National Dental Hygiene Certification Examination (NDHCE) — Questions and Answers

Question 1: A patient with Addison's disease (primary adrenal insufficiency) may exhibit which distinctive oral finding?

Geographic tongue
Torus mandibularis
Hairy tongue
Multifocal melanin pigmentation (Correct answer)

Correct answer: Multifocal melanin pigmentation

Addison's disease causes elevated ACTH, which stimulates melanocytes, resulting in diffuse or focal melanin hyperpigmentation of the oral mucosa, particularly the buccal mucosa and gingiva.

Question 2: A dental hygienist discovers that the autoclave failed its weekly spore test. What is the appropriate next step?

Continue using the autoclave and repeat the test next week
Remove the autoclave from service, recall possibly non-sterile instruments, and contact the manufacturer (Correct answer)
Switch to chemical disinfection instead
Increase the temperature setting and retest immediately

Correct answer: Remove the autoclave from service, recall possibly non-sterile instruments, and contact the manufacturer

A failed spore test indicates the autoclave did not achieve sterilization; it must be taken out of service, and instruments processed since the last successful test must be retrieved and re-sterilized.

Question 3: Which of the following muscles is responsible for depressing and retracting the tongue during swallowing?

Styloglossus
Genioglossus
Hyoglossus (Correct answer)
Palatoglossus

Correct answer: Hyoglossus

The hyoglossus muscle depresses and retracts the tongue; it originates from the hyoid bone and inserts into the lateral tongue.

Question 4: Which condition is characterized by bilateral, painful oral ulcers affecting the non-keratinized mucosa, often recurring monthly, and is NOT associated with trauma?

Recurrent herpes labialis
Behçet's disease
Recurrent aphthous stomatitis (RAS) (Correct answer)
Primary herpetic gingivostomatitis

Correct answer: Recurrent aphthous stomatitis (RAS)

Recurrent aphthous stomatitis presents as recurrent, painful ulcers on non-keratinized mucosa (e.g., buccal and labial mucosa), cycling approximately monthly, without a confirmed infectious etiology.

Question 5: What is the role of saliva in maintaining oral health?

Increasing the acidity in the mouth
Neutralizing acids and protecting teeth (Correct answer)
Removing stains from teeth
Enhancing the taste of food

Correct answer: Neutralizing acids and protecting teeth

Saliva plays a crucial role in maintaining oral health by neutralizing acids produced by bacteria after food consumption, which helps prevent demineralization of tooth enamel. It also aids in remineralization by providing minerals like calcium and phosphate, and its flow helps cleanse the mouth of food debris and bacteria, protecting against decay.

Question 6: Which type of radiograph provides the most comprehensive view of the entire dentition, jaws, and surrounding structures in a single image?

Cephalometric radiograph
Bitewing series
Panoramic radiograph (Correct answer)
Full-mouth series

Correct answer: Panoramic radiograph

A panoramic radiograph captures a broad view of the entire maxilla, mandible, teeth, TMJ, and surrounding structures on a single extraoral film.

Question 7: A patient's health history reveals they are taking warfarin. What precaution should the dental hygienist take?

Double the amount of local anesthetic used
Avoid all radiographs
Consult with the prescribing physician about INR levels before invasive procedures (Correct answer)
Refuse to treat the patient

Correct answer: Consult with the prescribing physician about INR levels before invasive procedures

Warfarin is an anticoagulant that increases bleeding risk; the dental hygienist should consult with the patient's physician to review current INR levels before performing subgingival scaling or other invasive procedures.

Question 8: Which hand hygiene method is MOST effective for reducing the number of microorganisms on hands before surgical procedures?

Routine handwashing with soap and water for 15 seconds
Wiping hands with disinfectant wipes
Alcohol-based hand rub applied once
Surgical hand antisepsis using antiseptic soap or alcohol-based product with persistent activity (Correct answer)

Correct answer: Surgical hand antisepsis using antiseptic soap or alcohol-based product with persistent activity

Surgical hand antisepsis uses a specific technique and antiseptic agent with residual (persistent) antimicrobial activity to reduce microorganisms to a minimum before surgical procedures.

Question 9: What does a furcation involvement Class II indicate during periodontal assessment?

Tooth requires immediate extraction
Probe can enter the furcation but cannot pass through (Correct answer)
Probe passes completely through the furcation
No furcation involvement detected

Correct answer: Probe can enter the furcation but cannot pass through

Class II furcation involvement means the probe can penetrate into the furcation area but cannot be passed through to the other side of the tooth.

Question 10: Which dental condition would appear radiopaque on a radiograph?

Periapical abscess
Dental caries
Amalgam restoration (Correct answer)
Pulp chamber

Correct answer: Amalgam restoration

Amalgam restorations are highly radiopaque because the metal alloy absorbs X-rays, appearing white on the radiograph.

Question 11: What is the recommended target distance (focal-film distance) for a standard periapical radiograph using paralleling technique?

16 inches (Correct answer)
8 inches
12 inches
20 inches

Correct answer: 16 inches

The paralleling technique uses a 16-inch focal-film distance to minimize image magnification and distortion.

Question 12: Which term describes the number of new cases of a disease occurring in a population during a specific time period?

Incidence (Correct answer)
Attack rate
Morbidity rate
Prevalence

Correct answer: Incidence

Incidence measures the rate at which new cases of a disease occur in a population during a defined time period, reflecting disease risk.

Question 13: What type of waste is generated when a dental hygienist disposes of extracted teeth with amalgam restorations?

Regular medical waste only
Sharps waste only
Amalgam waste requiring special disposal (Correct answer)
Radioactive waste

Correct answer: Amalgam waste requiring special disposal

Extracted teeth containing amalgam restorations are considered amalgam waste due to mercury content and must be disposed of through an EPA-compliant amalgam waste recycling program.

Question 14: What does the term 'fluorosis' refer to in community oral health?

An acute fluoride toxicity reaction
A developmental defect of enamel caused by excessive fluoride intake during tooth formation (Correct answer)
A periodontal condition related to fluoride overuse
An allergic reaction to fluoride treatments

Correct answer: A developmental defect of enamel caused by excessive fluoride intake during tooth formation

Dental fluorosis is a hypomineralization of enamel caused by excessive fluoride ingestion during the period of tooth development, resulting in white spots, streaking, or brown pitting.

Question 15: Which national survey provides data on the oral health of the U.S. population through physical examinations and interviews?

National Health and Nutrition Examination Survey (NHANES) (Correct answer)
Behavioral Risk Factor Surveillance System (BRFSS)
Current Population Survey (CPS)
Youth Risk Behavior Survey (YRBS)

Correct answer: National Health and Nutrition Examination Survey (NHANES)

NHANES includes both an interview and a standardized physical examination, including a dental exam, providing nationally representative data on oral health status.

Question 16: Which of the following medical conditions requires a physician consultation before dental hygiene treatment due to risk of infective endocarditis?

Seasonal allergies
Controlled hypertension
Prosthetic heart valve (Correct answer)
Type 2 diabetes

Correct answer: Prosthetic heart valve

Patients with prosthetic heart valves are at high risk for infective endocarditis and may require antibiotic prophylaxis before invasive dental procedures.

Question 17: What is the primary characteristic of periodontitis?

Bone loss around the teeth (Correct answer)
Presence of dental caries
Absence of clinical attachment loss
Inflammation limited to the gingiva

Correct answer: Bone loss around the teeth

Periodontitis is a chronic inflammatory disease that progresses beyond gingivitis, leading to the destruction of the supporting structures of the teeth. Its primary characteristic is irreversible bone loss around the teeth, along with clinical attachment loss and the formation of periodontal pockets, which can ultimately lead to tooth mobility and loss.

Question 18: Under OSHA's Bloodborne Pathogens Standard, the Exposure Control Plan must be reviewed and updated at least:

Only when regulations change
Every 5 years
Annually (Correct answer)
Every 2 years

Correct answer: Annually

OSHA requires the Exposure Control Plan to be reviewed and updated at least annually, and whenever new procedures or tasks are added.

Question 19: Which of the following is a common sign of gingivitis?

Gingival bleeding (Correct answer)
Abscess formation
Deep periodontal pockets
Tooth mobility

Correct answer: Gingival bleeding

Gingival bleeding, particularly during brushing, flossing, or probing, is one of the earliest and most common clinical signs of gingivitis. It indicates inflammation of the gum tissue, which becomes more fragile and prone to bleeding due to bacterial plaque accumulation along the gumline.

Question 20: What does the DMFT index measure in dental epidemiology?

Degree of malocclusion and facial trauma
Distribution of maximum fluoride treatment
Decayed, Missing, and Filled Teeth in the permanent dentition (Correct answer)
Depth of periodontal pockets in permanent teeth

Correct answer: Decayed, Missing, and Filled Teeth in the permanent dentition

The DMFT index records the number of permanent teeth that are Decayed, Missing due to caries, or Filled, providing a cumulative measure of caries experience.

Question 21: What is the function of the inferior alveolar nerve (IAN) in dental procedures?

Provides sensory innervation to the mandibular teeth, lower lip, and chin (Correct answer)
Controls motor function of the lower lip
Controls the muscles of facial expression
Innervates the tongue for taste

Correct answer: Provides sensory innervation to the mandibular teeth, lower lip, and chin

The inferior alveolar nerve (IAN), a branch of V3, provides sensory innervation to all mandibular teeth, the lower lip, and chin; blocking this nerve is the target of an inferior alveolar nerve block injection.

Question 22: What is the primary goal of scaling and root planing in periodontal therapy?

To provide orthodontic alignment
To remove calculus and smooth the root surfaces (Correct answer)
To whiten the teeth
To apply fluoride treatment

Correct answer: To remove calculus and smooth the root surfaces

Scaling and root planing is a non-surgical periodontal therapy aimed at treating periodontal disease. The primary goal is to meticulously remove bacterial plaque, calculus (hardened plaque), and toxins from above and below the gumline, and then to smooth the root surfaces to remove any remaining toxins and make it harder for bacteria to reattach, promoting reattachment of healthy gum tissue.

Question 23: Which muscle is responsible for elevating the mandible (closing the mouth) and is the most powerful muscle of mastication?

Medial pterygoid
Lateral pterygoid
Masseter (Correct answer)
Temporalis

Correct answer: Masseter

The masseter is considered the most powerful muscle of mastication and is the primary muscle responsible for elevating the mandible to close the mouth.

Question 24: Which of the following factors is least important when prioritizing dental treatments?

Patient's chief complaint
Severity of the condition
Potential for disease progression
Aesthetic preferences of the patient (Correct answer)

Correct answer: Aesthetic preferences of the patient

While aesthetic preferences are important for patient satisfaction, they are generally the least critical factor when prioritizing dental treatments, especially compared to urgent health concerns. Factors like the patient's chief complaint, the severity of the condition, and the potential for disease progression directly impact oral health and function, making them higher priorities for treatment.

Question 25: What is the minimum internal temperature required for a steam autoclave to achieve sterilization at standard pressure?

121°C (250°F) (Correct answer)
134°C (273°F)
100°C (212°F)
160°C (320°F)

Correct answer: 121°C (250°F)

Standard steam autoclaves operate at 121°C (250°F) at 15 psi for a minimum of 15–30 minutes to achieve sterilization.

Question 26: Which branch of the facial nerve is most commonly damaged during parotid gland surgery or infection, resulting in drooping of the corner of the mouth?

Zygomatic branch
Marginal mandibular branch (Correct answer)
Temporal branch
Buccal branch

Correct answer: Marginal mandibular branch

The marginal mandibular branch of the facial nerve runs near the lower border of the mandible and controls muscles of the lower lip; damage causes drooping at the corner of the mouth.

Question 27: The parotid salivary gland's duct (Stensen's duct) opens into the oral cavity at which location?

Posterior soft palate near the uvula
Floor of the mouth near the lingual frenum
Sublingual caruncle beneath the tongue
Buccal mucosa opposite the maxillary second molar (Correct answer)

Correct answer: Buccal mucosa opposite the maxillary second molar

Stensen's (parotid) duct opens on the buccal mucosa at a papilla opposite the maxillary second molar, delivering parotid saliva into the oral cavity.

Question 28: Which clinical parameter is considered the gold standard for diagnosing active periodontal disease progression?

Bleeding on probing
Probing depth alone
Clinical attachment loss (CAL) (Correct answer)
Gingival color change

Correct answer: Clinical attachment loss (CAL)

Clinical attachment loss (CAL) is the gold standard for diagnosing periodontal disease, as it measures the actual loss of the tooth's supporting structures from the CEJ.

Question 29: A dental hygienist records a gingival recession of 2 mm and a probing depth of 4 mm. What is the clinical attachment loss (CAL)?

8 mm
4 mm
6 mm (Correct answer)
2 mm

Correct answer: 6 mm

CAL is calculated by adding probing depth to recession: 4 mm + 2 mm = 6 mm, indicating 6 mm of total attachment loss.

Question 30: In treatment planning, why is it important to discuss the potential outcomes and risks with the patient?

To reduce the time spent on each treatment session
To comply with legal requirements
To ensure the patient agrees to the most expensive treatment
To obtain informed consent and align expectations (Correct answer)

Correct answer: To obtain informed consent and align expectations

Discussing potential outcomes and risks with the patient is crucial for obtaining informed consent, which is a legal and ethical requirement. This ensures the patient fully understands the proposed treatment, its benefits, risks, and alternatives, allowing them to make an autonomous decision and setting realistic expectations for the treatment's success and potential challenges.

Question 31: Which ionizing radiation unit measures the biological effect of radiation on human tissue?

Coulomb/kg
Roentgen
Rem (Sievert) (Correct answer)
Rad

Correct answer: Rem (Sievert)

The rem (or Sievert in SI units) measures the dose equivalent, accounting for the biological effect of radiation on tissue.

National Dental Hygiene Certification Examination (NDHCE)

The NDHCE is a Canadian national certification examination that assesses entry-to-practice knowledge, judgment, and clinical skills of dental hygiene graduates seeking licensure as registered dental hygienists across Canadian provinces.

Questions

35 min

Time Limit

70%

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These practice questions were written with AI tools. They are not real exam questions. Exam facts are checked against the official sources listed below. Not reviewed by a subject-matter expert. Editorial policy

Sources & references

Exam facts on this page (fees, format, dates, passing scores) are checked against these official sources; the date is our last check. Editorial policy

fdhrc.ca — Exam format, passing score, retake policy, fees, late registration, score release, exam dates, registration deadline, test dates, eligibility · verified Oct 2026
fdhrc.ysasecure.com — Exam information · verified Oct 2026
oralhealthbc.ca — Score validity · verified Oct 2026