Which of the following best describes the conditions under which a dental hygienist can practice?

A dental hygienist can practice based on the mandates set forth by the State Dental Act. This legislation outlines the scope of practice, licensing requirements, and regulatory guidelines that govern dental hygiene. Adhering to this act ensures that hygienists operate within the legal framework established for their profession, which includes duties allowed, the requirements for supervision or collaboration with dentists, and the standards of care they must uphold.

The other options do not appropriately represent the formal and regulated context of dental hygiene practice. Advertisements created by practitioners may reflect their services but do not govern the legal parameters of practice. Personal training may influence a hygienist's skills and knowledge but must be aligned with state regulations to ensure compliance and safety. Collaborating with unlicensed practitioners is not permissible under the law, as dental hygiene practice requires a license, and working outside of this framework could jeopardize patient safety and legal standing.