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

Complete Test Bank With Answers

Sample Questions Posted Below

Chapter 05: Principles of Bonding

MULTIPLE CHOICE

1.The most commonly used etchant or conditioner for tooth bonding is _____ in concentrations ranging from 10% to 38%.

ANS: B

The most commonly used etchant or conditioner for tooth bonding is phosphoric acid in concentrations ranging from 10% to 38%. Acid removes mineral from the surface to create roughness or microscopic porosity.

REF: p. 45 TOP: Basic Principles of Bonding (Preparation for Bonding)

2.When a resin bonding agent hardens, it creates projections that lock into the tooth, creating a _____ bond. The resin bonding agent will then form a _____ bond to other resins placed over it, such as composite resin.

ANS: C

When a resin bonding agent hardens, it creates projections that lock into the tooth, creating a mechanical bond. The resin bonding agent will then form a chemical bond to other resins placed over it, such as composite resin. The chemical bond, called a primary bond, is a true adhesion between atoms or molecules of the composite resin and the bonding resin.

REF: p. 45 TOP: Basic Principles of Bonding (Bonding to the Etched Surface)

3.When acid etching for bonding, it is desirable to have a _____ surface energy and a _____ angle of contact.

ANS: B

When acid etching for bonding, it is desirable to have a high surface energy and a low angle of contact. The high surface energy helps attract the resin to the etched surface. Surfaces that are poorly wet will cause beading of the liquid, similar to water on a newly waxed car. On an unwaxed car, the water easily spreads out and has a low angle of contact. Bonding agents are usually not very viscous (thick), so they will flow readily and wet the etched surface.

REF: p. 46 TOP: Basic Principles of Bonding (Surface Wetting)

4.Which of the following statements is true concerning bond strength?

ANS: D

Wetter dentin with more holes is more difficult to bond to consistently than shallower dentin. Bonding to enamel usually achieves consistently high bond strengths of around 30 MPa (megapascals). The bond strength to dentin is usually less than to enamel and varies according to how deeply into dentin the cavity preparation extends. The dentin near the dentinoenamel junction (DEJ) has fewer dentinal tubules, occupying 14% of the dentin surface, and they are smaller in diameter than in dentin closer to the pulp. Deeper dentin contains more tubules, and they are larger in diameter, occupying 20% to 30% of the dentin surface.

REF: p. 46 TOP: Basic Principles of Bonding (Bond Strength)

5.The etched surface of a permanent tooth should have a/an _____ appearance when dried.

ANS: B

The etched surface of a permanent tooth should have a frosty appearance when dried. When a cavity preparation involves the etching of both enamel and dentin, and the preparation is left slightly moist for wet dentin bonding, it cannot be determined whether the enamel has a frosty appearance.

REF: p. 47 TOP: Basic Principles of Bonding (Etching Times)

6.Why should primary teeth be etched for longer periods of time than adult teeth?

1.   The surface of the enamel has a prism pattern that is not well structured.

2.   The enamel is considered aprismatic.

3.   The enamel is less resistant to deep resin tag formation.

4.   There is a greater likelihood of salivary contamination during etching.

ANS: C

Primary teeth should be etched for longer periods of time than adult teeth because the surface of the enamel has a prism pattern that is not well structured, and the enamel is considered aprismatic. The enamel of primary teeth is more resistant to deep resin tag formation than that of adult teeth. If saliva contamination occurs during etching, drying the surface will leave residues that will interfere with the bond. The surface must be re-etched.

REF: pp. 46-47 TOP: Basic Principles of Bonding (Etching Times)

7.Which of the following is true of the smear layer?

ANS: D

The smear layer interferes with the formation of a bond to dentin and needs to be removed. It forms on the surface of the cut dentin and enamel. It is composed mostly of cut tooth structure and may also contain plaque, bacteria, pellicle, saliva, and even blood. The smear layer sticks tenaciously to the surface, plugs the openings of dentinal tubules, and cannot be washed off with the use of an air-water spray.

REF:p. 47TOP:Basic Principles of Bonding (Smear Layer)

8.For how many seconds should dentin be etched?

ANS: A

Dentin should be etched for 10 seconds. When etching both enamel and dentin as in a coronal cavity preparation, it is best to apply the acid first to the enamel for 10 seconds and then to the dentin for 10 seconds. That way, enamel will be etched for a total of 20 seconds and dentin for only 10 seconds. Etching dentin for 20 seconds or longer opens the tubules too wide and removes hydroxyapatite mineral to too great a depth.

REF: p. 48 TOP: Basic Principles of Bonding (Phosphoric Acid Etching)

9.Excess water left from the etching procedure is removed by gentle drying with air:

ANS: B

Excess water left from the etching procedure is removed by gentle drying with air, but the dentin is left moist so that it glistens. It is critical to not overdry the dentin at this stage.

REF: p. 48 TOP: Basic Principles of Bonding (Phosphoric Acid Etching)

10.What is done to the dentinal surface following etching?

ANS: C

Following etching, the dentin surface must be moist to keep the collagen fibrils fluffed up. If the dentin is dried, the collagen fibrils collapse and form a dense surface that occludes the tubules and blocks adequate penetration by the dentin bonding resins. Incomplete sealing of the dentinal tubules occurs and a much weaker bond results, because the dentin/resin interface will fracture more easily.

REF: p. 48 TOP: Basic Principles of Bonding (Phosphoric Acid Etching)

11.The oxygen-inhibited layer is a very thin coating of uncured resin. Where is it found?

ANS: C

The oxygen-inhibited layer is a very thin coating of uncured resin on the surface of the polymerized bonding resin. The resins used for composites and sealants will also form this layer of uncured resin on their surfaces. Polymerization is inhibited when the surface is exposed to oxygen in the air. Once the composite resin is placed over the bonding resin, its presence will exclude air, and that uncured layer on the bonding resin will cure when the composite is cured.

REF:p. 53TOP:Bonding Systems (Oxygen-Inhibited Layer)

12.Which of the following is correct regarding the dual-cure process for resin bonding agents?

ANS: D

A dual-cure process for resin bonding agents can be activated by light or can cure chemically without application of the curing light. It utilizes a combination of self-cure and light-cure ingredients.

REF: p. 53 TOP: Bonding Systems (Modes of Cure)

13.Silanes are used with which of the following dental materials?

ANS: B

Silanes are coupling agents that react with the porcelain and leave a coating of vinyl that will bond to the resin in the bonding agent. Next, the resin bonding agent is placed and light-cured, and the final composite restorative material is placed and finished.

REF: p. 55 TOP: Clinical Applications of Bonding (Ceramic Bonding and Repair)

14.Which etch or tooth conditioner is used when seating or repairing ceramic restorations?

ANS: D

To bond to ceramics, the acid most commonly used is hydrofluoric acid. It is dispensed in syringe form and may be used for intraoral or extraoral procedures.

REF: p. 55 TOP: Clinical Applications of Bonding (Ceramic Bonding and Repair)

15.Which of the following statements is true for bonding orthodontic brackets?

ANS: B

Because brackets cannot be used with conventional cements, they must be bonded to the enamel using adhesive materials. Orthodontic brackets have replaced bands for many uses, especially in the anterior part of the mouth. Self-cured, light-cured, or dual-cured adhesive bonding resins can be used for bonding orthodontic brackets. Because the metal or ceramic material will not allow light to reach and cure the resin cement directly under the bracket, the light is cast from mesial, distal, and lingual, as well as facial, directions to cure the resin with light that has passed through the enamel. With the indirect method for application of brackets, brackets are aligned on the diagnostic cast in the same position as they will be placed on the teeth and held with sticky wax. Then a matrix is formed over the brackets and the teeth on the cast. The brackets are picked up in the matrix and at the time of bonding are oriented in the same manner on the teeth as they were previously on the cast.

REF: p. 56 TOP: Clinical Applications of Bonding (Orthodontic Bracket Bonding)

16.When are posts placed within the roots of endodontically treated teeth to retain dental materials used to build up the teeth?

ANS: D

Posts are placed within the roots of endodontically treated teeth to retain dental materials used to build up the teeth when coronal tooth structure is inadequate for restoration with a crown.

REF: p. 57 TOP: Clinical Applications of Bonding (Bonding of Endodontic Posts)

17.The clinical technique of post cementation involves thoroughly rinsing off the phosphoric acid used to etch the canal and removing excess water with a:

ANS: A

The clinical technique of post cementation involves thoroughly rinsing off the phosphoric acid used to etch the canal and removing excess water with a paper point.

REF: p. 57 TOP: Clinical Applications of Bonding (Bonding of Endodontic Posts)

18.Which of the following correctly represents the sequence for tooth preparation before cementation of a post in an endodontically treated tooth?

1.   Self-curing or dual-curing composite resin cement is applied to both the canal and the post.

2.   A dentin primer is placed in the canal and air-dried to drive off any remaining water and the volatile solvents in the primer.

3.   The prepared canal is etched with phosphoric acid, and then the acid is rinsed off.

4.   Excess water is removed with a paper point.

ANS: C

The prepared canal is etched with phosphoric acid and then the acid is rinsed off, excess water is removed with a paper point, a dentin primer is placed in the canal and air-dried to drive off any remaining water and the volatile solvents in the primer, and self-curing or dual-curing composite resin cement is applied to both the canal and the post.

REF: p. 57 TOP: Clinical Applications of Bonding (Bonding of Endodontic Posts)

19.What is the purpose of a dental bonding?

ANS: C

In dentistry, the term bond, or bonding, is used to describe the process of attaching restorative materials, such as a bonded amalgam or a bonded composite resin, to the tooth by adhesion (attraction of atoms or molecules of two different contacting surfaces).

REF: p. 45 TOP: Basic Principles of Bonding

20.Which of the following materials would not be used when placing a direct resin restoration?

ANS: C

Preparing the tooth surface usually includes removing plaque and debris and then etching. When a resin bonding agent or primer is flowed over the etched surface, it penetrates into the microscopic pores.

REF: p. 45 TOP: Basic Principles of Bonding (Preparation for Bonding)

21.What is the wavelength of the curing light?

ANS: A

The second is a light-cure process that uses a light in the blue wave range to activate a chemical (photo-initiator) that sets off the polymerization reaction or curing process.

REF: p. 53 TOP: Bonding Systems (Modes of Cure)

22.Etch gel is typically a/an _____ solution of phosphoric acid.

ANS: D

The enamel of permanent teeth is usually etched for 20 to 30 seconds with 37% phosphoric acid.

REF: p. 46 TOP: Basic Principles of Bonding (Etching Times)

23.Overdrying of the dentin after etching can cause:

ANS: D

The following conditions can contribute to sensitivity: The tooth has been overdried (desiccated) during the bonding process, trapping air in the dentinal tubules; when the patient bites down, the restoration compresses the dentin, putting pressure on the air in the tubules.

REF: p. 55 TOP: Bonding Systems (Postoperative Sensitivity)

24.Contaminants on the surface of the tooth can greatly affect the longevity of the restoration and may include:

ANS: C

Contaminants on the surface, such as saliva or blood, can dramatically lower the strength of the bond to the enamel.

REF: p. 48 TOP: Basic Principles of Bonding (Enamel Bonding Resins)

25.The primer portion of the dental bonding agent is _____ to water.

ANS: A

A primer is more important on dentin than enamel because the primer contains hydrophilic (water-loving) groups that penetrate wet, etched dentin.

REF: p. 49 TOP: Basic Principles of Bonding (Dentin Bonding Resins)

26.When a composite resin is polymerized, a small layer of uncured material will remain. What is this called?

ANS: D

On the surface of the polymerized bonding resin is a thin coating of uncured resin, which is called the oxygen-inhibited layer.

REF:p. 53TOP:Bonding Systems (Oxygen-Inhibited Layer)

27.When would microleakage occur?

ANS: D

Contaminants can contribute to microleakage when they are not properly removed before and during the bonding process.

REF: p. 54 TOP: Bonding Systems (Microleakage)

28.Hypersensitivity may occur when _____ are irritated by procedures or chemicals associated with composite resin restorations.

ANS: C

Some patients may experience transient tooth sensitivity after a bonded restoration is placed. This usually lasts for only a short time, a few hours to a few days. The pain response comes from odontoblasts that lie in the pulp at its junction with the dentin.

REF: p. 55 TOP: Bonding Systems (Postoperative Sensitivity)

MATCHING

Match the items with the correct description below.

1.Hydrophilic

2.Hydrophobic

3.Total-etch system

4.Self-etch system

5.Hybrid layer

1.ANS:AREF:p. 45TOP:Key Terms Defined within the Chapter

2.ANS:DREF:p. 45TOP:Key Terms Defined within the Chapter

3.ANS:EREF:p. 45TOP:Key Terms Defined within the Chapter

4.ANS:BREF:p. 45TOP:Key Terms Defined within the Chapter

5.ANS:CREF:p. 45TOP:Key Terms Defined within the Chapter

SHORT ANSWER

1.What are the three modes of curing for resin bonding agents?

ANS:

• Self-cure: A process by which a chemical reaction occurs when the two resins, a base with chemical activators and a catalyst, are mixed together.

• Light-cure: A process that uses a light in the blue wave range to activate a chemical (photo-initiator) that sets off the polymerization reaction or curing process.

• Dual-cure: A process that uses a combination of self-cure and light-cure ingredients.

REF: p. 53 TOP: Bonding Systems (Modes of Cure)