The clinical board exam is the hands-on companion to the NBDHE — a skills-based test, run by a regional testing agency rather than a national board, that most states require before they'll issue an RDH license.
There's no single national clinical exam: candidates sit for one administered by ADEX or by CRDTS, depending on which agency their target state accepts.
Where the NBDHE tests what you know, the clinical board exam tests what you can actually do at the chair.
What is the clinical board exam?
Most states license a dental hygienist on three things: graduating from a CODA-accredited program, passing a national written exam, and passing a clinical exam.
The National Board Dental Hygiene Examination (NBDHE) covers the written piece.
The clinical board exam covers the third — a direct, hands-on demonstration that you can perform core hygiene procedures competently, evaluated by trained examiners against a fixed set of criteria.
Unlike the NBDHE, no single national body writes or administers the clinical exam.
It's regional: independent testing agencies build and run their own versions, and each state dental board decides which agency's results it will accept toward licensure.
That's the source of most of the confusion around this exam — the format and the agency both depend on where you plan to get licensed.
Verify the current format and fee with the testing agency and your state board
Who administers it: ADEX/CDCA-WREB vs. CRDTS
ADEX — the American Board of Dental Examiners — develops the exam and delivered its first dental hygiene version in 2007.
It's administered jointly with agencies that each bring their own separate history: the CDCA traces back to the Northeast Regional Board of Dental Examiners, founded in 1969 and renamed in 2015, while the WREB grew out of a group of western states that began collaborating in the mid-1970s.
The two now operate together — which is why you'll see the exam written as "ADEX/CDCA-WREB." CRDTS (the Central Regional Dental Testing Service) is a separate, independent regional testing agency with no ADEX affiliation; it develops and runs its own dental hygiene clinical exam for its member and participating states.
Neither organization is a federal or national licensing body — they're testing agencies that individual state boards choose to rely on.
A state board can accept ADEX, CRDTS, both, or (in some cases) a state-specific alternative, and each agency publishes its own map of which states currently accept its results.
Since that acceptance list changes, check the current map on the agency's own site rather than assuming last year's answer still holds.
What happens during the exam
Both agencies structure their dental hygiene exam around two components.
The first is a computer-based simulated clinical exam — an objective structured clinical exam (OSCE) style test that uses photographs, radiographs, and case data to assess your diagnosis and treatment-planning judgment, similar in spirit to the case-based half of the NBDHE but scored on applied clinical decisions rather than general knowledge.
The second component is the hands-on skills demonstration: detecting and removing calculus, taking accurate periodontal pocket-depth measurements, managing soft tissue, and following infection-control procedure, evaluated live by trained examiners.
Historically candidates performed this on a patient they brought in themselves; both ADEX and CRDTS now also offer — and in many locations primarily use — a manikin (typodont) format that replaces the live patient with a mounted model.
Which format applies at your test site is set by the current candidate manual, not by this page, so confirm it before you plan around either option.
How states decide which exam to accept
There's no requirement that every state accept every agency's exam.
A board sets its own clinical-exam requirement the same way it sets everything else about licensure, and that decision can include accepting one agency, accepting several, or granting licensure by credential to hygienists already licensed elsewhere.
The result is that two hygienists graduating from the same program can end up sitting for entirely different clinical exams, purely based on where each plans to get licensed first.
Some states also accept the JCNDE's Dental Hygiene Licensure Objective Structured Clinical Examination (DHLOSCE) toward the clinical requirement — a third option worth asking your program about alongside ADEX and CRDTS.
Before you register for any of them, confirm directly with the board of the state where you intend to practice first, since a clinical exam result doesn't automatically transfer to a state that doesn't recognize it.
Clinical boards vs. the NBDHE
It's easy to conflate the two exams because both stand between graduation and an RDH license, but they test different things and work differently.
The NBDHE is a single national written exam — one body (the JCNDE), one 350-item multiple-choice format, the same everywhere.
The clinical board exam is regional and hands-on — multiple possible agencies, a live or manikin-based skills demonstration, and a format that varies by where you're testing.
Most programs have students sit for the NBDHE during their final year, and the clinical board exam is typically scheduled around the same time, but there's no single required order — check your program's timeline and your target state's rules.
Passing both, plus most states' additional jurisprudence exam on state dental law, is what completes the licensure requirement covered in full in our step-by-step guide to becoming a dental hygienist.
For what the RDH credential these two exams lead to actually involves day to day, see our overview of what a dental hygienist does.
Two separate exams, two separate registrations
How to prepare
Because the exam is hands-on, the most effective preparation happens inside your program rather than from outside study materials.
Work with your clinical faculty and program coordinator early — they typically know which agency's exam your state uses and can walk you through that agency's specific grading criteria, since a technique that satisfies one agency's rubric can fall short of another's.
Practice under exam-day time pressure, not just for accuracy: calculus detection, periodontal probing, and tissue management are all graded on precision within a set time limit, and rushing under pressure is a different skill than performing the same task in an unhurried lab session.
Read the current candidate manual for your agency closely and early — infection-control and setup requirements are graded strictly, and a procedural misstep can cost you before the clinical work even starts.
If your test site still uses a live-patient format, line up a patient (or patients) who meet the required case criteria well in advance, since finding an eligible patient close to your test date is one of the most common last-minute scrambles candidates report.
This article is general career information, not legal or clinical advice. Clinical exam agencies, formats, fees, and state acceptance change over time — verify current details with ADEX, CRDTS, and the dental board of the state where you plan to practice.