Counselling, implant planning and occlusal vertical dimension

Correct answer: A. Counsel her about fetal alcohol syndrome and advise abstinence

• A. Correct. No amount of alcohol has been established as safe in pregnancy. Brief, non-judgemental counselling is within the dentist's scope and duty, and the effects — midface hypoplasia, a smooth philtrum, a thin upper lip, developmental delay — are irreversible.
• B. This is factually wrong — no threshold of safe consumption in pregnancy has been established.
• C. There is no reportable offence here. Reporting would destroy the trust needed to help her.
• D. Health counselling is squarely within the dentist's role as a health care provider, particularly where the oral and facial consequences are so direct.

Correct answer: D. Four

• A. A single implant is not a recognised protocol for an overdenture.
• B. Two implants is the accepted minimum in the mandible, where the anterior bone is dense and a two-implant overdenture performs well.
• C. Six implants gives excellent support and is often preferred for a fixed maxillary prosthesis, but four is the stated minimum for an overdenture.
• D. Correct. The maxilla requires at least four implants, because its bone quality is poorer (types III and IV) and the arch must resist greater rotational forces.

Note: For a fixed full-arch maxillary prosthesis the usual recommendation rises to six or more, depending on cantilever length and bone quality.

Correct answer: B. Inadequate overjet

• A. A deep overbite can traumatise the palatal mucosa or the labial gingiva of the lower incisors, but it does not trap the lip.
• B. Correct. When the upper anterior teeth do not project sufficiently in front of the lowers, the lip has nowhere to sit and gets caught between the teeth during closure and speech.
• C. Inadequate freeway space produces the same overclosure-related complaints, again through a different mechanism.
• D. An excessive vertical dimension causes a strained appearance, difficulty closing the lips, clicking teeth and soreness — not repeated lip biting.

Note: Cheek biting has the analogous cause in the posterior segment — insufficient horizontal overlap of the buccal cusps.

Correct answer: B. Rubber dam isolation combined with high-volume evacuation

• A. A preprocedural rinse lowers the microbial load of the aerosol but does not reduce its volume, and the effect is modest.
• B. Correct. Rubber dam eliminates saliva from the aerosol at source, and high-volume evacuation captures the great majority of what is generated. Together they are the most effective engineering control available.
• C. A mask is personal protective equipment — it protects the individual wearing it but does nothing to reduce the aerosol produced.
• D. Distance is impractical during operative treatment and does not address the source.

Note: This follows the hierarchy of controls: elimination and engineering controls outrank administrative measures, and PPE sits at the bottom.