Shared Flashcard Set

Details

Dental Materials Final
Review
387
Dentistry
Graduate
12/02/2014

Additional Dentistry Flashcards

 


 

Cards

Term

 Which of the following categories of information would generally be considered to provide the highest level of evidence to support clinical practice decisions?

Definition

 A systematic review of multiple randomized clinical trials

Term

What is the optimum region of application for the air/gas torch flame to melt alloy ingots for centrifugal casting?

Definition

At the tip of the reducing zone

Term

What is a hydrophilic primer coupling agent commonly found in current dentin bonding systems?

Definition

HEMA

Term

If a manufacturer forgot to use silane in the production of a microfilled composite resin, what would be the result?

Definition

     Increase in crack propagation

Term

   The “C-Factor” in a composite resin restoration refers to the

Definition

   Ratio of bonded composite surfaces to unbonded composite surfaces

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?

Definition

    1.5%

Term

     Approximately how thick is the hybrid zone in dentin created by current bonding systems?

Definition

     3 microns

Term

Compared to conventional amalgams, high-copper dental amalgams exhibit 

Definition

    Lower creep

Term

 

   An ideal elastic material with no viscous component has which of the following properties?

Definition

a. Strain will be completely reversed upon removal of stress

b. strain is independent of modulus upon application of stress

c. strain reveral after removal of stress will be time dependent

d. strain develops non linearly upon application of stress

Term

 Which  color property should be changed if the dentist wants increase the intensity of the specific color of a porcelain crown?

Definition

     Chroma

Term

    Over-trituration of dental amalgam alloy and mercury causes…

Definition

  Less working time

Term

 

 Which  property would provide the best indication of a new and unused complete denture’s resistance to fracture if it is dropped and hits the lab porcelain tile floor?

Definition

     Impact strength

Term

    Intertubular dentin is not normally found in which of the following?

Definition

   a.Peritubular dentin

b. sclerotic dentin

c. root dentin

d, primary dentin

e. secondary dentin

Term

   To demonstrate that a material is ductile, the material must be deformed in excess of its

Definition

Proportional limit

Term

  The bonding system category abbreviated      [EP]+B       eliminates the need for

Definition

     Use of an etching gel

Term

     Why is dentin kept moist just prior to the priming phase of dental bonding procedures?

Definition

     To promote formation of a hybrid layer

Term

The dispersed phase of microfilled composite resins usually consists mostly of

Definition

   Colloidal silica

Term

     If dental materials A and B have the same resilience value, which of the following statements is correct?

Definition

  a.The toughness values of A and B may be the same

b. The toughness values of A and B must be the same

c. The toughness values of A and B must be less than the respective resilience values

c. The toughness values of A and B may be less than the respective resilience values

Term

    A linear polymer chain that is made from ethyl methacrylate and butyl methacrylate  monomers is made by the process known as

Definition

     Co-polymerization

Term

   Compared to dentin, poly-(methyl methacrylate) has a high value of

Definition

    Linear thermal expansion

Term

Why do gold and platinum tend to resist corrosion? 

Both have relatively high…

Definition

Positive reduction potentials

Term

     What is added to reversible hydrocolloid by the manufacturer to improve the quality of the surface on gypsum models and dies?

Definition

 

b-     Potassium sulfate

Term

The “Gamma-1” phase of set dental amalgam consists of

Definition

     Silver-mercury

Term

     In comparison to typical microfilled composite resins, typical microhybrid composite resins have lower values of

Definition

     Polymerization shrinkage

Term

   The difference between homogeneous microfilled composites and heterogeneous microfilled composites is that heterogeneous microfilled composites contain

Definition

    Pre-cured composite particles

Term

     Which of the following properties would a material exhibit above its glass transition temperature compared to below its glass transition temperature?

Definition

   a. Increased permanent deformation

b. Increased resistance to indentation

c. Brittle fracture

d. Decreased polymerization

Term

     To provide the best visual match between a porcelain veneer and an adjacent natural tooth in the widest range of lighting conditions, both the veneer and the tooth should exhibit

Definition

    Isomerism and fluorescence

Term

1-     Compared to regular set alginate powder, fast-set alginate powder has more of which of the following compounds  for the purpose of retarding the setting reaction?

Definition

a- Sodium Phosphate

b- Calcium sulphate

c- calcium alginate

d- Guluronan

e- None of the above

Term

1-     To improve the flow of a dental die stone mix, a lab technician adds more water than recommended by the manufacturer.  What is the effect of this change?

Definition

a-     Decreased compressive strength of the set and dried die

Term

1-     When a metal alloy implant screw is stressed above its proportional limit, which of the following statements must be true?

Definition

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 fractional strength

Term

1-     How does paraffin wax differ from microcrystalline wax?

Definition

a-     Paraffin wax shrinks more upon solidification

Term

1-     Compared to reversible hydrocolloid, irreversible hydrocolloid

Definition

Captures less detail

Term
Colloidal systems can be
Definition

b-     A hydrosol

c- an emulsion

Term

To increase the compressive strength of a gypsum cast, a dentist tries the following:

Chooses densite rather than hydrocal

Increases the temp of the mixing water

Adds slurry water to the intial mix

Waits and uses the cast in the dry state

How many of these actions would increase the compressive strength?

Definition

a-     2

Term

1-     Which of the hydrocolloids, if any, normally exhibits less permanent deformation upon removal from the mouth after allowing sufficient recovery time?

Definition

a-     Reversible hydrocolloids

Term

1-     The calories is the unit of measurement for a material’s

Definition

a-     Specific heat

Term

1-     Which of the following color parameters are quantified in both the L*a*b* and Munsell color systems?

Definition

a.Value

b.Chroma

c. Hue

d. All of the above

Term

1-     What histologic components are found in both enamel and dentin?

Definition

a-     Hydroxyapatite crystals

Term

1-     According to the Sturdevant text, what is the mean size range of filler particles in typical microfilled composite resins?

Definition

a-     .01 – 0.1 microns

Term

1-     Which of the following restorations can be either a direct or an indirect restoration?

Definition

a-     Composite resin restoration

b.Occlusal sealants

b. cast gold crown

c. amalgam restoration

Term

1-     Hygroscopic expansion is a desired property for which of the following?

Definition

a-     Gypsum-bonded casting investment

b. general use of dental stone

c. mounting plaster

d. fast setting impression plaster

Term

1-     Which of the following components are present in both conventional dental amalgam alloy powder and high-copper dental amalgam alloy powder?

Definition

a- Gamma 1

b- Gamma 2

c- Free mercury

d- None of the above

Term

1-     During polymerization of methyl methacrylate in a light-activated system, which of the following molecules is the initial source of free radicals?

Definition

a-     Camphorquinone

b. Benzoyl peroxide

c. Urethane dimethacrylate

d. Ethylene glycol dimethacrylate

e. an organic amine

Term

1-     The requirement to have a MSDS (Material Safety Data Sheet) for materials used in the dental office is mandated by

Definition
OSHA
Term

 

1-     Which of the following would create a smear layer on dentin?

Definition

a-     Cutting with a diamond bur


b. forming a hybrid layer

c.applying bonding primer

d. etching with phosphoric acid

Term

1-     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?

Definition

a-     Doubled

Term

1-     How does microcrystalline wax differ from paraffin wax?

Definition

Microcrystalline wax shrinks less upon solidification

Term

1-     According to best management practices for handling amalgam waste, which of the following should be placed in biohazard waste receptacles for incineration?

Definition

a- Amalgam debris collected from chairside traps

b- contact amalgam scrap

c- bloody extracted teeth containing amalgam restorations

d- None of the above

Term

1-     Compared to reversible hydrocolloid, alginate

Definition

a-     Captures less detail

Term

1-     Acceleration of free radicals from benzoyl peroxide in dental acrylic polymerization systems is usually accomplished by

Definition

a-organic amines

b-heat

 

 

 

Term
Which of the following bonding system schemes is a “two-bottle, self-etch” system?
Definition

a-     [EP]+B

b. E+P+B

C. E +[PB]

d. EPB

Term

1-     Which of the following is/are thermosetting polymer(s)?

Definition

a- Polystyrene

b-Heat cured, cross linked PMMA

C-Cured epoxy used for dies

d- Two of the above

 

Term

1-     What is the primer coupling agent in dental bonding systems?

Definition

a-     HEMA

Term

1-     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?

Definition

a-     A button that is smaller than required

b. heating the gold alloy with the tip of the reducing zone of the torch flame

c. too much centrifugal casting force

d. sprue diamtere that is too large

Term

1-     Which of the following entities regulates dental materials and devices in the United States?

Definition

a-     FDA

Term

1-     Based upon thermal diffusivity, which of the following materials would be expected to cause the most thermal shock to a tooth upon application of a hot liquid?

Material                     Conductivity             Specific Heat            Density

A                                  Low                             Low                             Low

B                                  Low                             High                            High

C                                  High                            Low                             High

D                                 High                            Low                             Low

E                                  High                            High                            Low

Definition

    D

Term

1-     What is the purpose of the “P” in an “E+P+B” dental bonding system?

Definition

  To infiltrate demineralized dentin and create a “hybrid” layer

Term

1-     To perform a finite element stress analysis of a dental implant restoration you would need

Definition

  a.Knowledge of the properties of the materials involved

b. samples of the actual dental implantation after use intra orally

c. samples of the actual restoration materials after use intra orally

Term

1-     To improve the flow of a dental die stone mix, a lab technician adds more water than recommended by the manufacturer.  What is an effect of this change?

Definition

 Decreases compressive strength of the set and dried die

Term

1-     Compared to high-copper dental amalgams, conventional dental amalgams exhibit

Definition

 Higher creep

Term

1-     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?

Definition

Sodium phosphate

Term

1-     The powder in a powder/liquid kit of cold-cure dental acrylic is mostly composed of

Definition

 PMMA polymer

Term

1-     For which of the following would a gypsum-based casting investment not be appropriate?

Definition

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

Term

1-     According to the manufacturer, which of the following etching step times are correct when using the Prime and Bond NT system

Choice       Enamel etch time    Dentin etch time

A      at least 30 sec               no more than 30 sec

B       at least 15 sec               no more than 15 sec

C          no more than 30 sec           at least 30 sec

 D             no more than 15 sec           at least 15 sec

    E      no more than 30 sec              no more than 30 sec

 

Definition

 

 

 

     Choice B

Term

1-     To provide the best visual match between an all-porcelain crown and an adjacent natural tooth in the widest range of lighting conditions, both the crown and the natural tooth should exhibit

Definition

    Isomerism and fluorescence

Term

In high copper dental amalgams, gamma-2 is suppressed by the preferential formation of

Definition

  Tin-copper

Term

1-     The inorganic component of enamel in a fully erupted permanent tooth is mostly

Definition

Hydroxyapatite

Term

1-     Which of the following properties would a material exhibit above its glass transition temperature but not below its glass transition temperature?

Definition

  a. increased permanent deformation

b. increased resistance to indentation

c. brittle fracture

d. decreased poymerization

Term

1-     Which of the following expansion mechanisms contributes to the overall expansion of gypsum-based casting investments, but not to expansion of gypsum used for producing dies?

Definition

a-     Thermal

b- Hygroscopic

Term

1-     Natural teeth normally exhibit which of the following?

Definition

     a. value

b. chroma

c.fluorescence

d. all of the above

Term

1-     Dehydration of gypsum under pressure in the presence of water vapor creates

Definition

 Hydrocal

Term

1-     Which of the following is found in both fully-set conventional and fully-set high-copper dental amalgams?

Definition

a. Gamma-1 phase

b. Gamma 2 phase

c. Tin-mercury phase

d. Tin-copper phase

Term

1-     Over-trituration of dental amalgam alloy and mercury results in

Definition

     Less working time

Term

1-     Why is dentin kept moist after etching during dental bonding procedures?

Definition

    To facilitate primer infiltration

Term

1-     Which of the following has the lowest linear coefficient of thermal expansion?

Definition

a. Coronal dentin

b. casting pattern wax

c. cold cure acrylic resin

d. microfilled composite resin

Term

1-     All of the following are types of composite resin except one.  Which one is the exception?

Definition

a- hybrid

b-flowable

c-indirect

d-unfilled

e- packable

Term

1-     Which of the following is a component of the continuous phase of composite resins?

Definition

 a.bis-GMA

b. HEMA

c. 4-META

d. solvent: acetone or alcohol

e. colloidal silica

Term

1-     According to Sturdevant, what is the mean size range of filler particles in typical microfilled composite resins?

Definition

    .01 - .1 microns

Term

1-     The essential difference between homogeneous microfilled composites and heterogeneous microfilled composites is that heterogeneous microfilled composites contain

Definition

   pre-cured composite particles

Term

1-     The “C-Factor” for a cavity preparation with two unbound surfaces and four bound surfaces is

Definition
2
Term

1-     A composite resin that considerably yellows with age is most likely

Definition

Chemically cured

Term

1-     Within limits, which of the following will decrease wear of composite resin formulations?

Definition

   a.Increase filler volume

b. increase the percentage of uncured monomer

c. use TEGMA in the dispersed phase

d. use a chemically cured system

Term

1-    A linear polymer chain that was made from ethyl methacrylate and butyl methacrylate monomers is made by the process known as

Definition

a-    co-polymerization

Term

1-    The property of reversible hydrocolloid to change from a sol to a gel at a lower temperature than required to change from a gel to a sol is known as

Definition

 hysteresis

Term

1-    An axial compressive stress is applied to a 40.0 mm rod of composite resin resulting in a strain of 1%.  What is the dimension of this rod while under this stress?

Definition

39.6 mm

Term

1-    Which of the following would a material exhibit above its glass transition temperature compared to that below its glass transition temperature?

Definition

more permanent deformation

Term

1-    A property that indicates fracture of a dental material as a result of repeated loading and crack propagation is

Definition

fatigue strength

Term

1-    Compared to permanent dentin, poly-(methyl methacrylate) has a higher value of

Definition

a-    linear thermal expansion

Term
In high-copper dental amalgams, gamma-2 is suppressed by the formation of 
Definition

  tin-copper

Term

1-    The vertical axis in both the Munsell and L*a*b color system diagrams represents differences in

Definition

value

Term

1-    Communited dental alloy particles are made by

Definition

b- pulverization

c- lathe cutting

Term

1-    The largest proportion of reversible hydrocolloid is

Definition

a-    water

Term

Consider the following statements:

The stress on a material depends in part on the amount of force    that is applied  

The stress on a material is inversely proportional to the area over which the force is applied

Definition

a-    both statements are true

Term

Consider the following statements about thermal diffusivity 

It partially depends upon the density of the material

It is inversely proportional to the thermal conductivity of the material             

 It is the amount of heat required to raise 1g of the material 10C

Definition

a-    One statement is correct, the other two are false

Term

1-    A dental material that has become dull and discolored but has no visible loss of material or pitting on the surface is most likely and most directly due to which of the following processes?

Definition

  tarnishing

Term

1-    Each of the following mechanisms contributes to the expansion of gypsum-based casting investment expansion prior to casting, except one.  Which is the exception?

Definition

a. polymeric

b. hygroscopic

c. thermal

d. setting

Term
Hydrocal as received from the manufacturer is mostly composed of
Definition

  calcium sulphate hemihydrate

Term

Consider the following statement and reason

Synthetic waxes typically have physical and mechanical properites in a relatively narrow range

BECAUSE     

Synthetic waxes are synthesized from monomers resulting in a single species

Definition

  Both the statement and the reason are correct and related

Term

    Excessive tearing of an alginate impression when removing it from the mouth would most likely result from which of the following?

Definition

    a water-to-powder ratio that is too high

Term

1-    If an ingredient is added to a dental material to increase its KHN, resistance to which of the following will be increased as a result?

Definition

indentation

Term

1-    The powder component of autocuring dental acrylics used for orthodontic appliances is mostly

Definition

poly (methyl methacrylate)

Term

1-    Which of the following properties is generally increased by increasing cross-linking in a dental polymer system?

Definition

    hardness

Term

1-    Which of the following is a hydrophilic primer coupling agent used in bonding systems to form a hybrid layer?

Definition

 HEMA

Term

1-    The organic component of dentin is mostly

Definition

 collagen

Term

Compared to enamel, dentin has a higher value of

Definition

a- compressive strength

b- modulus of elasticity

c- hardness

d- None of the above

 

Term

1-    Why is dentin kept moist during the first phase of dental bonding procedures?

Definition

to promote formation of a hybrid layer

Term

1-    Phosphoric acid (37%) etching of a dentin wall in a cavity preparation for thirty seconds causes which of the following

Definition

 smear layer removed; smear plugs removed

Term
The dispersed phase of microfilled composite resins usually consists mostly of
Definition

colloidal silica

Term

1-    Recommended best practices for handling dental amalgam waste include

Definition
using filtration on chairside vacuum systems
Term

1-    To improve the speed at which a liquid dental adhesive will penetrate into an occlusal fissure, which of the following properties of the adhesive should be increased?

Definition

 surface tension

Term

1-    Silanes are used in composite resins to

Definition

 limit crack propagation

Term

1-    The maximum light wavelength absorption peak of camphoroquinone is about

Definition

    470nm

Term

1-    Which of the following should be increased if the dentist wants to make the intensity of the color of a porcelain veneer more apparent?

Definition

  chroma

Term

1-    A material that exhibits less elastic strain for a given amount of stress compared to another material subjected to the same amount of stress is

Definition

less flexible

Term

1-    Which of these materials is hardest?

Definition

a- Dental Porcelain

b- composite resin

c- gold casting alloy

d-dental amalgam alloy

Term

1-    A porcelain veneer appears to match the adjacent teeth under incandescent lighting but not under fluorescent lighting.  This phenomenon is called

Definition

  metamerism

Term

1-    The calorie is the unit of measurement for a material’s

Definition

 specific heat

Term

1-    Residual stress in a wax pattern is caused by

Definition

a-     non-uniform heating of layers during waxing

Term

1-    Which of the following types of dental composite resins utilizes camphoroquinone in the polymerization process?

Definition

 visible light-cured and dual-cured

Term

1-    Which of the following would create a dentin smear layer?

Definition

 cutting with a diamond bur

Term

1-    The bonding system category abbreviated    [EP]+B    eliminates the need for which of the following?

Definition

   use of an etching gel

Term

1-    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 could have caused this problem?

Definition

    a. a sprue diameter that is too small


b. heating the gold alloy 100 degrees F above its MP

c. a button that is larger than required

c. too much centrifugal casting force

Term

1-     What is the measuring unit for strain?

Definition

a-      percent

Term

1-     Compared to Sample #2, Sample #1 has twice the elastic strain for a given tensile stress.  Therefore, compared to Sample #2, Sample #1 must be

Definition

a-      more flexible.

Term

1-     To demonstrate that a material is ductile, the material must be deformed in excess of its

Definition

  proportional limit

Term

A certain dentin bonding agent is reported to have a shear bond strength of 10 megaPascals.  Which of the following is closest to this bond strength in pounds per square inch?

Definition

  1500 psi

Term

1-   Which of the following is equal to a millimeter of dentin thickness?

Definition

1000 microns

Term

1-   Which of the following is produced by dehydration under pressure in the presence of water vapor?

Definition

 hydrocal

Term

Which of the following actions will increase the strength of a gypsum cast?

1- Waiting until the cast has completely dried before using

2- Using mechanical vacuum mixing instead of hand spatulation

3- Increasing water to powder ratio

Definition

1 and 2

Term

  Which of the following, if added to paraffin, would decrease shrinkage during solidification?

Definition

   microcrystalline

Term

1-   Waxes are generally characterized as having high values of all of the following except one.  Which one is the exception?

Definition

a- flow

b- ductility

c-elastic modulus

d-thermal expansion

Term

1-   Which of the following pairs of materials exhibits the best wetting?

Definition

   

a.etched enamel and occlusal sealants

b. gold casting alloy and dental porcelain

c. teflon and water

d. acrylic and water

e. amalgam and water

Term

1-   Which of the following is true regarding dentin and enamel?

Definition

   enamel is anisotropic; dentin is anisotropic 

 

Term

1-   Hysteresis is a property of

Definition
reversible hydrocolloid
Term

1-   In comparing alginate to reversible hydrocolloid, alginate

Definition

captures less detail

Term

1-   If a manufacturer wants to decrease the setting time of its irreversible hydrocolloid, which of the following changes would be effective?

Definition

 a.decrease sodium phosphate proportion

b. increase calcium alginate proportion

c increase sodium sulfate proportion

d. decrease sodium sulfate proportion

e. increase sodium phosphate proportion

Term

1-   Which of the following color properties should be changed if the dentist wants to make the intensity of the color of a porcelain crown less apparent?

Definition

chroma

Term

1-   To provide the best optical match between an all-porcelain crown and an adjacent natural tooth in the widest range of lighting conditions, both the crown and the natural tooth should exhibit…

Definition

 isomerism and fluorescence

Term

1-   A composite resin surface with numerous 4-micron scratches would be perceived by the patient as

Definition

a- dull and rough

or 

b-dull and smooth

(both accepted: 4um in between rough and smooth)

Term

 Based upon thermal diffusivity, which of the following materials would be expected to cause the most thermal shock to a tooth upon application of a hot liquid?

 

     Material                      Conductivity            Specific Heat            Density

            A                                  High                            Low                             Low

             B                                  High                            High                            Low

              C                                 High                            Low                             High

               D                                 Low                             High                            High

                E                                  Low                             Low                             Low

Definition
A
Term

1-   The property that best indicates whether an acrylic base of a new and unused complete denture would fracture upon being dropped and hitting the laboratory tile floor is the material’s…

Definition

impact strength

Term

1-   If a material is altered to decrease its KHN, then the material would exhibit greater

Definition

a- thermal expansion

b- yield strength

c- resilience

d- resistance to indentation

e- none of the above

Term

1-   To perform a useful finite element stress analysis of a dental restoration requires

Definition

a- computer

b- knowledge of the properties of the materials involved

c- samples of the restortion made with the actual materials

d- two of the above

Term

1-   Over-trituration of dental amalgam alloy and mercury causes…

Definition

decrease in working time

Term

1-   Which of the following best describes the change in the compressive strength of a high-copper dental amalgam occurring from 30 minutes after placement to 24 hours after placement?

Definition

  increases by a factor of 4x or more

Term

1-   Free radical formation from benzoyl peroxide in dental acrylic polymerization processes is primarily accelerated by which of the following?

Definition

 organic amines &

heat

Term

1-   Which of the following is a feature of some condensation-type polymerization systems but not found in addition-type polymerization systems?

Definition

  water formed as byproduct

Term

1-   Polymerization of epoxy die material occurs by

Definition

   ring opening

Term

1-   Which of the following is/are removed from dentin by the total etch procedure?

Definition

a. Smear plugs

b. hybrid zone

c. enamel rods

d. odonotoblasts

Term

1-   Which of the following is a hydrophilic primer coupling agent commonly found in current dentin bonding systems?

Definition

  HEMA

Term

Which of the following is not a feature of the bonding system category abbreviated: [EP]+B  ?

Definition

requires rinsing enamel and dentin after etching

Term

                What is the approximate thickness of hybrid zones in dentin created by current bonding systems?

Definition

   3 microns

Term

In the current bonding systems using a 37% phosphoric acid gel etch and water rinsing, which of the following is true regarding the smear layer and smear plugs after water rinsing?

Definition

a- they will collapse if air dried

b- they will both become infiltrated with hydrophilic resins

c- only the smear plugs will become infiltrated with hydrophilic resin

d- only the smear layer will become infiltrated with hydrophilic resin

e- none of the above

Term

Camphorquinone is found in which of the following types of composite resins?

Definition

a-   visible light-cured and dual-cured

Term

    If a manufacturer failed to use silane in the production of a direct universal hybrid composite resin, what would be the expected effect of this error?

Definition

a-   increase in crack propagation

Term

      In an uncured composite resin, where is TEGMA found and what effect does it have when present?

Definition

     Location                                Effect 

a-      continuous phase                   binds filler

     b-      continuous phase       decreases viscosity

     c-      continuous phase            decreases shrinkage

 d-         dispersed phase                 binds filler

      e-      dispersed phase              forms hybrid layer

Term

        The “C-Factor” in a composite resin restoration refers to the…

Definition

 ratio of bonded to unbonded surfaces

Term

   For which of the following would a gypsum-based casting investment not be appropriate?

Definition

Porcelain fused to metal crown undercasting

Term

                What is the approximate total percent expansion required from all sources within a gypsum-based casting investment?

Definition

1.5%

Term

                  A cast gold alloy crown has rounded margins instead of the sharp margins that were produced in the wax pattern.  What could correct this problem upon recasting?

Definition

increase centrifugal casting force

Term

            What is the optimum region of application of the air/gas torch flame to melt alloy ingots for centrifugal casting?

Definition

   at the tip of the reducing zone

Term

1-    Dental plaster powder as you would receive it in a box from the manufacturer is primarily composed of which of the following?

Definition

calcium sulphate hemihydrate

Term

1-    The process in which dental stone powder sets with water to become a dental study cast is

Definition

a-precipitation

Term

1-Which of the following will accelerate the setting of dental stone?

Definition

d-add slurry water to the initial mix

Term

1-Which of the following terms is used to describe the setting stage of dental stone or plaster in which there is no flow but the mix can be molded, and the surface gloss of the mix has been lost?

Definition

 plastic

Term

1-Thermal expansion is a desired property associated with which of the following dental materials?

Definition

 gypsum-bonded casting investment

Term

1-Which of the following components in reversible hydrocolloid is added to improve the strength of set hydrocolloid material?

Definition

Borax

Term

1-After cooling a hydrocolloid impression in the mouth using a water-cooled tray, what would be the next step in the sequence of producing a stone model from the impression?

Definition

 disinfect and pour immediately

Term

1-Which of the following components initially limits the availability of CaSO4 during mixing and placement of irreversible dental alginate impression material?

Definition

e-sodium phosphate

Term

1-The memory effect of dental inlay pattern waxes is due to

Definition

 residual stress in the wax pattern

Term

1-The powder component of self-curing acrylics for temporary crowns mostly consists of

Definition

a-poly (methyl methacrylate)

Term

1-To mold a thermosetting polymer, the polymer must be heated above which of the following?

Definition

none, because thermosetting polymers cannot be molded by heating

 

Term

1-Self-curing dental acrylics polymerize in which of the following ways?

Definition

 by addition reaction, initiated by free radicals

Term

1-During the setting reaction of high-copper dental amalgams, the “gamma-two” phase is suppressed by the preferential formation of which of the following phases?

Definition

 tin-copper

Term

1-Which of the following is a characteristic of conventional dental amalgams compared to high-copper dental amalgams?  Conventional dental amalgams exhibit…

Definition

 higher creep

Term

1-Which of the following properties is increased by over-trituration of dental amalgam?

Definition
creep
Term

1-The inorganic component of enamel is mostly composed of

Definition

 hydroxyapatite

Term

1-Which of the following statements is true concerning secondary dentin?

Definition

a.Forms after root development is complete

b. Forms in response to stimuli

c. Forms on root canal walls but not on pulp chamber walls

Term

1-Compare the dentinal tubules normally found in dentin near the DEJ with those normally found near the pulp chamber.  The tubules found near the pulp chamber are…

Definition

closer together and larger in diameter

Term

Which of the following dentin specimens would normally have the GREATEST permeability?

Definition

 bur-cut non-carious (normal) dentin that HAS been acid-etched

Term

1-A contact angle of 135 degrees between a liquid and a solid indicates

Definition

 poor wetting of the solid by the liquid

Term

1-What is the function of the “moist bonding” technique for dentin?

Definition

 to promote formation of a hybrid layer

Term

1-Which of the following is an example of a hydrophilic primer agent found in current dentin bonding systems?

Definition

HEMA

Term

1-Adhesion of bonding agents to acid-etched enamel primarily occurs through which of the following mechanisms?

Definition

micromechanical interlocking

Term

1-During a direct composite resin restorative procedure, which of the following steps is performed right after application of phosphoric acid gel to dentin and enamel?

Definition

rinsing away the gel with water

Term

1-The dispersed phase of typical microfilled composite resins consists of

Definition

 colloidal silica

Term

1-Compared to typical “microhybrid” composite resins, “microfilled” composite resins have a higher value of

Definition

 polymerization shrinkage

Term

 How does the incorporation of silane in composite resin formulations improve their performance?

Definition

 limits crack propagation at resin/filler interface

Term

1-Which of the following factors affects the degree of polymerization of a light-cured composite resin if all other factors remain unchanged?

Definition

a- distance of curing light tip from restoration surface

b-exposure time to curing light radiation

c-energy output of the curing light t the light pipe tip

d- all of the above


Term

1-Cutting of enamel with a dental carbide bur is primarily accomplished by

Definition

shearing

Term

1-Which of the following materials is the hardest?

Definition

a- tungsten carbide

b-pumice

c-dental gold alloys

d-enamel

e-dentin

Term

1-Which of the following dentifrice ingredients functions as a detergent?

Definition

sodium lauryl sulfate

Term

1-If the rake angle of a dental carbide bur blade is zero degrees, then which of the following statements must be true?

Definition

d-the rake face is parallel to the corresponding radial axis of the bur

Term

1-Which of the following is the measuring unit for force?

Definition

Newtons

Term

1-Material “A” exhibits a 1% permanent deformation prior to breaking for a given tensile stress, and material “B” exhibits of 2% permanent deformation prior to breaking for the same tensile stress.  Which of the following best describes material “A” compared to material “B” based on the information just given?  Material A is…

Definition

less ductile

Term

1-Progressive fracture of a dental material as a result of repeated loading and crack propagation is known as

Definition
Fatigue
Term

1-A dentist adjusts the cusp tip on a gold crown so that the occlusal contacting area on the supporting cusp tip is increased to twice its original size.  Assuming that the biting force remains constant, what is the change in stress within the occlusal contacting area of that cusp tip?

Definition

                halved

Term

1-A material that exhibits less elastic strain for a given amount of stress when compared to another material must be

Definition

                     stiffer

Term

1-For a material to exhibit any ductility, it must be stressed beyond its

Definition

                                         proportional limit

Term

1-    What is the function of condensation of dental amalgam?

Definition

a-to force the material into all aspects of the cavity prep

b-to reduce air voids in the final set amalgam

Term

1-Which of the following impression materials recovers best when distorted upon removal from teeth containing undercuts?

Definition

 

Reversible hydrocolloid

 

 

Term

1-A feature of condensation-type polymerization not present in addition-type polymerization is

Definition

                                  formation of low molecular weight by-products

Term

1-How does the occlusal wear rate of dental amalgam compare to that of enamel?  Dental amalgam occlusal wear rate is…

Definition

  approximately equal to enamel.

Term

Recommended best management practices for handling dental amalgam waste include

Definition

                                      recycling chairside vacuum filter contents

Term

Where is predentin located in an erupted permanent tooth?

Definition

    adjacent to the odontoblasts

Term

1-Which of the following actions would create a smear layer on dentin?

Definition

                                  a.cavity preparation with a carbide bur

b.fracturing by trauma

c.etching with phospohoric acid gel

d. priming with hydrophilic monomer

Term

1-Which substance is added to some resin composite formulations to decrease the viscosity of the unpolymerized resin composite?

Definition

                                         TEGMA

Term

1-Which of the following materials is harder than diamond?

Definition

a- dental porcelain

b- tungsten carbide

c- silicon carbide

d- aluminum oxide

e- none of the above

Term

1-   In the evidence-based approach, the level of evidence needed to evaluate new dental materials depends upon the

Definition

 a-   level of innovation

b-   potential for harm to health of patient or dentist

c-   potential for financial loss to patient or dentist

d-  all of the above

Term

Which of the following types of research is required to test a new dental material for gross toxicity problems?

Definition

cell culture studies

Term

All scratches on gold alloy crown surface are smaller in width or depth than the wavelengths of visible light.  Therefore, the crown surface will be sensed by the patient as…

Definition

            shiny and smooth

Term

   According to O’Brien’s classification of composite resin restorative materials, the “hybrid” category contains which of the following types of filler particles?

Definition

silica or glass, and colloidal silica

Term

 Which of the following is a direct restoration?

Definition

occlusal amalgam

Term

   A dentist adjusts the cusp tip on a crown so that the occlusal contacting area on the cusp tip is reduced to one-half its original size.  Assuming that the biting force remains constant, what is the change in stress within the occlusal contacting area?

Definition
Doubled
Term

   Which of the following best describes the megaPascal?

Definition

unit of stress about equal to 150 psi

Term

   A material that exhibits more elastic strain for a given amount of stress when compared to another material is

Definition

   more flexible

Term

For a material to exhibit any ductility, it must be manipulated beyond its

Definition

proportional limit

Term

  Which of the following materials has the highest KHN?

Definition

a- enamel

b- dentin

c-composote resin

d- dental porcelain

e- cast gold alloy

Term
The calorie is a measure of
Definition
specific heat
Term

  Which of the following materials has the highest linear coefficient of thermal expansion?

Definition

a- gypsum for study casts

b- gypsum for casting investments

c- dentin

d- porcelain

e- Casting pattern wax

Term

 An anterior porcelain crown appears to match the adjacent teeth under the lighting in the dentist’s office but not in daylight.  This phenomenon is known as

Definition
Metamerism
Term

All of the following conditions exist for a titanium dental implant that has osseointegrated except one.  Which one is the exception?

Definition

a- structural association of bone with implant surface

b- ability to accept functional loading

c- normal mobility from functional PDL

d- biocompatability of impant surface at the cellular level

Term

1-   The plaster powder that is mixed with water and used to mount study casts in a dental articulator is primarily composed of

Definition

calcium sulphate hemihydrate

Term

   Which of the following describes dental stone powder particles compared to dental plaster powder particles?  Dental stone particles…

Definition

are formed by wet calcination.

Term

1-   All of the following are true regarding the setting time of gypsum except one.  Which one is the exception?  

Definition

a- proportional to water/powder ratio

b-increased by excessive spatulation

c-retarded by colder water

d-retarded by sodium citrate

e- retarded by slurry water

Term

What component is added to reversible hydrocolloid to provide good surfaces on gypsum models and dies?

Definition

   potassium sulfate

Borax

Term

   What component of irreversible alginate powder initially limits the setting reaction upon mixing the powder with water?

Definition

   sodium phosphate

Term

  The largest component of irreversible hydrocolloid is

Definition

 diatomaceous earth

Term

  An increased water/powder ratio in irreversible hydrocolloid will cause greater potential for

Definition
Tearing
Term

   Which of the following impression materials recovers best when distorted upon removal from a dental arch containing undercuts?

Definition

reversible hydrocolloid

Term

 Loss of detail in an irreversible hydrocolloid impression would result from which of the following factors?

Definition

a- Premature removal from the mouth

b- inadequate spatulation

Term

   The glass transition temperature is an important property for which of the following materials processes?

Definition

   a. molding of polymer

b. setting of gypsum

c. gelling of agar

d. distortion of wax

e. polishing of composite

Term

Residual stresses in wax casting patterns are caused by

Definition

 non-uniform heating during wax-up

Term

   A feature of condensation-type polymerization not found in addition-type polymerization is

Definition

 formation of low molecular weight by-products

Term

 Acceleration of free radicals from benzoyl peroxide in acrylic polymerization systems can be accomplished by

Definition

a- heat

b- organic amines

Term

The powder component of a powder/liquid self-curing acrylic for temporary crowns and bridges is composed mostly of

Definition

poly (methyl methacrylate)

Term

 Comminuted dental alloy particles are formed by

Definition

a- pulverization

b- lathe cutting

Term

 The “gamma” phase of traditional dental amalgam consists of which of the following?

Definition

  silver-tin

Term

 The “gamma-two” phase is suppressed during the setting reaction of high-copper dental amalgams by the preferential formation of which of the following phases?

Definition
Tin-copper
Term

How does the occlusal wear of dental amalgam compare to that of enamel?  Dental amalgam occlusal wear is…

Definition

 approximately equal to enamel.

Term

 What is the function of condensation of dental amalgam?

Definition

a- to force the material into all aspects of the cavoty preparation

b- to reduce air voids in the final set amalgam

Term
Zinc is added to some dental amalgam alloy formulations to
Definition

                                     serve as a preferential oxidizer.

Term

  Recommended best management practices for handling dental amalgam waste include

Definition

  recycling chairside vacuum filter contents

Term

 

  Where is predentin located in an erupted permanent tooth?

Definition

   adjacent to the layer of odontoblasts

Term

Which of the following actions would create a smear layer on dentin?

Definition

 shaping with a carbide bur

Term

 What is the pH value above which dissolution of enamel will normally not occur?

Definition
5.5
Term

 When compared to dentin, enamel has greater values for all of the following properties except one.  Which one is the exception?

Definition

a-compressive strength

b- tensile strength

c-hardness

d-modulus of elasticity 

Term

   To improve the speed with which a liquid dental adhesive will penetrate into a capillary space such as an occlusal fissure, which of the following properties of the adhesive should be increased?

Definition
surface tension
Term

  Which of the following pairs of materials has the lowest contact angle?

Definition

a. etched enamel : sealant

b. dental amalgam: water

c. acrylic: water

d. gold alloy: porcelain

Term

   Bonding to acid-etched enamel occurs mostly through which of the following mechanisms?

Definition

a-   micromechanical interlocking

 

Term

1-   Which of the following is an example of a hydrophilic primer coupling agent used in dentin adhesive systems?

Definition
HEMA
Term

1-   Which of the following characteristics of typical microhybrid resin composites have higher values compared to those of typical microfilled resin composites?  Typical microhybrid resin composites have higher values of…

Definition

 inorganic filler volume percent

 

Term

 

1-   Which of the following types of resin composite typically depend upon the scission of camphoroquinone for polymerization?

Definition

 visible light-cured and dual-cured

Term

A dentist made the following choices to decrease surface wear on the resin composite restorations she places.  Which of these choices is actually effective in decreasing wear?  Choosing a resin composite…

Definition

a- with increased filler volume

b-with silane coupling

c-that cures by visible light rather than by chemical means

d-all of the above

Term

What minimum energy output (mW/cm2) was recommended in the Sturdevant Operative Dentistry textbook and in lecture for quartz-tungsten-halogen (visible light) curing units?

Definition
300
Term

1-   The rake angle of the blades on a dental carbide finishing bur is zero degrees. Therefore, which of the following statements must be true?

Definition

 The blade rake face must be parallel to the radius of the bur.

Term

1-     Which of the following explains why gold does not normally tarnish when used intra-orally?

Definition

   Gold has a relatively large positive reduction potential.

Term

1-     The purpose of a conditioner when used with glass ionomer restorative materials is to

Definition

  Remove the surface smear layer

Term

1-     Clinical advantages of non-resin-containing glass ionomer restorations include all of the following except one.  Which one is the exception?

Definition

a- flouride releasing capability

b-low shrinkage compared to composite resin

c-low wear compared to dental amalgam

d-no separate bonding agent required for adhesion

Term

1-     In initially set glass ionomer restorations, the calcium ions that create the cross-linking of polyacrylic acid chains are slowly replaced by

Definition

a-     Aluminum ions

Term

Recharging” of glass ionomer restorations refers to

Definition

a-     Fluoride uptake

Term

1-     Which of the following entities develop(s) specifications for dental materials?

Definition

a-     ANSI/ADA

Term

1-     The location on a particular “wheel spoke” of the Munsell Color system diagram indicates what color quality?

Definition
Chroma
Term

1-     What are the major components of conventional low-copper dental amalgam alloy?

Definition

a-     Silver and tin

Term

1-     A property that indicates resistance to fracture of a dental composite as a function of repeated loading and resulting crack propagation is

Definition

a-     Fatigue strength

Term

1-     Hygroscopic expansion is a useful characteristic of which of the following dental materials applications?

Definition

a-     Calcium sulfate-bonded casting investments

Term

1-     Which of the following materials has the lowest linear coefficient of thermal expansion?

Definition

a-     Primary dentin

b. Casting pattern wax

c. cold cure acrylic resin

d. microfilled composite resin

Term

1-     During the setting reaction of high-copper amalgams, “gamma-2” is suppressed by the preferential formation of

Definition
Tin copper
Term

1-     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?

Definition

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 stress is removed

d. Recovery would be instantaneous but incomplete when stress is removed

Term

1-     When compared to human dentin, auto-curing acrylic resin has a higher value of which of the following properties?

Definition

a-KHN

b-young's modulus

c-proportional limit

d-ultimate tensile strength

e-none of the above

Term

1-     Free radical formation from benzoyl peroxide in dental acrylic polymerization is primarily accelerated by

Definition
organic amines & heat
Term

1-     A polymer exhibits which of the following below its glass transition temperature compared to above its glass transition temperature?  Below the glass transition temperature it would have

Definition

a-     Decreased ductility

Term

     A drop in temperature differential on a thermogram of a baseplate wax sample indicates

Definition
Phase transition
Term

1-     Inaccuracy of stone casts made from alginate impressions can be caused by

Definition

a-insufficient spatulation

b-premature removal of impression from mouth

c-soaking the impression in water 30 min prior to pouring

d-all of the above

Term

1-     In comparison to microfilled composites, microhybrid composites usually have lower values of

Definition

a-     Polymerization shrinkage

Term

1-     Which of these tests would be best to determine which of two new denture base acrylics would be the most resistant to fracture if accidently dropped by the patient during denture cleaning?

Definition
impact strength
Term

1-     When a metal alloy implant screw is stressed below its proportional limit which of the following must be true?

Definition

a-     The screw is reversibly lengthened

b. no strain occurs in the screw

c. the screw exhibits permanent deformation

d. the screw is stressed to its yield strength

Term

1-     Which of the following would generally be considered to provide the highest level of evidence to support clinical practice decisions?

Definition

a-     A systematic review of multiple randomized controlled clinical trials

Term

1-     Which of the following processes creates a linear polymer chain consisting of butyl methacrylate and ethyl methacrylate, made from the respective monomers?

Definition

a-     Co-polymerization

Term

1-     You notice that recently your gypsum casts do not have the surface hardness that they usually have.  Which of the following possible errors could have contributed to this problem?

Definition

a-possible change in water to powder ratio

b-possible new use of a new spray disinfectant on the set casts

c-possible incomplete drying due to decreased time between pour and use

d-all of the above

Term

1-     The essential difference between homogeneous microfilled composites and heterogeneous microfilled composites is that heterogeneous microfilled composites contain

Definition

a-     Pre-cured composite particles

Term

1-     What is the purpose of the “P” in an “E+P+B” dental bonding system?

Definition

a-     To infiltrate partially demineralized dentin

Term

1-     A compressive stress/strain test is performed on a rod-shaped sample of a material, resulting in the following decrease in length and increase in the diameter while under compression.  How much axial strain has occurred

        Original                Dimension while

                            Dimension         under compression            Change

 Length                  20mm                           18mm                    2mm

Diameter           10mm                           11mm                  1mm

Definition

a-      10%

Term

1-     According to the manufacturer of Prime & Bond NT©, which of the following actions should be taken immediately after the 20 second application of adhesive to the tooth surface?

Definition

a-     Gently air dry for five seconds

Term

 1-     How many errors are there in the following comparative summary chart of the properties of enamel versus dentin? (each of the ten shaded boxes counts as one error)

 

Compressive Strength

Tensile Strength

Modulus of elasticity

Hardness

Vitality

ENAMEL

LOWER

LOWER

HIGHER

HIGHER

NON-VITAL

DENTIN

HIGHER

HIGHER

LOWER

LOWER

VITAL

 

 

 

 

Definition
2
Term

1-     Which of the following steps in the lost-wax casting process is/are eliminated by using CAD/CAM systems to create indirect restorations?

Definition

a-wax up

b-investment

c-casting

d-devesting

e-all of the above

Term

  Which of the following would be most likely to occur if all solvent was allowed to evaporate from a liquid dentin bonding primer prior to application to dentin?

Definition

a-     The primer would not penetrate moist etched dentin as well

Term

1-     The main source of bond strength  in properly applied dentin bonding systems is normally

Definition

Infiltration of primer resin into partially demineralized collagen network

Term

1-     When using Prime & Bond NT, why is a gentle air stream applied as one step in the process described in the product’s directions for use?

Definition

To accelerate evaporation of the organic solvent

Term

1-     MMPs can affect durability of dentin bonds because they

Definition

a-     can degrade collagen in the hybrid zone

Term

1-     Which of the following steps is normally eliminated with self-etch bonding systems?

Definition

a-     Rinsing

Term

1-     Thermoset polymers have which of the following features that differentiates them from thermoplastic polymers?

Definition

a-     Crosslinking between polymer molecules

Term

1-     Which of the following dental materials is normally polymerized by free radical formation?

Definition

a-     Heat-cured cross-linked acrylic denture base material

Term

1-     All of the following are features of auto-cure acrylic resin used in dentistry except one.  Which one is the exception?

Definition

a-lower proportional limit than dentin

b-high polymerization shrinkage around 20%

c-incomplete monomer conversion upon reaching hard state

d-porosity caused by loss of polymer particles prior to complete curing

Term

1-      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?

 

 

Definition

RELATIVE TO                                 RELATIVE TO

 

            APPLIED FORCE                    AREA OF FORCE APPLICATION

a-     Directly                   indirectly

Term

1-     If 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?

Definition

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

Term

1-     Which of the following materials is found in resin-modified glass ionomers and is most compatible with the hydrogel component of resin-modified glass ionomers due to its hydrophilic nature?

Definition

a-     HEMA

Term

1-     In general, what advantages do cermets have relative to traditional non-resin-containing glass ionomers?

Definition

a-     Improved wear resistance

Term

1-     After placing a traditional non-resin-containing glass ionomer restoration, the dentist forgot to place a resin coating on the surface. Which of the following is the most likely result of this error?

Definition

a-     The water content in the restoration will be changed

Term

1-     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?

Definition

a-     Hysteresis

Term

1-     Compared to dentin, enamel has a lower value of

Definition

a-     Tensile strength

Term

1-     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?

Definition

a-     Devesting

b. occlusal adjustment

c. shade selection

d. cementation

Term

1-     When mixed with water and fully set, densite is mostly composed of

Definition

a-     Calcium sulfate dihydrate

Term

1-     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?

Definition
setting
Term

1-     Trituration of an amalgam capsule for less than the recommended time results in which of the following compared to trituration for the recommended time?

Definition

a-     More working time

Term

1-     Which of these are components of both conventional amalgam restorations and high-copper amalgam restorations?

Definition

a-     Gamma-1 phase

Term

1-     Advantages of high-copper amalgam restorations compared to conventional amalgam restorations include which of the following?

Definition

a- improved strength

b-improved marginal integrity

c-improved resistance to corrosion

d-all of the above

Term

1-     The formation of which of the following phases is suppressed by preferential formation of a tin/copper phase during the setting reaction of high-copper dental amalgams?

Definition

 a-     Tin/mercury

 

Term

1-     The rate at which a composite restoration with non-uniform temperature approaches temperature equilibrium is dependent upon

Definition

the specific heat, density and thermal conductivity of the composite material

Term

1-     Which of the following properties of zinc oxide / eugenol temporary restorative materials would be most helpful in treating a tooth that developed galvanism after restoration with dental amalgam?

Definition

a-     High electrical resistivity

Term

1-     The continuous phase of microfilled composite resins usually consists mostly of

Definition

a-     UDMA & bisGMA 

Term

1-     Why is the “C-Factor” an important consideration when restoring teeth with composite resin?

Definition

a-     It helps to predict the pattern of polymerization shrinkage

Term

1-     Two heterogeneous hybrid composite resins are identical in composition except that one has a 25% increased volume of pre-cured/ground composite resin particles.  Which of the following is the most likely effect of this 25% increase?

Definition

a-     Decreased polymerization shrinkage

Term

1-     Assuming a required 20-second curing time is used, which of the following light outputs would generally be sufficient to cure a 2mm thickness of composite resin?

Definition

a-     500mW @ 470nm peak

b. 100 mW @ 670 nm peak

c. 500 mW @ 370 nm peak

d. 100 mW @ 770nm peak

Term

1-     A diametral compressive strength test would be most appropriate for which of the following groups of dental materials?

Definition

a-     Gypsum

b. viscoelastic impression materials

c. gold casting alloys

d. round orthodontic wires

Term

Which of the following must be known to state a fatigue strength for a dental material?

Definition

a-     Number of cycles

Term

1-     Which of the following actions would be most effective to increase the efficiency of air abrasion cutting on dental enamel?

Definition

a-     Double the velocity of the air abrasion particles

Term

 

 

 

1-     In irreversible hydrocolloid materials, what is the source of the calcium that forms cross-linking between chains to create the gel state?

Definition

a-     Calcium sulfate

Term

1-     Of these four materials: [SET GYPSUM, HUMAN ENAMEL, SET GLASS IONOMER, POLYMERIZED COMPOSITE RESIN], how many are anisotropic?

Definition
1
Term

1-     Out of the following categories of biocompatibility tests for dental materials, which one can best be standardized and normally has good experimental control?

Definition
In vitro tests
Term

1-     You read in the product literature for an acrylic system designed for making custom impression trays that it contains both benzoyl peroxide and an organic amine.  Based on this information, which of the following would you expect?

Definition

  The product must be mixed prior to use

Term

   What is the function of AMSTAR, as explained in the assigned article, “A practitioner’s guide to developing critical appraisal skills” by Needleman et al.?

Definition

A tool to guide appraisal of systematic reviews

Term
How are bonds tested currently?
Definition
Microtensile
Term
What is deformation proportional to?
Definition
Cube of beam length and thickness
Term
How does viscosity change with increasing shear rate with Pseudo-plastic liquid? And what is its effect?
Definition

Viscosity DECREASES with increasing shear rate.

Flows MORE when under shear in impression syringe "thixotrophy"

Term
How does viscosity change with increasing shear rate with Newtonian liquid? And what is its effect?
Definition
Viscosity INDEPENDENT of shear rate. Always the same viscosity
Term
How does viscosity change with increasing shear rate with Dilatant liquid? And what is its effect?
Definition
Viscosity INCREASES with increasing shear rate. Flows best with lower shear rate.
Term
What is thixotropic and how is it produced?
Definition
Decreased viscosity leads to increased flow under increased shear rate. Produced by vibration/shaking or pressure in impression syringe.
Term
What is stress relaxation?
Definition
Reduction in stress with constant strain applied
Term
What is creep?
Definition
increase in strain with constant stress applied
Term
What has a bigger coefficient of friction, static or kinetic? And what does it depend on?
Definition
Static. Depends on material composition, surface finish and lubrication
Term
When talking about Munsell Color System, what does hue, chroma, value mean?
Definition

Hue: the color itself

Chroma: how much color is there

Value: the overall brightness

Term
What is the order of choosing the proper tooth shade?
Definition

1- Determine Value

2- Select Chroma

3- Determine Hue

Term
What is isomerism?
Definition
Matching under all light sources
Term
What is fluorescence?
Definition
emission of light from a material at wavelengths different than the illuminant
Term
What does the perceived color depend on?
Definition
Material properties, illuminant properties and receptor/sensor
Term
When is a tooth considered dull?
Definition
Scratches greater than 0.5 um
Term
When is a tooth considered rough? smooth?
Definition

ROUGH: Greater than 20 um

SMOOTH: Less than 2 um

Term
Can a surface be dull AND smooth?
Definition
YES with scratches greater than 0.5 um but less than 2 um
Term
What is thermal conductivity and how can it be calculated?
Definition

Speed of heat through material

=calories/second*cm*degree

Term
What is thermal diffusivity? And how is it calcualted?
Definition

Rate at which a body with non uniform temp approaches equilibrium

=conductivity/specific heat*density

Term
What is percolation?
Definition
the shrinking or expanding of dental restorations due to temp changes
Term
What is the electrode potential of an element?
Definition
Ability to gain or lose electrons in solution
Term
What is galvanism?
Definition
Presence of an electrical cell in the oral environment resulting in clinical sensation
Term
What causes a loss of material, roughness and pitting?
Definition
Corrosion
Term
Which can be molded by heat? Thermoset, thermoplastic, both or none of the above?
Definition
Thermoplastic
Term
Name 3 examples of thermoplastic substances
Definition
Polystyrene, PMMAcrylate, PVAcrylic
Term
Name 3 examples of thermoset substances
Definition
Silicones, Cross linked PMMA, and polyisoprene
Term
What is a substance like BELOW its glass transition temp? ABOVE?
Definition

Below: Glass like- showing Brittle Fracture

Above: Rubbery- showing Deformation

Term
How does camphorquinone become an active free radical?
Definition
Light
Term
What is the polymer? The monomer?
Definition

Polymer: powder

Monomer: liquid

Term
What are the clinical stages of acrylic?
Definition

Sandy

Runny/Liquid

Putty/Dough

Rubber

Hard

Term

 What is the best polymerization scheme for:

acrylic temp crown?

Definition
Light
Term

 What is the best polymerization scheme for:

acrylic denture base?

Definition
Heat
Term

 What is the best polymerization scheme for:

acrylic cement for an endodontic post?

Definition
Chemical
Term

 What is the best polymerization scheme for:

acrylic cement for a translucent porcelain veneer?

Definition
Light
Term

What is the best polymerization scheme for:

acrylic cement for a opaque porcelain veneer?

Definition
Chemical
Term

What is the best polymerization scheme for:

direct composite bonding agent?

Definition
Light
Term
What is the current approach to dental bonding?
Definition

ETCH: Chemically etch enamel/dentin

PRIME: Infilitrate enamel/dentin surface using hydrophilic primer

BOND: Provide resin coat with air inhibited layer with composite resin

Term

What is E+P+B?

 

Definition

Three step total etch:

Phospohoric acid etch, primer, adhesive

Term
What is E+[PB]?
Definition

One bottle total etch

Phosphoric acid etch, Primer-Adhesive combined

Term
What is [EP]+B?
Definition

Two bottle self etch

Acidic primer, adhesive (no separate etching! no rinsing!)

Term
What is EPB?
Definition

All in one self etch

One bottle, no mixing (no separate etching! no rinsing!)

Term
Name 2 bonding resins.
Definition
bis-GMA and UDMA
Term
How long should you etch enamel for? Dentin?
Definition

Enamel: at least 15 secs

Dentin: no more than 15 secs

Term
After adhesive is applied and kept wet with adhesive for 20 secs, what happens next?
Definition
Gently air dry for 5 secs to remove acetone solvent
Term
What is the next step after etching the enamel/dentin?
Definition
Rinse with water spray for 10 secs
Term
What is Gamma?
Definition
Amalgam Alloy: Silver/Tin
Term

Conventional Amalgam (Low Copper)

Gamma + Hg --->

Ag/Sn            

Definition

Gamma+ Gamma 1+ Gamma 2

Ag/Sn      Ag/Hg      Sn/Hg

Term
Which has more creep? High copper or Conventional amalgam?
Definition
Conventional
Term
What is trituration?
Definition
Combining amalgam alloy with mercury by vigorous mixing ro form a plastic mass of dental amalgam
Term
What is condensation?
Definition
Adaptation of the plastic dental amalgam mass into the cavity prep by compressing with pressure.
Term
What are the effects of over trituration?
Definition

Decrease in working time

Increase in compressive/tensile strength

Increase in creep

Increase in heat, speeding rxn rate

Term
What are the composite types?
Definition
Anterior, posterior, flowable, packable, core build up, lab (indirect)
Term
What are the 3 components of Dental Resin Composites?
Definition

1. Resin matrix continuous phase

2. Inorganic filler dispersed phase

3. Coupling agent (silane)

Term
What are the components of the polymer matrix continuous phase?
Definition
Bis GMA & UDMA
Term
What has higher conductivity? What has higher linear thermal expansion? Resin matrix or inorganic filler?
Definition

Matrix: Low conducticity, high linear thermal exp

Inorganic filler: High conductivity, low linear thermal expansion

Term
Which composites absorb more water? Microfilled, Microhybrids or Hybrids?
Definition
Microfilled
Term
What is a solvent of bis-GMA?
Definition
Alcohol
Term
Why does yellowing occur in composite resins?
Definition
Tertiary amine accelerator breakdown in chemically cured systems
Term
What are the main reasons for failures in composite resins?
Definition

Seconday caries

Restoration fractures

Term
What do cermets consist of?
Definition

GI chemistry with metal/glass

-Silver is primarily used

(gray color because of addition of metal)

Term
What does conditioner do?
Definition

Make your hair look fabulous

Just kidding, removes surface smear layer ONLY!

Keeps smear plugs

 

Term
In glass ionomers what is the dispersed phase consist of? Continous phase?
Definition

Dispersed phase: silicate glass particle

Continous: Cross linked polyacrylic acid

Term
What are the components of RMGI?
Definition
Polycarboxylic acid polymer, fluoroaluminosilicate glass partlicles, water, HEMA, Free radical intitiator system
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