TheoryFree Dental Hygiene NBDHE Practice Test
Take a free Dental Hygiene NBDHE practice test for 2026 with questions, answers, explanations, PDF download and timed mock exam links.
Dental Hygiene NBDHE Questions
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Q1In a healthy adult, what is the typical depth of the gingival sulcus measured with a periodontal probe?
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✓ Correct answer: 1 to 3 millimeters
A clinically healthy sulcus measures roughly 1 to 3 mm. Readings of 4 mm or more usually indicate attachment loss or a pseudopocket and warrant further evaluation.
Q2Which group of periodontal ligament fibers chiefly resists vertical (intrusive) occlusal forces by suspending the tooth in its socket?
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✓ Correct answer: Oblique fibers
Oblique fibers are the most numerous PDL group and run coronally from bone to apically on the cementum, resisting masticatory forces that tend to push the tooth into its socket.
Q3Under the 2017 AAP/EFP classification, a patient with 5 mm clinical attachment loss, probing depths of 6 mm, and bone loss extending to the middle third of the root is best staged as which periodontitis stage?
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✓ Correct answer: Stage III
Interdental CAL of 5 mm or more and radiographic bone loss reaching the mid-third of the root place the case in Stage III, which also carries potential for tooth loss without intervention.
Q4Subgingival calculus most commonly appears which color when detected clinically?
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✓ Correct answer: Dark brown or black
Subgingival calculus is darkened (brown to black) by blood pigments from inflamed pocket tissue, in contrast to the white-to-yellow supragingival calculus.
Q5When adapting a Gracey curet for subgingival scaling, what is the correct working-end angulation of the blade face to the tooth surface?
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✓ Correct answer: Between 45 and 90 degrees
An angulation between 45 and 90 degrees lets the cutting edge engage and remove the deposit; angles below 45 degrees burnish calculus and angles near 90 degrees can gouge.
Q6A Gracey 13/14 curet is specifically designed to instrument which surfaces?
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✓ Correct answer: Posterior distal surfaces
Gracey curets are area-specific: 13/14 is angled for distal surfaces of posterior teeth, while 11/12 is for mesial posterior surfaces.
Q7Which inflammatory mediator most directly stimulates osteoclastic alveolar bone resorption in periodontitis?
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✓ Correct answer: Prostaglandin E2
Prostaglandin E2, along with IL-1 and TNF-alpha, upregulates the RANKL pathway driving osteoclast activity and bone loss; IL-10 is anti-inflammatory.
Q8Which bacterium of the 'red complex' is most strongly associated with chronic periodontitis?
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✓ Correct answer: Porphyromonas gingivalis
Porphyromonas gingivalis, a Gram-negative anaerobe of the red complex, is a key periodontal pathogen; S. mutans and Lactobacillus are caries-related.
Q9The classic clinical triad of necrotizing ulcerative gingivitis (NUG) is pain, gingival bleeding, and which third sign?
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✓ Correct answer: Punched-out, cratered interdental papillae
NUG presents with necrosis producing punched-out, cratered papillae often covered by a gray pseudomembrane, accompanied by spontaneous bleeding and marked pain.
Q10A Nabers probe is the instrument of choice for assessing what periodontal finding?
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✓ Correct answer: Furcation involvement
The curved Nabers probe is designed to detect and grade horizontal furcation involvement on multirooted teeth.
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