Study your flashcards anywhere!

Download the official Cram app for free >

  • Shuffle
    Toggle On
    Toggle Off
  • Alphabetize
    Toggle On
    Toggle Off
  • Front First
    Toggle On
    Toggle Off
  • Both Sides
    Toggle On
    Toggle Off
  • Read
    Toggle On
    Toggle Off

How to study your flashcards.

Right/Left arrow keys: Navigate between flashcards.right arrow keyleft arrow key

Up/Down arrow keys: Flip the card between the front and back.down keyup key

H key: Show hint (3rd side).h key

A key: Read text to speech.a key


Play button


Play button




Click to flip

126 Cards in this Set

  • Front
  • Back
The primary objective of restorative dentistry
to replace diseased or lost tooth structure with materials that restore function and esthetics
Properties of Dental Materials
Dimensional Changes
Thermal Conductivity
Electrical Properties
Solubility and Sorption
Mechanical Properties
Dimensional change is
percent shrinkage or expansion of a material as a result of a chemical reaction
Types of stress
Tensile (away from each other)
Compressive (towards each other)
Shear (lateral)
Electrical properties (3)
1. Galvanism: electrical currents in the mouth due to different metals in the mouth that the patient can feel
2. Corrosion: Dissolution of metals in the mouth
Is the result of galvanic currents

3. Tarnish: Surface reaction of metals in the mouth from components in saliva or foods resulting in corrosion
mechanical properties of dental materials
-Biting force
-Elongation and compression
-Resilience and toughness
biting force of person with natural teeth

patients with restorations can experience decrease of 50 to 80%
stress-strain curve
with elastic modulus
The Elastic Modulus is the slope of the stress-strain curve in the initial straight-line portion.

at the upper right end (top of Y or stress axis) of curve is the fracture point
Proportional Limit
Is the stress on the stress-strain curve when it ceases to be linear or vertical

the lowest point on the y axis (stress)
Yield Strength
Is the stress at some arbitrarily selected value of permanent strain (each material has a different value)
-where strain begins to increase

just above proportional on Y axis
Ultimate Strength
is the stress at which the fracture occurs on stress strain curve (upper limit on Y axis)

(fracture point)
Elongation and Compression
The amount of deformation that a material can resist before rupture is reported

The percent of elongation and compression are measures of ductility and malleability, respectively

Elongation = Ductility
Compression = Malleability

Energy required to deform a material permanently

Energy necessary to fracture a material

(if stress strain curve has smaller slope it is much tougher)
measured in knopp hardness

-how deep the diamond goes in
Strain-Time Curves
Materials in which the strain is dependent on the time the load is maintained
t0 = Compressive load is applied
0-A = Rapid increase in strain
A-B = Strain gradually increase
t1 = Compressive load is removed
B-C = Rapid decrease in strain
C-D = Gradual decrease in strain
t2 = Permanent strain remained
D-E = Magnitude of strain
The shorter the time and the less force applied to the impression means what?
the lower the permanent strain and the more accurate the impression
the amount of water in milliliters added to 100 g of powder
By convention is expressed as a fraction, such as:
45/100 or 0.45
45 mL of water are added to 100 g of powder
Excess water mixed with model plaster does what
1. Increases setting time
2. Reduces strength
3. Reduces expansion
4. Reduces hardness
If one adds too much water to a gypsum material when it is mixed, one gets a material that has
a softer surface
The setting reaction of a plaster material is characterized by
the release of heat (exothermic)
what is gypsum made of?

what is the reaction?
Calcium sulfate dihydrate

CaSO4·½H2O + 1½ H2O ---> CaSO4·2H2O + heat
Increasing the water-to-powder ratio of a gypsum mix will cause the expansion of gypsum to
Aside from disinfection, an impression material should be rinsed thoroughly before pouring

Colloids on the impression will make the gypsum weak
If one gypsum model (A) has a compressive strength twice that of model B, which will have the higher surface hardness or abrasion resistance?
Upon removal of an alginate impression from its poured model, a dentist discovers several fractured teeth on the model. What are possible causes, assuming that the dentist used the correct removal technique?
The impression may have been removed before it reached full strength (45 to 60 minutes is required).

the impression may have been removed after the alginate dried out and became inflexible


-to look at structure

-for fabrications of restorations (implants,dentures)

-obtained from master cast
An assistant fails to add surfactant to a silicone impression before pouring in high-strength die stone. What is a likely problem with the cast?
to much water with gypsum will cause what
reduced strength, increased porosity,
increased setting time, decreased expansion, and decreased hardness.
The mix will likely be so soupy
short setting time of alginate could be a result of what
too little water
hot water
too much manipulation
An assistant pours an alginate impression with an epoxy material. What will you predict about the quality of the cast and why?
A poor quality cast will probably result with many bubbles and voids because epoxy (a water-hating material) is not compatible with alginate (a water-based material).
qualities of gypsum
1. Accuracy
2. Dimensional stability
3. Ability to produce fine details (margins)
4. Strength/resistance to abrasion
5. Ease adaptation to the impression
6. Color
7. Safety
type 1 gypsum (impression plaster) properties
-setting time 2.5 to 5 min
-low expansion .15
-lowest compression strength
-detail is ok
type 2 gypsum (model palster)
-setting time based on package
-expansion is .30
-compression strength is low
-detail is ok
type 3 gypsum (dental stone)
-expansion is .20
-compression is moderate
-detail is good
type 4 and 5 gypsum
4. high strentgh/low expansion
5. high strength/high expansion

only difference is the expansion is more on high expansion, compression is the same
physical form of gypsum is
Accelerators of gypsum
chemicals that increase the rate of setting:
- Potassium Sulfate
- Terra alba (set gypsum particles)
retarders of gypsum
chemicals that decrease the rate of setting:
- Borax
Properties of Gypsum Materials
Setting Time
Reproduction of Detail
Hardness and Abrasion Resistance
Dimensional Accuracy
warm water does what to gypsum and working time over 37C
it extends working time becasue heat is byproduct of reaction
Stone like material that can resist the high temperatures and forces experienced during burnout and casting
Investment – Types
1. Gypsum bonded
Resist temperatures less than 1200°c, ideal for gold Type II, III and IV
good for stronger metals
2. Phosphate-bonded investments
Used for higher-melting alloys, they are stronger, ideal for PFM and RPD frameworks
investment composition
Binders (gypsum)
Holds investment together

Refractory material (form of silica SiO2)
Resists the heat of burnout and casting
composite resin composition
-resin matrix
-inorganic filler particles
-coupling agent
-activator system
-optical modifier
resin matrix of composites info
bifunctional monomer called
inorganic filler particles of composites info
-improves physical, chemical, and mechanical strength
-reduces shrinkage
-reduces thermal expansion
composite coupling agent info
provides bonding of filler and resin matrix
composites method of polymerization
-light cure
-chemical cure
-dual cure
composite particle sizes
-microfill (for really smooth surfaces) great polishability
-hybrid (stronger than micro but does not polish as well)
what is the purpose of acid etching for composites
it decalcifies a thin outer layer of enamel
-creates mechanical undercuts
-cleans surface
composite bonding agents objectives
-minimize tooth prep
-reduce leakage
-reinforce tooth structure
characteristics of dentin bonding agents
-bond to dentin just as well as enamel
-very quick to get max. bond
-prevents microleakage
-stable in oral cavity
-easy to use
indications (when would you use) bonding agents
-direct composites
-indirect composites and veneers
-ceramic restorations that wil be resin bonded
-post and core restorations
-to densensitize dentin
composition of amalgam
metal alloy and mercury
metals in amalgam
Silver (Ag) 40-60 wt%
Tin (Sn) 27-30 wt%
Cooper (Cu) 6- 30 wt%
Zinc (Zn). 0.01-2 wt%
Palladium (Pd) less than 1%
Indium (In) 10–15 wt% in the Hg
gamma phase of amalgam
when alloy containing tin is cooled below 480 degrees C

silver + tin
When gamma phase is mixed with mercury to produce the dental amalgam

Mercury diffuses into the gamma phase and reacts with the silver and tin portions of the particles forming tow compounds: (know these)
1. Silver-mercury (gamma1 phase: Ag2Hg3)
2. Tin-mercury (gamma2 phase: Sn7-8Hg)
amalgam reaction
gamma phase (silver & tin) + mercury --->
gamma + gamma1 + Cu-Sn

increases composition of Cu in amalgam = stronger & less corrosion

up to 2 days to complete rxn.
dimensional changes of amalgam due to time
-contraction increases first 20 minutes
- after 20 minutes expansion increases for up to 8 hours
-bigger the restoration the larger the expansion
-expansion from zinc
-excessice expansion if zinc expossed to water
the problems if amalgam is not mixed properly (2-3 seconds off)
Undermixed: dull and crumbly

Normal: shiny and separates in a single mass from the capsule.

Overmixed: soupy and tends to stick to the walls of the capsule
tool used to insert amalgam
steps to fill with amalgam
-each incriment with condensor 1/3 to 1/2 prep
-make sure to push laterally against axial walls
-overpack 1mm to cover margins
-finish within 3.5 minutes
carving amalgam with cleoid discoid
-Part of the edge of the carver’s blade should rest on non prepared surface
-Mesial and distal fossae slightly deeper than proximal marginal ridges
-always go up with carving
sequence of steps to prep for amalgam
-Field isolation.
-Establish the outline.
-Remove caries.
-Smooth cavosurface angle. Must be in sound tooth structure.
-Place base if deep or close to pulp. (Dycal).
Follow the memo on policy of liners and bases
-Etch, place Prime &Bond NT and light cure.
-Insert amalgam as explained
what is an alloy
metal + non metal
-formed into restorations by casting
-produces better physical properties that orignal materials
name the ADA Classification of dental casting alloys
-high nobel
-base metal

**The alloy is determined by its yield strength and elongation
alloy type 1
-restoration for low stress and some inlays
-yield strength <140
-elongation 18%
alloy type 2
-restorations subject to medium stress (some inlays/onlays)
-yield strength 140-200
-elongation 18%
alloy type 3
- high stress, crowns, short veneer crowns, short span FPD
-yield strength 201-340
elongation 12%
alloy type 4

(test question)
-extra hard
-very high stress restorations
-thin veneer crowns, long span FPD, removable partials
-yield strength >340
-elongation 10%
Noble metals
○ Resist tarnish
○ Good luster when dry
○ Gold, platinum, palladium
(Gold content may be expressed in terms of 4 things)
-a noble metal
-Soft, malleable, has low strength
-MP 1063

-Content expressed
¨ %
¨ Karat
Karat=24 x %gold/100
24 karat is 100% pure gold
¨ Fineness
Multiply the % by 10
Used to determine dental solders (joining of two different metals
¨ Color
MP 1755
Hardness and strength is better than gold
MP 1555
Cheaper than platinum
base metals
-are requuired in alloys for their strength,flexibility,and wear
-they corrode
-present in gold alloys as a scavenger (deoxidizing agent)
-improves the castability and fluidity of the alloy
improves mechanical properties of gold alloys
improves mechanical properties of base metal alloys
metal alloys are made of
crystals and grain boundaries between crystals
when would gold-platinium be used (high nobel)
full cast, ceramic bonding
when would gold-palladium be used (high nobel)
full cast, ceramic bonding
when would gold-copper-silver be used (high nobel)
full cast applications
when would siver-gold-copper be used (nobel)
full cast applications
when would palladium copper be used (nobel)
full cast, ceramci bonding
when would silver palladium be used (nobel)
full cast, ceramic bonding
when would nickel based be used (base metal)
full cast, ceramic bonding, partial denture, wrought
when would copper based be used (base metal)
full cast, ceramic bonding, partial denture, wrought
when would titanium based be used (base metal)
fullc ast, ceramic bonding, partial denture, dentla implants
High-noble Alloys

-Need at least 60% of gold, platinum, or palladium
-At least 40% of this 60% must be gold
-Very low corrosion
-Easy to manipulate
-Most expensive
Noble alloys
- 25% must be noble metal
- Silver based
- Corrosion is low but not as low as high noble
- Main use is for crowns and Fixed Partial Dentures (FPD)
Base metal alloys
○ Nickel, cobalt, or titanium
○ Complex alloys
○ High corrosion and questionable biocompatibility
§ Is related primarly to their corrosion
§ Corrosion is based on releasing elements into mouth
§ Unpleasant taste
○ Very low cost
Wrought alloys
○ Shaped into another form by mechanical force
○ Main structure is grain fibers not crystals
○ Used for orthodontic wires and clasps for partials
Ceramic bonding alloys
○ Elements are added to high noble alloys to form oxide layer
-metal alloy can turn ceramic green
-can also cause debonding of ceramic
Solder uses
-Join an orthodontic wire to a band
-Join a clasp wire to a RPD
-Join two units of a FPD
-Add proximal contact
-Repair and occlusal defect in a casting
solder flux
material that cleans the alloy to be soldered and dissolves any surface oxide on the metal
polymer use
(10 of them)
1. CD or RPD base to support artificial teeth
2. Ortho appliance
3. Soft liners
4. Prosthetic Teeth
5. Provisionals
6. Composites and sealants
7. Impression trays
8. Impression materials
9. Maxillofacial material
10. Occlusal appliance
Is a short polymer composed of two, three, or four "mer" units
When two or more different types of monomers are joined
in polymerization reaction how is the initiator activated
initiator is an organic peroxide (benzoyl peroxide)

it is decomposed into active free radicals either by -heating (use heat-curing acrylic)
-addition of an organic accelerator (using amines termed chemically or self-curing acrylic)
Denture Base Polymers Properties
-Good color stability
-No taste
-No odor
-Good biocompatibility
-No allergic reactions if is properly process
-Water sorption is fairly high (0.6 mg/cm2) can go up to 2%
-The sorption of water causes the base to expand slightly, resulting in better fit
Heat-cured Acrylic Base
Most popular of denture based polymers
Lower cost of processing
Adequate strength
Fairly flexible
High resistance fatigue fracture
Less unreacted methyl methacrylate monomer
no odor or bad taste
Light-Cured Dimethacrylates uses
1. Repair of acrylic dentures
2. Orthodontic appliances
3. Reline dentures
4. Impression trays
5. Fabrication of dentures
Soft Liner uses
1. Severe undercuts of the ridge
2. Patients with continue sore ridges
3. Tissue treatment after oral surgery
4. Obturators for defects of the palate
soft liner classifications
1. Acrylic or long-term (months)
2. Silicone or short-term (days)
Prosthetic Teeth indications
1. Low-stress-bearing areas
2. Poor ridges
3. Opposing natural teeth
4. Limited interarch distance
purpose of a provisional
1. Maintain abutment relationships
2. Function
3. Esthetics
4. Periodontal Health
two main categories of ceramics
· Silica based/glass based
· Non silica based/high strength ceramics
two subcategories of silica based
-Traditional feldspathic porcelain
-Reinforced feldspathic porcelain
Traditional feldspathic porcelain specifics
(know the chemical formulas)
□ Is a very common material in dentistry
□ Feldspathic porcelin is what is fused to metal coping
□ 3 main ingredients
¨ Feldspar K2O-Al2O3-6SiO2
¨ Silica (unchanged during firing providing stability) in form of pure quartz ¨ Kaolin (clay) provides opaqueness Al2O3-2SiO2-2H2O
Materials that solidify without an organized crystalized structure
glass, super cooled liquids
what makes glass translucent
¨ High translucency is #1 property
¨ This is associated with low structural (flexual) strength, the crack does not meet anything is the substance to stop the crack
¨ 60-90 mega pascils in strength (very low)
¨ Discoloration can show through this porcelain
when do you use Traditional feldspathic porcelain
¨ Porcelain laminate veneers
¨ Single units (not common)
Reinforced feldspathic porcelain 2 types
Leucite reinforced feldspathic porcelain

Lithium disilicate reinforced feldspathic
what did Sir John Mclean Do?
¨ Took alumina and mixed with traditional feldspathic porcelain and put it in the furnace to 1000C
¨ Feldspathic at 1000C fuse to form glass
¨ Alumina (aluminum oxide) at 2000C
◊ These become stuck in the glass (the double the flexual strength to about 160 mega pascils)
◊ There is now something for the crack to run into (it is a filler in the material)
◊ If you have a matrix and a filler the matrix determines the restoration, explained is a glass based restoration
Leucite reinforced feldspathic porcelain specifics
¨ Is the most common now, leucite is glass based restoration
¨ Leucite grows during firing, it is not put in like the alumina above
¨ Preciable ceramics is the group
◊ Onlays
◊ Full coverage crowns
◊ Veneers
◊ Inlays
¨ Flexual strength is about 220
Leucite reinforced feldspathic porcelain Require a substrate to bind to
◊ A rough surface is created by applying a acidic agent like hydrofluoric acid to create porous and rough surface to apply bonding agent to. You apply this on restoration and tooth
◊ The adhesive is Bis Gma
Lithium disilicate reinforced feldspathic specifics
¨ Condense particles, making it the strongest material
¨ 360 mega pascils
¨ Do not use this material for a bridge, too stiff
¨ No metal is needed
two sub categories of non silica based
Alumina based

Zirconia based
Two categories of Alumina based
Glass infiltrated aluminous porcelain

Densely sintered alumina
what was Michael Sadoul's role in Glass infiltrated aluminous porcelain
he bipased the shrinkage of aluminum oxide (alumina)
how is shrinkage bipassed in Glass infiltrated aluminous porcelain
-Used pre centering temperature
► This is point where temp is high enough to make particles move and slightly fuse at the grain boundaries
► You can see some fusion but no shrinkage of alumina
-Cool it down
- This coping is very pourus so another stage to seal
◊ Takes glass in form of liquid and adds to coping and fires it so glass can infiltrate the coping and fill it in.
◊ The glass is a filler
◊ The alumina is the matrx
► This makes it a alumina based filler
► Has flexual strength of 450 mega pascils
► First cementable all ceramic restoration
No bonding agent needed
indications for Glass infiltrated aluminous porcelain
up to the first molar
Densely sintered alumina specifics
¨ No porosity here, it is very dense
¨ Flexual strength is 700 mega pascils
¨ Can be cemented anywhere in the dental arch
¨ You make the model big to calculate the shrinkage
¨ The use of a computer to calculate the precise shrinkage
¨ Alumina oxide can mask staining from amalgam and has a radio opacity is similar to enamel
Zirconia based (2nd on non silica)
□ Zirconium oxide
□ Flexual strength is 1000 mega piscals (the strongest)
□ All ceramic brides would use this
□ It shrinks during firing
□ Compensate for shrinkage like above in densely sintered
□ Procerkrzircon is method we use in clinic
what is an inlay
a restoration that is made to fit into a tapered cavity preparation and involves the occlusal and proximal surface(s) and possibly a cusp.
-prepared outside the mouth and cemented to the prepared tooth
what is an onlay
a restoration that involves the occlusal and proximal surface or surfaces and covers all the cusps