Final answer:
Registered Dental Hygienists must complete a varying number of Continuing Education Units depending on their state, ranging from 12 to 50 CEUs per renewal period, with renewal periods typically being annual or biennial.
Step-by-step explanation:
The number of Continuing Education Units (CEUs) required for Registered Dental Hygienists (RDHs) to renew their license varies by state. Generally, RDHs are required to complete between 12 to 50 hours of CEUs every renewal period. The renewal period can also differ by state, with some requiring biennial renewal and others requiring annual renewal. It's critical for RDHs to refer to their specific state's dental board for the exact requirements as they are subject to change and may have specific criteria regarding the types of courses that qualify for continuing education.