DHYG220 Periodontology Exam Prep – Real Practice
Questions, Answers & Detailed Rationales (Updated
2026) | Periodontal Disease & Gingivitis, Oral
Anatomy & Tissue Structures, Plaque & Calculus
Formation, Periodontal Assessment & Charting,
Scaling & Root Planing, Infection Control, Dental
Radiography, Patient Education & Preventive
Periodontal Care
Question 1: Which of the following tissues is NOT part of the periodontium?
A. Gingiva
B. Periodontal ligament
C. Alveolar bone
D. Dental pulp
CORRECT ANSWER: D. Dental pulp
Rationale: The periodontium consists of the supporting structures of the tooth, which
include the gingiva, periodontal ligament, cementum, and alveolar bone. Dental pulp is
located within the pulp chamber of the tooth and is not a component of the periodontium.
Question 2: The periodontal ligament primarily functions to:
A. Produce enamel
B. Anchor the tooth to the alveolar bone and absorb occlusal forces
C. Secrete saliva
D. Form the dental pellicle
CORRECT ANSWER: B. Anchor the tooth to the alveolar bone and absorb occlusal
forces
Rationale: The periodontal ligament (PDL) is a specialized connective tissue that
connects the cementum of the tooth root to the alveolar bone. Its primary functions
include supporting the tooth, transmitting occlusal forces to the bone, and acting as a
shock absorber during mastication.
Question 3: Cementum covers which portion of the tooth?
A. Anatomical crown
B. Clinical crown
,C. Tooth root
D. Enamel surface
CORRECT ANSWER: C. Tooth root
Rationale: Cementum is a calcified tissue that covers the anatomical root surface of the
tooth. It provides attachment for the principal fibers of the periodontal ligament and
continues to form throughout life.
Question 4: In the Löe and Silness Gingival Index, a score of 1 indicates:
A. No inflammation
B. Mild inflammation with slight color change and no bleeding on probing
C. Moderate inflammation with redness, edema, and bleeding on probing
D. Severe inflammation with spontaneous bleeding
CORRECT ANSWER: B. Mild inflammation with slight color change and no bleeding on
probing
Rationale: The Löe and Silness Gingival Index uses a 0–3 scale. A score of 1 signifies mild
gingivitis characterized by slight changes in color and texture of the gingiva without
bleeding upon gentle probing.
Question 5: Bleeding on probing is considered a reliable clinical sign of:
A. Healthy gingiva
B. Established gingivitis or active periodontal disease
C. Calculus presence only
D. Enamel hypoplasia
CORRECT ANSWER: B. Established gingivitis or active periodontal disease
Rationale: Bleeding on probing (BOP) indicates ulceration of the sulcular epithelium and
active inflammation. It is a key diagnostic indicator of gingivitis and active periodontitis,
reflecting increased vascular permeability and inflammatory cell infiltration.
Question 6: Clinical attachment level (CAL) is calculated by adding:
A. Probing depth and gingival recession
B. Probing depth and distance from gingival margin to CEJ
,C. Gingival recession and pocket depth
D. CEJ to mucogingival junction distance and probing depth
CORRECT ANSWER: B. Probing depth and distance from gingival margin to CEJ
Rationale: CAL represents the total loss of attachment from the cementoenamel junction
(CEJ). It is calculated by measuring the probing depth plus the distance from the gingival
margin to the CEJ (which may be positive if the margin is apical to the CEJ or negative if
coronal).
Question 7: A probing depth of 5 mm with the gingival margin 2 mm coronal to the
CEJ indicates a CAL of:
A. 3 mm
B. 5 mm
C. 7 mm
D. 2 mm
CORRECT ANSWER: A. 3 mm
Rationale: When the gingival margin is coronal to the CEJ, the distance is recorded as a
negative value. Thus, CAL = probing depth + (–2 mm) = 5 mm – 2 mm = 3 mm, indicating
3 mm of attachment loss.
Question 8: Dental plaque is best described as:
A. A loose collection of food debris
B. A calcified deposit on enamel
C. A structured microbial biofilm embedded in a matrix of polymers
D. A viral infection of the gingival tissue
CORRECT ANSWER: C. A structured microbial biofilm embedded in a matrix of
polymers
Rationale: Dental plaque is a complex, organized microbial community (biofilm) adherent
to tooth surfaces. It is embedded in an extracellular polymeric substance composed of
polysaccharides, proteins, and nucleic acids derived from both bacteria and host fluids.
Question 9: The non-specific plaque hypothesis suggests that:
, A. Only Porphyromonas gingivalis causes periodontitis
B. Disease results from the total accumulation of plaque regardless of specific species
C. Plaque cannot cause disease without systemic factors
D. Biofilm formation is irrelevant to gingivitis
CORRECT ANSWER: B. Disease results from the total accumulation of plaque
regardless of specific species
Rationale: The non-specific plaque hypothesis posits that the overall quantity of plaque,
rather than the presence of specific pathogens, determines the severity of periodontal
disease. This contrasts with the specific plaque hypothesis, which implicates particular
bacterial species.
Question 10: Supragingival calculus is primarily mineralized from ions derived
from:
A. Gingival crevicular fluid
B. Saliva
C. Dietary sources only
D. Blood plasma
CORRECT ANSWER: B. Saliva
Rationale: Supragingival calculus forms above the gingival margin and is mineralized
primarily by calcium and phosphate ions present in saliva. Subgingival calculus, in
contrast, derives minerals mainly from gingival crevicular fluid.
Question 11: Subgingival calculus is typically darker in color than supragingival
calculus due to:
A. Higher concentration of hemoglobin derivatives from gingival crevicular fluid
B. Greater exposure to light
C. Different bacterial species
D. Use of tobacco products
CORRECT ANSWER: A. Higher concentration of hemoglobin derivatives from
gingival crevicular fluid
Questions, Answers & Detailed Rationales (Updated
2026) | Periodontal Disease & Gingivitis, Oral
Anatomy & Tissue Structures, Plaque & Calculus
Formation, Periodontal Assessment & Charting,
Scaling & Root Planing, Infection Control, Dental
Radiography, Patient Education & Preventive
Periodontal Care
Question 1: Which of the following tissues is NOT part of the periodontium?
A. Gingiva
B. Periodontal ligament
C. Alveolar bone
D. Dental pulp
CORRECT ANSWER: D. Dental pulp
Rationale: The periodontium consists of the supporting structures of the tooth, which
include the gingiva, periodontal ligament, cementum, and alveolar bone. Dental pulp is
located within the pulp chamber of the tooth and is not a component of the periodontium.
Question 2: The periodontal ligament primarily functions to:
A. Produce enamel
B. Anchor the tooth to the alveolar bone and absorb occlusal forces
C. Secrete saliva
D. Form the dental pellicle
CORRECT ANSWER: B. Anchor the tooth to the alveolar bone and absorb occlusal
forces
Rationale: The periodontal ligament (PDL) is a specialized connective tissue that
connects the cementum of the tooth root to the alveolar bone. Its primary functions
include supporting the tooth, transmitting occlusal forces to the bone, and acting as a
shock absorber during mastication.
Question 3: Cementum covers which portion of the tooth?
A. Anatomical crown
B. Clinical crown
,C. Tooth root
D. Enamel surface
CORRECT ANSWER: C. Tooth root
Rationale: Cementum is a calcified tissue that covers the anatomical root surface of the
tooth. It provides attachment for the principal fibers of the periodontal ligament and
continues to form throughout life.
Question 4: In the Löe and Silness Gingival Index, a score of 1 indicates:
A. No inflammation
B. Mild inflammation with slight color change and no bleeding on probing
C. Moderate inflammation with redness, edema, and bleeding on probing
D. Severe inflammation with spontaneous bleeding
CORRECT ANSWER: B. Mild inflammation with slight color change and no bleeding on
probing
Rationale: The Löe and Silness Gingival Index uses a 0–3 scale. A score of 1 signifies mild
gingivitis characterized by slight changes in color and texture of the gingiva without
bleeding upon gentle probing.
Question 5: Bleeding on probing is considered a reliable clinical sign of:
A. Healthy gingiva
B. Established gingivitis or active periodontal disease
C. Calculus presence only
D. Enamel hypoplasia
CORRECT ANSWER: B. Established gingivitis or active periodontal disease
Rationale: Bleeding on probing (BOP) indicates ulceration of the sulcular epithelium and
active inflammation. It is a key diagnostic indicator of gingivitis and active periodontitis,
reflecting increased vascular permeability and inflammatory cell infiltration.
Question 6: Clinical attachment level (CAL) is calculated by adding:
A. Probing depth and gingival recession
B. Probing depth and distance from gingival margin to CEJ
,C. Gingival recession and pocket depth
D. CEJ to mucogingival junction distance and probing depth
CORRECT ANSWER: B. Probing depth and distance from gingival margin to CEJ
Rationale: CAL represents the total loss of attachment from the cementoenamel junction
(CEJ). It is calculated by measuring the probing depth plus the distance from the gingival
margin to the CEJ (which may be positive if the margin is apical to the CEJ or negative if
coronal).
Question 7: A probing depth of 5 mm with the gingival margin 2 mm coronal to the
CEJ indicates a CAL of:
A. 3 mm
B. 5 mm
C. 7 mm
D. 2 mm
CORRECT ANSWER: A. 3 mm
Rationale: When the gingival margin is coronal to the CEJ, the distance is recorded as a
negative value. Thus, CAL = probing depth + (–2 mm) = 5 mm – 2 mm = 3 mm, indicating
3 mm of attachment loss.
Question 8: Dental plaque is best described as:
A. A loose collection of food debris
B. A calcified deposit on enamel
C. A structured microbial biofilm embedded in a matrix of polymers
D. A viral infection of the gingival tissue
CORRECT ANSWER: C. A structured microbial biofilm embedded in a matrix of
polymers
Rationale: Dental plaque is a complex, organized microbial community (biofilm) adherent
to tooth surfaces. It is embedded in an extracellular polymeric substance composed of
polysaccharides, proteins, and nucleic acids derived from both bacteria and host fluids.
Question 9: The non-specific plaque hypothesis suggests that:
, A. Only Porphyromonas gingivalis causes periodontitis
B. Disease results from the total accumulation of plaque regardless of specific species
C. Plaque cannot cause disease without systemic factors
D. Biofilm formation is irrelevant to gingivitis
CORRECT ANSWER: B. Disease results from the total accumulation of plaque
regardless of specific species
Rationale: The non-specific plaque hypothesis posits that the overall quantity of plaque,
rather than the presence of specific pathogens, determines the severity of periodontal
disease. This contrasts with the specific plaque hypothesis, which implicates particular
bacterial species.
Question 10: Supragingival calculus is primarily mineralized from ions derived
from:
A. Gingival crevicular fluid
B. Saliva
C. Dietary sources only
D. Blood plasma
CORRECT ANSWER: B. Saliva
Rationale: Supragingival calculus forms above the gingival margin and is mineralized
primarily by calcium and phosphate ions present in saliva. Subgingival calculus, in
contrast, derives minerals mainly from gingival crevicular fluid.
Question 11: Subgingival calculus is typically darker in color than supragingival
calculus due to:
A. Higher concentration of hemoglobin derivatives from gingival crevicular fluid
B. Greater exposure to light
C. Different bacterial species
D. Use of tobacco products
CORRECT ANSWER: A. Higher concentration of hemoglobin derivatives from
gingival crevicular fluid
