6. Ceramics in Dentistry Flashcards
we try to mimic natural teeth as close as possible
- One of the things that helps us do that is materials.
- ____
- ____.
composite
ceramics
When it comes to: • \_\_\_\_ • \_\_\_\_ • \_\_\_\_ • \_\_\_\_ Ceramics have some advantages. Must be used for \_\_\_\_ restora?ons. It’s the way to go!
longevity esthetics durability biocompatibility indirect
Ceramics
Term comes from the ____ word.
“of/for ____”
greek
pottery
porcelain - ____, feldspar, ____, kaolin
ceramic - ____ non-metallic solid prepared by the action of ____ (sintering) and subsequent ____
- ____ (= glass) or (partial) ____
The ceramics we use don’t have ____ so he’s doesn’t like the term porcelain.
quartz clay inorganic heat cooling amorphous crystalline clay
ceramic materials
silica-based (____- based, feldspathic porcelain)
high-strength (____-based)
This is why the esthetic features are good:
because they have a high degree of ____
Enamel is almost completely translucent, the shade is determined by the ____ underneath.
glass
oxide
translucency
dentin
Ceramic materials
SILICA
traditions
reinforced feldspathic ceramic
____ glass ceramics
- ____ glass phase
- controlled ____ during firing
SILICA = traditional veneering porcelains.
• Traditional ones are used as veneering porcelain.
• These porcelains or ceramics have a glass phase and a certain crystalline content.
• BUT they’re too ____ to use by themselves
• Normally placed on a ____ or coping to support the ceramics, b/c they aren’t very strong.
polycrystalline amorphous crystallization weak framework
SILICA
feldspar: ____
silic: SiO2 - ____ during firing > provides ____
kaolin: ____; provides ____
• Then we have some metal oxides added to provide opaqueness but also to achieve different colors
• Teeth are not ____, there are translucencies, mamalons and opalescents that we want to
mimic
• That’s why cad cam is helpful but the biggest problem in dentistry is that every tooth is different
• We have to customize it for every patient.
By stacking ____ we can do this
K2O-Al2O3-6SiO2 unchanged stability Al2O3-2SiO2-2H2O opaqueness
monochromatic
porcelain
Silica
raw materials ____ and purified then ____ to form glass
fused glass is “fritted” in water, freezing it in an ____ state
We can:
• ____ it
• mill it from a block of ____
- Ceramic is more ____, not as easy to get the intricacies like translucencies.
- But we don’t stack powders together.
- The ingredients are sintered or melded together then thrown into water < this is Fri$ng
- it freezes it into a amorphous state.
- That frozen amorphous stat ceramic is then crushed in small pieces.
crushed sintered/fused amorphous stack ceramic monochromatic
Silica
ceramic/porcelain powder
- mixed with ____ fluids
- stacked in ____ to mimic tooth
- frit is ground and pigmented with ____ for shade and opacity
- Then they add modifiers and other ingredients like
- ____
- ____ (to provide opacities)
- The ground, pigmented pulverized material can be used to add water or other liquids to provide a slurry that we can stack onto a framework.
- This isn’t the ____ we would ultimately have but a dentist would mix it.
- You can see the base dentin, enamel powders that you mix with water (usually) and stack.
- Once you stack and dry it it goes into a furnace, at a certain temp the mass melts and shrinks.
- It’s a ____ process.
- Not just the shape but the intricacies as well.
water/special
layers
metal oxides
pigments
metal oxides
color
multistep
Ceramic oven/furnace - controlled firing in vacuum
• These are the furnaces and what they look like
• Under a ____ based on the framework and ceramic (they come in different fusing
temperature)
• Ex. Gold alloy (w/ lower melBng T) you can’t use a veneering porcelain that exceeds
that and melts the gold when you fire it.
• This right here, you place the restoraBon on top
• it goes up into the furnace
• Then you program the specific ____ you want for that porcelain to melt under certain
condiBons.
vacuum
heat
Opaque bake
first step creates oxide layer for bonding
- depends on core material
- ____ (precious/non-precious)
- ____ ceramics
Depending on what kind of frame you’re using, for ex.
• Metal > precious or non-precious
• Ceramics (high strength ceramic)
• w/ ____ or zirconium oxide as a core or framework material then to block out the underlying structure (like metal).
• If it’s metal and you didn’t block it out, the metal would shimmer through if porcelain was put on top, it would look grey.
• Step one is to place an ____, then you can recreate natural tooth estheHc parameters.
metal alloys
high-strength
aluminum oxide
opaquer
Selection of veneering ceramic depends on care material
Coefficient of Thermal Expansion (CTE)
____ (e-module)
____
framework design (support!)
Then we can see it looks kind of weird.
• Kind of over “steg?”
• The shrinkage is about 20% so you over build it
• The mammalons are the natural structure of the tooth and dentin so then you fire this
• The selection on the veneering ceramic depends on the core material b/c the CTE has to
match the ____.
• Diff metal alloys have diff CTE that’s why you have to use diff ____.
• If not, they will chip. Read the rest.
• ____ to support the veneering porcelains
• Areas of ____mm of just veneering porcelain it may not be strong enough.
• That’s why we have to design the framework so it can support the porcelain.
modulus of elasticity fracture toughness thermal degree veneering porcelain framework design 3
Dentin bake
- This is what it looks like after the first bake. !
- Now we can make adjustments, like making it not ____.
- Base it on what the pt wants, some ppl like darker teeth or whiter teeth.
- California likes toilet bowl white teeth “
- Check with pt before you give them something they don’t like.
then you do the ____
monochromatic
enamel bake
Silica
High fusing:
2,350 to 2500 F
Medium fusing:
2000 to 2300 F
Low fusing:
____ F
We normally use ____ fusing
1220 to 1950
low
Silica
Polycrystalline glass ceramics
- ____ glass phase
- ____ crystallization during firing
Traditional
Reinforced
Feldspathic
Ceramic
In this group of silica based ceramics we have:
• ____ porcelain (just showed as veneering porcelain)
• ____ reinforced Feldspathic (Empress)
• ____ (IPS e max)
amorphous controlled feldspathic leucite lithium disilicate
SILICA
GLASS BASED CERAMICS: A Simple Graph
• The grey box is the glassy matrix
• During the cooling process, Leucite crystals grow in the ceramic in a ____ manner
• You have a glassy matrix, you fire it, then due to certain (____) chemical components,
crystals grow during the cooling process in the ceramic
• We want to control this
• Want to make sure not too many or too few
• We can do this by changing the ____ component amounts
• This determines how many crystals we have
• they will effect ____ AND ____ properMes.
- Why do we care about more crystals?
- ____ changes and ____ changes
- When a crack happens, it goes through and might be stopped by one.
- So the more crystals, the ____ BUT the less ____.
- The fracture strength isn’t high of the materials.
controlled magnesium chemical optical physical modulus of elasticity fracture stronger translucent
Metal vs. ceramic
E-modulus
brittle ceramics need support
- ____ (metal alloy or high-strength ceramic)
- ____ with composite cement
metal alloys undergo plastic deformation
- ceramics are ____
Modulus of Elasticity (MOE): Huge difference in the fractural behavior in a metal alloy and a ceramic.
• Explained by ____ curve.
• Ex. Metal wire: you can bend ____ times before it breaks.
• Why? b/c metal can undergoes ____.
• What does this mean? It can deform itself before it breaks.
- ____ does not have the physical property of undergoing plastic deformation.
- Ex. Uncooked spaghetti, bend a little and it breaks < just like ceramic. • Why do we care? It effects how the materials act in the oral cavity.
- Ex. We can make metal thin, if you have a heavy bruxer pt you can use ____ and don’t have to worry about it chipping off.
- Ceramic onlay is too thin, it would fracture not to thick!
- Not more than 3mm but normally we use 1-1.5mm.
- Metal alloys undergo plastic deformation but ceramics are ____ < IMPORTANT.
- This is why the brittle ceramics need ____ through a core or resin bonding.
- Resin bonding w/ resin luting agent and pretreatment of tooth and restorative material (ceramic) increases fractural strength.
- Can increase fractural strength of silica ceramic by 50-80% by using adhesive technologies to bond in place.
core
resin bonding
brittle
stress strain
multiple
plastic deformation
ceramics
metal
brittle
support
Ceramic inlays/onlays
Posterior
• We can use them for posterior restora1ons for onlays/inlays.
• As early as possible I want to get you in the mind set of modern den1stry
• For many years there was a direct restora1on of amalgam and composite then we moved into “oh I need
a crown I need a crown” needing a crown.
• But this is trauma1c because we prepare all around the tooth.
• But keep this in mind, our goal is to help people keep their teeth
• Think about alterna1ves, like onlays
• You can s1ll do a crown later on if needed.
• Don’t go the most invasive, and don’t be stupid!
• You can do inlay now and crown later on! More monayy! !!!!
• Think long term, think career, build pt popula1on that will s1ck with you.
• Main reason inlay and onlay aren’t used and taught in this country b/c ____ DOESN’T PAY FOR IT.
Da fuq. “
• That determines the invasiveness of our procedures. “This was totally off topic” mmkthnxbai.
insurance
