Dental Materials - Pract Qs

transparency

a visual quality in which a distant image or element can be seen through a nearer one (characterized by its light transmission properties, whereas its color is given by its reflectance properties)

All of the following are thought to contribute to pulp irritation or damage EXCEPT one. Which one is the EXCEPTION? a) arrested dental caries b) marginal leakage after restoration c) cavity preterm-93paration d) thermal properties of the material

a) arrested dental caries

When light curing, inhomogeneous spectral emission and radiant exitance beam profiles can result in a) uneven photopolymerization within a resin restoration. b) increased depth of cure in a resin restoration. uniform temperature changes throughout a resin restoration.

a) uneven photopolymerization within a resin restoration.

Assume that a material is undergoing abrasive wear. As the ratio of material hardness to abrasive hardness increases, the amount of abrasive wear that is expected to occur ______________________ a. increases b. Decreases c. Does not change

b. Decreases

Which of the following fibers is common in fibers used to reinforced dental restorations (e.g., Ribbond)? a. carbon fiber b. Polyethylene fiber c. Kevlar fiber d. Nylon fiber

b. Polyethylene fiber

When thinking about the surfaces in a cavity preparation, the cavity configuration factor (C-Factor) is equal to the ratio of a) Unbonded surfaces to restoration volume b) Unbonded to bonded surfaces c) Bonded to Unbonded surfaces d)Bonded surfaces to restoration volume

c) Bonded to Unbonded surfaces

Which of the following are FALSE statements regarding friction? a. Friction is the force required to overcome the resistance to sliding of one stationary body on a second stationary bod measured in the plane of interface. b. Friction force is proportional to normal force. c. Friction force is disproportional to normal force. d. U(s) = F/ W

c. Friction force is disproportional to normal force.

Which of the following are true statements regarding friction? (Select all that are correct.) A. Friction force is proportional to normal force. B. Spreading a given load over a larger area of contact decreases the friction force. C. The friction force is the same as the coefficient of friction. D. Friction is the force required to overcome the resistance to sliding of one stationary body on a second stationary body measured in the plane of the interface.

A. Friction force is proportional to normal force. D. Friction is the force required to overcome the resistance to sliding of one stationary body on a second stationary body measured in the plane of the interface.

Which of the following is true based on pulp response after cutting? A. More reparative dentin is formed with wet low-speed cutting than with wet high-speed cutting. B. Greater short-term post-operative sensitivity would be expected with wet high-speed cutting than with wet low-speed cutting. C. Wet low-speed cutting results in a larger pulp response than wet high-speed cutting.

A. More reparative dentin is formed with wet low-speed cutting that with wet high-speed cutting. C. Wet low-speed cutting results in a larger pulp response than wet high speed cutting

All of the following are true regarding resin-modified glass ionomer luting cements EXCEPT one. Which one is the EXCEPTION? A. The polymerization reaction occurs slowly B. RMGI interacts with the calcium in hydroxyapatite C. They are supplied in powder/liquid or paste/paste formulations D. The set material is a brittle solid

A. The polymerization reaction occurs slowly

An elastic solid tested in tension produces a stress-strain curve that continues significantly beyond the proportional limit. This material is said to be ductile and not brittle. A. True B. False

A. True

Hydrofluoric acid etching and silanating do little to improve adhesion of resin luting materials to polycrystalline ceramics made of zirconia. A. True B. False

A. True

Knoop and Vickers hardness tests are commonly used for determining microhardness in dental material. A. True B. False

A. True

Cavity liners can reduce experienced polymerization stress because they often have a lower modulus of elasticity than do restorative resin composites. A. True B. False

A. True o Class 1 composites have a high C-factor o Class 5 composites have lower C-factors

MTA materials result in the precipitation of: A. carbonated apatite B. fluorapatite C. phosphate-rich apatite

A. carbonated apatite o MTA, in presence of calcium + phosphate, triggers precipitation of CARBONATED APATITE -------Forms nice reparative dentin bridges

When thinking about the surfaces in a cavity preparation: C-Factor = _________ / _________

Answer: bonded/unbonded

The most common photoinitiator in dental resin composites has a spectral absorption in the range of ___ nm. A. 390-460 B. 425-495 C. 390-410

B. 425-495 term-56 468 nm excites it into an excited triplet state

A primary goal of biocompatibility testing is to minimize risk of adverse biological response in A. providers. B. All three of the other choices represent groups whose biological risk is to be minimized. C. patients. D. laboratory technicians.

B. All three of the other choices represent groups whose biological risk is to be minimized.

A material viewed to be biocompatible is one that performs with an _____ host response in a ______ application. A. Appropriate; non-specific B. Appropriate; specific C. Exaggerated; non-specific D. Exaggerated; specific

B. Appropriate; specific

The property that describes the relative stiffness of rigidity of a material is called_____________. A. Strain B. Elastic modulus C. Stress D. Resilience

B. Elastic modulus

An elastic solid tested in tension produces a stress-strain curve that continues significantly beyond the proportional limit. This material is said to be brittle and not ductile. A. True B. False

B. False

Bonding restorations with self-adhesive resin luting materials to preparations with subgingival margins is a very predictable procedure because the TEGDMA in self-adhesive resin luting agents is inherently anti-cariogenic. A. True B. False

B. False

Metamerism is the phenomenon in which the color of an object is highly saturated. A. True B. False

B. False

Microhardness is commonly determined for dental materials using atomic force microscopy. A. True B. False

B. False (nanohardness tests for atomic force microscopy and Microhardness uses SEM)

In general, higher degrees of conversion result in less final stress being experienced in a polymerized resin-based composite material. A. True B. False

B. False · The higher the C-Factor, the more difficult to have bonded interfaces that are able to resist the stresses o This work demonstrated more gap width being generated between the composite and dentin as the C-Factor increased -C-factor = Bonded/Unbonded

All of the following are true statements regarding friction EXCEPT one. Which one is the EXCEPTION? A. Friction force is independent of the area of contact. B. Spreading the load decreases friction force. C. Friction force is proportional to normal force. D. The friction force/normal force ratio defines coefficient of friction.

B. Spreading the load decreases friction force.

All of the following are desired characteristics of biomaterials EXCEPT one. Which one is the EXCEPTION? A. no irritation of oral tissues B. causes systemic toxic responses C. doesn't provoke inflammatory response D. is not cariogenic

B. causes systemic toxic responses

A fluid that does not flow out of a jar easily is said to have a _____ viscosity. A. low B. high

B. high

When using an etch and rinse dental adhesive, you create a dentin interaction zone that contains the adhesive and demineralized collagen fibers. This zone is called the _________. A. adhesive layer B. hybrid layer C. smear layer

B. hybrid layer · These schematics represent a cross-section through a dentin tubule and demonstrate the formation of an interaction zone between the adhesive and demineralized dentin collagen - called the HYBRID LAYER

A fluid that flows easily out of a jar is said to have a ___________ viscosity. A. high B. low

B. low

The property that represents the amount of energy required for a specimen to reach its proportional limit is called: A. elastic modulus B. resilience C. toughness D. stress

B. resilience

All of the following are methods to measure flexure strength EXCEPT one. Which one is the EXCEPTION? A. three-point flexure B. single-edge notch C. four-point flexure D. biaxial flexure

B. single-edge notch (There is a diametral tensile strength test, three-point flexure test, four-point flexure test, piston-on-three-ball test for biaxial flexure)

The color dimension that communicates the amount of gray, position between white and black, that is seen in an object is called: A. metamerism B. value C. chroma D. hue

B. value o Hue - dominant wavelengths present o Value - how much gray is present between black and white extremes o Chroma - color saturation or intensity

A good thermal insulating material placed in a thickness of 0.25 mm would be expected to protect a pulp from thermal shock. A. True B.False

B.False (0.5-0.75mm) Thermal insulators are liners (Calcium Hydroxide, MTA, & Calcium Silicate Cement)

After cavity preparation, you expect there to be significant pulp reaction if there is a remaining dentin thickness of: A. 0.75 mm B. 2.0 mm C. <0.5 mm D. 1.0 mm

C. <0.5 mm < 0.5 mm RDT = Significant pulp reaction 0.5 mm RDT = 75% reduction in pulp reaction 1.0 mm RDT = 90% reduction 2.0 mm RDT = Little pulp reaction

Which of the following is considered a traditional cement? A. Compomer B. Self-adhesive composite C. Glass Ionomer D. Resin composite

C. Glass Ionomer

Most biocompatibility test programs include a __________ endpoint. A. systemic acute toxicity B. reproductive toxicity C. Sensitization

C. Sensitization???

Tribology is the science and technology of interacting surfaces in relative motion BECAUSE tribology is the study of statics. A. Both the statement and the reason are correct and related. B. Both the statement and the reason are correct but NOT related. C. The first statement is correct but the reason is NOT. D. The statement is NOT correct but the reason is correct. E. NEITHER the statement NOR the reason is correct.

C. The first statement is correct but the reason is NOT.

refraction

The bending of a wave as it passes at an angle from one medium to another (A ray of light of one wavelength/color in passing from air to glass is refracted, or bent)

Reflection

The bouncing back of a wave when it hits a surface through which it cannot pass.

Metamerism

The phenomenon in which the color of an object appears to be different when viewed under two different light sources

Cavity liners can reduce experienced polymerization stress when they have a lower modulus of elasticity than the restorative resin composite. True False

True

For a material to be viewed as biocompatible, it must be able to perform in a specific application with an appropriate host response. True False

True

T/F: A controlled clinical study by Loguerico showed roughening dentin before restoration of non-carious cervical lesions with dentin bonding agent had no effect.

True

T/F: E.Max (lithium disilicate reinforced glassy ceramic) can be fabricated in pressed or milled techniques.

True

T/F: The need for a ferrule when utilizing a post retained core seems to be different between fiber reinforced posts and custom cast Type IV gold.

True

T/F: The principle of material tissue interaction says that a material in contact with tissue fluids releases substances, which then act directly or indirectly on the tissue.

True

Fluorescence

When an object absorbs ultraviolet radiation and emits that radiation at a longer wavelength,

Which of the following general statements about polymerization is correct? a. Lower degrees of conversion are not predictive of the final stress in a polymerized resin composite. b. Lower degrees of conversion result in more final stress in a polymerized resin composite. c. Lower degrees of conversion result in less final stress in a polymerized resin composite.

c. Lower degrees of conversion result in less final stress in a polymerized resin composite. C-Factor = Ratio of Bonded to unbounded (bonded/unbonded) · The higher the C-Factor, the more difficult to have bonded interfaces that are able to resist the stresses o This work demonstrated more gap width being generated between the composite and dentin as the C-Factor increased

Polymerization stress in a resin composite can result in tooth cusp deflection, flexure, or even cracking. This cusp deformation/flexure is decreased by: a. using a high modulus of elasticity cavity liner on the cusp wall. b. increasing the quality of the bonding interface. c. increased amounts of remaining tooth cusp structure.

c. increased amounts of remaining tooth cusp structure.

We discussed the monoblock concept. Based on clinical studies, it appears: a. Fiber post restored teeth have increased fracture resistance relative to teeth restored with other post types. b. Fiber post restored teeth have reduced fracture resistance to sound dentition. c. Fiber posts are a viable treatment option for RCT treated teeth. d. All of the other choices are correct statements.

d. All of the other choices are correct statements.

Based on a systematic review of lab studies, it appears cleaning the prepared canal before bonding your fiber post is most practically accomplished with: a. Silane b. Ethyl acetate c. Xylene d. Ethanol e. EDTA

d. Ethanol

Which of the following is a relative advantage of using a glass ionomer restorative material instead of resin composite when managing high-risk caries patients? a .Glass ionomer has better esthetic qualities. b. Glass ionomer has a relatively low ability to recharge with topical fluoride therapy compared to resin composite. c. Glass ionomer has relatively low fluoride release compared to resin composite restorative material.. d. No need for a dental bonding agent when placing glass ionomer.

d. No need for a dental bonding agent when placing glass ionomer.

The ability of a material to elongate plastically under tensile stress represents its _________. A. ductility B. creep C. yield strength D. flow

ductility

What categories of Dentin Bonding Agents (DBA) did we discuss? a. 3-Step Etch and Rinse b. 2-Step Mild Self Etch c. 2-Step Ultramild Self Etch d. 2-Step Etch and Rinse e. All of the above

e. All of the above

All zirconia _________________________________. a. is the same b. undergoes martensitic deformation c. has the same preparation requirements d. is not translucent and must be layered with VM 9 e. None of the provided responses is correct.

e. None of the provided responses is correct. ??

translucency

optical property in which varying degrees of light pass through or are absorbed by an object

Corrosive Wear

related to the chemical activity of the wear surfaces

Which of the following is used in glass ionomer liquid specifically to increase working time and decrease setting time? itaconic acid tricarballylic acid tartaric acid maleic acid

tartaric acid

transmission

the passage of light through an object

Tribology

the science and technology of interacting surfaces in relative motion - to each other (the study of friction, wear, and lubrication)

friction

two stationary bodies in contact resist the sliding of one on the other The force required to overcome the resistance is measured in the place of the interface

In the Madariaga et al study, saliva _____________ was shown to have a positive relationship with tooth wear. buffer capacity pH viscosity flow rate

viscosity

absorption

we perceive the object as the complementary color, i.e., the color opposite the absorbed color on the color wheel

A common photoinitiator that has a broad absorption spectrum between about 425 to 495 nm is _______________. · PPD · Lucerin TPO · camphorquinone · Ivocerin

· camphorquinone

Which of the following types of wear is fundamentally involved when completing a crown preparation with a diamond bur? A. Abrasive wear B. Adhesive wear C. Corrosive wear D. Erosive wear

A. Abrasive wear

The measure of amorphous material's potential to deform under a small static load is _________. A. Creep B. Ductility C. Yield strength D. Flow

D. flow

Which of the following is appropriately related to irradiance? A. Joules per unit of surface area B. radiant flux in watts C. watts x time D. power (W)/unit of surface area

D. power (W)/unit of surface area · Power - amount of Radiant Flux - Watt (W) · Radiant Energy (Joules) - Watts x time · Irradiance - power (W)/unit of surface area · Radiant Exposure (J/unit of surface area) - irradiance x time

opacity

A measurement of the transparency of a color.

Polymerization stress in a resin composite can result in cusp deflection or flexure. This flexure is increased by 1. using a low modulus cavity liner on the cusp wall. 2. increasing the quality of the bonding interface. 3. increased amounts of remaining cusp tooth structure

2. increasing the quality of the bonding interface. Stress vs Strain Curve --> Slope = modulus of elasticity (MOD) Low elastic modulus = FLEXIBLE Flowable composites --> more flexible --> less filler and more matrix --> lower modulus of elasticity

Polymerization shrinkage stress is relieved or minimized by 1. maximizing post-gel cross-linking. 2. inhibiting post-polymerization hygroscopic expansion. 3. maximizing pre-gel polymerization shrinkage.

3. maximizing pre-gel polymerization shrinkage. · 3 approaches used to combat stress: o Low elastic modulus liner (flexible) o Incremental placement of the composite o Reduce the polymerization rate (by changing light output to maximize PRE-GEL shrinkage) -With rapid polymerization, increased stress is developed within the composite Hypothesis: increased interfacial stress --> more marginal defects (larger gaps)

All of the following are proper clinical guidelines when light-curing EXCEPT one. Which one is the EXCEPTION? A. be sure the light guide is free of damage and debris B. use proper eye protection C. begin the curing cycle with the light guide in contact with the resin D. stabilize the light guide during curing

C. begin the curing cycle with the light guide in contact with the resin o Clean and inspect tip before use o Apply plastic barrier to light o Set light to correct mode and time according to manufacturer's instructions § A1 = 10 seconds, A2 = 15 seconds, A3 = 20 seconds, B1 = 10 seconds, B4 = 30 seconds o Position Light to Minimize Thermal Damage to Soft Tissues and Air Cool if Needed o Wear Eye Protection § Stabilize tip § Watch when light curing o Cover Restoration with Tip o Position Tip Close to Restoration § Use Supplemental Lateral Exposures o Avoid Distance and Shadows § If ≥ 5mm distance, increase exposure time o Light Cure Restoration for Recommended Time Cleanand Disinfect Unit

Atomic rearrangement in an crystalline solid when that solid experiences an external load is termed: A. ductility B. yield strength C. creep D. flow

C. creep

If you place a direct restorative material in a tooth and the difference in the linear coefficient of thermal expansion between the tooth and the material is large, all of the following are potential related outcomes EXCEPT one. Which one is the EXCEPTION? A. dental caries B. microleakage C. flow D. post-operative sensitivity

C. flow o Large discrepancies in the coefficient of thermal expansion between a restorative material and tooth structure can result in significant challenges to the marginal integrity between the restoration and the tooth

The change in dimension per unit of initial dimension is called ___. A. resilience B. elastic modulus C. strain D. stress

C. strain

The atomic or molecular force within an elastic solid that is equal and opposite to a force or pressure exerted on that solid is called: A. strain B. elastic modulus C. stress D. resilience

C. stress

All of the following are factors that impact the ability of visible light to reach a given point on the bottom surface of a resin composite increment EXCEPT one. Which one is the EXCEPTION? A. distance B. intervening materials C. use of protective eyewear D. thickness of material

C. use of protective eyewear

When delivering a pressable lithium disilicate ceramic crown on a preparation with compromised retention form, which of the following would be the most preferred luting agent? A. Resin-modified glass ionomer B. Zinc phosphate C. Glass ionomer D. Adhesive resin

D. Adhesive resin

Glass based ceramics have ________________________________. A. Increased physical properties and increased translucency B. Decreased physical properties and decreased translucency C. Increased physical properties and decreased translucency D. Decreased physical properties and increased translucency

D. Decreased physical properties and increased translucency

The property that represents the ability of a material to absorb elastic energy and to deform plastically before fracturing is. A. Stress B. Resilience C. Elastic modulus D. Toughness

D. Toughness

Atomic rearrangement in an amorphous solid when that solid experiences an external load is termed: A. ductility B. yield strength C. creep D. flow

D. flow

T/F: The study by Moshonov et al. suggested the distance from the end of my post to the trans-polyisoprene obturation does not matter.

False

Vitrebond (resin-modified glass ionomer) is considered to be the "standard of care" material for direct pulp capping procedures. True False

False I believe its Calcium Hydroxide (Dycal)

T/F: The primary modification that differentiates resin-modified glass ionomer cement from conventional (traditional) glass ionomer cement involves a change in the fluoroaluminosilicate glass.

False, HEMA

T/F: A nano thin film of titanium dioxide coating on polymethyl methacrylate resin has no impact on the wear resistance of the resin.

False, improved wettability, resistance to wear, surface smoothness, and resistance to microbial adherence

T/F: Mickenautsch claims that controlled clinical trials provide evidence that dental amalgam restorations have a higher caries-preventive effect than direct posterior high-viscosity glass ionomer cement restorations in permanent teeth.

False, no difference

T/F: Matrix metalloproteinase inhibition is a necessity for the success of your bonded restorations.

False, no true evidence that it is beneficial although in theory it should

Which of the following is a proper clinical guideline when light-curing? a) use proper eye protection b) do not use supplement lateral exposures when curing proximal boxes c) do not look at the restoration or tooth while curing d) begin the curing cycle with the light guide in contact with the resin

a) use proper eye protection · Using Your Light o Clean and inspect tip before use o Apply plastic barrier to light o Set light to correct mode and time according to manufacturer's instructions § A1 = 10 seconds, A2 = 15 seconds, A3 = 20 seconds, B1 = 10 seconds, B4 = 30 seconds o Position Light to Minimize Thermal Damage to Soft Tissues and Air Cool if Needed o Wear Eye Protection § Stabilize tip § Watch when light curing o Cover Restoration with Tip o Position Tip Close to Restoration § Use Supplemental Lateral Exposures o Avoid Distance and Shadows § If ≥ 5mm distance, increase exposure time o Light Cure Restoration for Recommended Time Cleanand Disinfect Unit

Which of the following is a method to measure flexural strength that is designed to avoid the problem of edge fractures? a. Biaxial flexure b. 3-point flexure c. Single-edge notch d. 4-point flexure

a. Biaxial flexure

Which of the following is a desired characteristic of a biomaterial that is to be implanted into the body? a. It does not provoke an inflammatory response. b. It causes systemic toxic responses. c. It is cariogenic. d. It causes irritation of oral tissues.

a. It does not provoke an inflammatory response. o Does not interact negatively with or irritate oral or dental tissue o Should not contain diffusible substances that can cause systemic toxic responses o Should not provoke an inflammatory response o Should not contain potentially sensitizing agents o Should not have carcinogenic potential

Which type of resin cement appears to be the material of choice for fiber posts due to the inability to bond apical root dentin effectively and consistently? a. Self-Adhesive Resin Cement b. Adhesive Resin Cement c. Esthetic Resin Cement d. None of the cements identified in the other responses appears to be the material of choice.

a. Self-Adhesive Resin Cement

We discussed incompatibilities between bonding agents and a specific type of material. Which of the following combinations is of the most concern? a. Simplified DBA and Dual Cured Restorative Materials b. Non-simplified DBA and Light Cured Restorative Materials c. Simplified DBA and Light Cured Restorative Materials d. Non-simplified DBA and Self Cured Restorative Materials

a. Simplified DBA and Dual Cured Restorative Materials

Dentin bonding algorithms create a hybrid layer. This hybrid zone is typically: a. made up of demineralized collagen and unfilled monomers. b. residual debris adhered to the surfaces of the tooth preparation. c. not important for dentin bonding. d. none of the above.

a. made up of demineralized collagen and unfilled monomers.

To bond glass based ceramics, you require two of the following. Which two? a. silane b. 10-MDP c. hydrofluoric acid

a. silane c. hydrofluoric acid

Zirconia has four generations. All of the following statements about those generations is correct EXCEPT one. Which one is the EXCEPTION? a. 1st generation - framework 3YTZP b. 4th generation - reduced alumina 3YTZP c. 3rd Generation - 4Y and 5Y-TZP d. 2nd Generation - reduced alumina 3YTZP

b. 4th Generation - reduced alumina 3YTZP

Which of the following is true about the Atraumatic Restorative Technique (ART)? a .ART is limited to in-office applications. b. ART is useful for Interim Therapeutic Restorations. c. ART definitively removes all caries from a tooth. d. ART cavity preparation requires a high-speed handpiece.

b. ART is useful for Interim Therapeutic Restorations.

The measure of an amorphous material's potential to deform under a small static load is ______________. yield strength creep flow ductility

flow

Adhesive Wear

formation and disruption of micro-junctions

Abrasive Wear

harder material plowing or cutting a softer material

Surface Fatigue Wear

high localized stresses producing surface or subsurface cracks