National Board Dental Hygiene Examination (NBDHE) practice exam Questions And Correct Answers
(Verified Answers) Plus Rationales 2026 Q&A | Instant Download Pdf
1. Which of the following bacteria is most strongly associated with
periodontitis?
A. Streptococcus mutans
B. Porphyromonas gingivalis
C. Lactobacillus acidophilus
D. Actinomyces viscosus
Porphyromonas gingivalis is a key pathogen in chronic periodontitis, producing
virulence factors that destroy periodontal tissue and evade host defenses.
2. The primary mineral component of enamel is:
A. Calcium carbonate
B. Hydroxyapatite
C. Fluorapatite
D. Magnesium phosphate
Enamel is composed mainly of hydroxyapatite crystals, giving it hardness and
resistance to wear.
3. Which nerve supplies sensation to the anterior two-thirds of the tongue?
A. Hypoglossal nerve
B. Glossopharyngeal nerve
,National Board Dental Hygiene Examination (NBDHE) practice exam Questions And Correct Answers
(Verified Answers) Plus Rationales 2026 Q&A | Instant Download Pdf
C. Lingual nerve
D. Vagus nerve
The lingual nerve, a branch of the mandibular division of the trigeminal nerve
(V3), provides general sensation to the anterior two-thirds of the tongue.
4. The most effective method for sterilizing heat-sensitive dental instruments
is:
A. Steam autoclave
B. Dry heat
C. Chemical vapor sterilization
D. Boiling
Chemical vapor sterilization is suitable for heat-sensitive instruments and
effectively kills all microbial forms without corrosion.
5. A patient presents with a bluish-purple lesion on the lateral border of the
tongue. The lesion is painless and has been present for 3 months. The most
likely diagnosis is:
A. Candidiasis
B. Kaposi sarcoma
C. Fibroma
D. Leukoplakia
Kaposi sarcoma often appears as painless bluish-purple lesions in
immunocompromised patients, particularly those with HIV/AIDS.
6. The most common site for oral squamous cell carcinoma is:
A. Hard palate
B. Gingiva
C. Lateral border of the tongue
D. Buccal mucosa
The lateral border of the tongue is the most frequent site for oral squamous cell
carcinoma due to exposure to carcinogens and high epithelial turnover.
, National Board Dental Hygiene Examination (NBDHE) practice exam Questions And Correct Answers
(Verified Answers) Plus Rationales 2026 Q&A | Instant Download Pdf
7. Which vitamin deficiency is most likely to cause scurvy?
A. Vitamin A
B. Vitamin D
C. Vitamin C
D. Vitamin K
Vitamin C deficiency impairs collagen synthesis, leading to weakened
connective tissue, bleeding gums, and delayed wound healing.
8. The first line of defense in the immune system is:
A. T lymphocytes
B. Physical and chemical barriers
C. B lymphocytes
D. Macrophages
Physical and chemical barriers, such as skin and mucosa, prevent pathogens
from entering the body and are part of innate immunity.
9. The recommended fluoride concentration in drinking water in the United
States is:
A. 0.1 ppm
B. 0.5 ppm
C. 0.7 ppm
D. 1.5 ppm
The U.S. Public Health Service recommends 0.7 ppm fluoride in water to
prevent dental caries while minimizing fluorosis risk.
10. Which of the following conditions is a contraindication for ultrasonic
scaling?
A. Gingivitis
B. Periodontitis
C. Patients with pacemakers (older models)
D. Calculus deposits
Certain pacemakers may be affected by older ultrasonic devices; caution or
alternative methods should be used.
(Verified Answers) Plus Rationales 2026 Q&A | Instant Download Pdf
1. Which of the following bacteria is most strongly associated with
periodontitis?
A. Streptococcus mutans
B. Porphyromonas gingivalis
C. Lactobacillus acidophilus
D. Actinomyces viscosus
Porphyromonas gingivalis is a key pathogen in chronic periodontitis, producing
virulence factors that destroy periodontal tissue and evade host defenses.
2. The primary mineral component of enamel is:
A. Calcium carbonate
B. Hydroxyapatite
C. Fluorapatite
D. Magnesium phosphate
Enamel is composed mainly of hydroxyapatite crystals, giving it hardness and
resistance to wear.
3. Which nerve supplies sensation to the anterior two-thirds of the tongue?
A. Hypoglossal nerve
B. Glossopharyngeal nerve
,National Board Dental Hygiene Examination (NBDHE) practice exam Questions And Correct Answers
(Verified Answers) Plus Rationales 2026 Q&A | Instant Download Pdf
C. Lingual nerve
D. Vagus nerve
The lingual nerve, a branch of the mandibular division of the trigeminal nerve
(V3), provides general sensation to the anterior two-thirds of the tongue.
4. The most effective method for sterilizing heat-sensitive dental instruments
is:
A. Steam autoclave
B. Dry heat
C. Chemical vapor sterilization
D. Boiling
Chemical vapor sterilization is suitable for heat-sensitive instruments and
effectively kills all microbial forms without corrosion.
5. A patient presents with a bluish-purple lesion on the lateral border of the
tongue. The lesion is painless and has been present for 3 months. The most
likely diagnosis is:
A. Candidiasis
B. Kaposi sarcoma
C. Fibroma
D. Leukoplakia
Kaposi sarcoma often appears as painless bluish-purple lesions in
immunocompromised patients, particularly those with HIV/AIDS.
6. The most common site for oral squamous cell carcinoma is:
A. Hard palate
B. Gingiva
C. Lateral border of the tongue
D. Buccal mucosa
The lateral border of the tongue is the most frequent site for oral squamous cell
carcinoma due to exposure to carcinogens and high epithelial turnover.
, National Board Dental Hygiene Examination (NBDHE) practice exam Questions And Correct Answers
(Verified Answers) Plus Rationales 2026 Q&A | Instant Download Pdf
7. Which vitamin deficiency is most likely to cause scurvy?
A. Vitamin A
B. Vitamin D
C. Vitamin C
D. Vitamin K
Vitamin C deficiency impairs collagen synthesis, leading to weakened
connective tissue, bleeding gums, and delayed wound healing.
8. The first line of defense in the immune system is:
A. T lymphocytes
B. Physical and chemical barriers
C. B lymphocytes
D. Macrophages
Physical and chemical barriers, such as skin and mucosa, prevent pathogens
from entering the body and are part of innate immunity.
9. The recommended fluoride concentration in drinking water in the United
States is:
A. 0.1 ppm
B. 0.5 ppm
C. 0.7 ppm
D. 1.5 ppm
The U.S. Public Health Service recommends 0.7 ppm fluoride in water to
prevent dental caries while minimizing fluorosis risk.
10. Which of the following conditions is a contraindication for ultrasonic
scaling?
A. Gingivitis
B. Periodontitis
C. Patients with pacemakers (older models)
D. Calculus deposits
Certain pacemakers may be affected by older ultrasonic devices; caution or
alternative methods should be used.
