NBDE Ultimate 2 — Questions and Answers
Question 1: Which antibiotic is the first-line treatment for odontogenic infections in non-penicillin-allergic patients?
- Metronidazole
- Amoxicillin (Correct answer)
- Clindamycin
- Azithromycin
Correct answer: Amoxicillin
Amoxicillin is the first-line antibiotic for odontogenic infections due to its broad-spectrum coverage of oral flora and good bioavailability.
Question 2: Aspirin irreversibly inhibits cyclooxygenase enzymes. This type of inhibition is best classified as:
- Competitive inhibition
- Non-competitive inhibition
- Covalent (irreversible) inhibition (Correct answer)
- Allosteric inhibition
Correct answer: Covalent (irreversible) inhibition
Aspirin acetylates a serine residue on COX via a covalent bond, permanently inactivating the enzyme for the platelet's lifetime.
Question 3: Which microorganism is the primary etiologic agent of early childhood caries (ECC)?
- Streptococcus salivarius
- Lactobacillus acidophilus
- Streptococcus mutans (Correct answer)
- Actinomyces viscosus
Correct answer: Streptococcus mutans
Streptococcus mutans is the primary pathogen in ECC due to its acidogenicity, aciduricity, and ability to synthesize extracellular polysaccharides for biofilm adherence.
Question 4: A white, non-wipeable lesion on the floor of the mouth of a 60-year-old smoker is best classified as:
- Pseudomembranous candidiasis
- Leukoplakia (Correct answer)
- Fordyce granules
- Leukoedema
Correct answer: Leukoplakia
Leukoplakia is a clinical diagnosis for white plaques that cannot be scraped off and cannot be characterized as any other definable lesion.
Question 5: Which analgesic is classified as a selective COX-2 inhibitor?
- Ibuprofen
- Naproxen
- Celecoxib (Correct answer)
- Aspirin
Correct answer: Celecoxib
Celecoxib selectively inhibits COX-2, reducing inflammation with less GI toxicity than non-selective NSAIDs that also block COX-1.
Question 6: Which clinical scenario represents the strongest relative contraindication to vasoconstrictors in local anesthetics?
- Well-controlled type 2 diabetes
- Stable angina on beta-blockers
- Severe uncontrolled hypertension (Correct answer)
- Mild renal insufficiency
Correct answer: Severe uncontrolled hypertension
Severe uncontrolled hypertension is a relative contraindication to epinephrine because it can precipitate a hypertensive crisis or cardiac arrhythmia.
Question 7: Oral candidiasis is most commonly caused by which Candida species?
- Candida tropicalis
- Candida albicans (Correct answer)
- Candida glabrata
- Candida krusei
Correct answer: Candida albicans
Candida albicans accounts for approximately 70-80% of oral candidiasis cases due to its ability to form hyphae and evade host defenses.
NBDE Ultimate 2
Which antibiotic is the first-line treatment for odontogenic infections in non-penicillin-allergic patients?