Dental Materials Chapter 4

Which of the following are advantages of the use of single-paste composite compules? 1. Ease of use 2. Decrease in possibility of cross infection 3. Protection of paste from light exposure A. 1, 2, 3 B. 1, 2 C. 2, 3 D. 1, 3

A. 1, 2, 3 Advantages of the use of single-paste composite compules include ease of use, a decrease in potential cross-infection, and as a protection of the composite material from light exposure.

Composites provide good thermal insulation for the dental pulp. However, composite restorations have a greater change in dimensions with changes in oral temperatures than tooth structures. A. Both statements are true. B. Both statements are false. C. The first statement is true; the second statement is false. D. The first statement is false; the second statement is true.

A. Both statements are true. Both statements are true. Composites provide good thermal insulation for the dental pulp. However, composite restorations have a greater change in dimensions with changes in oral temperatures than tooth structures.

Which of the following composite color shades requires longer exposure time to the visible light to polymerize? A. Darker B. Lighter C. Translucent D. Microhybrid

A. Darker Darker shades or more opaque composites require longer exposure times than lighter shades or more translucent composites to polymerize. Lighter, more translucent, and microhybrid composites require less exposure time.

Composites are composed of which of the following? A. Resin matrix, inorganic filler particles, silane coupling agent B. Quartz, lithium aluminum silicate C. Barium, strontium, zinc D. Dimethacrylate methacrylate, Mis-GMA, urethane dimethacrylate oligomers

A. Resin matrix, inorganic filler particles, silane coupling agent Composites consist of three phases: resin matrix, dispersed inorganic filler particles, and silane coupling agent on the filler particles to produce a good bond between the matrix and the filler. Quartz and lithium aluminum silicate are used as fine fillers in composites. Barium, strontium, and zinc can also be used as fine fillers in composites. Dimethacrylate methacrylate, Mis-GMA, and urethane dimethacrylate oligomer are the most common resin matrix.

Marginal leakage of a composite fill more likely to occur under which of the following circumstances? A. When polymerization shrinkage exceeds the bond strength of a composite to tooth structure B. When the bond strength of a composite to tooth structure exceeds polymerization shrinkage C. When the composite is contaminated with saliva D. During the use of self-curing polymerization systems

A. When polymerization shrinkage exceeds the bond strength of a composite to tooth structure When polymerization shrinkage exceeds the bond strength of a composite to tooth structure, marginal leakage can occur.

Which of the following statements is true regarding initiators and accelerators?1. The principal system used to achieve polymerization is the self-curing system.2. In the visible light-curing system, the composite is polymerized by exposure to an intense blue light.3. The blue light is absorbed by a diketone, which, in the presence of an amine, initiates the polymerization reaction.4. In order for polymerization to occur fully, an exposure time of 60 seconds is needed.5. Diketone and amine are kept separate and not mixed until just prior to the placement of the restoration. A. All of the above B. 2, 3 C. 1, 2, 4 D. 2, 3, 5 E. Some other combination

B. 2, 3 In the visible light-curing system, the composite is polymerized by exposure to an intense blue light. The blue light is absorbed by a diketone, which, in the presence of an amine, starts the polymerization reaction.

Of the following, where are flowable composites best used? A. Posterior occlusal areas B. Abfraction areas C. Anterior incisals D. Anterior interproximal and incisals

B. Abfraction areas Flowable composites have a low modulus of elasticity, which may make them useful in cervical erosion and abfraction areas. Flowable composites would not be useful on occlusal or incisal surfaces.

In order to overcome or to minimize the effect of polymerization shrinkage, which of the following technique(s) should be considered? A. Utilize the visible blue light for the entire recommended 60 seconds B. Insert and polymerize the composite in layers C. Prepare a direct composite inlay and then cement the inlay to the tooth with low-viscosity resin cement D. B and C

B. Insert and polymerize the composite in layers Composite should be inserted and polymerized in layers. Exposure times of 20 to 40 seconds are needed for polymerization. Composite inlay should be indirect, not direct, and then cemented to the tooth with low-viscosity resin cement.

Which of the following is frequently used as an etchant solution? A. Calcium phosphorus B. Phosphoric acid C. Sulfuric acid D. Acidulated sodium phosphate

B. Phosphoric acid Phosphoric acid solution or gel is frequently supplied by the composite manufacturer as the etchant of choice. Phosphoric acid is a colorless, odorless, corrosive acid and can form toxic fumes when it comes into contact with alcohols, ketones and other organic compounds. It's used in soft drinks to provide a sharper, tangy taste and to help slow the growth of molds and bacteria in sugary formulas. Sulfuric acid is a very strong chemical that is corrosive. Corrosive means it can cause severe burns and tissue damage when it comes into contact with the skin or mucous membranes. Acidulated sodium phosphate fluoride is used as an anti-caries agent.

Which of the following is the purpose of the hybrid layer? A. Forms in place of the removed smear layer B. Provides micromechanical bonding retention to the dentin C. Evens out the morphology of the variations in the dentin, such as number and size of tubules D. All of the above

B. Provides micromechanical bonding retention to the dentin The formation of a hybrid layer provides micromechanical retention to the dentin. While it is true that bonding to dentin requires the removal of the smear layer, the hybrid layer does not form because the smear layer has been removed. Because the morphology of dentin varies with its location, number, and size of tubules, the bonding agent that penetrates the exposed collagen and forms a hybrid layer will also vary.

Which of the following statements best describes the function of silanes? A. Bifunctional, silicon-inorganic compounds that join resin matrix making it a nanofilled composite B. Silicon-organic compounds that join inorganic filler particles and resin matrix C. The compound that aids in the retention of the composite to the enamel or dentin of the tooth D. A sticky substance that produces a good bond between the tooth and the composite fill

B. Silicon-organic compounds that join inorganic filler particles and resin matrix Silanes are bifunctional, silicon-organic compounds that couple inorganic filler particles and resin matrix.

The purpose of adding dimethacrylate to the oligomers Bis-GMA and UDMA is which of the following? A. Bis-GMA and UDMA are viscous liquids that need to be in a different form for ease of use. B. Dimethacrylates are added to control the consistency of the composite paste. C. Both A and B are correct. D. Neither A or B is correct.

C. Both A and B are correct. Bis-GMA and UDMA oligomers are viscous liquids to which low-molecular-weight monomers, dimethacrylates, are added to control the consistency of the composite paste.

Advantages of packable composites include which of the following? A. Radiolucency B. High polymerization shrinkage C. Low wear rate D. Low depth of cure

C. Low wear rate Low wear rate is one advantage of packable composites. Radiopacity, low polymerization, and high depth of cure shrinkage are additional advantages of packable composites.

Microhybrid composites shrink less during polymerization than microfilled composites due to which of the following reasons? A. Microfilled composites have less resin. B. Microfilled composites have more resin. C. Microhybrid composites have less resin. D. Microhybrid composites have more resin.

C. Microhybrid composites have less resin.

Which of the following applies to the placement of a bonding agent under a resin-modified glass ionomer? A. Placing a bonding agent will expedite the release of fluoride. B. The bonding agent will serve as an insulator to protect the pulp of the tooth. C. Placing a bonding agent is contraindicated because it decreases fluoride release. D. The placement is of no clinical significance as resin-modified glass ionomer are recommended for patients with high risk of caries.

C. Placing a bonding agent is contraindicated because it decreases fluoride release. Placing a bonding agent is contraindicated because it decreases fluoride release; it does not increase fluoride release or protect the pulp.

The amount and duration of fluoride release from a composer is less than that of a glass and resin-modified glass ionomer. However, a composer recharges when fluoride treatments are applied or the patient brushes with a fluoride dentifrice. A. Both statements are true. B. Both statements are false. C. The first statement is true; the second statement is false. D. The first statement is false; the second statement is true.

C. The first statement is true; the second statement is false The amount and duration of fluoride released from a compomer and its duration is less than that of a glass and resin-modified glass ionomer. A compomer does not recharge from a reapplication of fluoride.

Which of the following can prevent postoperative sensitivity? A. Incremental placement of the composite B. Excellent isolation during composite placement C. Use of bases D. All of the above

D. All of the above Incremental placement of the composite, excellent isolation during composite placement and/or use of bases can prevent postoperative sensitivity.

Which of the following factors play a role in the selection of the restorative material to use for an esthetic restoration? A. Fluoride release B. Strength C. Wear resistance D. All of the above

D. All of the above Selection of a material is made based on a need for esthetics, fluoride release, wear resistance, strength, and ease of use.

Which of the following is the purpose of a provisional composite? A. To maintain the position of the prepared tooth B. To seal and insulate the preparation and protect the margins C. To establish vertical dimension D. All of the above

D. All of the above The purposes of a provisional restoration is to maintain the position of the prepared tooth, to seal and insulate the preparation and protect the margins, to establish vertical dimension, to aid in diagnosis and treatment planning, and to evaluate esthetic replacements.

Which of the following factors determine the classification of composites as to microhybrid, microfilled, or nanofilled? A. Concentration of filler B. Presence or absence of submicron filler particles C. Filler size and distribution of the particles D. Particle size and distribution of the filler

D. Particle size and distribution of the filler Composites can be classified as microhybrid, microfilled, and nanofilled, based on the particle size and distribution of the filler. While the microhybrid and nanofilled composites are composed of high concentrations of fillers, it is the particle size and the distribution of the filler that determine how they are classified.