A registered dental hygienist is authorized to perform the following procedures under direct supervision of a licensed dentist, after submitting to the dental hygiene board evidence of satisfactory completion of a course of instruction, approved by the dental hygiene board, in the procedures:

1. (a) Soft-tissue curettage.
2. (b) Administration of local anesthesia.
3. (c) Administration of nitrous oxide and oxygen, whether administered alone or in combination with each other.