Dental MCQ
Energy and fuel pathways · Biochemistry · INBDE Patient Cases

Metabolism INBDE Patient Cases

By Dr. Isaac Sun, DDS

5 ADA INBDE-format patient cases on metabolism. 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.

5 patient cases25 linked questionsADA INBDE formatFull distractor explanations

Five ADA INBDE-format patient cases connecting metabolism to dentistry: dental caries as bacterial fermentation of dietary sugar to acid and the critical enamel pH, how fluoride (inhibiting bacterial enolase and forming fluorapatite) and xylitol (a non-fermentable sweetener) prevent it, early childhood bottle caries and bacterial transmission, phenylketonuria and the aspartame warning on sugar-free products, and alcohol-related impairment of gluconeogenesis causing fasting hypoglycemia with liver-related bleeding risk. Topics include glycolysis and gluconeogenesis, the Krebs cycle and oxidative phosphorylation, amino acid metabolism, lipid metabolism and ketone bodies, and the fed-versus-fasting hormonal switch.

Case Coverage Map
What each case is testing
Rampant decay and a soda habit:
Caries as bacterial glycolysis to acid, the critical pH, why frequency beats amount, saliva recovery, and diet counseling.
How do fluoride and xylitol actually work:
Fluoride inhibiting bacterial enolase and forming fluorapatite, xylitol as a non-fermentable sweetener, and saliva-driven remineralization.
A toddler with a nighttime bottle:
Early childhood caries, the spared lower incisors, the same fermentation mechanism, bacterial transmission, and anticipatory guidance.
A patient with PKU and the gum label:
Phenylalanine metabolism, the aspartame warning, choosing xylitol and fluoride, and matching products to a patient's condition.
Heavy drinker, hasn't eaten, here for an extraction:
Alcohol impairing gluconeogenesis and causing hypoglycemia, liver-related bleeding risk, and stabilizing before surgery.
Patient case: Rampant decay and a soda habit
0 of 5 answered, 0 correct
Patient
Male, 25 years old
Chief Complaint
"I keep getting cavities even though I brush."
Background and/or Patient History
  • Presented with multiple new carious lesions
  • Sips regular soda and energy drinks throughout the day
  • Brushes twice daily but snacks frequently on sweets
  • No dry-mouth medications
Allergies
NKDA
Medications
  • None
Current Findings
  • Multiple active carious lesions, several at smooth surfaces
  • Heavy plaque
  • Normal salivary flow
  1. Question 1
    Moderate
    The acid that dissolves his enamel is produced when oral bacteria:
  2. Question 2
    Moderate
    Enamel begins to demineralize once plaque pH falls below the critical level of about:
  3. Question 3
    Moderate
    For caries risk, the most important feature of his soda habit is the:
  4. Question 4
    Easy
    Between acid attacks, what normally helps the enamel recover?
  5. Question 5
    Moderate
    The best dietary counseling for him is to:

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Patient case: How do fluoride and xylitol actually work
0 of 5 answered, 0 correct
Patient
Female, 30 years old
Chief Complaint
"My dentist recommended fluoride and xylitol gum. How do they help?"
Background and/or Patient History
  • Moderate caries risk, asking about prevention
  • Drinks non-fluoridated well water
  • Open to gum and rinses
  • No relevant medical history
Allergies
NKDA
Medications
  • None
Current Findings
  • A few early white-spot lesions
  • Otherwise sound dentition
  • Normal salivary flow
  1. Question 1
    Hard
    One way fluoride lowers bacterial acid production is by inhibiting the glycolytic enzyme:
  2. Question 2
    Moderate
    Fluoride also makes enamel more acid-resistant by forming:
  3. Question 3
    Moderate
    Xylitol helps prevent caries mainly because it:
  4. Question 4
    Easy
    Chewing xylitol gum after meals also helps by:
  5. Question 5
    Moderate
    Given her non-fluoridated well water, a reasonable recommendation is:

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Patient case: A toddler with a nighttime bottle
0 of 5 answered, 0 correct
Patient
Female, 2 years old, accompanied by parent
Chief Complaint
Parent: "Her front teeth are turning brown."
Background and/or Patient History
  • Brought in for brown discoloration of the upper front teeth
  • Falls asleep with a bottle of milk or juice every night
  • Frequent daytime sippy cup of juice
  • Mother has had many cavities herself
Allergies
NKDA
Medications
  • None
Current Findings
  • Decay on the upper anterior teeth, sparing the lower incisors
  • Heavy plaque
  • Otherwise healthy child
  1. Question 1
    Moderate
    Her pattern of decay is classic for:
  2. Question 2
    Hard
    The lower incisors are relatively spared mainly because:
  3. Question 3
    Moderate
    The underlying metabolic mechanism is the same as adult caries:
  4. Question 4
    Moderate
    Decay-causing bacteria are often first acquired by the child from:
  5. Question 5
    Moderate
    The most important counseling for the parent is to:

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Patient case: A patient with PKU and the gum label
0 of 5 answered, 0 correct
Patient
Female, 19 years old
Chief Complaint
"I have PKU. Can I use the sugar-free gum and rinse you recommend?"
Background and/or Patient History
  • Lifelong phenylketonuria, on a low-phenylalanine diet
  • Asking about sugar-free dental products for caries prevention
  • Reads labels carefully
  • No other medical issues
Allergies
NKDA
Medications
  • Medical dietary formula
Current Findings
  • Sound dentition, moderate caries risk
  • Highly motivated about prevention
  1. Question 1
    Moderate
    PKU is caused by an inability to metabolize the amino acid:
  2. Question 2
    Moderate
    Which sweetener must she avoid because it contains phenylalanine?
  3. Question 3
    Easy
    On a product label, the relevant warning for her reads:
  4. Question 4
    Moderate
    A safe and effective product choice for her caries prevention is:
  5. Question 5
    Moderate
    The broader lesson is that the dentist should:

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Patient case: Heavy drinker, hasn't eaten, here for an extraction
0 of 5 answered, 0 correct
Patient
Male, 49 years old
Chief Complaint
"I had a rough night and haven't eaten; I just want this tooth out."
Background and/or Patient History
  • Presented for an extraction
  • History of heavy daily alcohol use
  • Has not eaten since the day before and has been drinking
  • Reports feeling shaky and sweaty
Allergies
NKDA
Medications
  • None reported
Current Findings
  • Tremulous and diaphoretic
  • Smell of alcohol
  • Reports easy bruising
  1. Question 1
    Moderate
    His shakiness and sweating after drinking without eating most likely reflect:
  2. Question 2
    Hard
    Alcohol promotes fasting hypoglycemia mainly by:
  3. Question 3
    Moderate
    Chronic heavy alcohol use also raises bleeding concern because the liver may make fewer:
  4. Question 4
    Moderate
    The most appropriate immediate step, since he is conscious, is to:
  5. Question 5
    Moderate
    Before any extraction, this patient also needs:

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Keep studying
Metabolism core recall

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

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