NBDE Practice Test

NBDE Exam at a Glance

What changed for NBDE in 2026

• Oct 25, 2026: Delivery changed to Computer-based at Prometric test centers (US and Canada) (previously Computer-based at Prometric test centers (US, territories, Canada)).^[1]
• Oct 25, 2026: Passing score changed to Scale score 75 minimum pass (scale 49–99) (previously Pass/fail; scale score 75 = minimum pass (scale 49–99)).^[1]
• Oct 25, 2026: Score release changed to Within 4 weeks, usually within 3 weeks (previously About 3–4 weeks after the exam).^[1]
• Oct 25, 2026: Retake policy changed to 60-day wait; max 4 attempts per 12 months; 5 years/5 attempts rule (previously Wait 60 days; max 4 attempts per 12 months; pass within 5 years/5 attempts).^[1]
• Oct 25, 2026: Testing window changed to 6-month eligibility period after application is processed (previously 6-month eligibility window after application approval).^[1]
• Oct 25, 2026: Eligibility changed to Non-CODA graduates need ECE degree confirmation (previously Dean confirmation (CODA students); ECE credential evaluation for non-CODA candidates).^[1]

What the NBDE is and how it works

According to Joint Commission on National Dental Examinations (JCNDE), American Dental Association, “Scale scores range from 49 to 99, with a score of 75 representing the minimum passing score.”^[1]

The National Board Dental Examination tests whether a candidate can apply dental science and clinical knowledge safely. It is run by the Joint Commission on National Dental Examinations (JCNDE), part of the American Dental Association. The current JCNDE candidate guide covers the Integrated National Board Dental Examination (INBDE), and every rule below comes from that guide.

• Delivery: the exam is taken on a computer at Prometric test centers in the United States and Canada.
• Scoring: scale scores range from 49 to 99. The minimum passing score is 75.
• Results: the JCNDE aims to report results within 4 weeks of your exam date. Most results arrive within 3 weeks.
• Eligibility window: once your application is processed, you have a 6-month period to test. The guide lists the exceptions.
• Non-CODA graduates: if your dental program was not CODA-accredited, your degree must be confirmed through Educational Credential Evaluators Inc. (ECE).
• Retakes: after an unsuccessful attempt you must wait at least 60 days before testing again. You can take the exam no more than 4 times in any 12-month period. The guide sets further limits on total attempts.

This exam does not license you by itself. Each state dental board grants the license, and requirements beyond this exam vary from state to state. Rules can change, so check the JCNDE candidate guide and your state board's website before you apply.

Worked examples: how to reason through NBDE questions

These are practice questions written for this site, not questions from the real exam. Each explanation shows why the right answer is right and why the others are wrong.

Example 1

Question: Which type of dental radiograph is best for detecting interproximal caries?

1. Periapical
2. Occlusal
3. Bitewing
4. Panoramic

Answer: C. Bitewing

Explanation:

Bitewing (C) is correct. A bitewing shows the crowns of upper and lower posterior teeth in the same image, with the beam aimed through the contacts. That angle opens up the interproximal surfaces, where early caries is hard to see in a clinical exam. Periapical (A) covers the whole tooth down to the root apex. It suits periapical disease and root problems, and the contacts often overlap. Occlusal (B) gives a broad view of the arch from above. It helps with large lesions, impacted teeth or salivary stones, but not small lesions between teeth. Panoramic (D) surveys the whole jaw but shows less detail, and the contacts often overlap. Rule to remember: for interproximal caries and crestal bone levels, choose bitewings.

Example 2

Question: What promotes remineralization and has antibacterial qualities?

1. Tooth decay
2. Acid reflux
3. Saliva
4. Carioprotective

Answer: C. Saliva

Explanation:

Saliva (C) is correct. Saliva carries calcium and phosphate that redeposit into early enamel lesions, and its buffers neutralize plaque acids. It also contains antimicrobial proteins such as lysozyme, lactoferrin and secretory IgA, which limit bacterial growth. Tooth decay (A) is the result of demineralization, the opposite of what the question asks for. Acid reflux (B) brings stomach acid into the mouth and causes erosion, so it removes mineral instead of restoring it. Carioprotective (D) is an adjective for anything that protects against caries. It is not a substance, so it cannot be the answer, even though it sounds related. Rule to remember: if a question links remineralization, buffering and antibacterial action, the answer is saliva. Low salivary flow raises caries risk.

Example 3

Question: A clinician is preparing a Class II cavity for an amalgam restoration on a mandibular molar. To ensure adequate resistance form, which of the following design features is most important?

1. Convergent buccal and lingual walls.
2. A flat pulpal floor perpendicular to the long axis of the tooth.
3. Beveling the axiopulpal line angle.
4. Ensuring the isthmus width is less than one-fourth the intercuspal distance.

Answer: B. A flat pulpal floor perpendicular to the long axis of the tooth.

Explanation:

A flat pulpal floor perpendicular to the long axis (B) is correct. Resistance form is what lets the tooth and the restoration take chewing forces without fracturing. A flat floor at right angles to the long axis sends the occlusal load down the tooth instead of acting as a wedge that could split cusps. Convergent buccal and lingual walls (A) lock the amalgam in place. That is retention form, not resistance form. Beveling the axiopulpal line angle (C) reduces stress and adds amalgam bulk, but it is a secondary refinement, not the main resistance feature. A narrow isthmus (D) protects the cusps and supports resistance form, but the floor matters more for how force is carried. Rule to remember: flat floors and enough bulk resist fracture, while convergent walls and locks retain the restoration.

How to use these practice tests

Start with the official source. Read the eligibility, scoring and retake sections of the JCNDE candidate guide. Apply when it lets your 6-month eligibility period line up with your study time.

• Find your weak areas. Take the NBDE practice test without notes and list the topics you missed.
• Work by subject. Move to the sets that match your misses, such as Pharmacology and Pain Control, Periodontics, Oral Pathology and Radiology or Prosthodontics and Operative Dentistry. Read every explanation, including the ones for questions you got right.
• Practice clinical reasoning. Use Diagnosis and Treatment Planning and Professional Ethics and Management to apply facts to patient cases.
• Keep an error log. For each miss, write down the rule behind it, not just the correct letter. Review the log before each new session.
• Finish with mixed review. Close to test day, do the mixed NBDE review set and the NBDE preparation test under timed conditions. Then go back to your error log.

Sources & last verified

1. Joint Commission on National Dental Examinations (JCNDE), American Dental Association — passing score, retake policy, delivery, eligibility (official source). “Scale scores range from 49 to 99, with a score of 75 representing the minimum passing score.” Verified Oct 25, 2026.

How we verify: editorial & fact-checking policy. Report an error: contact us.