Dental MCQ
Catalysts and cofactors · Biochemistry · INBDE Patient Cases

Enzymes & Vitamins INBDE Patient Cases

By Dr. Isaac Sun, DDS

6 ADA INBDE-format patient cases on enzymes & vitamins. Each case is a shared patient box (chief complaint, history, medications, allergies, exam) followed by linked multiple-choice questions with full distractor explanations. Practice the way the real exam is structured.

6 patient cases30 linked questionsADA INBDE formatFull distractor explanations

Six ADA INBDE-format patient cases connecting enzymes and vitamins to dentistry: scurvy with spongy bleeding gums from vitamin C deficiency and defective collagen, vitamin D deficiency (rickets) with delayed eruption and enamel hypoplasia, warfarin as a vitamin K antagonist with INR-guided extraction management, isotretinoin (a vitamin A retinoid) causing severe cheilitis and mucosal dryness with teratogenic risk, pseudocholinesterase deficiency affecting ester local anesthetics and succinylcholine, and methotrexate as a folate antagonist causing oral mucositis with an NSAID interaction. Topics include enzyme kinetics (Km, competitive and noncompetitive inhibition, zymogens), vitamin-derived coenzymes and metal cofactors, fat-soluble versus water-soluble vitamins, and the oral signs of vitamin deficiency.

Case Coverage Map
What each case is testing
Bleeding, spongy gums and a poor diet:
Scurvy (vitamin C), collagen hydroxylation, distinguishing it from plaque gingivitis, and reversibility with repletion.
A toddler with delayed teeth and bowed legs:
Vitamin D deficiency and mineralization, delayed eruption and enamel hypoplasia, the activation steps, and pediatric coordination.
On a blood thinner and needs a tooth out:
Warfarin as a vitamin K antagonist, the vitamin K-dependent factors, checking the INR, continuing warfarin with local hemostasis, and reversal.
Cracked lips on an acne medication:
Isotretinoin as a vitamin A retinoid, cheilitis and mucosal dryness, teratogenicity, and fat-soluble vitamin toxicity.
A family history of slow anesthesia recovery:
Pseudocholinesterase deficiency, ester anesthetics and succinylcholine, choosing an amide, and enzyme deficiency prolonging drug effect.
Painful mouth ulcers on methotrexate:
Methotrexate as a folate antagonist inhibiting dihydrofolate reductase, mucositis, folate rescue, and the NSAID interaction.
Patient case: Bleeding, spongy gums and a poor diet
0 of 5 answered, 0 correct
Patient
Male, 60 years old
Chief Complaint
"My gums are swollen and bleed at the slightest touch."
Background and/or Patient History
  • Lives alone and eats almost no fruits or vegetables
  • Reports easy bruising and a leg wound that will not heal
  • Gum problems worsening over weeks despite brushing
  • Heavy alcohol use
Allergies
NKDA
Medications
  • None
Current Findings
  • Swollen, spongy, hemorrhagic gingiva
  • Scattered skin bruising and perifollicular hemorrhages
  • A slow-healing skin wound
  1. Question 1
    Moderate
    His spongy, bleeding gums with bruising and poor healing, on a diet lacking fruits and vegetables, suggest deficiency of:
  2. Question 2
    Moderate
    Vitamin C deficiency damages the gums and delays healing because vitamin C is required for:
  3. Question 3
    Moderate
    Which feature best separates this from ordinary plaque-induced gingivitis?
  4. Question 4
    Moderate
    The most appropriate management is to:
  5. Question 5
    Easy
    With vitamin C repletion, the expected outcome for his gums is:

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Patient case: A toddler with delayed teeth and bowed legs
0 of 5 answered, 0 correct
Patient
Male, 2 years old, accompanied by parent
Chief Complaint
Parent: "His teeth are coming in late and look pitted."
Background and/or Patient History
  • Exclusively breastfed without a vitamin D supplement
  • Limited sun exposure
  • Pediatrician noted bowing of the legs
  • Delayed eruption of the primary teeth
Allergies
NKDA
Medications
  • None
Current Findings
  • Delayed primary tooth eruption
  • Enamel hypoplasia on erupted teeth
  • General signs of poor bone mineralization
  1. Question 1
    Moderate
    The combination of delayed eruption, enamel hypoplasia, and bowed legs suggests deficiency of:
  2. Question 2
    Moderate
    Vitamin D supports tooth and bone mineralization by:
  3. Question 3
    Hard
    Vitamin D is activated through steps in the skin, liver, and finally the:
  4. Question 4
    Moderate
    Why is this child at particular risk?
  5. Question 5
    Moderate
    The appropriate dental response is to:

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Patient case: On a blood thinner and needs a tooth out
0 of 5 answered, 0 correct
Patient
Female, 68 years old
Chief Complaint
"I'm on warfarin and I need this tooth pulled."
Background and/or Patient History
  • Presented for extraction of a non-restorable tooth
  • Takes warfarin for atrial fibrillation
  • INR checked two days ago was 2.4 (her therapeutic range is 2 to 3)
  • No recent bleeding problems
Allergies
NKDA
Medications
  • Warfarin
Current Findings
  • Stable vitals
  • Single non-restorable tooth, no acute infection
  • No signs of over-anticoagulation
  1. Question 1
    Moderate
    Warfarin increases bleeding risk because it antagonizes:
  2. Question 2
    Hard
    The clotting factors reduced by warfarin are:
  3. Question 3
    Moderate
    The single most useful value to check before this extraction is the:
  4. Question 4
    Hard
    For this single extraction with a therapeutic INR, current guidance is generally to:
  5. Question 5
    Moderate
    If she were significantly over-anticoagulated and bleeding, the agent that reverses warfarin is:

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Patient case: Cracked lips on an acne medication
0 of 5 answered, 0 correct
Patient
Female, 19 years old
Chief Complaint
"My lips are painfully chapped and my mouth feels dry."
Background and/or Patient History
  • Taking isotretinoin, a vitamin A derivative, for severe acne
  • Severe lip chapping and dryness since starting the drug
  • Asking about an elective gum procedure
  • Otherwise healthy
Allergies
NKDA
Medications
  • Isotretinoin
Current Findings
  • Severe cheilitis with cracked, dry lips
  • Dry oral and nasal mucosa
  • No infection
  1. Question 1
    Moderate
    Her severe cheilitis and mucosal dryness are most likely caused by:
  2. Question 2
    Moderate
    Isotretinoin is a derivative of which fat-soluble vitamin?
  3. Question 3
    Moderate
    The most important counseling point with isotretinoin is its:
  4. Question 4
    Moderate
    For her cheilitis and dry mucosa during dental care, a reasonable approach is to:
  5. Question 5
    Moderate
    Her case illustrates a general property of fat-soluble vitamins (and their analogs): they can:

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Patient case: A family history of slow anesthesia recovery
0 of 5 answered, 0 correct
Patient
Male, 30 years old
Chief Complaint
"My brother needed a breathing machine for hours after surgery; is dental numbing safe for me?"
Background and/or Patient History
  • Reports a family history of prolonged paralysis after a muscle relaxant during general anesthesia
  • Presents for routine restorative care needing local anesthesia
  • No personal surgical history
  • Otherwise healthy
Allergies
NKDA
Medications
  • None
Current Findings
  • Healthy young adult
  • Needs operative dental care with local anesthesia
  1. Question 1
    Hard
    The family history of prolonged paralysis after succinylcholine most likely reflects a deficiency of:
  2. Question 2
    Hard
    Besides succinylcholine, the same enzyme normally metabolizes which dental drugs?
  3. Question 3
    Moderate
    For his dental local anesthesia, the safer choice is therefore an:
  4. Question 4
    Moderate
    This scenario illustrates that enzyme deficiencies can:
  5. Question 5
    Moderate
    The most appropriate step before treating him is to:

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Patient case: Painful mouth ulcers on methotrexate
0 of 5 answered, 0 correct
Patient
Female, 45 years old
Chief Complaint
"I keep getting painful mouth sores since my arthritis medication."
Background and/or Patient History
  • Rheumatoid arthritis treated with weekly methotrexate
  • Recurrent painful oral ulcers (mucositis)
  • Asks what she can take for dental pain
  • Also takes a folic acid supplement some days
Allergies
NKDA
Medications
  • Methotrexate (weekly)
  • Folic acid (intermittent)
Current Findings
  • Multiple painful oral ulcers
  • Otherwise stable
  1. Question 1
    Moderate
    Her oral ulcers are most likely a side effect of methotrexate, which acts as a:
  2. Question 2
    Hard
    Methotrexate blocks folate metabolism by inhibiting the enzyme:
  3. Question 3
    Moderate
    To reduce methotrexate's mucosal toxicity, patients are commonly given:
  4. Question 4
    Hard
    Which analgesic should be used cautiously or avoided because it can raise methotrexate toxicity?
  5. Question 5
    Moderate
    The appropriate dental management is to:

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Keep studying
Enzymes & Vitamins core recall

Refresh the anatomy facts these cases depend on: nerve numbers, foramina, functions, and lesion findings.

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