap during A resto?
- use explorer to define marginal ridge ASAP (MR is weakest point)
Resto should not be higher
than adjacent tooth.
How should you remove matrix
with hands, obliquely, carefule to not fracture
what is carving part of A?
using carvers which have cutting edges
do NOT carve
too deep fissures, bc it reduces strength of A
Occlusal Adj.
- art paper- shiny area= heavy contact
- avoid carving resto out of occlusion
Once done occ adj and no premature contact….
proceed to PCB to give it a glossy appearance
+
use floss, pass it against adjacent tooth until thru contact then move towards resto to assess tightness of contact.
not polishing
final stage
when is finishing and polishing done? importance
at least 24 hrs after
reduces plaque if glossy
If you use white stone for A, can u use it for composites
no dont mix, will stain
Burs we could use to finish
why use water when finishing amalgams?
- evaporation of mercury vapour reduced when we use water
How to get shiny polish?
conclusions
- we now use HIGH Cu Amalgam, reduces high corrosion
- cavity design need to follow
- GI is choice for pulp protection
- condensation = vertical and lateral angles
- finishing and polishing is next visit
