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

 A systematic review of multiple randomized clinical trials

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

At the tip of the reducing zone

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

HEMA

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

     Increase in crack propagation

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

   Ratio of bonded composite surfaces to unbonded composite surfaces

  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?

    1.5%

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

     3 microns

Compared to conventional amalgams, high-copper dental amalgams exhibit 

    Lower creep

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

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

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

     Chroma

    Over-trituration of dental amalgam alloy and mercury causes…

  Less working time

 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?

     Impact strength

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

   a.Peritubular dentin

b. sclerotic dentin

c. root dentin

d, primary dentin

e. secondary dentin

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

Proportional limit

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

     Use of an etching gel

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

     To promote formation of a hybrid layer

The dispersed phase of microfilled composite resins usually consists mostly of

   Colloidal silica

     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 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

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

     Co-polymerization

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

    Linear thermal expansion

Why do gold and platinum tend to resist corrosion? 

Both have relatively high…

Positive reduction potentials

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

b-     Potassium sulfate

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

     Silver-mercury

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

     Polymerization shrinkage

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

    Pre-cured composite particles

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

   a. Increased permanent deformation

b. Increased resistance to indentation

c. Brittle fracture

d. Decreased polymerization

     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

    Isomerism and fluorescence

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?

a- Sodium Phosphate

b- Calcium sulphate

c- calcium alginate

d- Guluronan

e- None of the above

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?

a-     Decreased compressive strength of the set and dried die

1-     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 fractional strength

1-     How does paraffin wax differ from microcrystalline wax?

a-     Paraffin wax shrinks more upon solidification

1-     Compared to reversible hydrocolloid, irreversible hydrocolloid

Captures less detail

b-     A hydrosol

c- an emulsion

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?

a-     2

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

a-     Reversible hydrocolloids

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

a-     Specific heat

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

a.Value

b.Chroma

c. Hue

d. All of the above

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

a-     Hydroxyapatite crystals

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

a-     .01 – 0.1 microns

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

a-     Composite resin restoration

b.Occlusal sealants

b. cast gold crown

c. amalgam restoration

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

a-     Gypsum-bonded casting investment

b. general use of dental stone

c. mounting plaster

d. fast setting impression plaster

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

a- Gamma 1

b- Gamma 2

c- Free mercury

d- None of the above

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

a-     Camphorquinone

b. Benzoyl peroxide

c. Urethane dimethacrylate

d. Ethylene glycol dimethacrylate

e. an organic amine

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

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

a-     Cutting with a diamond bur

b. forming a hybrid layer

c.applying bonding primer

d. etching with phosphoric acid

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?

a-     Doubled

1-     How does microcrystalline wax differ from paraffin wax?

Microcrystalline wax shrinks less upon solidification

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

a- Amalgam debris collected from chairside traps

b- contact amalgam scrap

c- bloody extracted teeth containing amalgam restorations

d- None of the above

1-     Compared to reversible hydrocolloid, alginate

a-     Captures less detail

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

a-organic amines

b-heat

a-     [EP]+B

b. E+P+B

C. E +[PB]

d. EPB

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

a- Polystyrene

b-Heat cured, cross linked PMMA

C-Cured epoxy used for dies

d- Two of the above

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

a-     HEMA

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?

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

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

a-     FDA

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

    D

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

  To infiltrate demineralized dentin and create a “hybrid” layer

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

  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

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?

 Decreases compressive strength of the set and dried die

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

 Higher creep

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?

Sodium phosphate

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

 PMMA polymer

1-     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

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

     Choice B

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

    Isomerism and fluorescence

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

  Tin-copper

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

Hydroxyapatite

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

  a. increased permanent deformation

b. increased resistance to indentation

c. brittle fracture

d. decreased poymerization

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?

a-     Thermal

b- Hygroscopic

1-     Natural teeth normally exhibit which of the following?

     a. value

b. chroma

c.fluorescence

d. all of the above

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

 Hydrocal

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

a. Gamma-1 phase

b. Gamma 2 phase

c. Tin-mercury phase

d. Tin-copper phase

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

     Less working time

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

    To facilitate primer infiltration

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

a. Coronal dentin

b. casting pattern wax

c. cold cure acrylic resin

d. microfilled composite resin

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

a- hybrid

b-flowable

c-indirect

d-unfilled

e- packable

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

 a.bis-GMA

b. HEMA

c. 4-META

d. solvent: acetone or alcohol

e. colloidal silica

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

    .01 - .1 microns

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

   pre-cured composite particles

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

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

Chemically cured

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

   a.Increase filler volume

b. increase the percentage of uncured monomer

c. use TEGMA in the dispersed phase

d. use a chemically cured system

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

a-    co-polymerization

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

 hysteresis

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?

39.6 mm

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

more permanent deformation

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

fatigue strength

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

a-    linear thermal expansion

  tin-copper

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

value

1-    Communited dental alloy particles are made by

b- pulverization

c- lathe cutting

1-    The largest proportion of reversible hydrocolloid is

a-    water

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

a-    both statements are true

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

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

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?

  tarnishing

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?

a. polymeric

b. hygroscopic

c. thermal

d. setting

  calcium sulphate hemihydrate

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

  Both the statement and the reason are correct and related

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

    a water-to-powder ratio that is too high

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?

indentation

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

poly (methyl methacrylate)

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

    hardness

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

 HEMA

1-    The organic component of dentin is mostly

 collagen

Compared to enamel, dentin has a higher value of

a- compressive strength

b- modulus of elasticity

c- hardness

d- None of the above

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

to promote formation of a hybrid layer

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

 smear layer removed; smear plugs removed

colloidal silica

1-    Recommended best practices for handling dental amalgam waste include

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?

 surface tension

1-    Silanes are used in composite resins to

 limit crack propagation

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

    470nm

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?

  chroma

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

less flexible

1-    Which of these materials is hardest?

a- Dental Porcelain

b- composite resin

c- gold casting alloy

d-dental amalgam alloy

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

  metamerism

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

 specific heat

1-    Residual stress in a wax pattern is caused by

a-     non-uniform heating of layers during waxing

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

 visible light-cured and dual-cured

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

 cutting with a diamond bur

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

   use of an etching gel

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?

    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

1-     What is the measuring unit for strain?

a-      percent

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

a-      more flexible.

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

  proportional limit

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?

  1500 psi

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

1000 microns

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

 hydrocal

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

1 and 2

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

   microcrystalline

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

a- flow

b- ductility

c-elastic modulus

d-thermal expansion

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

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

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

   enamel is anisotropic; dentin is anisotropic 

1-   Hysteresis is a property of

1-   In comparing alginate to reversible hydrocolloid, alginate

captures less detail

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

 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

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?

chroma

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…

 isomerism and fluorescence

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

a- dull and rough

or 

b-dull and smooth

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

 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

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…

impact strength

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

a- thermal expansion

b- yield strength

c- resilience

d- resistance to indentation

e- none of the above

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

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

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

decrease in working time

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?

  increases by a factor of 4x or more

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

 organic amines &

heat

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

  water formed as byproduct

1-   Polymerization of epoxy die material occurs by

   ring opening

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

a. Smear plugs

b. hybrid zone

c. enamel rods

d. odonotoblasts

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

  HEMA

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

requires rinsing enamel and dentin after etching

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

   3 microns

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?

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

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

a-   visible light-cured and dual-cured

    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?

a-   increase in crack propagation

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

     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

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

 ratio of bonded to unbonded surfaces

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

Porcelain fused to metal crown undercasting

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

1.5%

                  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?

increase centrifugal casting force

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

   at the tip of the reducing zone

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

calcium sulphate hemihydrate

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

a-precipitation

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

d-add slurry water to the initial mix

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?

 plastic

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

 gypsum-bonded casting investment

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

Borax

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?

 disinfect and pour immediately

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

e-sodium phosphate

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

 residual stress in the wax pattern

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

a-poly (methyl methacrylate)

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

none, because thermosetting polymers cannot be molded by heating

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

 by addition reaction, initiated by free radicals

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?

 tin-copper

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

 higher creep

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

1-The inorganic component of enamel is mostly composed of

 hydroxyapatite

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

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

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…

closer together and larger in diameter

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

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

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

 poor wetting of the solid by the liquid

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

 to promote formation of a hybrid layer

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

HEMA

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

micromechanical interlocking

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?

rinsing away the gel with water

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

 colloidal silica

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

 polymerization shrinkage

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

 limits crack propagation at resin/filler interface

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

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

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

shearing

1-Which of the following materials is the hardest?

a- tungsten carbide

b-pumice

c-dental gold alloys

d-enamel

e-dentin

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

sodium lauryl sulfate

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

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

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

Newtons

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…

less ductile

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

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?

                halved

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

                     stiffer

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

                                         proportional limit

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

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

b-to reduce air voids in the final set amalgam

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

Reversible hydrocolloid

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

                                  formation of low molecular weight by-products

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

  approximately equal to enamel.

Recommended best management practices for handling dental amalgam waste include

                                      recycling chairside vacuum filter contents

Where is predentin located in an erupted permanent tooth?

    adjacent to the odontoblasts

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

                                  a.cavity preparation with a carbide bur

b.fracturing by trauma

c.etching with phospohoric acid gel

d. priming with hydrophilic monomer

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

                                         TEGMA

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

a- dental porcelain

b- tungsten carbide

c- silicon carbide

d- aluminum oxide

e- none of the above

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

 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

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

cell culture studies

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…

            shiny and smooth

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

silica or glass, and colloidal silica

 Which of the following is a direct restoration?

occlusal amalgam

   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?

   Which of the following best describes the megaPascal?

unit of stress about equal to 150 psi

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

   more flexible

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

proportional limit

  Which of the following materials has the highest KHN?

a- enamel

b- dentin

c-composote resin

d- dental porcelain

e- cast gold alloy

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

a- gypsum for study casts

b- gypsum for casting investments

c- dentin

d- porcelain

e- Casting pattern wax

 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

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

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

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

calcium sulphate hemihydrate

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

are formed by wet calcination.

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

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

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

   potassium sulfate

Borax

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

   sodium phosphate

  The largest component of irreversible hydrocolloid is

 diatomaceous earth

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

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

reversible hydrocolloid

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

a- Premature removal from the mouth

b- inadequate spatulation

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

   a. molding of polymer

b. setting of gypsum

c. gelling of agar

d. distortion of wax

e. polishing of composite

Residual stresses in wax casting patterns are caused by

 non-uniform heating during wax-up

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

 formation of low molecular weight by-products

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

a- heat

b- organic amines

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

poly (methyl methacrylate)

 Comminuted dental alloy particles are formed by

a- pulverization

b- lathe cutting

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

  silver-tin

 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?

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

 approximately equal to enamel.

 What is the function of condensation of dental amalgam?

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

b- to reduce air voids in the final set amalgam

                                     serve as a preferential oxidizer.

  Recommended best management practices for handling dental amalgam waste include

  recycling chairside vacuum filter contents

  Where is predentin located in an erupted permanent tooth?

   adjacent to the layer of odontoblasts

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

 shaping with a carbide bur

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

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

a-compressive strength

b- tensile strength

c-hardness

d-modulus of elasticity 

   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?

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

a. etched enamel : sealant

b. dental amalgam: water

c. acrylic: water

d. gold alloy: porcelain

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

a-   micromechanical interlocking

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