Term
14- What property is in the numerator of the expression used to calculate Poisson’s ratio?
a- Ultimate tensile strength
b- Young’s modulus
c- Percent
d- Lateral strain
e- axial strain |
|
Definition
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|
Term
A cast gold alloy crown has rounded margins instead of the sharp margins that you created in the wax pattern. Which of these actions might correct this problem upon recasting?
a- Decrease the diameter of the sprue
b- Decrease the centrifugal casting force
c- Position the wax pattern further away from the closed end of the investment
d- Two of the above
e- None of the above |
|
Definition
|
|
Term
| A contact angle greater than 90 degrees indicates _______________ wetting |
|
Definition
|
|
Term
| A contact angle of 0 degrees indicates ____________ wetting |
|
Definition
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Term
A dentist adjusts the supporting cusp tip on a gold crown so that the occlusal contacting area on that cusp is decreased to half its original area. Assuming that the biting force remains constant, what is the change in stress within the occlusal contacting area of that cusp tip?
a- There is no stress
b- Doubled
c- Remains the same
d- Halved |
|
Definition
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|
Term
A dentist hand-mixed some plaster to mount a study cast in the articulator, but the mix began to set before the mounting could be completed. He repeated the procedure, making the following modifications to his mixing technique:
He used cooler water for the mix
He used less water for the same amount of plaster powder
He spatulated longer
How many of these three modifications would actually contribute to increased working time?
a- None
b- One
c- Two
d- All three |
|
Definition
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|
Term
A dentist notices a tear in an alginate impression upon removal from the mouth. Which of the following is the most likely cause of the tear?
a- over spatulation of the mix
b- water/powder ratio too high
c- delayed removal from the mouth
d- use of mixing water that is warmer than mouth temperature
e- use of fast set rather than regular set alginate |
|
Definition
| Water/powder ratio is too high |
|
|
Term
A dentist receives a gold alloy casting that does not fit the die properly because the casting is too large. Of the following, which is the most likely cause?
a- Insufficient water was used for hygroscopic investment expansion
b- Pattern wax was overheated during the wax-up process
c- Burnout was incomplete
d- Investment expansion not matched to alloy expansion
e- Time in burnout oven was too short but temperature was accurate |
|
Definition
| Investment expansion not matched to alloy expansion |
|
|
Term
A diametral compressive strength test would be most appropriate for which of the following groups of dental materials?
a- Visco-elastic impression materials
b- Gold casting alloys
c- Round orthodontic wires
d- Gypsum |
|
Definition
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|
Term
A drop in temperature differential on a thermogram of a dental wax product indicates which of the following?
a- volatility of one or more wax components
b- the presence of at least three components in the wax product
c- flow
d- phase transition
e- release of residual stress |
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Definition
|
|
Term
| A ductile material is represented on the stress/strain curve by...? |
|
Definition
| A long plastic part of the curve |
|
|
Term
| A flexible material is represented on the stress/strain curve by...? |
|
Definition
| A non-steep slope on the curve |
|
|
Term
A gypsum cast made from a reversible hydrocolloid impression is distorted. Which of the following processes would you suspect as the cause?
a- Imbibition
b- Polymerization
c- Precipitation
d- Hysteresis
e- Thermal expansion |
|
Definition
|
|
Term
| A low W/P ratio increases voids from...? How does this compare to an elevated W/P ratio? |
|
Definition
| Low w/p ratio increases voids from crystal growth. This differs from an elevated w/p ratio based on the origin of the voids. The voids of an elevated w/p ratio will be larger than the voids from a decreased w/p ratio |
|
|
Term
A manufacturer mistakenly adds less sodium phosphate to a batch of irreversible hydrocolloid powder than is specified in their formula. What will be the main effect of this mistake on the performance of the material compared to its intended performance?
a- Decrease stiffness
b- Decrease amount of water required
c- Decrease working time
d- Increase hysteresis
e- Increase tear strength |
|
Definition
|
|
Term
A manufacturer mistakenly adds more sodium phosphate to a batch of irreversible hydrocolloid powder than is specified in their formula. How will this mistake affect the performance of the material compared to its intended performance?
a- Increase stiffness
b- Increase amount of water required
c- Increase working time
d- Increase hysteresis
e- Increase tear strength |
|
Definition
|
|
Term
A material with low Young’s modulus will always exhibit which of the following properties compared to one with a high value?
a- less able to be formed into a sheet
b- less able to be formed into a wire
c- higher Poisson’s ratio
d- greater flexibility
e- less toughness |
|
Definition
|
|
Term
| A plaster undergoes dehydration under what conditions? |
|
Definition
|
|
Term
A property that indicates resistance to fracture of a dental composite as a function of repeated loading and resulting crack propagation is
a- Ductility
b- Malleability
c- Fatigue strength
d- Proportional limit
e- Ultimate tensile strength |
|
Definition
|
|
Term
A pulp irritation test of a dental cement is an example of which of the following types of biocompatibility tests?
a- Usage
b- Cell culture
c- Cytotoxicity
d- Mutagenesis
e- Non-specific toxicity |
|
Definition
|
|
Term
A pulpal irritation study of a new dental material in an adult patient is an example of which of the following types of biocompatibility studies?
a- cell culture
b- non-specific toxicity
c- cytotoxicity
d- mutagenesis
e- clinical trial |
|
Definition
|
|
Term
| A resilient material is represented by which area of a stress strain curve? |
|
Definition
| The area under the proportional limit |
|
|
Term
| A stiff material is represented on a stress/strain curve by...? |
|
Definition
| A steep slope in the elastic part of the curve |
|
|
Term
| A type 1 gypsum-bonded casting investment is used for...? |
|
Definition
| casting inlays and crowns |
|
|
Term
| A type 2 gypsum-bonded casting investment is used for...? |
|
Definition
| Casting complete denture and partial removable dental prosthesis bases. |
|
|
Term
| A vacuum mix vs. hand spatulated gypsum has what effect? |
|
Definition
|
|
Term
A viscoelastic dental impression material with both viscous and elastic properties would behave in which of the following ways after being stressed, upon removal of the stress?
a- Time would be required for recovery which may not be complete
b- Time would be required for recovery which would always be complete
c- Recovery would be instantaneous and complete when the stress is removed
d- Recovery would be instantaneous but incomplete when stress is removed |
|
Definition
| Time would be required for recovery which may not be complete |
|
|
Term
A viscoelastic dental impression material with both viscous and elastic properties would behave in which of the following ways after being stressed, upon removal of the stress?
a- Time would be required for recovery which may not be complete
b- Time would be required for recovery which would always be complete
c- Recovery would be instantaneous and complete when the stress is removed
d- Recovery would be instantaneous but incomplete when stress is removed |
|
Definition
| Time would be required for recovery which may not be complete |
|
|
Term
| According to Kelly, what type of article provides the best evidence regarding clinical performance of a dental material? |
|
Definition
| Systematic review of multiple clinical trials |
|
|
Term
| According to Kelly, what type of article provides the best evidence regarding clinical performance of a dental material? |
|
Definition
| Systematic review of multiple clinical trials |
|
|
Term
According to the Miniature Guide to Critical Thinking by Paul and Elder, which of the following question types requires evidence and reasoning within multiple systems?
a- Questions with one correct answer
b- Questions asking for your subjective opinion
c- Questions requiring judgment for better or worse answers
d- Questions depending primarily on knowledge to arrive at a correct answer |
|
Definition
| c- Questions requiring judgment for better or worse answers |
|
|
Term
After creating a cavity preparation in a tooth using a handpiece and a bur, smear plugs will be located
a- in dentinal tubules.
b- in predentin.
c- in interbular dentin.
d- between enamel rods.
e- between hydroxyapatite crystals. |
|
Definition
|
|
Term
Alginate sets by the formation of intermolecular bonds involving
a- sodium
b- fluoride
c- phosphate
d- sulfate
e- calcium |
|
Definition
|
|
Term
All of the following are true about paraffin wax except one. Which one is the exception?
a- It is a mineral wax
b- It is a natural wax
c- It can crystallize upon cooling
d- It shrinks about 2-3% upon solidification and cooling
e- It is made from high boiling point fractions of petroleum |
|
Definition
| It shrinks about 2-3% upon solidification and cooling |
|
|
Term
All of the following are true regarding the setting time of dental stone except one. Which one is not true?
a- increased by using slurry water
b- decreased by adding terra alba to the mix
c- proportional to water/powder ratio
d- decreased by using warmer mixing water at 90 versus 70 degrees F |
|
Definition
| Increased by using slurry water |
|
|
Term
An MSDS should include each of the following topics except one. Which one is the exception?
a- Composition
b- Hazards
c- Reactivity
d- Directions for use
e- Toxicology information |
|
Definition
|
|
Term
| An axial tension will result in what kind of deformation? |
|
Definition
|
|
Term
An elastic material with a viscous component would act in which of the following ways?
a- Strain reversal would be time-dependent upon removal of the stress
b- The material must return to its original shape upon removal of the stress
c- Strain would be independent of Young’s modulus up to the proportional limit
d- The material must exhibit ductility prior to reaching the proportional limit |
|
Definition
| Strain reversal would be time-dependent upon removal of the stress |
|
|
Term
| An elevated W/P ratio increases _________________ and therefore ___________________. |
|
Definition
| Increases water porosity and therefore voids |
|
|
Term
An endosteal dental implant that has achieved osseointegration must have
a- a thin layer of fibrous tissue between the bone and implant surface
b- close approximation of the bone to the implant material
c- the ability to survive loading by a dental prosthesis
d- b and c
e- a, b, and c |
|
Definition
B and C
remember that there can be NO fibrous tissue present to achieve osseointegration |
|
|
Term
| An ethyl silicate bonded investment is used for...? |
|
Definition
| Casting high-fusing metal partial denture alloys |
|
|
Term
| An extended nearly horizontal segment at the right half of a stress/strain curve indicates what mechanical property? |
|
Definition
|
|
Term
| An extended nearly horizontal segment at the right half of a stress/strain curve indicates what mechanical property? |
|
Definition
|
|
Term
An ideal elastic material with no viscous component has which of the following properties?
a- Strain is independent of modulus
b- Strain will always be completely reversed
c- Strain reversal after removal of stress will be time-dependent
d- Strain increases non-linearly upon removal of stress
e- Strain prevents return to original dimension |
|
Definition
| Strain will always be completely reversed |
|
|
Term
| An increase in mandibular angle will have what effect on occlusal forces? |
|
Definition
|
|
Term
| Are directions for use is a standard, regulation, or neither? |
|
Definition
|
|
Term
As a group, synthetic waxes have which of the following properties?
a- properties are within a narrow range compared to natural waxes as a group
b- each type is composed of a single molecular species
c- they are synthesized from monomers
d- all of the above |
|
Definition
|
|
Term
As presented in Craig’s Restorative Dental Materials 13th edition Chapter 14, which of the following restoration parameters were judged to be “perfect” more often when produced from digital impressions than when produced from traditional elastomeric impressions?
a- Shade
b- Occlusion
c- Surface finish
d- Buccal contours
e- Triangular fossae |
|
Definition
|
|
Term
Assuming same temperature, which of the following waxes has the highest elastic modulus?
a- Carnauba
b- Inlay
c- Paraffin
d- Beeswax |
|
Definition
|
|
Term
Assuming same temperature, which of the following waxes is the most flexible?
a- Beeswax
b- Type II inlay pattern wax
c- Carnauba wax
d- Paraffin wax |
|
Definition
|
|
Term
| Beta-calcium sulfate hemihydrate is known as? |
|
Definition
|
|
Term
Borax is added to reversible hydrocolloid formulations to improve
a- hysteresis
b- syneresis
c- flexibility
d- setting time
e- strength |
|
Definition
|
|
Term
By what approximate percentage is the dry compressive strength of gypsum greater than its wet compressive strength?
a- 100%
b- 50%
c- 25%
d- 10%
e- None, dry strength is equal to or less than wet compressive strength |
|
Definition
| 100% because it is 2x as strong |
|
|
Term
| Casting techniques involving gypsum-bonded investments are often classified as thermal or hygroscopic techniques. Both of these techniques use a different refractory material. Which material is used for thermal? Hygroscopic? And Why? |
|
Definition
Thermal - cristobalite, because it has a high thermal expansion
Hygroscopic - quartz, because it has a low thermal expansion, but higher hygroscopic expansion |
|
|
Term
Ccalories is the unit of measurement for a material’s
a- Heat flow
b- Specific heat
c- Thermal diffusivity
d- Thermal expansion
e- Thermal conductivity |
|
Definition
|
|
Term
| Chemically, how does agar and alginate retard the setting of gypsum products? |
|
Definition
| Agar and alginate are absorbed by the gypsum, thus it interferes with the hydration of hemihydrate to dihydrate |
|
|
Term
| Chemically, how does type 4 gypsum differ from type 5 gypsum? |
|
Definition
| Type 4 gypsum contains extra salts to reduce its setting expansion. |
|
|
Term
| Colloidal silica in water will have what effect on gypsum? |
|
Definition
| Increases surface hardness and strength |
|
|
Term
Colloidal systems can be
a- A hydrosol
b- An emulsion
c- A gas dispersed in another gas
d- a and b
e- a,b,and c |
|
Definition
|
|
Term
Compared to dentin, enamel has a lower value of which of the following:
a- Percent organic content by weight
b- Amelogenin content by weight
c- Average size of hydroxyapatite crystals
d- Compressive strength
e- None of the above |
|
Definition
| Percent organic content by weight |
|
|
Term
Compared to dentin, enamel has a lower value of which of the following?
a- hardness
b- Young’s modulus
c- compressive strength
d- (a) and (b)
e- none of the above |
|
Definition
|
|
Term
Compared to regular-set irreversible hydrocolloid powder, fast-set irreversible hydrocolloid powder contains less of which of the following?
a- Calcium alginate
b- Sodium alginate
c- Sodium phosphate
d- Sodium sulfate |
|
Definition
|
|
Term
Compared to reversible hydrocolloid, alginate
a- Contains the same chemical mechanism to retard the setting reaction
b- Contains the same filler component to provide bulk for impression-taking
c- Has greater recovery upon removal
d- Captures less detail
e- Contains less air |
|
Definition
|
|
Term
Compared to reversible hydrocolloid, irreversible hydrocolloid…
a- has higher permanent distortion upon removal.
b- records more detail.
c- contains fewer air voids.
d- contains less filler when set.
e- utilizes hysteresis in the setting reaction to create the gel. |
|
Definition
| has higher permanent distortion upon removal |
|
|
Term
| Contact angle is a measure of...? |
|
Definition
|
|
Term
Dehydration of gypsum under pressure in the presence of water vapor creates
a- Plaster
b- Hydrocal
c- Densite
d- Plaster and hydrocal
e- Plaster and densite |
|
Definition
|
|
Term
Dentin that forms in response to local disease such as a carious lesion is called
a- Mantle dentin
b- Coronal dentin
c- Primary dentin
d- Secondary dentin
e- Tertiary dentin |
|
Definition
|
|
Term
Dentin that forms in response to localized tooth wear is called
a- mantle dentin
b- primary dentin
c- peritubular dentin
d- intertubular dentin
e- tertiary dentin |
|
Definition
|
|
Term
| Fatigue strength of a material is usually a function of what phenomenon within that material? |
|
Definition
|
|
Term
| Fatigue strength of a material is usually a function of what phenomenon within that material? |
|
Definition
|
|
Term
For which of the following would a gypsum-based casting investment not be appropriate?
a- Cast post and core under a full crown restoration
b- Porcelain-fused-to-metal crown undercasting
c- Full gold crown restoration
d- Cast gold onlay
e- All of the above can be cast using a gypsum-based casting investment |
|
Definition
Porcelain-fused-to-metal crown undercasting
Porcelain's melting point it too high to use a gypsum investment |
|
|
Term
|
Definition
|
|
Term
Fracture of unsupported enamel using a chisel-type dental hand instrument occurs along lines defined by
a- striae of Retzius
b- perikymata
c- hydroxyapatite crystals
d- rods or prisms
e- the CEJ |
|
Definition
|
|
Term
Grain boundaries are found in which of the following classes of dental materials?
a- Metals
b- Ceramics
c- Composites
d- Polymers
e- All of the classes, above |
|
Definition
|
|
Term
How could one describe a burnout when referring to heating a gypsum investment?
What is occurring during a burnout?
What is the final product after a burnout? |
|
Definition
Heating an investment ot remove wax and create mold space
Excess water evaporating and calcium sulfate dihydrate losing water, leaving a final product called anhydrous calcium sulfate |
|
|
Term
| How could one describe the friable stage of gypsum setting? |
|
Definition
| Rigid solid, initially weak |
|
|
Term
How could one describe this reaction
2Na3PO4 + 3CaSO4 --> Ca3(PO4)2 + Na2SO4 |
|
Definition
| The reaction to initially limit the availability of calcium sulfate |
|
|
Term
| How do the various forms of gypsum have identical chemical formulas but different physical properties? |
|
Definition
| The physical properties are different because of each form of gypsum loses its water differently |
|
|
Term
| How does microcrystalline wax differ from paraffin wax? |
|
Definition
| Microcrystalline wax has less volumetric shrinkage upon solidification |
|
|
Term
How does microcrystalline wax differ from paraffin wax?
a- Microcrystalline wax has a lower melting point
b- Microcrystalline wax is petroleum-based
c- Microcrystalline wax is polymerized polyethylene
d- Microcrystalline wax shrinks less upon solidification
e- Microcrystalline wax cannot be used in casting wax formulas |
|
Definition
| Microcrystalline wax shrinks less upon solidification |
|
|
Term
How does microcrystalline wax differ from paraffin wax?
a- Microcrystalline wax is made from petroleum; paraffin wax is not
b- Microcrystalline wax has a lower melting range than paraffin wax
c- Microcrystalline wax contains synthetic additives; paraffin wax does not
d- Microcrystalline wax has less volumetric shrinkage upon solidification |
|
Definition
| Microcrystalline wax has less volumetric shrinkage upon solidification |
|
|
Term
| How does paraffin wax differ from microcrystalline wax? |
|
Definition
| Parrafin wax has more volumetric shrinkage upon solidification |
|
|
Term
How does paraffin wax differ from microcrystalline wax?
a- Paraffin wax has a higher melting point
b- Paraffin wax is polymerized polyethylene
c- Paraffin wax is petroleum-based
d- Paraffin wax cannot be used in casting wax formulas
e- Paraffin wax shrinks more upon solidification |
|
Definition
| Paraffin wax shrinks more upon solidification |
|
|
Term
| How does the calcination of gypsum occur? |
|
Definition
| Dehydration by long, slow heating below the melting point |
|
|
Term
How does the stress vary in a dental restoration that is loaded by an opposing tooth, relative to the amount of applied force and area of force application?
RELATIVE TO RELATIVE TO
APPLIED FORCE AREA OF FORCE APPLICATION
a- Directly directly
b- Indirectly indirectly
c- Directly indirectly
d- Indirectly directly |
|
Definition
|
|
Term
| How many nanometers are in one mm? |
|
Definition
|
|
Term
| How many nanometers are in one mm? |
|
Definition
|
|
Term
| Hydrocal undergoes dehydration under what conditions? |
|
Definition
| Pressure with water vapor |
|
|
Term
Hygroscopic expansion is a desired property for which of the following materials?
a- impression plaster
b- mounting plaster
c- general use dental stone
d- high flow stone for model bases
e- gypsum bonded investment |
|
Definition
|
|
Term
Hygroscopic expansion is a useful characteristic of which of the following dental materials applications?
a- Plaster study casts
b- Densite models for dental implant restorations
c- Fast-set plasters for mounting models to articulators
d- Calcium sulfate-bonded casting investments |
|
Definition
| Calcium sulfate-bonded casting investments |
|
|
Term
Hygroscopic expansion is a useful characteristic of which of the following dental materials applications?
a- Plaster study casts
b- Densite models for dental implant restorations
c- Fast-set plasters for mounting models to articulators
d- Calcium sulfate-bonded casting investments |
|
Definition
| Calcium sulfate-bonded casting investments |
|
|
Term
| Hysteresis when referring to a stress/strain curve is defined as...? |
|
Definition
| the activation portion of the curve is different from the deactivation portion |
|
|
Term
| If a material can be hammered or rolled into thin sheets without fracturing, it is said to be...? |
|
Definition
|
|
Term
| If a material can undergo a large amount of plastic deformation, it is said to be...? |
|
Definition
|
|
Term
| If a material can undergo only a small amount of plastic deformation, it is said to be...? |
|
Definition
|
|
Term
If a material’s KHN is decreased, resistance to which of the following will be decreased?
a- Crack propagation
b- Indentation
c- Flexure
d- Flow |
|
Definition
|
|
Term
If a sample of metal orthodontic wire is stressed below its proportional limit, which of the following statements must be true?
a- the wire flexes
b- the wire is exhibiting ductility
c- the wire is permanently deformed
d- the wire is stressed below its Young’s modulus
e- the ultimate tensile strength of the wire is exceeded
f- the fracture toughness of the wire is slightly exceeded |
|
Definition
|
|
Term
If dental materials A and B have the same resilience value, which of the following statements is correct?
a- The toughness values of A and B must be the same
b- The toughness values of A and B may be the same
c- The toughness of A and B must be less than the respective resilience values
d- The toughness of A and B may be less than the respective resilience values |
|
Definition
| The toughness values of A and B MAY be the same |
|
|
Term
| If gypsum comes into contact with alginate, what effect will this have on hardness? |
|
Definition
|
|
Term
| If one wished to break up gypsum crystals, how would that occur? |
|
Definition
| by increasing spatulation |
|
|
Term
| If one wished to create new crystallization centers in gypsum, how would that happen? |
|
Definition
| by increasing spatulation |
|
|
Term
If you modified a material so that it is twice as ductile as it was previously but did not change the material’s modulus or proportional limit, which of the following properties would most likely be increased?
a- Toughness
b- Resilience
c- Elastic deformation
d- Ultimate tensile strength
e- Fracture strength |
|
Definition
|
|
Term
In a tensile test below the proportional limit, a cylindrical material sample was found to have elongated twenty times as much as it decreased in diameter. Based on this observation, which of the following properties would this material have?
a- A relatively high Poisson’s ratio
b- A relatively high ultimate tensile strength
c- A relatively high modulus
d- A relatively high yield strength
e- None of the above |
|
Definition
|
|
Term
| In an investment used for casting gold-alloy crowns, what is the binder composed of? |
|
Definition
|
|
Term
| In an investment used for casting gold-alloy crowns, what is the binder composed of? |
|
Definition
|
|
Term
In determining the yield strength of a material, which of the following factors must be arbitrarily specified?
a- Force
b- Elastic deformation
c- Permanent strain
d- Elastic limit
e- Ultimate strength |
|
Definition
|
|
Term
In irreversible hydrocolloid materials, what is the source of the calcium that forms cross-linking between chains to create the gel state?
a- Alginic acid
b- Calcium sulfate
c- Calcium phosphate
d- Diatomaceous earth |
|
Definition
|
|
Term
| In order, what are the 4 stages of gypsum setting? |
|
Definition
| Fluid --> Plastic --> Friable --> Carvable |
|
|
Term
| In regards to alginate recovery, if you wanted to minimize the amount of unnecessary undercuts, what would you do? |
|
Definition
| Decrease the amount of compression upon removal |
|
|
Term
| In regards to gypsum, what are nucleation centers? |
|
Definition
| Unreacted residual gypsum. Another definition is an area of undissolved hemihydrate |
|
|
Term
| In regards to gypsum, what is occurring during the setting reaction? What two things does this reaction allow to occur? |
|
Definition
Aqueous solution is depleted of calcium and sulphate ions
Allows more hemihydrate to go into solution
Allows more precipitation of gypsum crystals |
|
|
Term
| In regards to investments, if the silica/binder ratio is increased, what effect does this have on hygroscopic expansion and strength? |
|
Definition
Increases hygroscopic expansion
Decreases strength |
|
|
Term
| In regards to investments, what is a binder. What are examples? |
|
Definition
| A material which will set and bind together the particles of a refractory substance. Common binders are plaster or stone |
|
|
Term
| In regards to the alginate setting reaction, what you you add to initially limit the availability of calcium sulfate? |
|
Definition
|
|
Term
In the assigned Journal of Prosthetic Dentistry article by RJ Kelly, a scheme is presented for classification of dental materials according to which of the following criteria?
a- Clinical versus laboratory use
b- Direct versus indirect restoration
c- Biocompatibility and complexity
d- Duration and type of function
e- Physical and mechanical properties |
|
Definition
| Duration and type of function |
|
|
Term
In the assigned Journal of Prosthetic Dentistry article by RJ Kelly, a scheme is presented for classification of dental materials according to which of the following?
a- duration and type of function
b- applicable regulations and biocompatibility status
c- chemical and mechanical properties
d- clinical versus laboratory use
e- direct restoration versus indirect restoration |
|
Definition
| Duration and type of function |
|
|
Term
| In the mouth, the effort of the class 3 lever is represented by the... |
|
Definition
|
|
Term
| In the mouth, the fulcrum of the class 3 lever is represented by the... |
|
Definition
|
|
Term
| In the spring, dashpot diagram, what does the dashpot represent? |
|
Definition
|
|
Term
| In what 3 ways can a gypsum investment expand? |
|
Definition
Setting expansion
Hygroscopic expansion
Thermal expansion |
|
|
Term
Inaccuracy of stone casts made from alginate impressions can be caused by
a- Insufficient spatulation of the alginate mix
b- Premature removal of the impression from the mouth
c- Soaking the impression in water for 30 minutes prior to pouring
d- Two of the above
e- All of the above |
|
Definition
|
|
Term
Inaccuracy of stone casts made from alginate impressions can be caused by
a- Insufficient spatulation of the alginate mix
b- Premature removal of the impression from the mouth
c- Soaking the impression in water for 30 minutes prior to pouring
d- Two of the above
e- All of the above |
|
Definition
|
|
Term
| Increasing gypsum's W/P ratio has what effect, if any, on expansion |
|
Definition
|
|
Term
Increasing which of the following factors would increase the penetration coefficient of a liquid when all other relevant factors are kept equal?
a- refractive index
b- surface tension
c- contact angle
d- viscosity |
|
Definition
|
|
Term
Intertubular dentin is not normally found in which of the following?
a- Sclerotic dentin
b- Peritubular dentin
c- Root dentin
d- Primary dentin
e- Secondary dentin |
|
Definition
|
|
Term
MMP's can affect durability of dentin bonds because they
a- can degrade the cross-linking bonds in bonding polymers
b- are normally found in oral bacteria such as s. mutans
c- can degrade collagen in the hybrid zone
d- are acidic and etch surrounding dentin |
|
Definition
| Can degrade collagen in the hybrid zone |
|
|
Term
| Materials that have mechanical properties independent of loading rates are termed... |
|
Definition
|
|
Term
| Materials that have mechanical properties that are dependent on loading rates are termed... |
|
Definition
|
|
Term
| OSHA is primarily concerned with... |
|
Definition
| maintaining workplace safety |
|
|
Term
|
Definition
|
|
Term
| Other than gypsum or water, what is the second largest major component of gypsum-based casting investments? |
|
Definition
| Refractory (silica, quartz, filler) |
|
|
Term
| Other than gypsum or water, what is the second largest major component of gypsum-based casting investments? |
|
Definition
| Refractory (silica, quartz, filler) |
|
|
Term
Out of the following categories of biocompatibility tests for dental materials, which one can best be standardized and normally has good experimental control?
a- Usage tests
b- In vitro tests
c- In vivo tests
d- Pulp irritation tests |
|
Definition
|
|
Term
Permanent deformation of irreversible alginate impressions can be reduced by which of the following methods?
a- more rapid removal from the mouth
b- waiting a few minutes prior to pouring
c- increasing the temperature of the mixing water
d- two of the above
e- a, b, and c, above |
|
Definition
|
|
Term
Progressive fracture within a dental material due to repeated loading and crack propagation is known as
a- fatique
b- ductility
c- malleability
d- yield strength
e- proportional limit |
|
Definition
|
|
Term
Regular set alginate powder has more of which of the following compounds compared to fast set alginate powder for the purpose of retarding the setting reaction?
a- Calcium sulphate
b- Sodium phosphate
c- Calcium alginate
d- Guluronan
e- None of the above |
|
Definition
|
|
Term
| Specifically, what are the two ways that one can achieve hygroscopic expansion? Which way allows more expansion to occur? |
|
Definition
1) placing a wet liner inside the casting ring in which the investment is poured
2) the casting ring is placed in a water bath, post investing
Option 2 allows more expansion |
|
|
Term
| Specifically, what bioactive quality is desirable for a restorative base? |
|
Definition
| Able to induce tubule closure and secondary dentin formation |
|
|
Term
| The "necking" effect when referring to Poisson's ratio is associated with what dental material trait? |
|
Definition
|
|
Term
| The ability to be drawn and shaped by means of tension is the definition of which dental material trait? |
|
Definition
|
|
Term
| The ability to deform plastically without fracture or energy required for fracture is known as the? |
|
Definition
|
|
Term
The amount of reaction water needed to convert equal volumes (not weights) of the hemihydrate forms for hydrocal and densite to their dihydrate forms
a- is less for the hydrocal volume than for the densite volume
b- is greater for the hydrocal volume than for the densite volume
c- is the same for both the hydrocal volume and for the densite volume
d- is more than required to actually mix the hydrocal or densite volume |
|
Definition
| is less for the hydrocal volume than for densite volume |
|
|
Term
The amount of reaction water required to convert equal weights of the hemihydrate forms of plaster and densite to their dihydrate forms
a- is less for plaster than for densite.
b- is greater for plaster than for densite.
c- depends upon the mixing method used.
d- depends upon the amount of mixing water actually used.
e- is less than needed to actually mix the powder and water. |
|
Definition
| Is less than needed to actually mix the powder and water |
|
|
Term
| The cad/cam brand CEREC AC uses what technology to take digital impressions? |
|
Definition
|
|
Term
| The cad/cam brand E4 Dentist uses what technology to take digital impressions? |
|
Definition
|
|
Term
| The cad/cam brand LAVA C.O.S. uses what technology to take digital impressions? |
|
Definition
| Active optical wavefront technology |
|
|
Term
| The cad/cam brand iTero uses what technology to take digital impressions? |
|
Definition
| Parallel confocal imaging |
|
|
Term
| The change in length per unit of length of material when that material is subjected to an external force is known as? |
|
Definition
|
|
Term
| The chemical name for gypsum in a model is? |
|
Definition
| Calcium sulphate dihydrate |
|
|
Term
| The chemical name for gypsum powder is? |
|
Definition
| Calcium sulphate hemihydrate |
|
|
Term
| The correct water powder ratio for gypsum is? |
|
Definition
|
|
Term
| The internal resistance to an externally applied force is known as? |
|
Definition
|
|
Term
The largest proportion of reversible hydrocolloid is
a- Agar
b- Water
c- Inorganic filler
d- Sodium alginate
e- Calcium alginate |
|
Definition
|
|
Term
The margins of a cast gold alloy restoration are rounded unlike the sharp margins that were present in the invested wax pattern. Which of the following is the most likely cause?
a- Heating the gold alloy with the tip of the reducing zone of the torch flame
b- A button that is smaller than required
c- Too much centrifugal casting force
d- A sprue diameter that is too large
e- Two of the above |
|
Definition
| A button that is smaller than required |
|
|
Term
The maximum light wavelength absorption peak of camphorquinone is about
a- 570 nm
b- 470 nm
c- 370 nm
d- 270 nm
e- 170 nm |
|
Definition
|
|
Term
The metal orthodontic wire has been stressed in tension beyond the proportional limit of the metal, which of the following could be a result, assuming removal of the force?
a- The wire may have fractured
b- The wire may have returned to its original shape
c- The wire must have returned to its original shape
d- The cross-sectional area of the wire may have increased |
|
Definition
| The wire may have fractured |
|
|
Term
| The most common type of implant used today is? |
|
Definition
|
|
Term
| The non-curved section before the proportional limit is known as the...? |
|
Definition
| Slope = modulus of elasticity |
|
|
Term
| The poisson's ratio can be calculated by? |
|
Definition
| lateral strain/axial strain |
|
|
Term
| The process by which the desired properties of various dental waxes are obtained is primarily...? |
|
Definition
|
|
Term
The purpose of the “moist dentin” bonding technique is to
a- maintain pulp vitality
b- dilute the dentinal tubule fluid
c- increase peritubular demineralization
d- promote formation of the hybrid layer
e- reduce polymerization shrinkage of bonding resin |
|
Definition
| Promote formation of the hybrid layer |
|
|
Term
The relatively thin outer-most layer of dentin with a unique mineralization pattern and structure is…
a- primary dentin
b- secondary dentin
c- tertiary dentin
d- reparative dentin
e- mantle dentin |
|
Definition
|
|
Term
The surface of a dental restoration contains multiple scratches about 0.05 microns in width and depth. Based on the size of these scratches, the surface can be described as
a- shiny and smooth
b- dull and smooth
c- shiny and rough
d- dull and rough |
|
Definition
|
|
Term
| The term refers to the channel to send molten alloy to a crown mold. |
|
Definition
|
|
Term
| The ultimate strength point of a stress/strain curve is also known as the...? |
|
Definition
|
|
Term
| The unit used for stress is? |
|
Definition
|
|
Term
The “memory effect” of dental inlay pattern waxes is primarily caused by
a- low thermal expansion of inlay pattern wax
b- residual stress in the wax pattern
c- burning of the wax during the wax-up process
d- volatilization of some wax components
e- presence of microcrystalline wax |
|
Definition
| Residual stress in the wax pattern |
|
|
Term
The “memory effect” of dental pattern wax is caused by
a- Residual stress in the wax pattern
b- Thermal expansion of the wax pattern
c- Accidental burning of the wax during the waxing process
d- Application of stress after the wax pattern has fully solidified |
|
Definition
| Residual stress in the wax pattern |
|
|
Term
The “memory effect” of dental pattern wax is caused by
a- Residual stress in the wax pattern
b- Thermal expansion of the wax pattern
c- Accidental burning of the wax during the waxing process
d- Application of stress after the wax pattern has fully solidified |
|
Definition
| Residual stress in the wax pattern |
|
|
Term
Thermal expansion is a required property for which of the following materials?
a- Fast-set mounting plaster
b- Improved stone for master models and crown dies
c- Improved stone for master models for implant cases
d- Gypsum products for study casts
e- Gypsum-based casting investment |
|
Definition
| Gypsum based casting investment |
|
|
Term
| This class of dental material can undergo high levels of stress, is stiff, and brittle. |
|
Definition
|
|
Term
| This class of dental material is composed of calcium phosphates with varying ratios of calcium:phosphate. |
|
Definition
|
|
Term
| This class of dental material is strong, has moderate stiffness, and is ductile. |
|
Definition
|
|
Term
| This class of dental material is weak, flexible, and ductile. |
|
Definition
|
|
Term
| This type of review provides a comprehensive review of research, has a broad focus, and does not involve formal critical appraisal of considered research. |
|
Definition
|
|
Term
| This type of review provides a comprehensive review of research, has a narrow focus, and is a form of research itself |
|
Definition
|
|
Term
| Tissue engineering would require which class of regulation as set by the FDA? What are the requirements for this particular class |
|
Definition
Class III
Requires
-GMP
-Evidence of meeting standards
-Evidence of safety/efficacy |
|
|
Term
To demonstrate that a material is ductile, the material must be deformed in excess of its
a- Young’s modulus
b- Proportional limit
c- Toughness
d- Ultimate tensile strength
e- Fracture strength |
|
Definition
|
|
Term
To increase the compressive strength of her patients’ gypsum casts, a dentist tries the following:
1) Chooses stone rather than plaster
2) Increases the spatulation time
3) Delays use until the cast is fully dried
4) Uses “slurry water” in the initial mix
How many of these four actions would actually increase compressive strength? |
|
Definition
|
|
Term
| To normalize length change, what would you divide by? |
|
Definition
|
|
Term
| To normalize the force, what would you divide by? |
|
Definition
|
|
Term
To perform a finite element stress analysis of a dental implant restoration you would need
a- Samples of the actual dental implant restoration after use intraorally
b- Samples of the actual restoration materials after use intraorally
c- Knowledge of the properties of the materials involved
d- Two of the above
e- None of the above |
|
Definition
| Knowledge of the properties of the materials involved |
|
|
Term
| Torsional deformation results from what type of external force? |
|
Definition
|
|
Term
| True/False permanent deformation of irreversible alginate impressions can be reduced by more rapid removal from the mouth |
|
Definition
|
|
Term
| True/False sodium phosphate is found in gelled irreversible hydrocolloid as a result of the setting reactions? |
|
Definition
| False, sodium sulfate is found |
|
|
Term
| True/False the addition of NaCl increases the setting expansion and shortens the setting time. |
|
Definition
|
|
Term
| True/False, Alginate sets by the formation of intermolecular bonds that include sodium. |
|
Definition
|
|
Term
| True/False, Borax is known to be a retarder to gypsum setting |
|
Definition
|
|
Term
| True/False, Dissolution of enamel will normally occur at a pH greater than 5.5. |
|
Definition
| False, 5.5 is the upper limit |
|
|
Term
| True/False, Evidence of meeting standards such as ISO is required by the FDA for class i, ii, and iii dental materials |
|
Definition
| false, class ii and iii only |
|
|
Term
| True/False, Force is measured in megaPascals or Pascals. |
|
Definition
| False, Force is measured in Newtons |
|
|
Term
| True/False, Hot agar is known as gel while cold agar is known as sol |
|
Definition
|
|
Term
| True/False, Hydrocal is used to formulate low-to-moderate dental stone while densite is used to formulate high-strength dental stone |
|
Definition
|
|
Term
| True/False, Hydrocolloid sols can exhibit syneresis prior to gelling and become hydrocolloid gels by the process of imbibition. |
|
Definition
Both statements are false
hydrocolloid sols can exhibit syneresis after gelling |
|
|
Term
| True/False, Increasing guluronan content relative to mannuronan content in an alginate formula increases gel stiffness |
|
Definition
|
|
Term
| True/False, MSDS's for dental materials are required by the FDA |
|
Definition
|
|
Term
| True/False, Permanent deformation occurs in both reversible and irreversible hydrocolloid impression materials upon setting and removal from undercut areas in the mouth . |
|
Definition
|
|
Term
| True/False, Poisson’s ratio is the ratio of a sample’s (axial length while under axial tension or compression) to (original axial length). |
|
Definition
|
|
Term
| True/False, Roughening the surface of a sample would increase the total surface energy of the surface as a system |
|
Definition
|
|
Term
| True/False, Sodium alginate is a gel when set |
|
Definition
| False, calcium alginate is a gel when set, sodium alginate is a sol when first mixed with water |
|
|
Term
| True/False, The amount of “reaction water” required to convert equal weights of the hemihydrate forms of plaster and stone to their dihydrate forms is less than needed to actually mix the powder and water. |
|
Definition
|
|
Term
| True/False, Thermal expansion normally occurs during the setting reaction of dental stone used for fabricating study casts |
|
Definition
|
|
Term
| True/False, Yield strength includes a specified amount of permanent deformation |
|
Definition
|
|
Term
| True/False, Yield strength includes a specified amount of permanent deformation |
|
Definition
|
|
Term
| True/False, a cad/cam digital impression can be used to fabricate a restoration using older technology |
|
Definition
|
|
Term
| True/False, a dental material that has less elastic strain for a specific amount of stress compared to another dental material subjected to the same amount of stress is less flexible |
|
Definition
|
|
Term
| True/False, a greater amount of intertubular dentin is likely to be found near the pulp vs. near the DEJ |
|
Definition
| False, more intertubular dentin is likely to be found near the DEJ |
|
|
Term
| True/False, according to Kelly, opinions of authorities are the weakest form of clinical evidence |
|
Definition
|
|
Term
| True/False, according to Kelly, opinions of authorities are the weakest form of clinical evidence |
|
Definition
|
|
Term
| True/False, alginate is synonymous with irreversible hydrocolloid |
|
Definition
|
|
Term
| True/False, all forms of silica are in their alpha forms when in the investment |
|
Definition
|
|
Term
| True/False, all indirect restorations have their shape formed outside of the mouth |
|
Definition
|
|
Term
| True/False, all types of stresses can be resolved into combinations of axial and/or shear stresses |
|
Definition
|
|
Term
| True/False, ameloblasts are dentin-forming cells |
|
Definition
| False, they're enamel-forming cells |
|
|
Term
| True/False, an investment should be porous to allow the escape of air and other gases. |
|
Definition
|
|
Term
| True/False, beeswax is brittle at room temperature and plastic at body temperature. |
|
Definition
|
|
Term
| True/False, cad/cam systems that use lasers to take digital impressions do not require a contrasting agent (oxide powder). |
|
Definition
|
|
Term
| True/False, calcium sulfate-bonded investments are usually limited to gold castings only |
|
Definition
| True, because the calcium sulfate portion decomposes at temperatures over 700 degrees C where other castings have a higher melting point |
|
|
Term
| True/False, capillary penetration is defined as liquid movement into a crevice |
|
Definition
|
|
Term
| True/False, cementum is isotropic |
|
Definition
|
|
Term
| True/False, cementum is isotropic |
|
Definition
|
|
Term
| True/False, compared to dentin, enamel has a higher value of tensile strength |
|
Definition
| False, enamel has a lower value of tensile strength compared to dentin |
|
|
Term
| True/False, compared to other dental materials, dental waxes have a relatively low value of thermal expansion. |
|
Definition
| False, high value of thermal expansion |
|
|
Term
| True/False, copal and shellac are common resin additives to wax. |
|
Definition
|
|
Term
| True/False, cristobalite, quartz, and tridymite (all forms of silica) each exist in two polymorphic forms, one that's stable at a lower temperature, and one that's stable at a higher temperature. |
|
Definition
| False, Cristobalite and quartz exist in two polymorphic forms however, tridymite exists in three polymorphic forms |
|
|
Term
| True/False, dentin is more resilient than enamel |
|
Definition
|
|
Term
| True/False, dentin near the DEJ has fewer tubules/mm^2, smaller diameter of tubules, and a lower amount of intertubular dentin |
|
Definition
False, Dentin near the DEJ has
fewer tubules
Smaller diameter
More intertubular dentin |
|
|
Term
| True/False, enamel has a lower young's modulus but higher hardness compared to dentin |
|
Definition
| False, enamel has a higher young's modulus and hardness compared to dentin |
|
|
Term
| True/False, enamel has higher compressive strength but lower tensile strength compared to dentin |
|
Definition
|
|
Term
| True/False, enamel needs dentin's support while dentin needs enamel's protection |
|
Definition
|
|
Term
| True/False, for a restorative base, the coefficient of thermal expansion should be greater than dentin. |
|
Definition
| False, should be equal to that of dentin |
|
|
Term
| True/False, for a restorative base, the compressive strength should be equal to that of dentin |
|
Definition
|
|
Term
| True/False, for a restorative base, thermal conductivity should be equal to or greater than dentin. |
|
Definition
| False, should be equal to or less than dentin |
|
|
Term
| True/False, for hygroscopic expansion, the additional water must be provided during the setting phase, before the loss of gloss occurs |
|
Definition
|
|
Term
| True/False, governmental agencies such as the FDA, EPA, and OSHA set standards for the practice of dentistry. |
|
Definition
| False, governmental agencies set regulations, non-governmental agencies set standards |
|
|
Term
| True/False, high surface tension and low contact angle results in poor penetration |
|
Definition
| False, it results in good penetration |
|
|
Term
| True/False, higher guluronan = stiffer gel |
|
Definition
|
|
Term
| True/False, if a material is known to be anisotropic, it expands the same in all directions |
|
Definition
| False, it expands in at least one direction differently |
|
|
Term
| True/False, if a phase transition is occurring on a thermogram of a dental wax product, a drop in temperature differential is likely occurring. |
|
Definition
|
|
Term
| True/False, if a sample metal orthodontic wire is stressed to its 0.2% yield strength, it has been permanently deformed. |
|
Definition
|
|
Term
| True/False, if there is a low viscosity, there is likely to be good penetration |
|
Definition
|
|
Term
| True/False, in regards to alginate manipulation, a low water to powder ratio will decrease working and setting times |
|
Definition
|
|
Term
| True/False, in regards to reversible hydrocolloids, cooling a sol will turn it into gel |
|
Definition
|
|
Term
| True/False, in regards to reversible hydrocolloids, heating a gel to 100 degrees C will turn it into sol |
|
Definition
|
|
Term
| True/False, in regards to thermal expansion, quartz expands more than cristobalite |
|
Definition
| False, cristobalite expands more than quartz |
|
|
Term
| True/False, liquids with high pH accelerate gypsum setting. |
|
Definition
|
|
Term
| True/False, natural waxes are composed of monomers with identical chemical structure |
|
Definition
|
|
Term
| True/False, natural waxes typically have narrow-range physical and mechanical properties |
|
Definition
|
|
Term
| True/False, paraffin is the major component of most dental wax products |
|
Definition
|
|
Term
| True/False, paraffin is the major component of most dental wax products |
|
Definition
|
|
Term
| True/False, plaster is known to be high density |
|
Definition
|
|
Term
| True/False, plaster uses a wet calcination. |
|
Definition
|
|
Term
| True/False, plastic deformation is desirable when shaping an orthodontic arch wire or adjusting a clasp on a removable partial denture |
|
Definition
|
|
Term
| True/False, plastic deformation is irreversible but moldable |
|
Definition
|
|
Term
| True/False, refractory materials are found in ALL dental investments. |
|
Definition
|
|
Term
| True/False, reversible hydrocolloids are strongest when stressed quickly |
|
Definition
|
|
Term
| True/False, reversible hydrocolloids normally exhibit less permanent deformation upon removal from the mouth when compared to alginate |
|
Definition
|
|
Term
| True/False, secondary dentin differs from tertiary dentin because secondary dentin does not react to a specific stimuli. |
|
Definition
|
|
Term
| True/False, secondary dentin is synonymous with circumpulpal dentin |
|
Definition
|
|
Term
| True/False, setting expansion is linear |
|
Definition
|
|
Term
| True/False, soldering investments are designed to have lower setting and thermal expansions versus casting investments. |
|
Definition
|
|
Term
| True/False, some disinfectants will increases gypsum hardness |
|
Definition
| False, some will decrease hardness |
|
|
Term
| True/False, stress is proportional to force and area |
|
Definition
False,
stress is proportional to force
stress is inversely proportional to area |
|
|
Term
| True/False, synthetic waxes typically have narrow-range physical and mechanical properties |
|
Definition
true
because synthetic waxes are composed of monomers with identical chemical structures |
|
|
Term
| True/False, synthetic waxes typically have narrow-range physical and mechanical properties because they are synthesized from monomers resulting in a single species |
|
Definition
|
|
Term
| True/False, terra alba works better at concentrations above 1%. |
|
Definition
| False, terra alba works better at lower concentrations typically less that 1% |
|
|
Term
| True/False, tertiary dentin is synonymous with reparative dentin |
|
Definition
|
|
Term
| True/False, the compressive strength of hardening gypsum increases uniformly. |
|
Definition
|
|
Term
| True/False, the conversion of gypsum powder to its dihydrate form is exothermic |
|
Definition
|
|
Term
| True/False, the crystal structure of stone consists of irregular particles |
|
Definition
|
|
Term
| True/False, the crystaline structure of plaster consists of irregular particles |
|
Definition
|
|
Term
| True/False, the moist bonding technique can be used on both dentin and enamel |
|
Definition
|
|
Term
| True/False, the particle size of silica has a significant effect on hygroscopic expansion whereas the particle size of calcium sulfate hemihydrate has little effect. |
|
Definition
|
|
Term
| True/False, the poisson's ratio is higher for brittle materials. |
|
Definition
|
|
Term
| True/False, the poisson's ratio is higher for ductile materials. |
|
Definition
|
|
Term
| True/False, the thermal expansion of refractory materials is linear |
|
Definition
|
|
Term
| True/False, the yield strength is a point on the stress/strain curve that lies just below the proportional limit |
|
Definition
| False, lies slightly higher than proportional limit |
|
|
Term
| True/False, to achieve osseointegration with a dental implant, the fibrous tissue between the implant and bone must be 10 nm or less. |
|
Definition
| False, NO fibrous tissue is allowed to achieve osseointegration |
|
|
Term
| True/False, translucency is used to judge the thickness of wax |
|
Definition
|
|
Term
| True/False, water porosity voids are greater than voids from crystal growth. |
|
Definition
|
|
Term
| True/False, wax has a low elastic modulus, ductility, and compressive strength. |
|
Definition
| False, wax does have a low elastic modulus and compressive strength. However, it has high ductility |
|
|
Term
| True/False, when Barnsdahl wax is added to paraffin wax, there is a decreased shrinkage during solidification. |
|
Definition
| False, Barnsdahl increases paraffin's melt range, hardness, and decreases flow |
|
|
Term
| True/False, with phosphate-bonded investments, the hygroscopic expansion when using water, instead of silica sol, is negligible. |
|
Definition
|
|
Term
| True/false, Mold expansion compensates for alloy cooling shrinkage |
|
Definition
|
|
Term
| True/false, if a material has a high value of fracture toughness, it is very resistant to crack propagation |
|
Definition
|
|
Term
| True/false, increasing mannuronan content in an alginate formula increases gel stiffness |
|
Definition
|
|
Term
| True/false, most of the intermolecular bonds that cause alginate to gel are in molecular copolymer regions that are rich in mannuronan |
|
Definition
|
|
Term
| True/false, penetration of a liquid into a substrate can be enhanced by lower surface tension and/or lower surface energy. |
|
Definition
| False, penetration of a liquid into a substrate can be enhanced by lower viscosity |
|
|
Term
| True/false, the masseter muscle represents the load in a class 3 lever system |
|
Definition
| false, muscles represent the effort |
|
|
Term
Two dental materials each have the same amount of toughness. Which of the following statements describes a correct relationship of various properties for the two materials?
a- The Young’s modulus must be the same
b- The ductility must be the same
c- The yield strength must be the same
d- The proportional limit must be the same
e- None of the above |
|
Definition
|
|
Term
Two dental materials each have the same amount of toughness. Which of the following statements describes a correct relationship of various properties for the two materials?
a- The Young’s modulus must be the same
b- The ductility must be the same
c- The yield strength must be the same
d- The proportional limit must be the same
e- None of the above |
|
Definition
|
|
Term
Two dental materials each have the same amount of toughness. Which of the following statements describes a correct relationship of various properties for the two materials?
a- The flexibility MUST be the same
b- The ductility MUST be the same
c- The ultimate tensile strength MUST be the same
d- The proportional limit MUST be the same
e- none of the above |
|
Definition
|
|
Term
| Type 1 dental brazing investments are used for? |
|
Definition
| Gypsum-bonded dental brazing investments |
|
|
Term
| Type 2 dental brazing investments are used for? |
|
Definition
| Phosphate-bonded dental brazing investments |
|
|
Term
| Water above 100 degrees F will have what effect on gypsum? |
|
Definition
|
|
Term
Waxes generally have high values of all of the following except one. Which one is the exception?
a- thermal expansion
b- elastic modulus
c- ductility
d- flow |
|
Definition
|
|
Term
| What 3 major effects does increasing temperature to 100 degrees F have on gypsum? |
|
Definition
Lowers set time
Lowers flow
Increases expansion |
|
|
Term
| What 3 major effects does using silica sol instead of water have on phosphate-bonded investments? |
|
Definition
Increased strength
Higher setting expansion
Hygroscopic expansion |
|
|
Term
| What 3 steps are required to form densite? |
|
Definition
Boiling in calcium chloride
Washing with hot water
Grinding product to powder form |
|
|
Term
| What 3 steps are required to form densite? |
|
Definition
Boiling in calcium chloride
Washing with hot water
Grinding product to powder form |
|
|
Term
| What 3 steps are required to form densite? |
|
Definition
Boiling in calcium chloride
Washing with hot water
Grinding product to powder form |
|
|
Term
| What 3 ways can one measure the set time for gypsum? |
|
Definition
Loss of gloss
Temperature rise
Penetrometer |
|
|
Term
| What are the 2 major disadvantages of ethyl silicate investments? |
|
Definition
Gives off flammable components during processing
Expensive |
|
|
Term
| What are the 2 types of cad/cam seen in a dental office? |
|
Definition
Acquisition only (digital impressions only)
Scan and mill |
|
|
Term
| What are the 3 components of a cad/cam system? |
|
Definition
| Scanner, software, fabrication technology/mill |
|
|
Term
| What are the 3 factors that need to be taken into account when describing a force? |
|
Definition
Application point
Magnitude
Direction |
|
|
Term
| What are the 5 iso classifications of gypsum? |
|
Definition
1 – impression plaster
2 – plaster
3 – stone
4 – stone, high strength, low exp.
5 – stone high strength, high exp. |
|
|
Term
| What are the names of the 3 polymorphic forms of silica? |
|
Definition
| Quartz, tridymite, and cristobalite |
|
|
Term
| What are the two binders for a phosphate-bonded investment? |
|
Definition
| Magnesium-oxide and phosphate |
|
|
Term
| What are the two main effects that a change in temperature has on the physical properties of gypsum? |
|
Definition
1) Increasing temperature changes the relative solubilities of hemihydrate and dihydrate
2) Increases in ion mobility of the calcium and sulfate ions, which increases the rate of reaction and shortens the setting time. |
|
|
Term
| What are the two phases of colloids? |
|
Definition
| Dispresed and continuous phases |
|
|
Term
| What area under a stress/strain curve does toughness fall under? |
|
Definition
|
|
Term
| What can be added to prevent the negative effects of alginate and agar on gypsum? |
|
Definition
|
|
Term
| What does the bolus represent in a class iii lever system? |
|
Definition
| Load (the load is in the mouth) |
|
|
Term
| What effect does NaCl have on gypsum? |
|
Definition
|
|
Term
| What effect does slurry water have on gypsum? |
|
Definition
| accelerates gypsum set time |
|
|
Term
| What effect would potassium sulfate have on gypsum? |
|
Definition
| Accelerates the setting time |
|
|
Term
| What effect would sodium citrate have on gypsum? |
|
Definition
|
|
Term
| What effect, if any, would increased spatulation have on the compressive strength of gypsum? |
|
Definition
|
|
Term
| What effect, if any, would increased spatulation have on the set time, flow, and expansion with gypsum? |
|
Definition
Decreased set time
Decreased flow
Increased expansion |
|
|
Term
| What effect, if any, would increasing the W/P ratio of gypsum have on set time, flow, and expansion? |
|
Definition
Increased set time
Increased flow
Decreased expansion |
|
|
Term
| What effect, if any, would increasing the temperature of water added to gypsum (up to 100 degrees F) have on expansion? |
|
Definition
|
|
Term
| What effect, if any, would increasing the temperature of water added to gypsum (up to 100 degrees F) have on the compressive strength? |
|
Definition
|
|
Term
| What effect, if any, would increasing the temperature of water added to gypsum (up to 100 degrees F) have on the flow? |
|
Definition
|
|
Term
| What effect, if any, would increasing the temperature of water added to gypsum (up to 100 degrees F) have on the set time? |
|
Definition
|
|
Term
| What is a refractory substance and what effect does it have on investments? |
|
Definition
| A material that will withstand high temperatures without decomposing. Such as quartz or cristobalite |
|
|
Term
| What is another term for brazing? |
|
Definition
|
|
Term
| What is hygroscopic expansion? |
|
Definition
| Expansion by submersion in water. Seen in gypsum |
|
|
Term
| What is isotropic expansion? |
|
Definition
| Expansion in all directions (3D expansion) |
|
|
Term
| What is terra alba? What effect does it have on gypsum and how? |
|
Definition
Small amounts of set calcium sulfate dihydrate that is ground and mixed with model plaster.
Acts as an accelerant, because it provides nuclei of crystallization. |
|
|
Term
What is the approximate total percent expansion required within a gypsum-based casting investment to compensate for alloy shrinkage upon solidification from the melted state?
a- None
b- 15%
c- 1.5%
d- 0.15%
e- 0.015% |
|
Definition
|
|
Term
| What is the basic organizational unit of enamel structure? |
|
Definition
|
|
Term
| What is the binder material used in a gypsum-bonded casting investment? |
|
Definition
| alpha Calcium sulfate hemihydrate |
|
|
Term
| What is the binder used in an Ethyl silicate-bonded investment? |
|
Definition
|
|
Term
| What is the common value for yield strength? |
|
Definition
|
|
Term
| What is the critical pH of the oral cavity? |
|
Definition
|
|
Term
What is the effect on the properties of set irreversible hydrocolloid of increasing the water/powder ratio during mixing?
a- decreases working time
b- decreases setting time
c- decreases strength
d- increases imbibition |
|
Definition
|
|
Term
| What is the function of diatomaceous earth in irreversible alginate formulations? |
|
Definition
|
|
Term
What is the main effect of adding slurry water to dental stone powder at the beginning of the mix?
a- decreases working time
b- decreases air porosity in the set gypsum
c- decreases water porosity in the set gypsum
d- increases the required amount of reaction water
e- increases flow during pouring of the mix into a mold |
|
Definition
|
|
Term
| What is the major concern of CPC resorption when referring to implants? |
|
Definition
| implant micromotion and loosening |
|
|
Term
| What is the most common type of investment for casting high-melting point alloys? Why can't a calcium sulfate-bonded investment be used? |
|
Definition
Phosphate-bonded investment
CaSO4 investments cant be used because it degrades at 700 degrees C and high melting point alloys typically melt above 850 degrees C |
|
|
Term
| What is the name of the form of quartz, tridymite, or cristobalite that is stable at a lower temperature? Higher temperature? |
|
Definition
Lower = alpha form
Higher = beta form |
|
|
Term
| What is the refractory material for phosphate bonded investments? |
|
Definition
|
|
Term
| What is the refractory material in an ethyl silicate-bonded investment |
|
Definition
|
|
Term
| What is the relationship between the particle size of silica and setting expansion and hygroscopic expansion? |
|
Definition
| Finer silica particles produce higher setting and hygroscopic expansions |
|
|
Term
| What is the temperature ranges used in the oven for calcium sulfate-bonded investments? |
|
Definition
|
|
Term
| What is the unit for strain? |
|
Definition
|
|
Term
| What is the unit for strain? |
|
Definition
|
|
Term
| What makes up most of the organic portion of dentin? |
|
Definition
|
|
Term
| What occurs when alginate comes into contact with agar? |
|
Definition
|
|
Term
| What process would one use to send molten alloy into an investment mold? |
|
Definition
|
|
Term
| What purpose does an oxide powder serve in cad/cam? |
|
Definition
| It reduces optical highlights (glare) from the tooth surface to allow for a more accurate digital impression. The powder ensures that all surfaces are uniform in color and reflectance. |
|
|
Term
| What referring to casting, what does devesting mean? |
|
Definition
| removing investment material surrounding cast restoration |
|
|
Term
| What term is described as the strength of a material at a predetermined permanent strain? |
|
Definition
|
|
Term
What term is this describing?
Dark lines in enamel in longitudinal sections probably representing incremental growth; neonatal line is a special example |
|
Definition
|
|
Term
| What term refers to the material poured around a wax pattern to create a mold? |
|
Definition
|
|
Term
| What theory (name and mechanism) explains of setting for gypsum? |
|
Definition
Crystalline theory
Calcium sulfate dihydrate is less soluble than the hemihydrate form. When the hemihydrate form dissolves in water, the dihydrate form supersaturates, and precipitates out of solution from points of nucleation, because it is less soluble. The crystals then bind to one another, resulting in a final cohesive structure. |
|
|
Term
| What two specific things indicate that a dental material has good ductility? |
|
Definition
Reduction in area
Elongation at the breaking point |
|
|
Term
| What two things do flaws create? |
|
Definition
| Stress concentration and crack propagation |
|
|
Term
| What type of deformation is exhibited from the proportional limit to the failure point? |
|
Definition
|
|
Term
| What type of deformation is exhibited up to the proportional limit? |
|
Definition
|
|
Term
| What type of dental prostheses can be fabricated with a type 2 phosphate-bonded investment? |
|
Definition
|
|
Term
| What type of dental protheses can be fabricated with a type 1 phosphate-bonded investment? |
|
Definition
| Inlays, crowns, and other FIXED restorations |
|
|
Term
| What would happen if you were to reheat an investment that has already been cooled to room temperature? |
|
Definition
| Internal cracking because the investment does not expand thermally to the previous level. |
|
|
Term
When a metal alloy implant screw is stressed above its proportional limit, which of the following statements must be true?
a- The screw exhibits strain
b- No permanent deformation results
c- The ultimate tensile strength of the metal alloy is exceeded
d- The screw is stressed to its fracture strength |
|
Definition
| The screw exhibits strain |
|
|
Term
When a metal alloy implant screw is stressed below its proportional limit which of the following must be true?
a- No strain occurs in the screw
b- The screw exhibits permanent deformation
c- The screw is stressed to its yield strength
d- The screw is reversibly lengthened |
|
Definition
| The screw is reversibly lengthened |
|
|
Term
When a metal alloy implant screw is stressed below its proportional limit which of the following must be true?
a- No strain occurs in the screw
b- The screw exhibits permanent deformation
c- The screw is stressed to its yield strength
d- The screw is reversibly lengthened |
|
Definition
| The screw is reversibly lengthened |
|
|
Term
| When comparing dentinal tubules near the DEJ vs. near the pulp, which has the highest number of denin per mm^2? |
|
Definition
|
|
Term
| When referring to gypsum setting, how could one describe the final setting time? |
|
Definition
| The time at which the material can be separated from the impression without distortion or fracture. |
|
|
Term
| When referring to gypsum setting, how could one describe the working time? |
|
Definition
| The time when the gypsum's viscosity increases, and the mass can no longer flow easily into the fine details of the mold |
|
|
Term
| When talking about implants, what does it mean for it to be biointegrated? |
|
Definition
| Implant and bone are fused and continuous with one another |
|
|
Term
| Which class of dental material diffusely shares valence electrons? |
|
Definition
|
|
Term
| Which class of dental material is a mixture of metallic and non-metallic molecules? |
|
Definition
|
|
Term
| Which dental material is a blend of metal, ceramic, and polymer? |
|
Definition
|
|
Term
| Which externally applied variable has the greatest effect on gypsum's physical property? |
|
Definition
|
|
Term
| Which form of gypsum is the least dense? Most dense? |
|
Definition
Least dense - plaster
Most dense - densite |
|
|
Term
| Which form of gypsum requires the most amount of mixing water? Why is this value different than the required amount of gypsum? |
|
Definition
Plaster requires only 18.6g of H2O to fulfill the reaction, chemically. However, by only adding this much H2O the plaster would not be a usable, flowable consistency. Thus, plaster requires roughly 45g H2O to be flowable. However, the 26.4g of excess H2O does not participate in the chemical reaction and is distributed as free water.
Additionally, the difference in physical shape and the nature of the crystals between the various forms of gypsum allows for a difference in the uptake of H2O |
|
|
Term
| Which form of silica shows the highest amount of expansion? |
|
Definition
|
|
Term
| Which form of silica shows the lowest amount of expansion? |
|
Definition
|
|
Term
| Which gypsum setting accelerant is known to increase expansion? |
|
Definition
|
|
Term
| Which gypsum setting stage is known for pseudoplasticity? |
|
Definition
Fluid stage
Pourable slurry = pseudoplasticity |
|
|
Term
| Which gypsum setting stage would one be in when the gypsum no longer has a surface gloss? |
|
Definition
|
|
Term
| Which iso-types (1-5) of gypsum are composed of densite? |
|
Definition
|
|
Term
Which of the following causes unwanted swelling of reversible hydrocolloid in the gel state at room temperature?
a- syneresis
b- metamerism
c- imbibition
d- viscoelasticity
e- hysteresis |
|
Definition
|
|
Term
Which of the following expansion processes is a component of the overall expansion of both gypsum-based casting investments and densite used for making master casts and dies?
a- Setting
b- Thermal
c- Hygroscopic
d- Polymeric |
|
Definition
|
|
Term
Which of the following gypsum powders is a β-calcium sulfate hemihydrate?
a- Plaster
b- Hydrocal
c- Densite
d- All of the above
e- None of the above |
|
Definition
|
|
Term
Which of the following is added to reversible hydrocolloid by the manufacturer to improve the quality of the surface on gypsum models and dies?
a- Borax
b- Potassium sulfate
c- Benzoyl peroxide
d- Diatomaceous earth
e- Slurry water
f- A and B |
|
Definition
|
|
Term
Which of the following is added to reversible hydrocolloid to improve the strength of the set hydrocolloid?
a- diatomaceous earth
b- potassium sulfate
c- water
d- borax |
|
Definition
|
|
Term
Which of the following is an unwanted phenomenon that occurs primarily as a result of building up a wax pattern in unevenly cooled increments?
a- flow decreases
b- creep decreases
c- residual stress increases
d- resilience increases
e- toughness increases |
|
Definition
| Residual stress increases |
|
|
Term
Which of the following is found in set irreversible hydrocolloid as a by-product of the setting reaction?
a- Sodium phosphate
b- Sodium sulfate
c- Calcium phosphate
d- Calcium sulfate |
|
Definition
|
|
Term
Which of the following is often added to reversible hydrocolloid formulations to improve the surface of gypsum that sets within the impression?
a- potassium sulfate
b- diatomaceous earth
c- calcium phosphate
d- sodium alginate
e- borax |
|
Definition
|
|
Term
Which of the following materials has the highest linear coefficient of thermal expansion?
a- enamel
b- dental amalgam
c- resin composite
d- inlay wax
e- acrylic |
|
Definition
|
|
Term
Which of the following materials has the highest linear coefficient of thermal expansion?
a- enamel
b- dental amalgam
c- resin composite
d- inlay wax
e- acrylic |
|
Definition
|
|
Term
Which of the following materials has the lowest linear coefficient of thermal expansion?
a- microfilled composite resin
b- self-curing acrylic resin
c- inlay pattern wax
d- human dentin |
|
Definition
|
|
Term
Which of the following must be known to state a fatigue strength for a dental material?
a- Poisson’s ratio
b- Number of cycles
c- Ultimate tensile strength
d- Ultimate tensile strength and proportional limit |
|
Definition
|
|
Term
Which of the following must occur for reversible hydrocolloid to change from a gel to a sol at a higher temperature than needed to change from a sol to a gel?
a- Syneresis
b- Imbibition
c- Exceeding glass transition temperature
d- Hysteresis |
|
Definition
|
|
Term
Which of the following pairs of materials exhibits the smallest contact angle?
a- Etched enamel and occlusal sealants
b- Gold casting alloys and dental porcelain
c- Teflon and water
d- Acrylic and water
e- Amalgam and water |
|
Definition
| Etched enamel and occlusal sealants |
|
|
Term
Which of the following properties is the best indicator of whether an acrylic base of a newly fabricated complete denture would fracture upon being dropped on the floor?
a- diametral compressive strength
b- bond strength
c- fatigue strength
d- impact strength
e- yield strength |
|
Definition
|
|
Term
Which of the following properties of a liquid fissure sealant should be increased to improve the speed with which the sealant will penetrate a capillary space such as an occlusal fissure?
a- surface tension
b- viscosity
c- volume % filler
d- contact angle
e- silanization |
|
Definition
|
|
Term
Which of the following reacts chemically with wet mixed unset alginate during the formation of set alginate?
a- sodium phosphate
b- calcium phosphate
c- sodium chloride
d- sodium sulfate
e- calcium sulfate |
|
Definition
|
|
Term
Which of the following requires the least amount of mixing water to obtain the same completeness of reaction and the same consistency of mix, assuming equal weights of each powder?
a- Hydrocal
b- Plaster
c- Densite
d- They all require the same amount of mixing water per powder weight |
|
Definition
|
|
Term
Which of the following requires the least amount of reaction water to obtain the same completeness of reaction, assuming equal weights of each powder?
a- Densite
b- Hydrocal
c- Plaster |
|
Definition
| trick question because they all require the same amount of reaction water |
|
|
Term
Which of the following steps in the clinical and laboratory steps of the lost-wax casting process is eliminated by switching to CAD/CAM systems to create indirect restorations?
a- Occlusal adjustment
b- Devesting
c- Shade selection
d- Cementation |
|
Definition
|
|
Term
Which of the following steps in the lost-wax casting process is/are eliminated by using CAD/CAM systems to create indirect restorations?
a- Wax-up
b- Investment
c- Casting
d- Devesting
e- All of the above |
|
Definition
|
|
Term
Which of the following steps in the lost-wax casting process is/are eliminated by using CAD/CAM systems to create indirect restorations?
a- Wax-up
b- Investment
c- Casting
d- Devesting
e- All of the above |
|
Definition
|
|
Term
Which of the following structures would normally be in contact with a smear layer after the dentin was cut during a cavity preparation?
a- Odontoblasts
b- Predentin
c- Intertubular dentin
d- Perikymata
e- None of the above |
|
Definition
|
|
Term
Which of the following will occur when carnauba wax is added to paraffin wax?
a- decrease heat retention and decrease thermal expansion
b- decrease heat retention and increase thermal expansion
c- decrease tackiness and decrease hardness
d- increase melt range and increase hardness
e- increase melt range and increase tackiness |
|
Definition
| Increase melt range and increase hardness |
|
|
Term
Which of the following would create a smear layer on dentin?
a- fracturing by trauma
b- etching with phosphoric acid gel
c- shaping with a carbide bur
d- priming with a hydrophilic monomer
e- applying a total etch bonding system |
|
Definition
| Shaping with a carbide bur |
|
|
Term
Which one of the following is correct regarding the setting time of hydrocal?
a- Increased by using warmer mixing water at 90 versus 70 degrees F
b- Inversely proportional to water/powder ratio
c- Increased by adding terra alba at the beginning of the mix
d- Decreased by using slurry water |
|
Definition
| Decreased by using slurry water |
|
|
Term
| Why are CPCs not used alone in dental implants? |
|
Definition
|
|
Term
| Why are implants known to be conservative? |
|
Definition
| They conserve tooth structure by eliminating the reduction of adjacent abutment teeth |
|
|
Term
| Why do synthetic waxes typically have narrow-range physical and mechanical properties? |
|
Definition
| Because synthetic waxes are composed of monomers with identical chemical structures |
|
|
Term
| Why does an increased amount of spatulation accelerate the formation of dihydrate? |
|
Definition
| Because an increased amount of spatulation causes more nuclei centers to be formed, the conversion of calcium sulfate hemihydrate to dihydrate is accelerated |
|
|
Term
| Why does the surface hardness increase at a faster rate than the compressive strength? |
|
Definition
| Because the surface of the hardened mass reaches a dry state earlier than the inner portion of the mass. |
|
|
Term
Why is dentin kept moist after etching during dental bonding procedures?
a- To facilitate primer infiltration
b- To promote demineralization
c- To reduce polymerization shrinkage
d- To maintain pulp vitality
e- To dilute dentinal tubule fluid |
|
Definition
| Facilitate primer infiltration |
|
|
Term
| Why is model plaster the weakest form of gypsum? |
|
Definition
| Because it is the most porous |
|
|
Term
| Why must gypsum product be kept in a closed container and protected from moisture in the air? |
|
Definition
| An increase in humidity can cause the conversion of the hemihydrate to dihydrate |
|
|
Term
| Why would you want an investment to be weak after casting? |
|
Definition
|
|
Term
| With gypsum, if one were to increase the w/p ratio, what effect, if any, would occur in compressive strength? |
|
Definition
|
|
Term
Wof the following is an effect of adding barnsdahl wax to paraffin?
a- decrease thermal expansion
b- decrease melt range
c- increase flow
d- increase hardness |
|
Definition
|
|
Term
| alpha-calcium sulfate hemihydrate is known as? |
|
Definition
|
|
