NBDE Part II 2 — Questions and Answers
Question 1: A patient presents with a periapical abscess on tooth #19. After incision and drainage, the most appropriate antibiotic of choice in a non-penicillin-allergic patient is:
- Amoxicillin 500mg TID x 7 days (Correct answer)
- Metronidazole 500mg TID x 7 days
- Clindamycin 300mg TID x 7 days
- Azithromycin 250mg QD x 5 days
Correct answer: Amoxicillin 500mg TID x 7 days
Amoxicillin is the first-line antibiotic for odontogenic infections in non-penicillin-allergic patients due to its broad-spectrum coverage of oral flora.
Question 2: During a class II amalgam preparation, which wall provides the most resistance to occlusal loading?
- Axial wall
- Pulpal floor (Correct answer)
- Gingival floor
- Proximal wall
Correct answer: Pulpal floor
The pulpal floor provides the primary resistance form by being perpendicular to the long axis of the tooth and distributing occlusal forces.
Question 3: A 7-year-old child has avulsed tooth #8 (maxillary right central incisor, permanent). The tooth has been extraoral for 90 minutes in a dry environment. The best management is:
- Replant immediately after cleaning with saline
- Do not replant; space maintenance only (Correct answer)
- Replant after 30-minute fluoride soak
- Place in Hank's Balanced Salt Solution and replant within 24 hours
Correct answer: Do not replant; space maintenance only
Teeth with a dry extraoral time exceeding 60 minutes have non-viable periodontal ligament cells, and replantation is not recommended due to inevitable ankylosis and root resorption.
Question 4: Which local anesthetic has the longest duration of action and is commonly used for prolonged surgical procedures?
- Lidocaine 2%
- Mepivacaine 3%
- Bupivacaine 0.5% (Correct answer)
- Prilocaine 4%
Correct answer: Bupivacaine 0.5%
Bupivacaine 0.5% provides up to 8–12 hours of pulpal anesthesia, making it ideal for lengthy oral surgical procedures and postoperative pain control.
Question 5: In periodontal disease classification, Stage III Grade C periodontitis is characterized by:
- Mild bone loss with slow progression and no risk factors
- Severe bone loss with rapid progression and significant risk factors like smoking or diabetes (Correct answer)
- Moderate bone loss in a young patient with no systemic disease
- Localized bone loss limited to molars and incisors
Correct answer: Severe bone loss with rapid progression and significant risk factors like smoking or diabetes
Grade C indicates rapid rate of progression and/or specific risk factors (e.g., smoking ≥10 cigarettes/day or HbA1c ≥7%), combined with Stage III's severe complexity factors.
Question 6: Which of the following best describes the 'critical pH' for enamel demineralization?
- pH 7.0
- pH 6.5
- pH 5.5 (Correct answer)
- pH 4.5
Correct answer: pH 5.5
Enamel begins to demineralize at pH 5.5 because this is the point at which saliva becomes undersaturated with respect to hydroxyapatite.
Question 7: A patient undergoing extraction develops sudden onset of extreme pain 3–4 days post-operatively with an empty socket and exposed bone. The most likely diagnosis is:
- Acute osteomyelitis
- Alveolar osteitis (dry socket) (Correct answer)
- Pericoronitis
- Ludwig's angina
Correct answer: Alveolar osteitis (dry socket)
Alveolar osteitis (dry socket) presents 3–5 days post-extraction with loss of the blood clot, exposed alveolar bone, and severe radiating pain.
NBDE Part II 2
A patient presents with a periapical abscess on tooth #19.
After incision and drainage, the most appropriate antibiotic of choice in a non-penicillin-allergic patient is: