NDHCE EXAM 300 REAL EXAM QUESTIONS & DETAILED
ANSWERS WITH RATIONALES |NATIONAL DENTAL
HYGIENE CERTIFICATION EXAMINATION STUDY EXAM ALREADY
GRADED A+| |BRAND NEW VERSION!!
Domains Covered:
Domain 1: Clinical Dental Hygiene (Qs 1-75)
Domain 2: Patient Assessment & Medical History (Qs 76-150)
Domain 3: Periodontics & Instrumentation (Qs 151-200)
Domain 4: Radiology & Imaging (Qs 201-230)
Domain 5: Pharmacology & Pain Management (Qs 231-260)
Domain 6: Ethics, Jurisprudence & Professionalism (Qs 261-300)
DOMAIN 1: CLINICAL DENTAL HYGIENE (Questions 1-75)
Q1. Jennifer, 18 years old, presents for her continuing care appointment. Jennifer
indicates, "Right after my last appointment, I got a big cold sore on my lower lip,
and come to think of it, the same happened after my appointment before that."
Jennifer asks, "Are these cold sores caused by something in this dental office?"
How should the dental hygienist respond?
A. "Cold sores are unlikely to be connected to dental hygiene therapy visits. We
sterilize our instruments and use standard precautions."
B. "Cold sores are caused by a virus that is dormant in many people's bodies.
Factors such as stress, sunlight, or slight irritation can reactivate it."
C. "Cold sores are an occasional occurrence after dental appointments. There are
many theories explaining why this might happen, but none of them have been
conclusively proven."
D. "Cold sores are caused by a virus. It is unlikely that it was reactivated during a
visit to the office."
Correct Answer: B
Rationale: Cold sores (herpes labialis) are caused by HSV-1, which remains
dormant in nerve ganglia. Reactivation can be triggered by stress, trauma,
sunlight, or minor irritation—including dental procedures. Option B provides
accurate, patient-centered education without dismissing the patient's concern.
1
,Q2. In which one of the following cases should a dental hygienist use ultrasonic
instrumentation?
A. Intrinsic stain on mandibular anterior teeth
B. Mature calculus on titanium implants
C. Interproximal overhanging amalgam restorations
D. Calculus on the occlusal surfaces of porcelain crowns
Correct Answer: C
Rationale: Ultrasonic instrumentation is appropriate for removing calculus around
interproximal overhanging amalgam restorations. Ultrasonic tips should NOT be
used on titanium implants (can scratch the surface), porcelain crowns (can cause
fracture), or for removing intrinsic stains (which require different treatment).
Q3. Bill, 15 years old, arrives for his continuing care appointment. He presents
with moderate calculus deposits, red gingiva and generalized 4 mm periodontal
probing depths. Bill states that he flosses regularly and brushes often. Which one
of the following actions by the dental hygienist is most appropriate?
A. Refer Bill to a periodontist
B. Calculate Bill's plaque score
C. Use the Gingival Bleeding Index (GBI)
D. Conduct a lactobacillus test
Correct Answer: C
Rationale: The Gingival Bleeding Index (GBI) is the most appropriate assessment
tool here. Despite Bill's report of regular flossing and brushing, the clinical signs
(red gingiva, 4 mm probing depths, calculus) indicate inflammation. GBI provides
objective evidence of gingival inflammation that can be shared with the patient to
motivate improved home care. Referral to a periodontist is premature without
further assessment.
Q4. Which chemotherapeutic agent for the control of bacterial plaque and
gingivitis offers the greatest substantivity?
A. Stannous fluoride
B. Chlorhexidine
C. Phenolic compounds
D. Oxygenating agents
Correct Answer: B
2
,Rationale: Chlorhexidine has the greatest substantivity (ability to bind to oral
tissues and be released over time) of any chemotherapeutic agent. It binds to
pellicle, tooth surfaces, and mucosa, providing prolonged antimicrobial activity.
Stannous fluoride has some substantivity but less than chlorhexidine.
Q5. Mr. Foster, 80 years old, has severe Parkinson's disease. He presents at the
dental office accompanied by his son. Periodontal assessment reveals moderate
chronic periodontitis and a periodontal abscess on tooth 4.6. His son requests
that all the rest of his father's teeth be removed. Mr. Foster does not concur with
this request and appears agitated. Which one of the following actions should the
dental hygienist take?
A. Refer Mr. Foster to a periodontist
B. Advise Mr. Foster and his son of all the options available
C. Reassure Mr. Foster that his son has his best interests in mind
D. Discuss the issue with Mr. Foster only
Correct Answer: B
Rationale: The dental hygienist must respect patient autonomy while
acknowledging the son's concerns. The best approach is to present all treatment
options to BOTH Mr. Foster and his son, ensuring the patient's wishes are
respected. Discussing with Mr. Foster only (D) ignores the son's legitimate role as
caregiver. Referring out (A) avoids the ethical responsibility.
Q6. Which one of the following oral health measures should be emphasized for a
15-year-old client with controlled type 1 diabetes mellitus?
A. Dental plaque control to prevent oral infections
B. Fluoride therapy for caries control
C. Reduction of sugar intake
D. Application of pit and fissure sealants
Correct Answer: A
Rationale: Patients with diabetes are at increased risk for periodontal disease and
oral infections due to impaired immune response. While all options are
important, dental plaque control is the MOST critical measure for a diabetic
patient to prevent infections that can complicate glycemic control.
3
, Q7. Which one of the following statements best describes why the dental
hygienist must be able to evaluate research findings and modify practice to reflect
current knowledge?
A. To promote effective client care
B. To prevent negligent practice
C. To validate personal preferences
D. To eliminate practitioner bias
Correct Answer: A
Rationale: The primary purpose of evidence-based practice is to promote
effective client care by integrating the best available research evidence with
clinical expertise and patient values. While preventing negligence (B) is important,
it is a secondary benefit.
Q8. When reviewing an article related to the efficacy of a desensitizing agent, the
inclusion of which one of the following research variables would be most
important in suggesting that the study's findings are valid?
A. The sample size was larger than 50
B. A convenience sample was used
C. A control group was included
D. Informed consent was obtained
Correct Answer: C
Rationale: The inclusion of a control group is the most important factor in
establishing internal validity and determining whether the desensitizing agent
actually caused the observed effect. A control group allows comparison and helps
rule out confounding variables. Sample size (A) is important but secondary to
study design.
Q9. Which tissues have nerve innervation?
A. Dentin
B. Pulp and dentin
C. Pulp and periodontal ligaments
D. Cementum
E. All of the above
Correct Answer: C — Pulp and periodontal ligaments
4
ANSWERS WITH RATIONALES |NATIONAL DENTAL
HYGIENE CERTIFICATION EXAMINATION STUDY EXAM ALREADY
GRADED A+| |BRAND NEW VERSION!!
Domains Covered:
Domain 1: Clinical Dental Hygiene (Qs 1-75)
Domain 2: Patient Assessment & Medical History (Qs 76-150)
Domain 3: Periodontics & Instrumentation (Qs 151-200)
Domain 4: Radiology & Imaging (Qs 201-230)
Domain 5: Pharmacology & Pain Management (Qs 231-260)
Domain 6: Ethics, Jurisprudence & Professionalism (Qs 261-300)
DOMAIN 1: CLINICAL DENTAL HYGIENE (Questions 1-75)
Q1. Jennifer, 18 years old, presents for her continuing care appointment. Jennifer
indicates, "Right after my last appointment, I got a big cold sore on my lower lip,
and come to think of it, the same happened after my appointment before that."
Jennifer asks, "Are these cold sores caused by something in this dental office?"
How should the dental hygienist respond?
A. "Cold sores are unlikely to be connected to dental hygiene therapy visits. We
sterilize our instruments and use standard precautions."
B. "Cold sores are caused by a virus that is dormant in many people's bodies.
Factors such as stress, sunlight, or slight irritation can reactivate it."
C. "Cold sores are an occasional occurrence after dental appointments. There are
many theories explaining why this might happen, but none of them have been
conclusively proven."
D. "Cold sores are caused by a virus. It is unlikely that it was reactivated during a
visit to the office."
Correct Answer: B
Rationale: Cold sores (herpes labialis) are caused by HSV-1, which remains
dormant in nerve ganglia. Reactivation can be triggered by stress, trauma,
sunlight, or minor irritation—including dental procedures. Option B provides
accurate, patient-centered education without dismissing the patient's concern.
1
,Q2. In which one of the following cases should a dental hygienist use ultrasonic
instrumentation?
A. Intrinsic stain on mandibular anterior teeth
B. Mature calculus on titanium implants
C. Interproximal overhanging amalgam restorations
D. Calculus on the occlusal surfaces of porcelain crowns
Correct Answer: C
Rationale: Ultrasonic instrumentation is appropriate for removing calculus around
interproximal overhanging amalgam restorations. Ultrasonic tips should NOT be
used on titanium implants (can scratch the surface), porcelain crowns (can cause
fracture), or for removing intrinsic stains (which require different treatment).
Q3. Bill, 15 years old, arrives for his continuing care appointment. He presents
with moderate calculus deposits, red gingiva and generalized 4 mm periodontal
probing depths. Bill states that he flosses regularly and brushes often. Which one
of the following actions by the dental hygienist is most appropriate?
A. Refer Bill to a periodontist
B. Calculate Bill's plaque score
C. Use the Gingival Bleeding Index (GBI)
D. Conduct a lactobacillus test
Correct Answer: C
Rationale: The Gingival Bleeding Index (GBI) is the most appropriate assessment
tool here. Despite Bill's report of regular flossing and brushing, the clinical signs
(red gingiva, 4 mm probing depths, calculus) indicate inflammation. GBI provides
objective evidence of gingival inflammation that can be shared with the patient to
motivate improved home care. Referral to a periodontist is premature without
further assessment.
Q4. Which chemotherapeutic agent for the control of bacterial plaque and
gingivitis offers the greatest substantivity?
A. Stannous fluoride
B. Chlorhexidine
C. Phenolic compounds
D. Oxygenating agents
Correct Answer: B
2
,Rationale: Chlorhexidine has the greatest substantivity (ability to bind to oral
tissues and be released over time) of any chemotherapeutic agent. It binds to
pellicle, tooth surfaces, and mucosa, providing prolonged antimicrobial activity.
Stannous fluoride has some substantivity but less than chlorhexidine.
Q5. Mr. Foster, 80 years old, has severe Parkinson's disease. He presents at the
dental office accompanied by his son. Periodontal assessment reveals moderate
chronic periodontitis and a periodontal abscess on tooth 4.6. His son requests
that all the rest of his father's teeth be removed. Mr. Foster does not concur with
this request and appears agitated. Which one of the following actions should the
dental hygienist take?
A. Refer Mr. Foster to a periodontist
B. Advise Mr. Foster and his son of all the options available
C. Reassure Mr. Foster that his son has his best interests in mind
D. Discuss the issue with Mr. Foster only
Correct Answer: B
Rationale: The dental hygienist must respect patient autonomy while
acknowledging the son's concerns. The best approach is to present all treatment
options to BOTH Mr. Foster and his son, ensuring the patient's wishes are
respected. Discussing with Mr. Foster only (D) ignores the son's legitimate role as
caregiver. Referring out (A) avoids the ethical responsibility.
Q6. Which one of the following oral health measures should be emphasized for a
15-year-old client with controlled type 1 diabetes mellitus?
A. Dental plaque control to prevent oral infections
B. Fluoride therapy for caries control
C. Reduction of sugar intake
D. Application of pit and fissure sealants
Correct Answer: A
Rationale: Patients with diabetes are at increased risk for periodontal disease and
oral infections due to impaired immune response. While all options are
important, dental plaque control is the MOST critical measure for a diabetic
patient to prevent infections that can complicate glycemic control.
3
, Q7. Which one of the following statements best describes why the dental
hygienist must be able to evaluate research findings and modify practice to reflect
current knowledge?
A. To promote effective client care
B. To prevent negligent practice
C. To validate personal preferences
D. To eliminate practitioner bias
Correct Answer: A
Rationale: The primary purpose of evidence-based practice is to promote
effective client care by integrating the best available research evidence with
clinical expertise and patient values. While preventing negligence (B) is important,
it is a secondary benefit.
Q8. When reviewing an article related to the efficacy of a desensitizing agent, the
inclusion of which one of the following research variables would be most
important in suggesting that the study's findings are valid?
A. The sample size was larger than 50
B. A convenience sample was used
C. A control group was included
D. Informed consent was obtained
Correct Answer: C
Rationale: The inclusion of a control group is the most important factor in
establishing internal validity and determining whether the desensitizing agent
actually caused the observed effect. A control group allows comparison and helps
rule out confounding variables. Sample size (A) is important but secondary to
study design.
Q9. Which tissues have nerve innervation?
A. Dentin
B. Pulp and dentin
C. Pulp and periodontal ligaments
D. Cementum
E. All of the above
Correct Answer: C — Pulp and periodontal ligaments
4
