Dental assistant certification: national exams, state rules

1. Choose a training route. One is a dental assisting program accredited by CODA; the other is learning on the job after high school while a licensed dentist supervises and later verifies your hours. Both lead to the same national certification.
2. Look up what the board in your state allows before accepting a job that includes x-rays, coronal polishing or other expanded duties.
3. Take the exams that have no prerequisites first. Radiation Health and Safety and Infection Control (ICE) are open to anyone, including students.
4. Finish the certification once you qualify for General Chairside: all three exams inside the time limit, plus a CPR card from a hands-on course (BLS or ACLS cards qualify too).
5. Keep it active with yearly renewal and continuing education.

Time to qualify varies with the route. A program sets its own length; the work route asks for supervised dental assisting work totaling 3,500 hours over 2–4 years, verified by the dentist.

The certification is the sum of three separately scored exams, and each can be taken alone, in a pair or all at once:

• GC: 95 questions in 75 minutes. The only part with entry rules: an education or work pathway and a CPR card.
• RHS: 75 questions in 60 minutes. Open to anyone; covered in full on the RHS pages.
• ICE: 75 questions in 60 minutes. Open to anyone.

All three have to be passed within 5 years. Fees, pathways and every condition sit on the certification overview.

• Student or new to the chair: start with Radiation Health and Safety and Infection Control. Neither has prerequisites, and both count toward the certification later.
• Taking x-rays, or about to: check whether your state appears in the table below with the radiography exam listed; if it does, that exam is the usual starting point.
• Program graduate, or the supervised hours are done: the full three-part DANB CDA, in one sitting or in pieces.
• Already passed the radiography exam: it counts as one of the three parts, as long as the other two follow within the time limit.

The three abbreviations look parallel but come from different places.

• The DANB CDA is a national certification. It is the same credential in every state, and it is renewed yearly with continuing education. It shows knowledge; it does not, by itself, authorize any duty.
• An RDA (registered dental assistant) is a state title. The board that keeps the register sets the education, the exams and the renewal, and the title does not carry over automatically to another state. Some states build national exams into their registration; others write their own.
• An EFDA (expanded function dental assistant) is a state permit or license for restorative or preventive work beyond basic chairside duties. Boards set the training and the exams; DANB offers certifications in this area too, such as the CPFDA and the CRFDA. Nevada is a recent example of a board linking the two. The state EFDA license recognizes DANB's CDA, CPFDA and CRFDA exams (in effect July 1, 2026).

We do not count how many states use each title: the boards change those rules often, and the table below is limited to what the national board's state pages list.

As of our November 2026 check, DANB lists the DANB CDA exam application on the dental assisting pages of 36 states and the District of Columbia. For the radiography exam, DANB lists its RHS exam application on the dental assisting pages of 24 states and the District of Columbia. Several states without the radiography listing set their own radiography courses or exams.

Texas and California are among them: the national board's pages for both list the certification application but not the radiography exam, so the requirements for x-rays and registration come from the Texas State Board of Dental Examiners and the Dental Board of California.

Board rules move every year. One 2026 example, as DANB's state summary records it:

• Iowa: Dental assistants may practice without registration after a set term of supervised practical training (in effect June 3, 2026).

Radiography changes in Connecticut and New Mexico are on the RHS overview.

Two renewals can apply to the same person, and they are independent. The national certification renews every year (12 CDE a year, plus a current CPR card); details are on its own page. A state registration, permit or license renews on the board's own schedule and fee. The radiography certificate on its own does not expire.