NBDHE EXAM ACTUAL EXAM 2025
QUESTIONS 1 to 150 DETAILED
CORRECT ANSWERS WITH
RATIONALES GRADE A+
VERIFIED | INSTANT DOWNLOAD
NBDHE Exam Actual Exam 2025
Question 1
A 45-year-old male patient presents for a routine dental hygiene
appointment. During the intraoral examination, the dental hygienist
notes a well-demarcated, painless, white patch on the left lateral border
of the tongue that cannot be wiped off with gauze. The patient has a 20
pack-year smoking history. Which term should the hygienist use to
document this clinical finding, and what is the next step in management?
A. Candidiasis; prescribe a topical antifungal medication.
B. Leukoplakia; refer the patient for a biopsy to rule out dysplasia or
malignancy.
C. Leukoedema; reassure the patient that it is a benign variation of
normal mucosa.
D. Lichen planus; instruct the patient to rinse daily with an alcohol-
based mouthwash.
Correct Answer: B. Leukoplakia; refer the patient for a
biopsy to rule out dysplasia or malignancy.
Rationale: Leukoplakia is a clinical term for a white patch or plaque
that cannot be rubbed off and cannot be characterized clinically as any
other disease. Given the patient's extensive smoking history and the
high-risk location (lateral border of the tongue), immediate referral for
a definitive histological diagnosis via biopsy is mandatory to check for
epithelial dysplasia or squamous cell carcinoma.
,Question 2
A patient with a history of infective endocarditis is scheduled for
periodontal scaling and root planing. The patient has a documented
anaphylactic allergy to penicillin. Which antibiotic regimen should the
dental hygienist verify that the patient consumed exactly 1 hour prior to
the appointment?
A. Amoxicillin 2 g orally
B. Clindamycin 600 mg orally
C. Cephalexin 2 g orally
D. Azithromycin 500 mg orally
Correct Answer: D. Azithromycin 500 mg orally
Rationale: According to the current American Heart Association
(AHA) guidelines for the prevention of infective endocarditis, patients
with a severe, anaphylactic allergy to penicillin or amoxicillin should
receive oral azithromycin (500 mg) or clarithromycin (500 mg), or
doxycycline (100 mg) 30 to 60 minutes before the procedure.
Clindamycin is no longer recommended by the AHA for antibiotic
prophylaxis due to adverse side effects.
Question 3
During a routine periodontal assessment, the dental hygienist notes that
a patient has generalized 5 to 6 mm pocket depths, 3 to 4 mm of clinical
attachment loss (CAL), and radiographic bone loss extending into the
middle third of the root. The patient has lost two teeth due to
periodontal disease. According to the AAP/EFP Periodontal
Classification, how should this patient's periodontal status be staged?
A. Stage I Periodontitis
B. Stage II Periodontitis
C. Stage III Periodontitis
D. Stage IV Periodontitis
Correct Answer: C. Stage III Periodontitis
Rationale: Stage III periodontitis is characterized by pocket depths
≥6 mm, clinical attachment loss ≥5 mm, radiographic bone loss
extending into the middle third of the root or beyond, and ≤4 teeth lost
due to periodontitis. Stage IV requires ≥5 teeth lost to periodontal
disease and more advanced dentition collapse.
Question 4
,A dental hygienist is preparing to scale the distal surface of a mandibular
first molar. Which Gracey curette is anatomically designed specifically to
adapt to and debride the distal surfaces of posterior teeth?
A. Gracey 1/2
B. Gracey 7/8
C. Gracey 11/12
D. Gracey 13/14
Correct Answer: D. Gracey 13/14
Rationale: Gracey curettes are area-specific instruments. The Gracey
13/14 (and 17/18) is specifically designed with a pronounced shank
curvature to adapt effectively to the distal surfaces of posterior teeth.
The Gracey 11/12 (and 15/16) is used for the mesial surfaces of posterior
teeth.
Question 5
A 7-year-old child presents with a high caries risk. The dental hygienist
notes that the permanent first molars have completely erupted, and the
occlusal pits and fissures are deep and narrow but currently caries-free.
Which preventive intervention is most effective for this patient?
A. Apply a custom-fitted tray containing 1.23% acidulated phosphate
fluoride gel.
B. Recommend an over-the-counter antimicrobial mouthrinse twice
daily.
C. Place resin-based pit and fissure sealants on the permanent first
molars.
D. Perform aggressive enameloplasty on the occlusal grooves using a
diamond bur.
Correct Answer: C. Place resin-based pit and fissure
sealants on the permanent first molars.
Rationale: Pit and fissure sealants provide a highly effective physical
barrier that prevents food particles and plaque acid from accumulating
in the deep, narrow grooves of newly erupted permanent molars,
drastically reducing the risk of occlusal caries in high-risk pediatric
patients.
Question 6
While reviewing a patient’s panoramic radiograph, the dental hygienist
notes a well-defined, radiolucent area located inferior to the mandibular
, canal in the region of the mandibular second molar. The patient is
asymptomatic, and the adjacent teeth are vital. What is the most likely
interpretation of this radiographic finding?
A. Ameloblastoma
B. Radicular cyst
C. Stafne defect (Static bone cyst)
D. Odontogenic keratocyst
Correct Answer: C. Stafne defect (Static bone cyst)
Rationale: A Stafne bone defect is a classic developmental anomaly
representing a well-demarcated cortical depression on the lingual
surface of the mandible containing salivary gland tissue. It
characteristically appears below the inferior alveolar nerve canal in the
posterior mandible, is benign, asymptomatic, and requires no
therapeutic intervention.
Question 7
A dental hygienist is performing a dietary analysis for a patient with
rampantly active smooth-surface dental caries. Which carbohydrate is
considered the most cariogenic substrate for acid-producing oral
bacteria, specifically driving extracellular polysaccharide matrix
synthesis?
A. Fructose
B. Glucose
C. Lactose
D. Sucrose
Correct Answer: D. Sucrose
Rationale: Sucrose is the most cariogenic carbohydrate because oral
bacteria, specifically Streptococcus mutans, utilize it not only for
glycolysis (producing lactic acid) but also to synthesize water-insoluble
glucans (extracellular polysaccharides). These glucans promote
bacterial adherence to the enamel surface and shield the plaque biofilm
from salivary buffering.
Question 8
A patient with an extensive history of chronic generalized periodontitis is
scheduled for a dental hygiene maintenance appointment. The hygienist
notes that the patient's subgingival microflora has shifted toward a
highly pathogenic anaerobic profile. Which bacterial species belongs to
QUESTIONS 1 to 150 DETAILED
CORRECT ANSWERS WITH
RATIONALES GRADE A+
VERIFIED | INSTANT DOWNLOAD
NBDHE Exam Actual Exam 2025
Question 1
A 45-year-old male patient presents for a routine dental hygiene
appointment. During the intraoral examination, the dental hygienist
notes a well-demarcated, painless, white patch on the left lateral border
of the tongue that cannot be wiped off with gauze. The patient has a 20
pack-year smoking history. Which term should the hygienist use to
document this clinical finding, and what is the next step in management?
A. Candidiasis; prescribe a topical antifungal medication.
B. Leukoplakia; refer the patient for a biopsy to rule out dysplasia or
malignancy.
C. Leukoedema; reassure the patient that it is a benign variation of
normal mucosa.
D. Lichen planus; instruct the patient to rinse daily with an alcohol-
based mouthwash.
Correct Answer: B. Leukoplakia; refer the patient for a
biopsy to rule out dysplasia or malignancy.
Rationale: Leukoplakia is a clinical term for a white patch or plaque
that cannot be rubbed off and cannot be characterized clinically as any
other disease. Given the patient's extensive smoking history and the
high-risk location (lateral border of the tongue), immediate referral for
a definitive histological diagnosis via biopsy is mandatory to check for
epithelial dysplasia or squamous cell carcinoma.
,Question 2
A patient with a history of infective endocarditis is scheduled for
periodontal scaling and root planing. The patient has a documented
anaphylactic allergy to penicillin. Which antibiotic regimen should the
dental hygienist verify that the patient consumed exactly 1 hour prior to
the appointment?
A. Amoxicillin 2 g orally
B. Clindamycin 600 mg orally
C. Cephalexin 2 g orally
D. Azithromycin 500 mg orally
Correct Answer: D. Azithromycin 500 mg orally
Rationale: According to the current American Heart Association
(AHA) guidelines for the prevention of infective endocarditis, patients
with a severe, anaphylactic allergy to penicillin or amoxicillin should
receive oral azithromycin (500 mg) or clarithromycin (500 mg), or
doxycycline (100 mg) 30 to 60 minutes before the procedure.
Clindamycin is no longer recommended by the AHA for antibiotic
prophylaxis due to adverse side effects.
Question 3
During a routine periodontal assessment, the dental hygienist notes that
a patient has generalized 5 to 6 mm pocket depths, 3 to 4 mm of clinical
attachment loss (CAL), and radiographic bone loss extending into the
middle third of the root. The patient has lost two teeth due to
periodontal disease. According to the AAP/EFP Periodontal
Classification, how should this patient's periodontal status be staged?
A. Stage I Periodontitis
B. Stage II Periodontitis
C. Stage III Periodontitis
D. Stage IV Periodontitis
Correct Answer: C. Stage III Periodontitis
Rationale: Stage III periodontitis is characterized by pocket depths
≥6 mm, clinical attachment loss ≥5 mm, radiographic bone loss
extending into the middle third of the root or beyond, and ≤4 teeth lost
due to periodontitis. Stage IV requires ≥5 teeth lost to periodontal
disease and more advanced dentition collapse.
Question 4
,A dental hygienist is preparing to scale the distal surface of a mandibular
first molar. Which Gracey curette is anatomically designed specifically to
adapt to and debride the distal surfaces of posterior teeth?
A. Gracey 1/2
B. Gracey 7/8
C. Gracey 11/12
D. Gracey 13/14
Correct Answer: D. Gracey 13/14
Rationale: Gracey curettes are area-specific instruments. The Gracey
13/14 (and 17/18) is specifically designed with a pronounced shank
curvature to adapt effectively to the distal surfaces of posterior teeth.
The Gracey 11/12 (and 15/16) is used for the mesial surfaces of posterior
teeth.
Question 5
A 7-year-old child presents with a high caries risk. The dental hygienist
notes that the permanent first molars have completely erupted, and the
occlusal pits and fissures are deep and narrow but currently caries-free.
Which preventive intervention is most effective for this patient?
A. Apply a custom-fitted tray containing 1.23% acidulated phosphate
fluoride gel.
B. Recommend an over-the-counter antimicrobial mouthrinse twice
daily.
C. Place resin-based pit and fissure sealants on the permanent first
molars.
D. Perform aggressive enameloplasty on the occlusal grooves using a
diamond bur.
Correct Answer: C. Place resin-based pit and fissure
sealants on the permanent first molars.
Rationale: Pit and fissure sealants provide a highly effective physical
barrier that prevents food particles and plaque acid from accumulating
in the deep, narrow grooves of newly erupted permanent molars,
drastically reducing the risk of occlusal caries in high-risk pediatric
patients.
Question 6
While reviewing a patient’s panoramic radiograph, the dental hygienist
notes a well-defined, radiolucent area located inferior to the mandibular
, canal in the region of the mandibular second molar. The patient is
asymptomatic, and the adjacent teeth are vital. What is the most likely
interpretation of this radiographic finding?
A. Ameloblastoma
B. Radicular cyst
C. Stafne defect (Static bone cyst)
D. Odontogenic keratocyst
Correct Answer: C. Stafne defect (Static bone cyst)
Rationale: A Stafne bone defect is a classic developmental anomaly
representing a well-demarcated cortical depression on the lingual
surface of the mandible containing salivary gland tissue. It
characteristically appears below the inferior alveolar nerve canal in the
posterior mandible, is benign, asymptomatic, and requires no
therapeutic intervention.
Question 7
A dental hygienist is performing a dietary analysis for a patient with
rampantly active smooth-surface dental caries. Which carbohydrate is
considered the most cariogenic substrate for acid-producing oral
bacteria, specifically driving extracellular polysaccharide matrix
synthesis?
A. Fructose
B. Glucose
C. Lactose
D. Sucrose
Correct Answer: D. Sucrose
Rationale: Sucrose is the most cariogenic carbohydrate because oral
bacteria, specifically Streptococcus mutans, utilize it not only for
glycolysis (producing lactic acid) but also to synthesize water-insoluble
glucans (extracellular polysaccharides). These glucans promote
bacterial adherence to the enamel surface and shield the plaque biofilm
from salivary buffering.
Question 8
A patient with an extensive history of chronic generalized periodontitis is
scheduled for a dental hygiene maintenance appointment. The hygienist
notes that the patient's subgingival microflora has shifted toward a
highly pathogenic anaerobic profile. Which bacterial species belongs to
