Dental Materials Clinical Applications for Dental Assistants and Dental Hygienists 3rd Edition By W. Stephan Eakle -Test Bank

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Dental Materials Clinical Applications for Dental Assistants and Dental Hygienists 3rd Edition By W. Stephan Eakle -Test Bank

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WITH ANSWERS
Dental Materials Clinical Applications for Dental Assistants and Dental Hygienists 3rd Edition By W. Stephan Eakle -Test Bank

Chapter 02: Oral Environment and Patient Considerations

 

MULTIPLE CHOICE

 

  1. Some dental materials may be therapeutic in small quantities or if in contact with tissues for a short period of time. Dental materials may be irritating or toxic with longer or larger doses.
a. Both statements are true.
b. Both statements are false.
c. The first statement is true, and the second statement is false.
d. The first statement is false, and the second statement is true.

 

 

ANS:  A

Some dental materials may be therapeutic in small quantities or if in contact with tissues for a short period of time but also may be irritating or toxic with longer or larger doses. Topical fluoride is of great benefit when used according to manufacturers directions but can be irritating to soft tissues and can even excessively etch enamel if used improperly.

 

REF:   p. 9                TOP:   Biocompatibility

 

  1. Normal masticatory forces on the occlusal surfaces of molar teeth can increase to as much as _____ pounds per square inch on a cusp tip.
a. 280
b. 1000
c. 10,000
d. 28,000

 

 

ANS:  D

Normal masticatory forces on the occlusal surfaces of molar teeth can increase to as much as 28,000 pounds per square inch on a cusp tip. Normal masticatory forces on the occlusal surfaces of molar teeth average 90 to 200 pounds. Masticatory forces decrease in incisor areas and can increase during bruxing or clenching.

 

REF:   p. 10              TOP:   Force and Stress

 

  1. _____ force is applied when two surfaces slide against each other in opposite directions.
a. Compressive
b. Shearing
c. Tensile
d. Axial

 

 

ANS:  B

Shearing force is applied when two surfaces slide against each other or in a twisting or rotating motion. An incisor used for cutting is an example of shearing forces.

 

REF:   p. 10              TOP:   Force and Stress

 

  1. Stress is the amount of force exerted from within an object, and _____ is the amount of change that the force has produced.
a. strain
b. tension
c. compression
d. chemical bonding

 

 

ANS:  C

Stress is the amount of force exerted from within an object, and strain is the amount of change that the force has produced. The normal process of chewing rarely involves only one type of stress; these combinations of stresses form complex stress combinations.

 

REF:   p. 11              TOP:   Force and Stress

 

  1. Which of the following materials has the highest ultimate compressive strength (lbs/in2)?
a. Acrylic
b. Porcelain
c. Amalgam
d. Composite resins

 

 

ANS:  C

Amalgam has the highest ultimate compressive strength (45,000 to 64,000 lbs/in2), followed by composite resins (30,000 to 60,000 lbs/in2), porcelain (21,000 lbs/in2), and acrylic (11,000 lbs/in2). Amalgam and composite resins more closely replicate enamel in compressive strength, but porcelain falls short. Porcelain is more likely to fracture under compressive stresses.

 

REF:   p. 11

TOP:   Table 2-1: Ultimate Compressive and Tensile Strengths of Tooth and Restorative Structures

 

  1. Which of the following statements is correct about fatigue failure?
a. It is not a factor for restorative dental materials.
b. It is not dependent on conditions in the oral cavity.
c. It occurs as the result of a large, single-force application.
d. It occurs as the result of microscopic flaws that grow over time.

 

 

ANS:  B

Fatigue failure occurs as the result of microscopic flaws that grow over time. Failures rarely occur in a single-force application; rather, they occur when stress is frequently repeated. A metal wire will eventually break when bent repeatedly. Restorative materials are subject to repeated fatigue testing for all forces. Conditions of the oral cavity such as humidity and temperature and pH fluctuations may also increase fatigue failure.

 

REF:   p. 11              TOP:   Force and Stress

 

  1. The normal resting pH of saliva ranges from 6.2 to _____, which is neutral.
a. 1
b. 6.6
c. 7
d. 14

 

 

ANS:  C

The normal resting pH of saliva ranges from 6.2 to 7, which is neutral. It can fluctuate higher or lower by several points during the course of a day. Many materials that would be compatible in a neutral environment will not be compatible in an acidic one.

 

REF:   p. 11              TOP:   Moisture and Acid Levels

 

  1. The staining of resins and acrylics from repeated exposure to coffee, tea, and other dyed beverages is due to:
a. compressive forces.
b. water sorption.
c. galvanism.
d. tarnish.

 

 

ANS:  B

The staining of resins and acrylics from repeated exposure to coffee, tea, and other dyed beverages is due to water sorption. Water sorption is the ability to absorb moisture. Dentures, when placed in a glass of water, will take up the liquid and become slightly larger. Some acrylics will absorb both odors and tastes from foods.

 

REF:   p. 11              TOP:   Moisture and Acid Levels

 

  1. Which of the following dental restorative materials is particularly susceptible to corrosion?
a. Acrylic
b. Dental porcelain
c. Dental amalgam
d. Composite resin

 

 

ANS:  C

Dental amalgam is particularly susceptible to corrosion, causing marginal breakdown and discoloration of tooth structures. In newer, high-copper amalgams, this may not be as critical to their longevity.

 

REF:   pp. 11-12       TOP:   Moisture and Acid Levels

 

  1. Which of the following has been suggested to delay formation of surface tarnish on dental amalgams?
a. Incremental addition
b. Polishing
c. Use of noncopper-containing dental amalgam
d. Undercondensation

 

 

ANS:  B

Polishing of amalgams to produce a smooth surface has been recommended to help delay the process of surface tarnish. Surface tarnish, discoloration due to oxidation of the metals surface, can accelerate in crevices between a tooth and restoration and on rough surfaces.

 

REF:   p. 12              TOP:   Moisture and Acid Levels

 

  1. Which of the following is true of galvanism?
a. It is an electrical current transmitted between two similar metals.
b. It is observed in patients with composite resin but not silver amalgam restorations.
c. Galvanic stimulation will decrease with time as oxides form on the surface of the metal.
d. The salts of the saliva inhibit the movement of electrical current from one type of metal to another.

 

 

ANS:  C

Galvanic stimulation will decrease with time as oxides form on the surface of the metal. Galvanism is an electrical current transmitted between two dissimilar metals. An environment containing moisture, acidity, and dissimilar metals makes the generation of electrical current possible. The salts of the saliva facilitate the movement of electrical current from one type of metal to another. The current may result in stimulation to the pulp, called galvanic shock.

 

REF:   p. 12              TOP:   Galvanism

 

  1. What could excessive expansion of a restorative material result in?
a. Corrosion
b. Galvanism
c. Fracture of cusps
d. Leakage of fluid and bacteria into the gaps

 

 

ANS:  C

Excessive expansion of a restorative material may result in fracture of cusps. Excessive contraction may result in leakage of fluid and bacteria into the open gaps, resulting in sensitivity. Expansion and contraction are measured using the coefficient of thermal expansion, the measurement of change in volume or length in relationship to change in temperature.

 

REF:   p. 12              TOP:   Temperature

 

  1. What is percolation?
a. The rate at which heat flows through a material
b. A form of chemical rather than mechanical retention
c. Something that helps seal the interface between tooth and restorative material
d. Something that allows the ingress of bacteria and oral fluids and may lead to recurrent caries, staining, and pulpal irritation

 

 

ANS:  D

Percolation allows the ingress of bacteria and oral fluids and may lead to recurrent caries, staining, and pulpal irritation. Percolation is the repeated shrinkage and expansion of the restoration during ingestion of cold and hot fluids, producing the opening and closing of a gap between the restoration and the tooth surface.

 

REF:   p. 12              TOP:   Temperature

 

  1. Which of the following is the best thermal conductor?
a. Gold
b. Dentin
c. Enamel
d. Ceramic

 

 

ANS:  A

Gold is one of the best thermal conductors; nonmetals such as ceramics, resins, cements, enamel, and dentin are poor conductors. Poor conductors can be used as insulators; dentin is a natural insulator.

 

REF:   p. 12              TOP:   Temperature

 

  1. Which of the following restorative materials has a coefficient of thermal expansion and thermal conductivity closest to enamel?
a. Gold
b. Amalgam
c. Porcelain
d. Composite resin

 

 

ANS:  C

Porcelain has a coefficient of thermal expansion (106/C) of 15 and thermal conductivity (k) ([mcalcm]/cm sec/C) of 2.50; enamel has a coefficient of thermal expansion of 11 and thermal conductivity of 2.0. In contrast, the coefficient of thermal expansion of amalgam is 20 to 28, and the thermal conductivity of amalgam is 54, but the coefficient of thermal expansion of composite resin is 26 to 40, and the thermal conductivity of composite resin is 2.60.

 

REF:   p. 13              TOP:   Table 2-2: Thermal Properties of Tooth and Restorative Structures

 

  1. The technique of chemical bonding rather than mechanical means to produce retention requires _____ removal of tooth structure and produces a _____ retentive force between tooth and restoration.
a. more; stronger
b. more; weaker
c. less; stronger
d. less; weaker

 

 

ANS:  C

The technique of chemical bonding rather than mechanical means to produce retention requires less removal of tooth structure and produces a stronger retentive force between tooth and restoration. Additionally, it can seal the margin of the restoration to prevent seepage of bacteria and fluids through percolation.

 

REF:   p. 13              TOP:   Retention

 

  1. Which of the following statements is true for the property of wetting as related to dental materials?
a. The Teflon surface of cooking equipment has good wetting.
b. A thin film of dental cement is desirable to cement crowns.
c. Liquids generally spread better over low surface energy surfaces.
d. A surface has high surface energy when liquids bead up on the surface.

 

 

ANS:  B

A thin film of dental cement is desirable to cement crowns. This allows the cement to completely wet the surfaces and for excess material to flow from under the crown when it is seated under pressure during cementation. The Teflon surface of cooking equipment has poor wetting. The surface has low surface energy such as on wax or many plastics when liquids bead up on the surface. Liquids generally wet or spread over high surface energy surfaces better; metals, ceramics, and enamel have high surface energies.

 

REF:   p. 14              TOP:   Retention

 

  1. Microleakage into the interface between tooth structure and restorative material is responsible for much of the _____ observed following tooth restoration.
  2. recurrent decay
  3. marginal staining
  4. postoperative sensitivity
  5. tarnish
a. 1, 2, 3, 4
b. 1, 2, 3
c. 2, 3, 4
d. 1, 2

 

 

ANS:  B

Microleakage into the interface between tooth structure and restorative material is responsible for much of the recurrent decay, marginal staining, and postoperative sensitivity observed following tooth restoration.

 

REF:   p. 14              TOP:   Microleakage

 

  1. _____ refers to the intensity or strength of the color.
a. Hue
b. Value
c. Chroma
d. Opacity

 

 

ANS:  C

Chroma refers to the intensity or strength of the color. Hue is the dominant color of the wavelength detected. Value describes how light or dark the color is. If light is completely absorbed by the object, it is opaque.

 

REF:   p. 14              TOP:   Esthetics

 

  1. Which of the following is considered to be the most reliable means of clinical assessment of composite and glass ionomer restorations?
a. The patient history
b. Evaluation of radiographs
c. Use of the air-water syringe
d. Tactile evaluation of the tooth surface

 

 

ANS:  D

Tactile evaluation of the tooth surface is considered to be the most reliable means of clinical assessment of composite and glass ionomer restorations. Some composite and glass ionomer restorations may have a rougher surface than enamel. Tracing the enamel surface onto the restoration with the sharp tip of an explorer is the best way to distinguish this difference. The clinician will detect a smooth surface on the enamel and a scratchy surface on the restoration.

 

REF:   pp. 15-16       TOP:   Detection of Restorative Materials

 

  1. Which of the following would not be an adverse effect of a material?
a. Toxicity
b. Hyposensitivity
c. Hypersensitivity
d. Postoperative sensitivity

 

 

ANS:  B

Adverse responses may include postoperative sensitivity, toxicity, and hypersensitivity.

 

REF:   p. 9                TOP:   Biocompatibility

 

  1. Of the three types of forces, which is most concerned with the stretching of a material?
a. Tensile force
b. Compressive force
c. Shearing force

 

 

ANS:  A

Tensile force is applied in the opposite direction as it pulls or stretches an object.

 

REF:   p. 10              TOP:   Force and Stress

 

  1. When an object cannot resist force, _____ occurs.
a. deformation
b. distortion
c. deformation and distortion

 

 

ANS:  C

If the stress within an object cannot resist the force, distortion or deformation occurs.

 

REF:   p. 11              TOP:   Force and Stress

 

  1. Torque is a combination of which forces?
a. Compressive and tensile
b. Compressive and torsion
c. Shearing and tensile
d. Shearing and compressive

 

 

ANS:  A

Torque, a.k.a. torsion, is a combination of compressive and tensile forces.

 

REF:   p. 10              TOP:   Force and Stress

 

  1. Which material listed would show the lowest level of solubility?
a. Amalgam
b. Composite resin
c. Porcelain
d. Cement

 

 

ANS:  C

Porcelain and high noble metals have low solubility. Other restorative materials such as amalgam, composite resin, and cement have varying levels of solubility depending on the properties of each material.

 

REF:   p. 11              TOP:   Moisture and Acid Levels

 

  1. Most modern dental materials are made to be moisture resistant.
a. True
b. False

 

 

ANS:  B

Most materials react adversely to moisture either during placement or over time.

 

REF:   p. 11              TOP:   Moisture and Acid Levels

 

  1. Contact between two dissimilar metals in the mouth may result in what reaction?
a. Galvanic shock
b. Metallic taste
c. Electrical current
d. All of the above are possible.

 

 

ANS:  D

An environment containing moisture, acidity, and dissimilar metals makes the generation of electrical current possible. This is known as galvanism. The current may result in stimulation of the pulp, called galvanic shock. It may also create a metallic taste in the mouth.

 

REF:   p. 12              TOP:   Galvanism

 

  1. Why is the coefficient of thermal expansion significant in dental materials?
a. It measures the change in volume and length of a restoration.
b. It measures the amount of percolation of the restoration interface.
c. It measures the change in oral temperature related to foods ingested.
d. It measures the amount of stress and strain placed on the restoration.

 

 

ANS:  A

Expansion and contraction are measured using the coefficient of thermal expansion (CTE). This measures the change in volume or length in relationship to the change in temperature.

 

REF:   p. 12              TOP:   Temperature

 

  1. Which of the following is not a good conductor of temperature?
a. Gold crown
b. Amalgam restoration
c. Composite resin restoration

 

 

ANS:  C

Metals, such as gold and amalgam, are good conductors of temperature, but nonmetals are poor conductors of temperature.

 

REF:   p. 12              TOP:   Temperature

 

  1. Some materials give off heat when mixed. What is this called?
a. Chemical reaction
b. Exothermic reaction
c. Thermal conductivity
d. Coefficient of thermal expansion

 

 

ANS:  B

Some materials when mixed will produce heat. This exothermic reaction must be minimized to protect the tooth structures from excess heat, thus causing sensitivity or pulpal damage.

 

REF:   p. 13              TOP:   Temperature

 

  1. What causes microleakage?
a. A poorly placed restoration
b. A fracture within a restoration
c. Expansion and contraction of a restoration
d. All of the above could cause microleakage.

 

 

ANS:  D

The space between the walls of the preparation and the preparation is called the interface. If the interface is not sealed, fluids and microorganisms can penetrate between the tooth surface and the restorative material. This seepage of harmful materials, or microleakage, results in tooth sensitivity, recurrent decay, and marginal staining.

 

REF:   p. 14              TOP:   Microleakage

 

  1. Which term describes the thicker or thinner a material is?
a. Density
b. Viscosity
c. Flowability
d. Thixotropic

 

 

ANS:  D

Viscosity is a materials ability to flow. The thicker the material, the harder it is to flow.

 

REF:   p. 13              TOP:   Retention

 

  1. Adhesion is the method of _____ retention.
a. chemical
b. mechanical
c. dual

 

 

ANS:  A

Retention may be mechanical, chemical through adhesion, or a combination of the two.

 

REF:   p. 13              TOP:   Retention

 

  1. The color range of a tooth is usually seen by the human eye as yellow or brown. What is this component classified as?
a. Hue
b. Value
c. Chroma

 

 

ANS:  A

The three components of color result in hue, chroma, and value. Hue is the dominant color of the wavelength detected. Teeth are predominately seen in the yellow and brown ranges. Chroma is the intensity or strength of the color. Value describes how light or dark the color is.

 

REF:   p. 14              TOP:   Esthetics

 

  1. Which of the following is not a concern regarding identification of dental materials in the mouth?
a. Therapeutic agents could erode some materials.
b. Scaling could damage the surfaces of some materials.
c. Both are concerns when materials are identified.

 

 

ANS:  C

It is important that oral health care professionals are able to identify restorative materials within the oral environment, to treat them appropriately. Heavy pressure during scaling, the use of sonic and ultrasonic scaling or air polishing, and inappropriate use of polishing agents may gouge or scratch the surface of a restoration.

 

REF:   p. 15              TOP:   Detection of Restorative Materials

 

  1. What is the thermal conductivity of composite resin?
a. Similar to tooth structure
b. Lower than tooth structure
c. Similar to metal restorations
d. Does not conduct temperature

 

 

ANS:  A

Thermal conductivity is the rate at which heat flows through a material. Metals are particularly excellent conductors. Gold is one of the best thermal conductors, but non-metals such as ceramics, resins, cements, enamel, and dentin are poor conductors.

 

REF:   p. 12              TOP:   Temperature

 

MATCHING

 

Match the items with the correct description below.

a. Electrical current between two dissimilar metals
b. Discoloration due to oxidation of the metals surface
c. Deterioration of the metal due to moisture and acid present in the oral
d. The rate at which heat flows through a material
e. Opening and closing of a gap between the restoration and the tooth surface

 

 

  1. Corrosion

 

  1. Tarnish

 

  1. Galvanism environment

 

  1. Thermal conductivity

 

  1. Percolation

 

  1. ANS:  C                    REF:   p. 11              TOP:   Moisture and Acid Levels

 

  1. ANS:  B                    REF:   p. 12              TOP:   Moisture and Acid Levels

 

  1. ANS:  A                    REF:   p. 12              TOP:   Galvanism

 

  1. ANS:  D                    REF:   p. 12              TOP:   Temperature

 

  1. ANS:  E                    REF:   p. 12              TOP:   Temperature

 

SHORT ANSWER

 

  1. List and describe the three basic types of force.

 

ANS:

  • Compressive force. Force applied to compress an object. Posterior teeth are ideally suited for this type of force. The large occlusal surface and the multirooted base will resist a crushing force.
  • Tensile force. Force applied in opposite directions to stretch and object. When biting forces are used to stretch a material, the tooth is exerting tensile forces.
  • Shearing force. Force applied when two surfaces slide against each other or in a twisting or rotating motion. An incisor used for cutting is an example of shearing forces.

 

REF:   p. 10              TOP:   Force and Stress

 

  1. List and describe the three components of color.

 

ANS:

  • Hue: The dominant color of the wavelength reflected
  • Value: How light or dark the color is
  • Chroma: The intensity or strength of the color

 

REF:   p. 14              TOP:   Esthetics

 

Chapter 18: Provisional Restorations

 

MULTIPLE CHOICE

 

  1. How long would it take a prepared tooth without occlusal/incisal and proximal contact to migrate laterally or occlusally/incisally?
a. Days
b. Weeks
c. Months
d. Years

 

 

ANS:  A

A prepared tooth without occlusal/incisal and proximal contact may migrate laterally or occlusally/incisally within as soon as a few days. The restoration, which was designed to fit the tooth in its original position, may now be too high because of occlusal/incisal migration or may not seat properly as a result of lateral migration of the prepared tooth.

 

REF:   p. 326

TOP:   Criteria for Provisional Coverage (Maintain Prepared Tooth Position Relative to Adjacent and Opposing Teeth)

 

  1. If the provisional restoration itself is too high, the results may be those associated with:
a. trauma from occlusion.
b. occlusal drifting of the prepared tooth.
c. gingival irritation from food impaction.
d. lateral migration of the prepared tooth.

 

 

ANS:  A

If the provisional restoration itself is too high, the results may be those associated with trauma from occlusion. If it does not contact the adjacent teeth, gingival irritation from food impaction is likely. It is important that the precise occlusal/incisal and proximal contacts be provided for. The provisional restoration should share the forces of adjacent and opposing teeth.

 

REF:   p. 326

TOP:   Criteria for Provisional Coverage (Maintain Prepared Tooth Position Relative to Adjacent and Opposing Teeth)

 

  1. If the surfaces of a provisional restoration are _____, the process of chewing will excessively force food directly into the gingiva. An _____ restoration may trap plaque by not allowing for any self-cleansing or gingival stimulation from the chewing process.
a. overcontoured; overcontoured
b. overcontoured; undercontoured
c. undercontoured; overcontoured
d. undercontoured; undercontoured

 

 

ANS:  C

If the surfaces of a provisional restoration are undercontoured, the process of chewing will excessively force food directly into the gingiva. An overcontoured restoration may trap plaque by not allowing for any self-cleansing or gingival stimulation from the chewing process. Both scenarios may lead to irritation, inflammation, and recession.

 

REF:   p. 327            TOP:   Criteria for Provisional Coverage (Protect the Gingival Tissues)

 

  1. Which of the following provisional materials is limited to intracoronal placement?
a. Provisional cement
b. Provisional acrylic
c. Provisional composite
d. Provisional polycarbonate crown

 

 

ANS:  A

Provisional cement is limited to intracoronal placement. Provisional acrylic and composites can be used for extracoronal coverage as well. Provisional restorations, such as stainless steel or polycarbonate crowns, may be preformed or made specifically for individual procedures, such as custom acrylic or composite crowns and intracoronal restorations.

 

REF:   p. 328            TOP:   Provisional Crown Materials

 

  1. Which of the following is the most durable of the preformed crowns?
a. Polycarbonate crown
b. Stainless steel crown
c. Aluminum shell crown
d. Celluloid crown form lined with acrylic or composite materials

 

 

ANS:  B

The stainless steel crown is the most durable of the preformed crowns, providing provisional coverage lasting months and even years. The stainless steel crown has been used traditionally to restore primary teeth. These durable and economical restorations are now being considered for older adults, when financial and health concerns would otherwise result in the recommendation of extraction.

 

REF:   p. 329            TOP:   Provisional Crown Materials  (Stainless Steel Crowns)

 

  1. A/An _____ provisional crown is crimped and contoured at the contact and margins with crimping and contouring pliers.
a. polycarbonate
b. celluloid crown form lined with composite
c. aluminum shell
d. stainless steel

 

 

ANS:  D

A stainless steel provisional crown is crimped and contoured at the contact and margins with crimping and contouring pliers. If the stainless steel crown is replacing the use of a cast restoration for prolonged periods of time, minimal reduction of the tooth is ideal to preserve natural strength and protect the pulp.

 

REF:   p. 329            TOP:   Provisional Crown Materials  (Stainless Steel Crowns)

 

  1. Which of the following is true of preformed polycarbonate provisional crowns?
a. They are incompatible with acrylic resins.
b. Like metal, they are flexible and may be crimped with contouring pliers.
c. The primary advantage is their esthetics for replacement of anterior teeth.
d. Unlike their metal partners, they do not come in several sizes and shapes.

 

 

ANS:  C

The primary advantage of preformed polycarbonate provisional crowns is their esthetics for replacement of anterior teeth. Like their metal partners, they come in several sizes and shapes. Unlike metal, they are rigid and may need to be adapted with acrylic burs and disks or may be carefully cut with sharp crown scissors. Their compatibility with acrylic resins allows for further customization of the fit and margins.

 

REF:   p. 329

TOP:   Provisional Crown Materials  (Polycarbonate and Celluloid Crown Forms)

 

  1. What are preformed celluloid forms and polymer crowns filled with?
a. Acrylic or BIS-acrylic composite
b. Zinc oxide eugenol cement
c. Gutta percha
d. Resin cement

 

 

ANS:  A

Preformed celluloid forms and polymer crowns are filled with acrylic or BIS-acrylic composites. These are matched to the tooth shade and then inserted onto the prepared tooth, in much the same way a template is used in the direct fabrication technique.

 

REF:   p. 329

TOP:   Provisional Crown Materials  (Polycarbonate and Celluloid Crown Forms)

 

  1. Why are one or two small holes usually placed in the occlusal portion of the preformed celluloid or polymer crown form?
a. To establish occlusion with the opposing dentition
b. To create a proximal contact with the adjacent tooth
c. To capture the occlusal contour of the opposing dentition
d. To allow excess resin or composite material to flow out when the crown form is seated

 

 

ANS:  D

Holes are placed to allow excess resin or composite material to flow out when the crown form is seated. This prevents air trapping and creation of voids in the material.

 

REF:   p. 329

TOP:   Provisional Crown Materials  (Polycarbonate and Celluloid Crown Forms)

 

  1. Which of the following is the most common choice of matrix or template material for multi-unit and indirect provisional techniques?
a. Thermoplastic wax
b. Silicone impression materials
c. Alginate
d. Vacuum-formed plastic

 

 

ANS:  D

Vacuum-formed plastic is the most common choice of matrix or template material for multi-unit and indirect provisional techniques. Alginate and wax are the easiest and least expensive templates and are used extensively for single-unit, direct-technique provisionals.

 

REF:   p. 330            TOP:   Provisional Crown Materials  (Customized Provisional Crowns)

 

  1. Which of the following is true of the direct technique for provisional coverage?
a. An impression of the area is made and poured in stone; the template is then made on this model.
b. The provisional is fabricated on a model and then relined before it is placed on the preparation.
c. A template of the tooth before preparation is obtained using wax or an impression material directly in the mouth.
d. The direct technique allows for superior access and enhances the time and convenience of making multi-unit bridges or crowns in difficult-to-access areas.

 

 

ANS:  C

A template of the tooth before preparation is obtained using wax or an impression material directly in the mouth. After the tooth is prepared, the template is filled with a provisional material and reinserted into the mouth. This technique is faster than the indirect technique and provides a provisional restoration that duplicates the original tooth.

 

REF:   p. 331            TOP:   Provisional Crown Materials  (Direct Technique)

 

  1. Which of the following is the primary disadvantage of the use of acrylic provisional materials?
a. High cost
b. Poor esthetics
c. High shrinkage
d. Difficult manipulation

 

 

ANS:  C

The high shrinkage and heat released during polymerization and patient complaints regarding the acrylic odor and taste are distinct disadvantages. Acrylic materials in the form of methacrylates have been used for many years as custom temporaries. Their good esthetics, ease of manipulation, and low cost made them a popular choice over preformed crowns.

 

REF:   p. 330            TOP:   Provisional Crown Materials  (Acrylic Provisional Materials)

 

  1. Why must care be taken in the fabrication of provisionals by utilizing acrylic materials to pump the template on and off the preparation after initial polymerization?
a. Accelerate the set of the material
b. Seal off the exposed dentinal tubules on the tooth
c. Prevent them from locking on the tooth
d. Open proximal contacts

 

 

ANS:  C

Care must be taken in the fabrication of provisionals by utilizing acrylic materials to pump them on and off the preparation after initial polymerization to prevent them from locking on the tooth and to protect the tooth from heat generated during polymerization. If these materials are allowed to polymerize outside the preparation, the amount of shrinkage may be sufficient to inhibit their seat.

 

REF:   p. 330            TOP:   Provisional Crown Materials  (Acrylic Provisional Materials)

 

  1. _____ generated during the polymerization of chemical-cured acrylic can potentially damage the pulp or burn soft tissues.
a. Heat
b. Off-gassing
c. Chemical by-products
d. Hydroquinone

 

 

ANS:  A

Heat generated during the polymerization of chemical-cured acrylic can potentially damage the pulp or burn soft tissues.

 

REF:   p. 330            TOP:   Provisional Crown Materials  (CAUTION BOX)

 

  1. Which of the following are advantages of composite provisional materials in contrast to acrylic provisional materials?
  2. High shrinkage during curing
  3. High heat release during curing
  4. More wear
  5. Biocompatibility
a. 1, 2, 3, 4
b. 2, 3, 4
c. 3, 4
d. 4

 

 

ANS:  D

Low shrinkage and low heat release during curing, good strength, less wear, and biocompatibility are distinct advantages of composite provisional materials when contrasted with acrylic provisional materials. These advantages come with a noticeable increase in cost, and some of these materials are too brittle for long-span bridges, especially when used on bruxers.

 

REF:   p. 331

TOP:   Provisional Crown Materials  (Bis-Acrylic Composite Provisional Materials)

 

  1. Cement provisionals are most frequently fabricated with which material?
a. Zinc polycarboxylate
b. Zinc oxide eugenol
c. Calcium hydroxide
d. Zinc phosphate

 

 

ANS:  B

Cement provisionals are most frequently fabricated with zinc oxide eugenol. The additional palliative benefits of the cement may be helpful to sensitive or traumatized teeth.

 

REF:   p. 332            TOP:   Intracoronal Cement Provisionals

 

  1. Zinc oxide provisionals should not be used if a permanent restoration is to be cemented with a _____ luting agent.
a. resin
b. glass ionomer
c. zinc phosphate
d. zinc polycarboxylate

 

 

ANS:  A

Zinc oxide provisionals should not be used if a permanent restoration is to be cemented with a resin luting agent. Eugenol-containing cements inhibit polymerization of the resin cement.

 

REF:   p. 332            TOP:   Intracoronal Cement Provisionals  (CLINICAL TIP BOX)

 

  1. Which of the following is true concerning patient education for provisional coverage?
a. Provisional coverage provides the same results as permanent coverage.
b. The patient need not call the office if the provisional is dislodged or lost.
c. No increase in temperature sensitivity is associated with the provisional material.
d. Limitations in esthetics may include imperfections in color matching, anatomic contour, and smoothness.

 

 

ANS:  D

Limitations in esthetics may include imperfections in color matching, anatomic contour, and smoothness. Provisional coverage does not give the same results as permanent coverage. A possible increase in temperature sensitivity and taste is associated with the provisional material. The patient must be told to call the office immediately if the provisional is dislodged or lost.

 

REF:   p. 333            TOP:   Patient Education

 

  1. If a provisional crown comes off during a time that the dental office is closed, the patient can be instructed to replace it after cleaning the interior of the crown and placing a small amount of _____ into the crown.
a. cyanoacrylate (super glue)
b. liquid nails cement
c. denture adhesive
d. chewing gum

 

 

ANS:  C

If a provisional crown comes off during a time that the dental office is closed, the patient can be instructed to replace it after cleaning the interior of the crown and placing a small amount of denture adhesive into the crown. The patient should be told to never use any household cements.

 

REF:   p. 333            TOP:   Patient Education  (CLINICAL TIP BOX)

 

  1. What home care instructions would be given to a patient with a provisional restoration?
a. Do not brush or floss the restoration.
b. Brush but do not floss the restoration.
c. Brush and floss the restoration as you would any other tooth.
d. Brush and floss the restoration, sliding the floss through the cervical embrasure.

 

 

ANS:  D

Home care instructions for a patient with a provisional restoration include brushing and flossing the restoration but removing the floss by pulling it out to the side under the contact rather than back in an occlusal/incisal direction. Removing the floss back through the contact in an occlusal/incisal direction might dislodge the provisional coverage because it is usually cemented with a weak provisional cement.

 

REF:   p. 333            TOP:   Patient Education

 

  1. Which of the following would not be a necessary function of a posterior provisional restoration?
a. Esthetics
b. Reduced sensitivity
c. Maintaining occlusion
d. Eliminating migration

 

 

ANS:  A

Materials used in areas of esthetic concern must match tooth structures and have good color stability and stain resistance.

 

REF:   p. 333            TOP:   Summary

 

  1. Accurate margins of an extracoronal provisional restoration are important because they:
a. maintain accurate contour.
b. protect the tooth from microleakage.
c. keep food from packing into the embrasure.
d. maintain occlusion and prevent supereruption.

 

 

ANS:  B

Well-adapted provisional restorations protect the finish line from fracture and from the marginal leakage of oral fluids and bacteria.

 

REF:   p. 326

TOP:   Criteria for Provisional Coverage (Protect the Exposed Tooth Surfaces and Margins)

 

  1. Which factor, associated with a provisional restoration, is responsible for irritation, inflammation, and recession of the gingiva?
a. Chewing hard foods
b. Poor marginal coverage
c. Contour of the provisional
d. Brushing and flossing the provisional

 

 

ANS:  C

If surfaces are undercontoured or contacts weak or nonexistent, the process of chewing will excessively force food directly onto the gingiva rather than deflecting it facially and lingually. An overcontoured restoration may trap plaque by not allowing for any self-cleansing or gingival stimulation from the chewing process. Both scenarios may lead to irritation, inflammation, and recession.

 

REF:   p. 327            TOP:   Criteria for Provisional Coverage (Protect the Gingival Tissues)

 

  1. Provisional restorations are recommended only for 2 to 3:
a. days
b. weeks
c. months
d. There is no time limit.

 

 

ANS:  B

The patient wears this provisional coverage to protect the tooth for a short period of time, generally 2 weeks to a month. Most provisional restorations are in place for up to 2 to 3 weeks.

 

REF:   p. 328            TOP:   Properties of Provisional Materials

 

  1. Which of the following would not make a good extracoronal provisional restoration?
a. Polycarbonate crown
b. Aluminum shell
c. Stainless steel crown
d. Zinc oxide eugenol cement

 

 

ANS:  D

Cement provisionals are most frequently fabricated with zinc oxide eugenol cement; the additional palliative benefits of the cement may be helpful to sensitive or traumatized teeth.

 

REF:   p. 326

TOP:   Criteria for Provisional Coverage (Maintain Prepared Tooth Position Relative to Adjacent and Opposing Teeth)

 

  1. Which of the following would not occur if the provisional crown does not contact the adjacent teeth?
a. Tooth may migrate laterally
b. Tooth will supererupt
c. Gingival irritation
d. Food impaction

 

 

ANS:  B

A prepared tooth without proximal contact may migrate laterally or within a few days. If the provisional restoration itself is too high, the results may be th

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