Illinois Dental Hygienist Licensing
Exam With Actual Questions &
Verified Answers,Plus
Rationales/Expert Verified For
Guaranteed Pass Graded A+/2026
/Latest Update/Instant Download Pdf
1. The primary function of fluoride in caries prevention is to:
A. Kill bacteria in the oral cavity
B. Strengthen enamel by remineralization
C. Stimulate saliva production
D. Prevent plaque formation
B. Strengthen enamel by remineralization
Rationale: Fluoride enhances remineralization of enamel and inhibits
demineralization, reducing the risk of dental caries.
2. The recommended angle for a standard ultrasonic scaler tip against the
tooth surface is:
A. 0–15 degrees
B. 15–30 degrees
C. 45–60 degrees
D. 90 degrees
B. 15–30 degrees
Rationale: Proper angulation maximizes calculus removal while minimizing
damage to the tooth surface and gingiva.
3. The primary cause of dental caries is:
A. Trauma
, B. Bacterial activity
C. Poor alignment
D. Fluoride deficiency
B. Bacterial activity
Rationale: Acid-producing bacteria, particularly Streptococcus mutans,
metabolize carbohydrates and lead to demineralization of enamel.
4. The most common site for oral cancer is:
A. Tongue
B. Soft palate
C. Gingiva
D. Buccal mucosa
A. Tongue
Rationale: The lateral borders of the tongue are highly susceptible to
squamous cell carcinoma and should be examined carefully during oral
exams.
5. The term “periodontitis” refers to:
A. Inflammation of the pulp
B. Inflammation of the gingiva only
C. Inflammation of the supporting structures of teeth
D. Enamel demineralization
C. Inflammation of the supporting structures of teeth
Rationale: Periodontitis affects the alveolar bone, periodontal ligament, and
gingiva, leading to potential tooth loss.
6. Which of the following is the most effective method for plaque removal?
A. Toothbrushing alone
B. Dental floss alone
C. Combination of brushing and interdental cleaning
D. Mouth rinse alone
C. Combination of brushing and interdental cleaning
Rationale: Toothbrushing removes plaque from accessible surfaces, while
flossing removes plaque between teeth, providing comprehensive oral
hygiene.
, 7. Nitrous oxide sedation is contraindicated in patients with:
A. Hypertension
B. Chronic obstructive pulmonary disease (COPD)
C. Mild anxiety
D. Gingivitis
B. Chronic obstructive pulmonary disease (COPD)
Rationale: Nitrous oxide may cause respiratory complications in patients with
severe pulmonary disease due to potential hypoxia.
8. The most appropriate response to a patient experiencing syncope in the
dental chair is to:
A. Administer nitrous oxide
B. Place the patient in a supine position and elevate legs
C. Immediately give sugar
D. Sit the patient upright
B. Place the patient in a supine position and elevate legs
Rationale: This position improves cerebral perfusion and helps resolve
fainting episodes.
9. The CDC recommends hand hygiene in dental settings:
A. Before and after patient contact only
B. Only when hands are visibly soiled
C. Before and after patient contact, after glove removal, and after
contact with contaminated surfaces
D. Once per shift
C. Before and after patient contact, after glove removal, and after contact
with contaminated surfaces
Rationale: Comprehensive hand hygiene reduces the risk of cross-
contamination and infection transmission.
10.The active ingredient in most professional dental desensitizing agents is:
A. Fluoride
B. Potassium nitrate
C. Chlorhexidine
D. Hydrogen peroxide
Exam With Actual Questions &
Verified Answers,Plus
Rationales/Expert Verified For
Guaranteed Pass Graded A+/2026
/Latest Update/Instant Download Pdf
1. The primary function of fluoride in caries prevention is to:
A. Kill bacteria in the oral cavity
B. Strengthen enamel by remineralization
C. Stimulate saliva production
D. Prevent plaque formation
B. Strengthen enamel by remineralization
Rationale: Fluoride enhances remineralization of enamel and inhibits
demineralization, reducing the risk of dental caries.
2. The recommended angle for a standard ultrasonic scaler tip against the
tooth surface is:
A. 0–15 degrees
B. 15–30 degrees
C. 45–60 degrees
D. 90 degrees
B. 15–30 degrees
Rationale: Proper angulation maximizes calculus removal while minimizing
damage to the tooth surface and gingiva.
3. The primary cause of dental caries is:
A. Trauma
, B. Bacterial activity
C. Poor alignment
D. Fluoride deficiency
B. Bacterial activity
Rationale: Acid-producing bacteria, particularly Streptococcus mutans,
metabolize carbohydrates and lead to demineralization of enamel.
4. The most common site for oral cancer is:
A. Tongue
B. Soft palate
C. Gingiva
D. Buccal mucosa
A. Tongue
Rationale: The lateral borders of the tongue are highly susceptible to
squamous cell carcinoma and should be examined carefully during oral
exams.
5. The term “periodontitis” refers to:
A. Inflammation of the pulp
B. Inflammation of the gingiva only
C. Inflammation of the supporting structures of teeth
D. Enamel demineralization
C. Inflammation of the supporting structures of teeth
Rationale: Periodontitis affects the alveolar bone, periodontal ligament, and
gingiva, leading to potential tooth loss.
6. Which of the following is the most effective method for plaque removal?
A. Toothbrushing alone
B. Dental floss alone
C. Combination of brushing and interdental cleaning
D. Mouth rinse alone
C. Combination of brushing and interdental cleaning
Rationale: Toothbrushing removes plaque from accessible surfaces, while
flossing removes plaque between teeth, providing comprehensive oral
hygiene.
, 7. Nitrous oxide sedation is contraindicated in patients with:
A. Hypertension
B. Chronic obstructive pulmonary disease (COPD)
C. Mild anxiety
D. Gingivitis
B. Chronic obstructive pulmonary disease (COPD)
Rationale: Nitrous oxide may cause respiratory complications in patients with
severe pulmonary disease due to potential hypoxia.
8. The most appropriate response to a patient experiencing syncope in the
dental chair is to:
A. Administer nitrous oxide
B. Place the patient in a supine position and elevate legs
C. Immediately give sugar
D. Sit the patient upright
B. Place the patient in a supine position and elevate legs
Rationale: This position improves cerebral perfusion and helps resolve
fainting episodes.
9. The CDC recommends hand hygiene in dental settings:
A. Before and after patient contact only
B. Only when hands are visibly soiled
C. Before and after patient contact, after glove removal, and after
contact with contaminated surfaces
D. Once per shift
C. Before and after patient contact, after glove removal, and after contact
with contaminated surfaces
Rationale: Comprehensive hand hygiene reduces the risk of cross-
contamination and infection transmission.
10.The active ingredient in most professional dental desensitizing agents is:
A. Fluoride
B. Potassium nitrate
C. Chlorhexidine
D. Hydrogen peroxide
