NBDE Periodontics 5 — Questions and Answers
Question 1: Periodontal maintenance therapy (supportive periodontal therapy) intervals are typically set at every 3 months because:
- Bone remodeling cycles complete in 90 days
- Subgingival microbiota recolonize to pre-treatment levels in approximately 9–11 weeks (Correct answer)
- Insurance plans reimburse only quarterly visits
- Calculus mineralizes fully within 90 days
Correct answer: Subgingival microbiota recolonize to pre-treatment levels in approximately 9–11 weeks
Studies show subgingival microbiota recover to pathogenic composition in roughly 9–11 weeks, making 3-month intervals clinically justified.
Question 2: Which of the following best characterizes plaque-induced gingival disease modified by medication?
- Gingival enlargement caused by Candida overgrowth
- Inflammatory overgrowth exacerbated by calcium channel blockers, phenytoin, or cyclosporine (Correct answer)
- Acute gingival necrosis in immunosuppressed patients
- Desquamative changes from pemphigoid triggered by medications
Correct answer: Inflammatory overgrowth exacerbated by calcium channel blockers, phenytoin, or cyclosporine
Drug-influenced gingival enlargement is a well-documented adverse effect of calcium channel blockers, phenytoin, and cyclosporine, superimposed on pre-existing plaque-induced inflammation.
Question 3: The 'red complex' bacteria most strongly associated with severe chronic periodontitis includes:
- Aa, Prevotella intermedia, Fusobacterium nucleatum
- Porphyromonas gingivalis, Tannerella forsythia, Treponema denticola (Correct answer)
- Streptococcus mutans, Lactobacillus, Actinomyces
- Campylobacter rectus, Eikenella corrodens, Capnocytophaga
Correct answer: Porphyromonas gingivalis, Tannerella forsythia, Treponema denticola
Socransky's red complex—P. gingivalis, T. forsythia, and T. denticola—are most strongly associated with deep pockets and severe periodontal destruction.
Question 4: A 5 mm infrabony defect is treated with an open-flap debridement alone. The most likely type of healing is:
- True periodontal regeneration with new PDL, cementum, and bone
- Long junctional epithelium repair (Correct answer)
- Ankylosing reattachment
- Guided tissue regeneration response
Correct answer: Long junctional epithelium repair
Without a membrane or graft, healing occurs predominantly by long junctional epithelium formation (repair), not true regeneration.
Question 5: Tetracycline is used as an adjunct in aggressive periodontitis primarily because it:
- Kills gram-positive cocci responsible for secondary infections
- Achieves GCF concentrations 2–10× higher than serum and inhibits Aa (Correct answer)
- Acts as a potent anti-inflammatory by blocking COX-2
- Is bactericidal against anaerobes in established biofilms
Correct answer: Achieves GCF concentrations 2–10× higher than serum and inhibits Aa
Tetracycline concentrates in gingival crevicular fluid at levels far exceeding serum, making it effective against Aggregatibacter actinomycetemcomitans in aggressive periodontitis.
Question 6: Which type of alveolar bone defect is classified as a 'crater'?
- A one-wall defect on the facial surface only
- A two-wall infrabony defect with facial and lingual walls remaining (Correct answer)
- A three-wall defect surrounded by bone on three sides
- A suprabony defect with horizontal bone loss
Correct answer: A two-wall infrabony defect with facial and lingual walls remaining
An interproximal crater is a two-wall infrabony defect with the facial and lingual bony walls intact but the interproximal septum lost.
Question 7: Widman flap surgery (modified Widman flap) differs from resective osseous surgery in that it:
- Removes pocket epithelium and provides access for root debridement without deliberate bone removal (Correct answer)
- Eliminates pockets by apically positioning the flap
- Includes osteoplasty to achieve positive bony architecture
- Requires placement of a barrier membrane
Correct answer: Removes pocket epithelium and provides access for root debridement without deliberate bone removal
The modified Widman flap excises pocket epithelium and provides access for thorough root debridement but does not intentionally resect bone.
NBDE Periodontics 5
Periodontal maintenance therapy (supportive periodontal therapy) intervals are typically set at every 3 months because: