EFDA Chapter 44 Dental Liners, Bases,
and Bonding Systems Exam Questions
and Answers
Section 1: Pulpal Protection & Dental Liners
(Questions 1–25)
Question 1
Which dental material is placed in a thin layer at the deepest point of a cavity preparation to
stimulate the formation of secondary or reparative dentin?
A. Polycarboxylate base
B. Calcium hydroxide
C. Zinc phosphate cement
D. Cavity varnish
Correct Answer: B
Rationale: Calcium hydroxide stimulates pulpal cells to form reparative dentin, protecting the
nerve in deep preparations near pulpal exposure. Polycarboxylate and zinc phosphate are used
as thicker insulating bases rather than thin therapeutic liners directly over near-exposures.
Question 2
Why is zinc oxide-eugenol (ZOE) contraindicated for use as a liner or base directly under
composite resin restorations?
A. The eugenol interferes with and inhibits the polymerization reaction of composite resin.
B. Eugenol expands and cracks the composite restoration after setting.
C. ZOE causes severe discoloration along the enamel margins.
D. ZOE releases high levels of acid that etch the pulpal floor.
Correct Answer: A
Rationale: Eugenol oil disrupts composite polymerization, leaving the resin soft and uncured at
the cavity floor. Glass ionomer or calcium hydroxide should be selected when restoring with
composite materials.
Question 3
What is the primary purpose of applying a dental base under a deep amalgam restoration?
A. To etch the enamel rods for micro-mechanical retention
B. To provide thermal insulation for the dental pulp against temperature changes
C. To polish the internal line angles of the cavity preparation
D. To seal the cavosurface margins against microleakage
Correct Answer: B
Rationale: Amalgam conducts heat quickly, so a thick dental base acts as a thermal barrier to
protect the pulp from hot and cold shock. Etching and marginal sealing are handled by etchants
and adhesives rather than structural bases.
, Question 4
Which component of the tooth structure must be removed or modified by acid etchant to allow
effective bonding agent penetration into dentin?
A. Enamel rod sheath
B. Pulp cap matrix
C. Smear layer
D. Hydroxyapatite core
Correct Answer: C
Rationale: The smear layer consists of microscopic debris created during drilling that plugs
dentinal tubules. Phosphoric acid removes or alters this layer so bonding resin can penetrate
and form a hybrid layer with dentin collagen.
Question 5
When applying 37% phosphoric acid etchant to a cavity preparation, what is the standard
recommended etching time for permanent enamel?
A. 5 to 10 seconds
B. 15 to 20 seconds
C. 45 to 60 seconds
D. 90 to 120 seconds
Correct Answer: B
Rationale: Fifteen to twenty seconds properly etches enamel rods without over-etching dentin.
Over-etching dentin degrades collagen fibers and weakens final bond strength.
Question 6
What visual appearance indicates that enamel has been properly acid-etched and dried?
A. Shiny and glossy surface
B. Translucent grey tint
C. Frosty, chalky white surface
D. Dark yellow glaze
Correct Answer: C
Rationale: Etched enamel turns a dull, frosty white once completely dried with oil-free air. A
shiny surface indicates under-etching or moisture/saliva contamination.
Question 7
Which cavity liner material releases fluoride continuously to help prevent recurrent decay
around restoration margins?
A. Calcium hydroxide
B. Glass ionomer
C. Copal varnish
D. Zinc phosphate
Correct Answer: B
Rationale: Glass ionomer liners chemically adhere to tooth structure and continually release
fluoride to inhibit secondary caries. Calcium hydroxide and varnish do not offer sustained
fluoride release.
Question 8
and Bonding Systems Exam Questions
and Answers
Section 1: Pulpal Protection & Dental Liners
(Questions 1–25)
Question 1
Which dental material is placed in a thin layer at the deepest point of a cavity preparation to
stimulate the formation of secondary or reparative dentin?
A. Polycarboxylate base
B. Calcium hydroxide
C. Zinc phosphate cement
D. Cavity varnish
Correct Answer: B
Rationale: Calcium hydroxide stimulates pulpal cells to form reparative dentin, protecting the
nerve in deep preparations near pulpal exposure. Polycarboxylate and zinc phosphate are used
as thicker insulating bases rather than thin therapeutic liners directly over near-exposures.
Question 2
Why is zinc oxide-eugenol (ZOE) contraindicated for use as a liner or base directly under
composite resin restorations?
A. The eugenol interferes with and inhibits the polymerization reaction of composite resin.
B. Eugenol expands and cracks the composite restoration after setting.
C. ZOE causes severe discoloration along the enamel margins.
D. ZOE releases high levels of acid that etch the pulpal floor.
Correct Answer: A
Rationale: Eugenol oil disrupts composite polymerization, leaving the resin soft and uncured at
the cavity floor. Glass ionomer or calcium hydroxide should be selected when restoring with
composite materials.
Question 3
What is the primary purpose of applying a dental base under a deep amalgam restoration?
A. To etch the enamel rods for micro-mechanical retention
B. To provide thermal insulation for the dental pulp against temperature changes
C. To polish the internal line angles of the cavity preparation
D. To seal the cavosurface margins against microleakage
Correct Answer: B
Rationale: Amalgam conducts heat quickly, so a thick dental base acts as a thermal barrier to
protect the pulp from hot and cold shock. Etching and marginal sealing are handled by etchants
and adhesives rather than structural bases.
, Question 4
Which component of the tooth structure must be removed or modified by acid etchant to allow
effective bonding agent penetration into dentin?
A. Enamel rod sheath
B. Pulp cap matrix
C. Smear layer
D. Hydroxyapatite core
Correct Answer: C
Rationale: The smear layer consists of microscopic debris created during drilling that plugs
dentinal tubules. Phosphoric acid removes or alters this layer so bonding resin can penetrate
and form a hybrid layer with dentin collagen.
Question 5
When applying 37% phosphoric acid etchant to a cavity preparation, what is the standard
recommended etching time for permanent enamel?
A. 5 to 10 seconds
B. 15 to 20 seconds
C. 45 to 60 seconds
D. 90 to 120 seconds
Correct Answer: B
Rationale: Fifteen to twenty seconds properly etches enamel rods without over-etching dentin.
Over-etching dentin degrades collagen fibers and weakens final bond strength.
Question 6
What visual appearance indicates that enamel has been properly acid-etched and dried?
A. Shiny and glossy surface
B. Translucent grey tint
C. Frosty, chalky white surface
D. Dark yellow glaze
Correct Answer: C
Rationale: Etched enamel turns a dull, frosty white once completely dried with oil-free air. A
shiny surface indicates under-etching or moisture/saliva contamination.
Question 7
Which cavity liner material releases fluoride continuously to help prevent recurrent decay
around restoration margins?
A. Calcium hydroxide
B. Glass ionomer
C. Copal varnish
D. Zinc phosphate
Correct Answer: B
Rationale: Glass ionomer liners chemically adhere to tooth structure and continually release
fluoride to inhibit secondary caries. Calcium hydroxide and varnish do not offer sustained
fluoride release.
Question 8
