NBDE Periodontics and Endodontics 2 — Questions and Answers
Question 1: Which furcation classification indicates that a probe can pass completely through the furcation from one side to the other?
- Class I
- Class II
- Class III (Correct answer)
- Class IV
Correct answer: Class III
Class III furcation involvement means the probe passes completely through the furcation (through-and-through), indicating complete bone loss in the furcation area.
Question 2: A patient presents with a 'cracked tooth.' Which pulp diagnosis is MOST likely if the crack extends into the pulp chamber?
- Normal pulp
- Reversible pulpitis
- Irreversible pulpitis (Correct answer)
- Pulp necrosis
Correct answer: Irreversible pulpitis
A crack extending into the pulp chamber typically causes irreversible pulpitis due to bacterial contamination and inflammation that cannot resolve.
Question 3: What is the primary goal of scaling and root planing in the treatment of periodontitis?
- Complete elimination of all subgingival bacteria
- Removal of calculus and bacterial biofilm to reduce inflammation (Correct answer)
- Surgical exposure of root surfaces
- Stimulation of new bone formation
Correct answer: Removal of calculus and bacterial biofilm to reduce inflammation
Scaling and root planing aims to remove calculus and bacterial biofilm from root surfaces to reduce periodontal inflammation and promote tissue healing.
Question 4: Which irrigant is used during root canal treatment primarily for its ability to dissolve organic tissue?
- Chlorhexidine gluconate
- Sodium hypochlorite (Correct answer)
- EDTA
- Sterile saline
Correct answer: Sodium hypochlorite
Sodium hypochlorite (NaOCl) is the most widely used endodontic irrigant because of its unique ability to dissolve organic tissue including pulp remnants and necrotic debris.
Question 5: In periodontal disease, which cell type is primarily responsible for releasing collagenase that destroys the periodontal ligament?
- Neutrophils (Correct answer)
- T-lymphocytes
- Fibroblasts
- Osteoclasts
Correct answer: Neutrophils
Neutrophils release collagenase (matrix metalloproteinases) as part of the host inflammatory response, which inadvertently destroys collagen in the periodontal ligament.
Question 6: A patient has a sinus tract that leads to a periapical abscess. What is the appropriate treatment?
- Incision and drainage of the sinus tract
- Root canal treatment of the offending tooth (Correct answer)
- Antibiotic therapy alone
- Extraction and immediate implant placement
Correct answer: Root canal treatment of the offending tooth
A sinus tract from a periapical abscess is treated by performing root canal therapy on the source tooth, which eliminates the infection causing the sinus tract.
Question 7: Which periodontal fiber group runs perpendicular to the root surface and is the principal fiber group resisting intrusive forces?
- Alveolar crest fibers
- Horizontal fibers
- Oblique fibers (Correct answer)
- Apical fibers
Correct answer: Oblique fibers
The oblique fiber group, the largest periodontal ligament fiber group, runs at a 45-degree angle and is primarily responsible for resisting vertical/intrusive occlusal forces.
NBDE Periodontics and Endodontics 2
Which furcation classification indicates that a probe can pass completely through the furcation from one side to the other?