porcelain repair and crown sectioning Flashcards
do we always fix the chipping
1) esthetics
2) plaque accumulation
3) sharp edges
indirect failures
1) leaking margin
2) recurrent caries
- if tooth is restorable => remove crown, address caries, replace crown
3) nonrestorable => extraction
porcelain repair
1 )chipped porcelain
2) chipped porcelain and metal exposed
chipped porcelain
1( diamond bur => HF etch => silane => bond
2) diamond bur => micro etch with AlO2 -> HF etch => silane => bond (strongest)
chipped porcelain and metal exposed
1) porcelain: diamond bur => micro etch with AlO2 (increase surface area only) => HF etch
2) exposed metal => siljet (clean with air no water)
3) silane/bond both substrates
diamond bur
1) scratches in porcelain - mechanical retention
2) lowest strength repair
microetch with AlO2
1) 50 micron AlO2 at 45 psi
- micromechanical
- silica based prior to HF application
- excellent for cleaning intaglio of gold, PFM
microetch with silject
1) tribochemically attaches silica to surface of metal, then appl silane
- very strong bond to metal, zirconia, and alumina
HF etch +silane
1) very strong bond to porcelain, LDS, especially following microetcher at 45 psi
zirconia primer
1) MDP
- improves bond strength to zirconia
2) component scotchbond universal
- z-prime and zirconia primer
danville microetcher
1 )45 -90 psi
tribochemically bonding
1) tribo - friction to rub
2) chemical - relating to chemistry
3) converts kinetic energy to thermal energy that fuses glass to a hard substrate
microetcher body with silject sand
1) makes it a bondable surface
2) high velocity silica balls will fuse to zirconia due to high pressure
- high temp at 1200C
3) portions of alumina will fall out, but some will stay
silane
1) a bifunctional molecule (coupling agent)
2) do not rinse with water like AlO2, you air thin
3) apply HF acid
4) forms a bond between organic resin molecules and silica quartz filler particles
5) acts as a wetting agent for adhesive resins, penetrating etched porcelain
safety of HF
1) wear PPE
- lab coat, gloves, mask, loupes
2) work within the mannequins mouth
- keep mannequin suction running
- direct handpiece spray plume into mouth
3) use constant HVE
4) never work over skin or tissue
HF properties
1) chemically etches porcelain, silica, glass
2) corrosive to metal
3) causes severe bio damage
3) metabolic imbalance, resp problems, arrythmia, cardia arrest
- up to 24 hours after exposure
siljet
1) can cause air emphysema if pushed into soft tissue
project chip in porcelain
1) use diamond t ocut MI corner of 3x3 eMax #9 crown
- cut MI 0.5 mm bevel
2) teflon tape on adjacent tooth
3) HF acid for 10 seconds (very carefully)
- apply from dappen dish microapplicator
- small bore HVE, large bore HVE with rinse
4) silane let air dry 60 seconds and gentle air thin
- do not allow to dry undisturbed
5) apply scotch bone universal for 20 seconds, air dry, light cure
6) composite applied and light cure for 40 seconds
porcelain etch
1) 9% HF
2) extremely corrosive, reactive
- loss of vision
- readily penetrates skin
apply porcelain etch
1) dappen dish
apply for 10 seconds
2) use HVE to remove it
- rinse it off with water
- spray rinse mannikins throat
3) keep HVE near the etch as it works
4) LDS needs to etch for 10 seconds
silane and scotchbone
1) apply silane and scotchbond
2) then you can use composite
isolation materials
1) rubber dam REQUIRED for HF
2) opal dam that hardens around soft tissue
3) etch arrest as a barrier and neutralizer of HF
after suctioning off the isolation material
1) bone dry it
2) apply bonding material
3) create restoration
