NBDHE Study Guide 2026
Everything you need to pass the NBDHE exam in one place: the exam format, every topic to study, real practice questions with explanations, flashcards, and full-length practice tests. Free, no sign-up needed.
📋 NBDHE Exam Format at a Glance
📚 NBDHE Topics to Study (103)
✍️ Sample NBDHE Questions & Answers
1. Which type of cyst is the most common odontogenic cyst of the jaws?
Radicular (periapical) cysts are the most common odontogenic cysts, forming from epithelial cell rests at the apex of a non-vital tooth.
2. Which ethical principle is violated when a dental hygienist continues treatment against a patient's clearly expressed wishes?
Autonomy is the patient's right to self-determination; continuing treatment against expressed wishes violates this fundamental ethical principle.
3. In the hierarchy of prevention, tertiary prevention in community oral health is best exemplified by:
Tertiary prevention addresses disability and loss of function that has already occurred — replacing missing teeth with prostheses or implants rehabilitates function after disease has progressed beyond treatment, distinguishing it from primary (preventing disease onset) and secondary (early detection and treatment) prevention.
4. A radiolucent lesion associated with the crown of an unerupted tooth is most likely a:
Dentigerous (follicular) cysts form by expansion of the follicular space around the crown of an unerupted tooth.
5. Compared to a round (cylindrical) position-indicating device (PID), the use of a rectangular collimator reduces the patient's radiation exposure by approximately:
A round PID exposes a circular field roughly 2.75 inches in diameter, much larger than the film or sensor. A rectangular collimator restricts the beam to just slightly larger than the receptor, reducing the irradiated tissue area and lowering patient dose by approximately 60% (range 55–70%). This makes rectangular collimation one of the most effective dose-reduction strategies in intraoral radiography.
6. The Bass toothbrushing technique is most effective at removing plaque from:
The Bass technique positions bristles at 45 degrees toward the gingival sulcus, making it highly effective at removing subgingival plaque at the gingival margin.