2025 Comprehensive Guide to the National Board
Dental Hygiene Examination (NBDHE): Study Tips,
Practice Questions, and Expert Strategies for
Success
1. Each of the following oral microorganisms could colonize soft tissue EXCEPT
one. Which one is this EXCEPTION?
A. Neisseria sicca
B. Candida albicans
C. Streptococcus mitis
D. Streptococcus mutans
E. Streptococcus salivarius
Correct Answer: D. Streptococcus mutans
Rationale:
• Streptococcus mutans primarily colonizes hard surfaces such as enamel and is
heavily implicated in dental caries, not soft tissues.
• Neisseria sicca, Candida albicans, Streptococcus mitis, and Streptococcus
salivarius can colonize soft tissues like the tongue, cheeks, or mucosa.
2. The virus responsible for which of the following diseases is the MOST resistant to
chemical and physical agents?
A. AIDS
B. Herpes
C. Measles
D. Influenza
E. Hepatitis
Correct Answer: E. Hepatitis
Rationale:
• Hepatitis viruses, particularly Hepatitis B, are highly resistant to heat,
desiccation, and many disinfectants.
• HIV (AIDS) is easily inactivated outside the body.
, • Herpes, measles, and influenza viruses are all enveloped and generally less
resistant to environmental stressors.
3. Root hypersensitivity diminishes as the tooth forms which of the following?
A. Mantle dentin
B. Secondary dentin
C. Cellular cementum
D. Acellular cementum
Correct Answer: C. Cellular cementum
Rationale:
• Cellular cementum covers the apical portion of the root and helps protect
dentinal tubules, reducing hypersensitivity.
• Mantle dentin and secondary dentin are involved in dentinogenesis, but don't
directly reduce root sensitivity as cellular cementum does.
• Acellular cementum is found at the cervical portion and is more involved in
tooth anchorage than sensitivity reduction.
4. A 21-year-old woman, third trimester pregnancy, has a 3 mm pyogenic
granuloma. After oral hygiene instructions, the NEXT step is:
A. Perform an oral prophylaxis.
B. Suggest that the patient see a periodontist.
C. Refer for excision of the granuloma.
D. Wait for hormonal influences to subside.
E. Reappoint one month later.
Correct Answer: A. Perform an oral prophylaxis
Rationale:
• A conservative approach is best during pregnancy. Professional cleaning can
reduce local inflammation and potentially shrink the granuloma.
• Referring for excision or periodontist consultation may be premature.
• Waiting or reappointing later delays treatment that could relieve symptoms
with minimal risk.
,5. Which of the following nerves supplies the intrinsic muscles of the tongue?
A. Vagus
B. Facial
C. Lingual
D. Hypoglossal
E. Glossopharyngeal
Correct Answer: D. Hypoglossal
Rationale:
• The hypoglossal nerve (cranial nerve XII) innervates all intrinsic and most
extrinsic tongue muscles.
• The lingual nerve provides sensory, not motor, innervation.
• Facial, glossopharyngeal, and vagus nerves are involved in taste and
pharyngeal muscle control, not tongue muscle movement.
6. Which of the following tissues and organs is/are the MOST radioresistant?
A. Nerves
B. Glands
C. Skin
D. Bone marrow
E. Reproductive organs
Correct Answer: A. Nerves
Rationale:
• Nerve tissue has a low mitotic rate, making it highly resistant to radiation
damage.
• Bone marrow and reproductive organs have rapidly dividing cells, making them
radiosensitive.
• Skin and glands are moderately sensitive but not as radioresistant as nerves.
7. Superficial lymphatic vessels of the breast drain primarily into which of the
following nodes?
A. Axillary
B. Cervical
, C. Substernal
D. Subclavicular
E. Supraclavicular
Correct Answer: A. Axillary
Rationale:
• The axillary lymph nodes are the primary drainage site for the majority of
breast tissue, especially the outer quadrants.
• Substernal (internal thoracic) nodes also play a role but to a lesser extent.
• Cervical, subclavicular, and supraclavicular nodes may be involved in
advanced disease or metastasis.
Primarily, systemic fluorides protect the teeth by which of the following actions?
A. Lowering their surface energy
B. Creating bacteriostasis
C. Inhibiting enzyme activity
D. Reducing the fluoroapatite solubility
E. Improving their morphology - - correct ans- -D
Bell's palsy involves which of the following cranial nerves?
A. III
B. IV
c. V
D. VII
E. IX - - correct ans- -D
Periodontal disease is considered to be controlled when
Dental Hygiene Examination (NBDHE): Study Tips,
Practice Questions, and Expert Strategies for
Success
1. Each of the following oral microorganisms could colonize soft tissue EXCEPT
one. Which one is this EXCEPTION?
A. Neisseria sicca
B. Candida albicans
C. Streptococcus mitis
D. Streptococcus mutans
E. Streptococcus salivarius
Correct Answer: D. Streptococcus mutans
Rationale:
• Streptococcus mutans primarily colonizes hard surfaces such as enamel and is
heavily implicated in dental caries, not soft tissues.
• Neisseria sicca, Candida albicans, Streptococcus mitis, and Streptococcus
salivarius can colonize soft tissues like the tongue, cheeks, or mucosa.
2. The virus responsible for which of the following diseases is the MOST resistant to
chemical and physical agents?
A. AIDS
B. Herpes
C. Measles
D. Influenza
E. Hepatitis
Correct Answer: E. Hepatitis
Rationale:
• Hepatitis viruses, particularly Hepatitis B, are highly resistant to heat,
desiccation, and many disinfectants.
• HIV (AIDS) is easily inactivated outside the body.
, • Herpes, measles, and influenza viruses are all enveloped and generally less
resistant to environmental stressors.
3. Root hypersensitivity diminishes as the tooth forms which of the following?
A. Mantle dentin
B. Secondary dentin
C. Cellular cementum
D. Acellular cementum
Correct Answer: C. Cellular cementum
Rationale:
• Cellular cementum covers the apical portion of the root and helps protect
dentinal tubules, reducing hypersensitivity.
• Mantle dentin and secondary dentin are involved in dentinogenesis, but don't
directly reduce root sensitivity as cellular cementum does.
• Acellular cementum is found at the cervical portion and is more involved in
tooth anchorage than sensitivity reduction.
4. A 21-year-old woman, third trimester pregnancy, has a 3 mm pyogenic
granuloma. After oral hygiene instructions, the NEXT step is:
A. Perform an oral prophylaxis.
B. Suggest that the patient see a periodontist.
C. Refer for excision of the granuloma.
D. Wait for hormonal influences to subside.
E. Reappoint one month later.
Correct Answer: A. Perform an oral prophylaxis
Rationale:
• A conservative approach is best during pregnancy. Professional cleaning can
reduce local inflammation and potentially shrink the granuloma.
• Referring for excision or periodontist consultation may be premature.
• Waiting or reappointing later delays treatment that could relieve symptoms
with minimal risk.
,5. Which of the following nerves supplies the intrinsic muscles of the tongue?
A. Vagus
B. Facial
C. Lingual
D. Hypoglossal
E. Glossopharyngeal
Correct Answer: D. Hypoglossal
Rationale:
• The hypoglossal nerve (cranial nerve XII) innervates all intrinsic and most
extrinsic tongue muscles.
• The lingual nerve provides sensory, not motor, innervation.
• Facial, glossopharyngeal, and vagus nerves are involved in taste and
pharyngeal muscle control, not tongue muscle movement.
6. Which of the following tissues and organs is/are the MOST radioresistant?
A. Nerves
B. Glands
C. Skin
D. Bone marrow
E. Reproductive organs
Correct Answer: A. Nerves
Rationale:
• Nerve tissue has a low mitotic rate, making it highly resistant to radiation
damage.
• Bone marrow and reproductive organs have rapidly dividing cells, making them
radiosensitive.
• Skin and glands are moderately sensitive but not as radioresistant as nerves.
7. Superficial lymphatic vessels of the breast drain primarily into which of the
following nodes?
A. Axillary
B. Cervical
, C. Substernal
D. Subclavicular
E. Supraclavicular
Correct Answer: A. Axillary
Rationale:
• The axillary lymph nodes are the primary drainage site for the majority of
breast tissue, especially the outer quadrants.
• Substernal (internal thoracic) nodes also play a role but to a lesser extent.
• Cervical, subclavicular, and supraclavicular nodes may be involved in
advanced disease or metastasis.
Primarily, systemic fluorides protect the teeth by which of the following actions?
A. Lowering their surface energy
B. Creating bacteriostasis
C. Inhibiting enzyme activity
D. Reducing the fluoroapatite solubility
E. Improving their morphology - - correct ans- -D
Bell's palsy involves which of the following cranial nerves?
A. III
B. IV
c. V
D. VII
E. IX - - correct ans- -D
Periodontal disease is considered to be controlled when
