What is a duty that can only be accomplished under the supervision of a dentist?

Applying cavity liners on exposed pulp is a duty that requires a high level of knowledge and expertise and must be performed under the direct supervision of a dentist. This procedure involves making significant clinical judgments that only a licensed dentist is qualified to oversee. It is a critical aspect of dental treatment that has implications for patient health and safety, which is why it cannot be delegated to expanded duty dental assistants without appropriate supervision.

In contrast, patient education can be carried out by dental assistants since it typically involves explaining general oral hygiene practices and other non-invasive information that doesn't require a dentist's direct involvement. Taking dental x-rays may also be performed by trained dental assistants, but only under the general supervision of a dentist who has established protocols for the practice. Filling out patient charts is usually a clerical task that does not require the clinical expertise of a dentist, allowing dental assistants to handle that independently. Thus, applying cavity liners is the only choice that necessitates direct supervision from a dentist.