Final answer:
The priority nursing intervention when providing oral hygiene for an unconscious client is positioning the client correctly. This helps prevent aspiration and allows for proper drainage of oral secretions.
Step-by-step explanation:
The priority nursing intervention when providing oral hygiene for an unconscious client is positioning the client correctly. When positioning the client correctly, the nurse ensures that the client's head is tilted to the side, with the chin slightly lifted. This position helps prevent aspiration and allows for proper drainage of oral secretions. It also helps maintain an open airway for the client.