DDS Periodontics 1 — Questions and Answers
Question 1: Which fibers of the periodontal ligament embed directly into the cementum and alveolar bone?
- Elastic fibers
- Sharpey's fibers (Correct answer)
- Oxytalan fibers
- Reticular fibers
Correct answer: Sharpey's fibers
Sharpey's fibers are the terminal portions of principal periodontal ligament fibers that insert into cementum and alveolar bone, anchoring the tooth in its socket.
Question 2: What is the accepted normal sulcus probing depth in a clinically healthy periodontium?
- 0–1 mm
- 1–3 mm (Correct answer)
- 4–5 mm
- 6–7 mm
Correct answer: 1–3 mm
A healthy gingival sulcus measures 1–3 mm on probing; depths ≥4 mm indicate pathological pocket formation.
Question 3: In a healthy periodontium, the apical termination of the junctional epithelium coincides with the:
- Alveolar crest
- Cemento-enamel junction (CEJ) (Correct answer)
- Mid-root cementum
- Free gingival margin
Correct answer: Cemento-enamel junction (CEJ)
Under healthy conditions, the apical end of the junctional epithelium is located at the CEJ, with no apical migration onto the root surface.
Question 4: According to Hamp's furcation classification, Class II involvement is defined as:
- Horizontal loss less than one-third the width of the tooth
- Horizontal loss exceeding one-third the width but not encompassing the total width (Correct answer)
- Horizontal loss encompassing the total width of the furcation area
- Vertical bone loss greater than 4 mm in the furcation
Correct answer: Horizontal loss exceeding one-third the width but not encompassing the total width
Hamp Class II means the probe penetrates horizontally more than one-third the tooth width but cannot pass completely through the furcation.
Question 5: The 'biologic width' of the periodontium comprises which two structures?
- Sulcus depth and free gingiva
- Junctional epithelium and supracrestal connective tissue attachment (Correct answer)
- Alveolar bone and periodontal ligament
- Free and attached gingiva
Correct answer: Junctional epithelium and supracrestal connective tissue attachment
Biologic width (~2 mm) consists of the junctional epithelium (~1 mm) and the supracrestal connective tissue attachment (~1 mm); violations cause chronic inflammation.
Question 6: Which pattern(s) of alveolar bone loss can occur in periodontitis?
- Horizontal bone loss only
- Vertical bone loss only
- Both horizontal and vertical bone loss (Correct answer)
- Periodontitis does not cause bone loss
Correct answer: Both horizontal and vertical bone loss
Periodontitis may produce horizontal bone loss (uniform reduction in bone height), vertical/angular defects, or both, depending on local anatomy and plaque distribution.
Question 7: Which cell type is primarily responsible for alveolar bone resorption in periodontitis?
- Osteoblasts
- Fibroblasts
- Osteoclasts (Correct answer)
- Cementoblasts
Correct answer: Osteoclasts
Osteoclasts are multinucleated cells derived from monocyte precursors that resorb bone via acids and proteolytic enzymes in response to inflammatory cytokines.
DDS Periodontics 1
Which fibers of the periodontal ligament embed directly into the cementum and alveolar bone?