Fluoride, preparation design, syphilis and patient communication

Correct answer: B. The bioavailability of free fluoride ion

• A. Viscosity affects handling and how well a varnish stays put, but it is not what determines the anticaries effect.
• B. Correct. Only free, ionisable fluoride can enter the tooth surface and drive remineralisation. Formulations in which fluoride is bound by incompatible abrasives deliver far less benefit than their stated concentration suggests.
• C. Colour stability is a cosmetic property of varnishes with no bearing on efficacy.
• D. Flavouring improves acceptance, especially in children, but contributes nothing to the mechanism.

Note: ⚑ The recall listed 'bioavailability' and 'substantivity' as the two competing options and did not mark a key. Both are defensible: bioavailability governs how much active fluoride is delivered, while substantivity — prolonged retention and slow release — is the reason varnish outperforms a rinse. Expect either to be arguable; discuss in the group.

Correct answer: A. Retention grooves in the axial walls

• A. Correct. When the axial walls are short, grooves and boxes add resistance and retention form by limiting the paths along which the restoration could be displaced.
• B. Increasing the taper reduces retention. The optimum convergence is around 6 to 10 degrees total.
• C. The margin design determines the finish line and the bulk of material at the margin; it does not supply retention.
• D. More occlusal reduction removes still more tooth structure and shortens the walls further — the opposite of what is needed.

Correct answer: B. Congenital syphilis

• A. Fetal alcohol syndrome gives midface hypoplasia, a smooth philtrum and thin upper lip, together with developmental delay.
• B. Correct. Screwdriver-shaped, notched incisors and multicusped mulberry molars form the dental component of the Hutchinson triad, alongside interstitial keratitis and eighth-nerve deafness.
• C. Regional odontodysplasia is a localised, non-hereditary defect producing 'ghost teeth' in one quadrant.
• D. Congenital rubella causes cataracts, cardiac defects and deafness, with enamel hypoplasia but not this specific morphology.

Correct answer: C. Set a quit date

• A. A chest film is not part of a cessation protocol.
• B. Pharmacotherapy supports the attempt but comes after the commitment and the date are established.
• C. Correct. Once a patient has expressed readiness, setting a specific quit date — ideally within two weeks — converts intention into a concrete plan and is the anchor of the assist stage.
• D. Gradual reduction is generally less successful than a defined quit date; abrupt cessation with support has better outcomes.

Note: In the 5 A's framework — ask, advise, assess, assist, arrange — 'set a quit date' sits within assist. If 'ask about tobacco use' appears as an option, that is the first step of the framework overall.

Correct answer: C. "What makes you think you have cavities?"

• A. Also closed, and it directs the patient toward a narrow factual reply.
• B. Closed, and worse, it is leading: it signals the answer you want and invites the patient to give it.
• C. Correct. It cannot be answered yes or no. It invites the patient to explain in their own words and gives you information you would never have thought to ask for.
• D. This is closed — it yields a single-word answer and closes the topic.

Note: Open-ended questions are the backbone of motivational interviewing. Typical stems: what, how, tell me about, describe.