Reading...
Play button
Play button
Use LEFT and RIGHT arrow keys to navigate between flashcards;
Use UP and DOWN arrow keys to flip the card;
H to show hint;
A reads text to speech;
80 Cards in this Set
- Front
- Back
|
This is the measure of the body's response to a specific material.
|
Biocompatibility
|
|
|
What are some possible reactions to dental materials?
|
Chemical irritation
Unpleasant tastes Localized rxn Generalized rxns Cytotoxicity Inflammatory rxn |
|
|
This is the percent shrinkage or expansion of a material due to a chemical reaction.
|
Dimensional change (expressed as a percentage)
|
|
|
Linear thermal expansions is expressed as...
|
...coefficient of thermal expansion.
|
|
|
What is percolation?
|
Contraction of restoration due to cool temperature. When the temperature returns to normal the fluid is forced out of the space.
|
|
|
Materials with high conductivity are ________ conductors of heat and cold.
|
good
|
|
|
What is galvanism?
|
Generation of electrical currents that the patient can feel.
Comes from the presence of dissimilar metals in the mouth. |
|
|
This is the dissolution of metals in the mouth.
|
Corrosion
|
|
|
Corrosion is the result of these.
|
Galvanic currents
|
|
|
This is the surface reactions of metals in the mouth from components in saliva or foods resulting in corrosion.
|
Tarnish
|
|
|
The _________ of the materials in the mouth and the ___________ of oral fluids by the material are important criteria in their selection.
|
Solubility
Sorption |
|
|
What is wettability?
|
A solid's affinity for liquid-hydrophobic & hydrophilic.
|
|
|
What is the average biting force of a person with natural teeth?
|
77 kg.
|
|
|
What are the molars biting forces?
|
580 N
|
|
|
What are the biting forces of the bicuspids?
|
310 N
|
|
|
What are the biting forces of the cuspids?
|
220 N
|
|
|
What are the biting forces of the incisors?
|
180 N
|
|
|
Patients with restorations and prothesises can have their biting forces decreased by...
|
...50-80%
|
|
|
What are the 3 types of stress a dental material can experience?
|
1. Tensile (pulling)
2. Compressive (squeezing) 3. Shear (sliding) |
|
|
Deformation/Length=
|
strain
|
|
|
Elastic modulus (stress/strain) is a measure of...
|
...the stiffness of a material
|
|
|
2 reasons for dentures to be made from a rigid material:
|
1. Load distribution
2. To be used in thin sections without bending |
|
|
What is a material's proportional limit?
|
The stress on the stress/strain curve when it ceases to be linear. Where it begins to bend.
|
|
|
What is a material's yield limit?
|
The stress at which it is permanently bent.
|
|
|
What is the ultimate strength of a material?
|
The stress at which that material fractures.
|
|
|
Elongation & Compression...what are they?
|
The amount of deformation that a material can withstand before rupture. The material's brittleness. (Elongation-tensile; compression-compressive stress)
|
|
|
Elongation is a measurement of...
|
...ductility.
|
|
|
Compression is a measurement of...
|
...malleability.
|
|
|
Ductility is related to ________ stress.
|
tensile
|
|
|
Malleability is related to ________ stress.
|
compressive
|
|
|
Alloys with less than __ percent elongation are considered to be brittle.
|
5%
|
|
|
What is resilience?
|
Energy required to deform a material permanently.
|
|
|
What is toughness?
|
Energy required to fracture a material.
|
|
|
What is hardness?
What is hardness measured by? |
Hardness is the ability of a material to resist indentation.
Hardness is measured in Knoop hardness. |
|
|
What is an intaglio surface?
|
The inner surface of a veneer restoration.
|
|
|
What are the 2 major categories of all ceramic systems?
|
1. Silica based (glass based)
2. Non-silica based (high strength) |
|
|
Feldspathic porcelain...what are the 3 main ingredients?
|
1. Feldspar (alkaline alumina silica)
2. Silica 3. Kaolin (Clay) |
|
|
What is the chemical formula for feldspar?
|
K20*Al2O3*6SiO2
|
|
|
What is the chemical formula for silica in the form of pure quartz?
|
SiO2
|
|
|
What is the chemical formula for Kaolin?
|
Al2O3*2SiO2*2H2O
|
|
|
What does kaolin add to feldspathic porcelain?
|
Opaqueness. Also more sticky so the tech can more easily shape the material.
|
|
|
Define glasses.
|
Materials that solidify without an organized, crystalline structure.
|
|
|
What makes glass translucent?
|
It is one continuous matrix...there is nothing to scatter the light.
|
|
|
Glass-flexual strength?
Brittleness? |
Low flexual strength and high brittleness.
|
|
|
Why is it so easy for a crack in glass to spread?
|
There are no boundaries to stop its 'flow'.
|
|
|
What is the strength of glass?
|
60-90 megapascals. Could not be used as a 'stand alone' material. It must be bonded to other, stronger materials.
|
|
|
Besides traditional feldspathic porcelain, what is the other silica-based material used for ceramics?
Who invented it? |
Reinforced feldspathic porcelain.
Introduced by John McClain (also developed glass ionomer cement) |
|
|
How is reinforced feldspathic porcelain created in the lab?
|
Combine feldspathic porcelain powder with Al Oxide (alumina) powder. Fire them to the MP of feldspathic powder (~1000 degrees C--with 2 ingredients fire to the lower MP).
|
|
|
How is alumina suspended in reinforced feldspathic porcelain?
|
Alumina's MP is way higher (~2000 degrees C) than feldspathic's. FS melts and then rehardens with the unmelted particles of alumina stuck in the glass. Alumina particles prevent cracks from perpetuating.
|
|
|
What is the flexual strenght of traditional feldspathic?
Of reinforced feldspathic? |
Trad: 60-90 megapascals
Reinforced: about 160 megapascals |
|
|
Reinforced feldspathic porcelain is a _______ based restoration.
|
Glass. Glass is the matrix, alumina is the filler.
|
|
|
What is the most popular type of reinforced FS porcelain?
|
Leucite reinforced FS porcelain
|
|
|
How do you create a leucite reinforced FS porcelain?
|
Fire FS porcelain against an oxide layer.
|
|
|
For what are leucite reinforced FS porcelains used?
|
*Onlays (up to 1st molar)
*Single units (up to 1st molar) *Veneers *Inlays |
|
|
What is the flexual strength of the leucite reinforced FS porcelain?
|
220 megapascals--still require bonding for longevity.
|
|
|
What are the limitations of leucite reinforced FS porcelain?
|
1. 220 megapascals, require bonding for longevity
2. very translucent, if going over discolored teeth it cannot mask the foundation color. |
|
|
How do you bond reinforced FS restorations?
|
1. Roughen the surface by applying an acidic agent (usually HF acid)
2. Apply adhesive (usually Bis GMA) to this roughened surface for a mechanical lock |
|
|
Can silica based agents be etched?
|
Yes.
|
|
|
What are the three types of reinforced FS porcelains?
|
1. Alumina reiniforced FS
2. Leucite reinforced FS 3. Lithium disilicate reinforced FS |
|
|
What percentage of Lithium disilicate particles are condensed in glass? What does this tell us?
|
66%-The strongest silica based material (360 megapascals)
|
|
|
What is the flexual strength of Lithium disilicate reinforced FS?
|
360 megapascals
|
|
|
What were lithium disilicate reinforced FS designed for primarily?
|
Fixed partial bridges and dentures (very strong)
|
|
|
What are the 2 types of non-silica based ceramic-type materials?
|
1. Alumina based (aluminum oxide based)
2. Zirconium based (zirconium oxide based) |
|
|
What are the two types of alumina based non-silica materials?
|
1. Glass infiltrated aluminous porcelain
2. Densely sintered alumina |
|
|
What was the major problem in fabricating a coping/framework for alumina?
|
Shrinkage
|
|
|
What is the precentering temperature?
|
A temperature high enough to cause the particles to start moving, one towards the other and fuse at the grain boundaries.
Not a lot of fusion, but still good enough to prevent shrinkage-higher temp causes more fusion but mor shinking Allows for glass infiltrated aluminous porcelain |
|
|
Glass infiltrated aluminous porcelain is a ______ based restoration.
|
Alumina. Glass is the filler, alumina is the matrix.
|
|
|
What is the flexual strength of glass infiltrated aluminous porcelain?
|
450 megapascals
|
|
|
Glass infiltrated aluminous porcelain was the first ceramic crown that was able to do what?
|
Be cemented on its own. (Still have to apply FS on top of it-this is just the coping) It was the first to be able to survive the forces of mastication.
|
|
|
What are the indications of the glass infiltrated aluminous porcelain?
|
Single units up to the 1st molar.
|
|
|
What is densely sintered alumina?
|
Non-silica.
Alumina particles are fired all the way. Densely sintered-no porosity. |
|
|
What is the flexual strength of densely sintered alumina?
|
700 megapascals
|
|
|
Where can a densely sintered alumnia crown be used?
|
Anywhere in the arch.
|
|
|
What is the biggest obsticles with densely sintered alumina?
|
Shrinkage (Al oxide 5-20% shrinkage)
|
|
|
How can one compensate for the inevitable shrinkage of densely sintered alumina?
|
Put alumina on bigger die, raise temp until stable, pull die out yielding a big coping.
Now raise temp all the way up, will keep shinking when reaches original dimension of die. Uses CAD (comp assisted design) CAM and milling |
|
|
The radiopacity of densely sintered alumina?
|
Similar to tooth dentin.
|
|
|
Non-silica based vs. Silica based with regard to translucency?
|
Non-silica-Opaque
Silica-Translucent |
|
|
What is the flexual strength of zirconia based non-silica?
|
About 1000 megapascals
The strongest coping of all ceramic materials. |
|
|
In an all ceramic bridge, what dental material are you most likely to use?
|
Zirconia based non-silica.
|
|
|
What is major limitation of zirconia based ceramic?
|
Shrinkage-need to formula of shrinkage so you can compensate for it. (Enlarge die with gypsum or other methods)
|
