dental ceramics for contemporary dentist Flashcards
butt margin implication
porcelain on facial metal on the lingual
PFM
lithium disilicate is
emax
“blue state” refers to what and why
emax - lithium dislicate glass ceramic
when blue composed primarily of lithium metasilicate - which is EASIER TO MILL AND RESULTS IN LOWER BUR WEAR
after milling process completed - the material is heat treated and glazed in one step, forming the final lithium dislicate, prepared for CAD/CAM use
glass matrix ceramics gets broken down to
- feldspathic
- synthetic
- glass infiltrated
main type of porcelain that is applied on PFM’s today
Feldspathic
feldpahic porcelain is made of
traditional group of ceramic based on a ternary material
- clay/ kaolin (hydrated aluminasilicate)
- quartz (silica)
- feldspar (potassim and sodium aluminasilicates)
examples = IPS empress esthetic, IPS emress CAD, IPS classic , ivoclar vivadent ; vitadur, Vita VMK , vitablocks
IPS emax ceram is?
emax reinorced with zirconia
- type of fluroapatite based
part of synthetic!
examples of synthetic
- leucite based
- lithium dislicate and derivates
- fluroapatite- based
composition of synthetic
silicone dioxide
potassium oxide
sodium oxide
alumnium oxide
combined with apetite crystals or leucite
leucite ***
crystals REINFORCES the glass by defecting and arresting the propagation of cracks,
the residual glass with CTE (coefficient of thermal expansion) slighlty lower than the leucite crystals are put in compression, which further enhances the strength of glass ceramic
makes stronger
limit crack propagation
why do leucite glass ceramics present with good esthetic
because high and adjustable translucency and the possibility of coloring the glass in natural tooth shades through addition of metal oxide pigments
major example of polycrystalline ceramic we need to know
STABALIZED ZIRCONIA
glass matrix ceramics glass infiltrated
not used as much
alumina
alumina and magnesiu and alumina and zirconia
describe polycrystalline ceramics
major off the all ceramics (like own category)
aluminum oxide, stablized zirconia, zirconia toughened alumina and Alumina toughened zirconia ZTA and ATZ
fine grain crystalline structure, provides strength and fracture toughness
limited translucency due
to the absence of glass phase
difficult to etc with hydrophloric acid
why major failings with zirconia
didnt understand the cooling properties
and CTE properties
gets hot and then dos not cool at the same rate
MISMATCH OF THE CTE
patient bruxer give? why
zirconia – because fine grain crystalline structure - provides strength and fracture toughness
but this also the reason why it is more opaque – if fine crystalline structure - no room for light to come through
example of resin matrix ceramic
enamic
organic matrix highly filled with ceramic particles
greater crystalline content results in
higher flexural strength but also can decrease translucency
general rule for relationship between strength and esthetics
inverse
what happens when light passes through a translucent material
***reduced by the scattering of small sized particles, such as filler particles and porosity voids
the portion of incident light that emerges as diffuse transmission is essential for coloour perception and appearance of dental ceramics
loose matrix - more optical properties
vs zirconia - dense matrix – cant pass through
example of feldspathic porcelain
vita mark II Feldspar ceramic
flexural strength of vita mark II Feldspar ceramic
125 +- 10 mpa
most esthetic porcelain
vita mark II Feldspar ceramic
presented with more translucency than IPS emax CAD at both .5 and 1.0 mm thickness
if lower translucency - may be due to
the alumina content
vita enamic is what type?
flexural strength?
resin matrix
170+-mpa
has lower translucency than other resin cermic hybrid materials might be related to the aluminum content
emax comes from
- breakdown
all ceramic
glass matrix ceramics
synthetic
it is a synthetic type
emax strneght
360 mpa +_ 40 mpa
CAD/CAM prosthesis must be __ after
washed and the milling process does not create a smooth surface ready for cementation – the ceramic material must be contoured and finished post-milling to make it ready for delivery
two types of ceramic materials avalaible for chairside CAD/CAM restorations that can be
- hand-finished
- glaze fired in a porcelain oven
if make any adjusmtent then have to
POLISH IT
POLISHING
polishing must create a smooth surface to maximize the flexural strength of the restoration, minimize the risk of chipping or fracture, minimize abrasive wear of opposing teeth and restorations, and maximize biocompatibility by limiting adherence of bacteria to the surface of the restoraions
finishing and polishing also enhance
the esthetic appearance of the milled CAD/CAM restorations by resulting in a glossy surface that has similar reflection and refraction characteristics as natural teeth
smoothest surface seen is
polished!
polished was smoother than a glazed surface (previous gold standard)
even if going to be glazed
need to be polished before
gross adjustments ad pre polishing with?
exa cerapol wheel
if use this do not need to use the blue wheel in the blue pink and yellow
pink wheel
medium
then grey
obtain a high shine polish with
grey wheels and points
we also have white robinson brush that is white - with diamond paste
T/F we have a polishing kit for poly cerams
true
cementation
luting agents
any material used to attach or cement indirect restorations to prepared teeth
cementation
non-adhesive
this traditional cement acts by filling a space and binding adjacent surfaces
cementatin
adhesive
this category of cements CHEMICALLY interacts with the surface of the tooth and or restoration
adherence or bonding to the surface is involved
resin modified glass ionomer cement
powder?
glass?
powder is glass – aluminum silicate fluoride glass
liquid – polyalkalnic acid + resin - hydrophilic resin (HEMA)
advantages of resin modified glass ionomer cement
chemical bond / (acid from cement) resin bond
fluoride release
good compressive strength
easy to manipulate
advantages of resin modified glass ionomer cement
expansion (hygroscopic)
soluble in oral fluids *
filled resin cement advantage
bond to tooth
high compressive strength
essentially insoluble
filled resin cement disadvantages
technique sensitive
very expensive
sensitivity to eugenol (poison the catalyst)
inhibition layer (cement line)
radiogrpahs
- how does an all ceramic appear?
- how does the cement appear?
ceramic material is radiolucent
cement is opaque
when an image is taken that BISECTS the margin at 90 degree angle, the overlap of the opaque material gives the illusion that there is an open margin filled with resin material
illusion there is an open margin filled with resin material?
when an image is taken that bisects the margin at 90 degree angle
material we can etch
- lithium dislicate (emax)
- celtra duo
- enamic
- feldspathic
etch directions for lithium dislicate
20 seconds with 5% HF
etch directions for celtra duo
apply 5- 9% hydrofl uoric acid etching gel - available separately
- to the INTERIOR of the restoration only
etching time is 30 seconds
etch directions for enamic
60 seconds wit 5% HF or 30 seconds with 9% HF
etchind directions for feldspathic
60 seconds wit 5 % HF
multilink - if restoration has been etched already
if restoration has been previously etched and it has been re tried in the mouth , clean intaglio of restoration with ivoclean
multilink etch what
the surface only – if it has bot been previously etched in the lab
after etch next step in multilink
apply monobond to INTAGLIO of restoration for 1 minute – air dry
clean and dry tooth
place mr thirsty if tooth is a lower molar
implication of vital vs non-vital tooth with multilink
if vital – SELECTIVELY etch the enamel margins with phosphoric acid for 20 seconds
if non-vital – etch the ENTIRE tooth surface
after etch the tooth with multilink procedure then what
mix 1 drop of A and one drop of B togther
apply to TOOTH and agitate for 30 seconds
- air dry
then dispence cement from syringe INTO RESTORATION
for adjustments start with
proximals then fit checker
take a radiograph if needed (and is recommended)
isolation is most important during which steps
scanning and cementation
after mxed drop of a and b and agitated tooth for 30 seconds - air dry , cement is in restoration then what?
seat restoration with PRESSURE
- clean interproximals with microbrushes and floss
then wait for cement to begin to gel and clean the remainder
- you can light cure for 1-2 seconds, but be careful not to overcure
- take post op radiogrpah to check for excess cement
once all is clean light cure
polish margins with composite finishing burs – only done if needed and only by faculty
mark II and enamic gain strength from? implication on bonding
gain strength from bonding so want to make more adjustments after bonded on – to decrease liklihood of fracturing occcuring
hydrofluoric acid vs phosphoric acid
- general
never put hydofluoric acid in the patients mouth
etch everything basically besides
zirconia
restoration should only be etched?
once - more than once - it can decrease the strength and can crack
if try in – need to be cleaned afterwards with ivoclean
applying monobond where and when
intaglio of restoration for 1 minute - air dry
primer with multilink is the
a and b
best tool to tell if open closed margin
explorer and then fit checker
first thing you do when get crown from lab
check proximal contacts first prior to doing anything
