Integrated National Board Dental Examination (INBDE) — Questions and Answers

Question 1: What is the primary purpose of EDTA in root canal treatment?

Antimicrobial activity
Dissolution of organic tissue
Lubrication of instruments
Removal of the smear layer (chelation of inorganic components) (Correct answer)

Correct answer: Removal of the smear layer (chelation of inorganic components)

EDTA (ethylenediaminetetraacetic acid) chelates calcium ions in the smear layer and dentinal walls, removing the inorganic component to open dentinal tubules.

Question 2: Fixed partial denture (bridge) pontic designs should ideally contact the residual ridge:

With maximum pressure to prevent food impaction
In a broad flat contact (full ridge lap)
With light contact that can be cleansed (modified ridge lap or ovate) (Correct answer)
Without any contact (sanitary/hygienic pontic)

Correct answer: With light contact that can be cleansed (modified ridge lap or ovate)

The modified ridge lap and ovate pontic designs provide acceptable aesthetics with light tissue contact that can be cleaned, balancing appearance and hygiene.

Question 3: Which benzodiazepine is most commonly used for IV conscious sedation in dentistry?

Diazepam
Triazolam
Midazolam (Correct answer)
Lorazepam

Correct answer: Midazolam

Midazolam is preferred for IV conscious sedation in dentistry due to its rapid onset, short duration, water solubility, and superior amnestic properties.

Question 4: The closest speaking space refers to:

The closest vertical relationship of upper and lower teeth during speech (Correct answer)
Occlusal vertical dimension
Freeway space (interocclusal distance)
The distance between the lips at rest

Correct answer: The closest vertical relationship of upper and lower teeth during speech

The closest speaking space (1–2 mm) is the minimum distance between maxillary and mandibular teeth observed during phonation of sibilant sounds like 's'.

Question 5: Protrusive records in complete denture fabrication are used to set the:

Horizontal overlap of anterior teeth
Centric relation position
Occlusal vertical dimension
Condylar guidance angle on the articulator (Correct answer)

Correct answer: Condylar guidance angle on the articulator

Protrusive records allow the clinician to program the condylar guidance angle (Hanau's formula: H = P/8 + 12) on the semi-adjustable articulator.

Question 6: The Christensen phenomenon describes:

The development of a posterior open bite in protrusive movement with balanced occlusion dentures (Correct answer)
Condylar guidance angle's effect on cusp height
Bennett movement of the condyle
Disclusion of posterior teeth in lateral excursion

Correct answer: The development of a posterior open bite in protrusive movement with balanced occlusion dentures

The Christensen phenomenon is the opening of a wedge-shaped space posteriorly during protrusive movement in complete dentures without balanced occlusion.

Question 7: The vertical dimension of rest (VDR) is typically how much greater than the vertical dimension of occlusion (VDO)?

2–4 mm (Correct answer)
8–10 mm
5–7 mm
0–1 mm

Correct answer: 2–4 mm

The interocclusal distance (freeway space) between VDR and VDO is typically 2–4 mm, representing the resting position of the mandible where the elevator muscles are in tonic equilibrium.

Question 8: Dental porcelain is classified as a ceramic primarily because it contains:

Organic polymer matrix
Inorganic non-metallic crystalline or glass materials (Correct answer)
Metal oxides only
Zinc phosphate cement

Correct answer: Inorganic non-metallic crystalline or glass materials

Ceramics are inorganic, non-metallic materials; dental porcelain is primarily composed of silica, feldspar, and alumina in a glass matrix.

Question 9: Glass ionomer cement bonds to tooth structure primarily through:

Chemical bonding to collagen
Van der Waals forces
Micromechanical retention via etching
Ionic bonding to calcium in hydroxyapatite (Correct answer)

Correct answer: Ionic bonding to calcium in hydroxyapatite

Glass ionomer cement bonds chemically to tooth structure via ionic interactions between its polyacrylic acid component and calcium and phosphate in hydroxyapatite.

Question 10: Medicare Part: D Coverage: ?

Physical therapy
Engineering control
Holistic medication
Prescription medication (Correct answer)

Correct answer: Prescription medication

Medicare Part D is the part of Medicare that provides coverage for prescription drugs. This plan helps Medicare beneficiaries pay for the medications prescribed by their doctors, reducing out-of-pocket costs for both brand-name and generic drugs.

Question 11: Which of the following is the most effective way to grow a dental clinic?

Create a business plan (Correct answer)
Self-insurance
Decrease the copayments
Accept more insurance plans

Correct answer: Create a business plan

A comprehensive business plan will help outline strategies for growth, identify target markets, set financial goals, and create a roadmap for achieving them. It encompasses all aspects of the business, including marketing, operations, and financial planning, providing a structured approach to growth.

Question 12: Which salivary gland produces the most serous secretion?

Submandibular gland
Minor labial glands
Sublingual gland
Parotid gland (Correct answer)

Correct answer: Parotid gland

The parotid gland is entirely serous and produces a watery, enzyme-rich (amylase) secretion comprising about 25% of total saliva volume.

Question 13: A patient on bisphosphonate therapy presents for a dental extraction. The primary concern is:

Impaired wound healing due to immunosuppression
Medication-related osteonecrosis of the jaw (MRONJ) (Correct answer)
Drug interaction with local anesthetic
Increased bleeding risk

Correct answer: Medication-related osteonecrosis of the jaw (MRONJ)

Bisphosphonates inhibit osteoclast activity, impairing bone remodeling and healing, which can lead to MRONJ following invasive dental procedures.

Question 14: Clinical attachment level (CAL) is calculated as:

Probing depth minus recession from CEJ to gingival margin
Probing depth plus recession (distance from CEJ to gingival margin) (Correct answer)
Distance from CEJ to alveolar crest
Probing depth alone

Correct answer: Probing depth plus recession (distance from CEJ to gingival margin)

CAL = probing depth + recession (when the gingival margin is apical to the CEJ), giving a true measure of attachment loss from the CEJ.

Question 15: Tetracyclines are contraindicated in children under 8 years of age because they:

Cause hepatic failure
Cause permanent tooth discoloration and enamel hypoplasia (Correct answer)
Cause nephrotoxicity
Inhibit bone growth

Correct answer: Cause permanent tooth discoloration and enamel hypoplasia

Tetracyclines chelate calcium and incorporate into developing teeth and bone, causing permanent yellow-gray discoloration and enamel hypoplasia in children under 8.

Question 16: An employee is sick and asked to stay at home. What is the correct term for this control measure?

Work practice control
Administrative control
Engineering control (Correct answer)
Hazard control

Correct answer: Engineering control

Engineering controls involve physical modifications or changes to the work environment or equipment to reduce or eliminate workplace hazards. Examples include installing ventilation systems or using barriers to separate workers from hazards. Staying at home when sick does not fall under engineering control measures.

Question 17: The Bonwill triangle in prosthodontics represents:

The angle of the eminence to the Frankfurt horizontal
The path of condylar movement in protrusion
The cusp height formula for posterior teeth
The relationship between condyles and the incisors forming an equilateral triangle (Correct answer)

Correct answer: The relationship between condyles and the incisors forming an equilateral triangle

Bonwill's triangle is an equilateral triangle with 4-inch sides connecting the two condyles and the mesial contact point of the mandibular central incisors.

Question 18: The maximum recommended dose of lidocaine with epinephrine in a healthy adult is:

3.0 mg/kg (max 200 mg)
10 mg/kg (max 600 mg)
4.4 mg/kg (max 300 mg)
7.0 mg/kg (max 500 mg) (Correct answer)

Correct answer: 7.0 mg/kg (max 500 mg)

The maximum dose of lidocaine with epinephrine is 7.0 mg/kg up to a maximum of 500 mg in a healthy adult patient.

Question 19: Heparin is a rapidly acting, potent anticoagulant that has many important clinical uses. Which of the following is an action of heparin?

activates prothrombin
acts with antithrombin III to inhibit thrombin activity (Correct answer)
decreases prothrombin time
inhibits calcium action

Correct answer: acts with antithrombin III to inhibit thrombin activity

Heparin acts as an anticoagulant because it accelerates the action of antithrombin III to inhibit thrombin activity.

Question 20: Osseous surgery in periodontics involves resection of bone to:

Increase attached gingiva
Stimulate bone regeneration
Create positive osseous architecture (Correct answer)
Fill infrabony defects

Correct answer: Create positive osseous architecture

Positive osseous architecture (where interproximal bone is higher than facial/lingual bone) is the physiologic ideal achieved through osteoplasty and ostectomy.

Question 21: Galvanism in the oral cavity occurs when:

Amalgam corrodes in an acid environment
Gold alloy undergoes tarnish
Two dissimilar metals in saliva create an electrical current (Correct answer)
Composite polymerization creates heat

Correct answer: Two dissimilar metals in saliva create an electrical current

Oral galvanism results from the electrochemical coupling of two dissimilar metals (e.g., amalgam and gold) in the electrolyte of saliva, generating a measurable galvanic current.

Question 22: Amalgam's strength is primarily derived from which phase?

Gamma phase (unreacted silver-tin)
Gamma-1 phase (silver-mercury) (Correct answer)
Delta phase (copper-tin)
Gamma-2 phase (tin-mercury)

Correct answer: Gamma-1 phase (silver-mercury)

The gamma-1 phase (Ag2Hg3) is the matrix phase that gives amalgam its strength, while gamma-2 (Sn7-8Hg) is the weakest and most corrosion-prone phase.

Question 23: Which furcation classification indicates that the furcation can be completely probed through from one side to the other?

Class I
Class IV
Class II
Class III (Correct answer)

Correct answer: Class III

Class III (through-and-through) furcation involvement means the probe passes completely through the furcation from the buccal to lingual/palatal surface.

Question 24: Aggressive periodontitis in young patients is most commonly associated with which organism?

Tannerella forsythia
Aggregatibacter actinomycetemcomitans (Correct answer)
Prevotella intermedia
Treponema denticola

Correct answer: Aggregatibacter actinomycetemcomitans

Aggregatibacter actinomycetemcomitans (Aa) is strongly associated with localized aggressive periodontitis, particularly in adolescents and young adults.

Question 25: Necrotizing ulcerative gingivitis (NUG) is characterized by:

Punched-out interdental papillae, pseudomembrane, and fetid breath (Correct answer)
Generalized gingival recession
Furcation involvement in molars
Deep periodontal pockets with bone loss

Correct answer: Punched-out interdental papillae, pseudomembrane, and fetid breath

NUG presents with necrosis and ulceration of interdental papillae (giving a 'punched-out' appearance), a gray pseudomembrane, fetid breath, and pain.

Question 26: The neutral zone in complete denture construction represents:

The space between the residual ridges
The area where buccal and lingual muscle forces are in equilibrium (Correct answer)
The occlusal plane height
The area of maximum bone support

Correct answer: The area where buccal and lingual muscle forces are in equilibrium

The neutral zone is the area in the edentulous mouth where the outward tongue pressure equals the inward cheek and lip pressure, providing the ideal location for artificial teeth.

Question 27: Amelogenesis imperfecta primarily affects which aspect of tooth development?

Enamel matrix formation and/or mineralization (Correct answer)
Root formation
Pulp calcification
Dentin matrix formation

Correct answer: Enamel matrix formation and/or mineralization

Amelogenesis imperfecta is a hereditary condition affecting the quantity and/or quality of enamel due to defects in enamel matrix proteins or their regulation.

Question 28: Osseointegration of a dental implant refers to:

The process of implant insertion surgery
Soft tissue healing around the abutment
Direct structural and functional connection between bone and the implant surface (Correct answer)
Fibrous connective tissue encapsulation of the implant

Correct answer: Direct structural and functional connection between bone and the implant surface

Osseointegration is the direct bone-to-implant contact without an intervening fibrous layer, providing the rigid anchorage that dental implants depend upon.

Question 29: Internal root resorption appears radiographically as:

External notching of the root surface
Blunting of the root apex
A radiolucency with irregular borders around the root
A symmetric oval or round radiolucency within the root canal space (Correct answer)

Correct answer: A symmetric oval or round radiolucency within the root canal space

Internal resorption appears as a smooth, round-to-oval radiolucent enlargement within the root canal, caused by clastic cells activated within the pulp.

Question 30: A newly hired dental assistant notices that several of the staff are not following proper infection control protocols. Where should this observation be reported?

COBRA
FDA
EPA
OSHA (Correct answer)

Correct answer: OSHA

OSHA is responsible for ensuring safe and healthy working conditions, which includes enforcing proper infection control protocols in dental offices to protect staff and patients.

Question 31: Guided tissue regeneration (GTR) works by:

Excluding epithelium and allowing periodontal ligament cells to repopulate the root surface (Correct answer)
Grafting autogenous bone into the defect
Stimulating bone formation with growth factors
Applying enamel matrix proteins to the root surface

Correct answer: Excluding epithelium and allowing periodontal ligament cells to repopulate the root surface

GTR uses barrier membranes to prevent fast-growing epithelial and gingival connective tissue cells from occupying the defect space, allowing slower PDL and bone cells to regenerate.

Question 32: The most common cause of complete denture instability in the mandible is:

Severe mandibular ridge resorption (Correct answer)
Incorrect tooth arrangement
Improper shade selection of teeth
Excessive vertical dimension

Correct answer: Severe mandibular ridge resorption

Severe mandibular ridge resorption reduces the supporting base area and alveolar height, making it difficult to achieve a stable, retentive mandibular denture.

Question 33: Canine-protected occlusion refers to:

The canines bearing all lateral excursive contacts while posterior teeth disclude (Correct answer)
Equal distribution of forces on all teeth in lateral excursion
Group function on both working and balancing sides
Immediate posterior disclusion via the anterior teeth

Correct answer: The canines bearing all lateral excursive contacts while posterior teeth disclude

In canine-protected (mutually protected) occlusion, the canines bear and guide all lateral excursive forces, allowing the posterior teeth to disclude and be protected from lateral forces.

Question 34: The principal fiber group that resists intrusive forces on a tooth is:

Alveolar crest fibers
Horizontal fibers
Apical fibers
Oblique fibers (Correct answer)

Correct answer: Oblique fibers

Oblique fibers are the most numerous PDL fibers and are oriented at 45° to resist vertical (intrusive) occlusal forces by converting them into tensile forces on alveolar bone.

Question 35: A radiolucent lesion associated with the crown of an unerupted tooth is found on radiograph of a 20-year-old. Histology shows a thin epithelial lining with no dysplasia. What is the diagnosis?

Calcifying odontogenic cyst
Lateral periodontal cyst
Odontogenic keratocyst
Dentigerous cyst (Correct answer)

Correct answer: Dentigerous cyst

A dentigerous cyst (follicular cyst) is the most common developmental odontogenic cyst, enclosing the crown of an unerupted tooth at the cementoenamel junction.

Question 36: A 45-year-old patient presents with a white patch on the lateral border of the tongue that cannot be wiped off. Biopsy reveals epithelial dysplasia. What is the most appropriate diagnosis?

Lichen planus
Candidiasis
Leukoedema
Leukoplakia (Correct answer)

Correct answer: Leukoplakia

Leukoplakia is a clinical term for a white patch that cannot be wiped off and has no other identifiable cause; dysplasia on biopsy confirms its premalignant potential.

Question 37: Centric relation (CR) is best defined as:

The habitual closure position of the mandible
The most superior, anterior position of the condyles in the glenoid fossae (Correct answer)
The most retruded position of the mandible
The position of maximum intercuspation of the teeth

Correct answer: The most superior, anterior position of the condyles in the glenoid fossae

Centric relation is the maxillomandibular relationship in which the condyles are in their most superior (and slightly anterior) position in the glenoid fossae, independent of tooth contact.

Question 38: Deflective occlusal contacts (prematurities) in centric relation that shift the mandible to maximum intercuspation are called:

Centric relation-centric occlusion (CR-CO) discrepancies (Correct answer)
Interferences
Fremitus
Working contacts

Correct answer: Centric relation-centric occlusion (CR-CO) discrepancies

CR-CO discrepancy occurs when premature contacts in centric relation force the mandible to shift anteriorly and laterally to reach maximum intercuspation (centric occlusion).

Question 39: Which condition is characterized by intense burning of the oral mucosa with no identifiable clinical or laboratory abnormality and predominantly affects postmenopausal women?

Contact mucositis
Erythema migrans
Atrophic glossitis
Burning mouth syndrome (Correct answer)

Correct answer: Burning mouth syndrome

Burning mouth syndrome (BMS) is a chronic orofacial pain disorder with burning sensations but no identifiable mucosal lesions; it predominantly affects postmenopausal women and has multifactorial etiology.

Question 40: The retention of a full-crown preparation is most influenced by:

Occlusal reduction amount
Taper of the axial walls (convergence angle) (Correct answer)
Margin design (chamfer vs feather edge)
Surface roughness of the preparation

Correct answer: Taper of the axial walls (convergence angle)

Axial wall taper (convergence angle) is the most critical retention factor; ideally 6–10° total occlusal convergence maximizes both retention and withdrawal path.

Question 41: Which material is most commonly used as an intracanal medicament between appointments in root canal therapy?

Formocresol
Iodoform paste
Zinc oxide eugenol
Calcium hydroxide (Correct answer)

Correct answer: Calcium hydroxide

Calcium hydroxide is the most widely used intracanal medicament because its high pH (~12.5) is bactericidal, promotes periapical healing, and prevents reinfection between visits.

Question 42: Which finish line design provides the best marginal seal and esthetics for an all-ceramic crown?

Featheredge
Deep chamfer or shoulder with rounded internal line angle (Correct answer)
Knife-edge margin
Beveled shoulder

Correct answer: Deep chamfer or shoulder with rounded internal line angle

A deep chamfer or shoulder (0.8–1.5 mm) with a rounded internal line angle provides adequate ceramic bulk for strength and good marginal fit for all-ceramic restorations.

Question 43: Medicare Part: B Coverage: ?

Inpatient or hospital based coverage
Outpatient medical coverage (Correct answer)
Prescription medication
Inpatient or hospital based coverage

Correct answer: Outpatient medical coverage

This is the correct choice for Medicare Part B coverage. Part B primarily covers outpatient medical services, including doctor visits, diagnostic tests, preventive care, durable medical equipment, and some home health services.

Question 44: A patient taking warfarin requires a dental extraction. The INR is 2.5. The most appropriate management is to:

Proceed with extraction using local hemostatic measures (Correct answer)
Stop warfarin 3 days before extraction
Refer to physician to switch to heparin
Postpone treatment indefinitely

Correct answer: Proceed with extraction using local hemostatic measures

For patients on warfarin with an INR ≤3.5, routine dental extractions can proceed safely with local hemostatic measures such as pressure and sutures.

Question 45: Which cell organelle is involved in concentration packaging and transportation of secretory material inside the cell?

Ribosomes
Golgi complex (Correct answer)
Endoplasmic reticulum
Mitochondria

Correct answer: Golgi complex

The Golgi complex is prominent in glandular cells and is thought to function in the production, concentration packaging, and transportation of secretory material.

Question 46: Which radiographic finding is most consistent with a diagnosis of condensing osteitis?

Loss of lamina dura
Periapical radiopacity with diffuse borders (Correct answer)
Widened periodontal ligament space
Periapical radiolucency with diffuse borders

Correct answer: Periapical radiopacity with diffuse borders

Condensing osteitis appears as a periapical radiopacity representing localized bone sclerosis in response to a low-grade inflammatory stimulus from the pulp.

Question 47: Hunter-Schreger bands in enamel are best described as:

Cracks caused by acid etching
Alternating zones of enamel rods cut in different planes (Correct answer)
Incremental lines of enamel formation
Hypomineralized areas near the DEJ

Correct answer: Alternating zones of enamel rods cut in different planes

Hunter-Schreger bands are optical phenomena produced by the alternating direction of enamel rods when viewed in reflected light.

Question 48: The best disinfection method for a digital radiographic sensor covered with a disposable hygienic barrier is to

spray and wipe with 69% isopropyl alcohol.
spray and wipe with 71% isopropyl alcohol.
spray and wipe with 70% isopropyl alcohol. (Correct answer)
spray and wipe with 45% isopropyl alcohol.

Correct answer: spray and wipe with 70% isopropyl alcohol.

By increasing the rate of production, the clinic can see more patients, perform more procedures, and generate higher revenue, leading to improved business performance. This can be achieved through optimizing operational efficiency, improving scheduling, and enhancing staff productivity

Question 49: The disorder referred to as macrocytic anemia is caused by a deficiency in which of the following vitamins?

biotin
niacin
ascorbate
folate (Correct answer)

Correct answer: folate

Macrocytic anemia is caused by a deficiency in folate (folic acid), which is the vitamin component of tetrahydrofolate, THF.

Question 50: Which test is most reliable for diagnosing pulp necrosis?

Thermal heat test
Percussion test
Thermal cold test
Electric pulp test (Correct answer)

Correct answer: Electric pulp test

The electric pulp test (EPT) is used to assess pulp vitality and is most reliable for identifying pulp necrosis; a necrotic pulp will show no response.

Question 51: The zona pellucida of the enamel organ is also known as:

Outer enamel epithelium
Cervical loop
Stellate reticulum (Correct answer)
Stratum intermedium

Correct answer: Stellate reticulum

The stellate reticulum is the star-shaped cell layer of the enamel organ that provides a cushioning effect and nutrition to the inner enamel epithelium.

Question 52: The most critical determinant of the longevity of a dentin bonding agent is:

Adequate hybridization of the intertubular dentin (Correct answer)
The number of adhesive layers applied
The pH of the primer
The light intensity of the curing unit

Correct answer: Adequate hybridization of the intertubular dentin

Hybrid layer formation through resin infiltration into demineralized intertubular dentin is the primary mechanism of dentin bonding and the key determinant of bond durability.

Question 53: A 5-year-old child presents with bilateral jaw swelling causing an upward gaze appearance. Radiographs show multilocular radiolucencies. What is the most likely diagnosis?

Giant cell granuloma
Cherubism (Correct answer)
Osteosarcoma
Fibrous dysplasia

Correct answer: Cherubism

Cherubism is an autosomal dominant condition causing bilateral fibrous replacement of jaw bone in childhood, producing multilocular radiolucencies and the characteristic upward gaze due to orbital floor involvement.

Question 54: Cementum differs from bone primarily because cementum:

Is avascular (Correct answer)
Undergoes continuous remodeling
Contains Haversian systems
Is derived from the dental follicle

Correct answer: Is avascular

Cementum is avascular and receives its nutrition from the periodontal ligament, unlike bone which has its own blood supply via Haversian canals.

Question 55: Which salivary gland tumor is most common overall and is characterized by a biphasic histology with both epithelial and mesenchymal-like components?

Mucoepidermoid carcinoma
Adenoid cystic carcinoma
Warthin's tumor
Pleomorphic adenoma (Correct answer)

Correct answer: Pleomorphic adenoma

Pleomorphic adenoma (mixed tumor) is the most common salivary gland neoplasm, characterized by a mixture of epithelial cells and chondromyxoid stroma.

Question 56: Which type of oral cancer is most strongly associated with high-risk HPV infection, particularly HPV-16?

Lower lip squamous cell carcinoma
Oropharyngeal squamous cell carcinoma (Correct answer)
Floor of mouth squamous cell carcinoma
Buccal mucosa squamous cell carcinoma

Correct answer: Oropharyngeal squamous cell carcinoma

High-risk HPV-16 is strongly associated with oropharyngeal squamous cell carcinoma (tonsils, base of tongue), particularly in younger non-smokers, and carries a better prognosis than HPV-negative tumors.

Question 57: A 35-year-old female presents with bilateral parotid swelling, dry eyes, and dry mouth. What autoimmune condition should be suspected?

Rheumatoid arthritis
Sarcoidosis
Sjogren's syndrome (Correct answer)
Systemic lupus erythematosus

Correct answer: Sjogren's syndrome

Sjogren's syndrome is an autoimmune exocrinopathy presenting with bilateral parotid enlargement, xerostomia, and keratoconjunctivitis sicca (dry eyes).

Question 58: Flumazenil is used as an antagonist for which drug class?

Antihistamines
Opioids
Benzodiazepines (Correct answer)
Barbiturates

Correct answer: Benzodiazepines

Flumazenil is a competitive benzodiazepine receptor antagonist used to reverse the sedative effects of benzodiazepines in overdose or post-procedure.

Question 59: Which of the following is a contraindication to implant placement?

Single tooth replacement in posterior region
History of radiation to the head and neck (Correct answer)
Age over 60
Controlled type 2 diabetes (HbA1c <7%)

Correct answer: History of radiation to the head and neck

Prior radiation therapy to the head and neck significantly compromises bone vascularity and healing, increasing the risk of osteoradionecrosis and implant failure.

Question 60: Which bacteria is most strongly associated with adult chronic periodontitis?

Fusobacterium nucleatum
Actinomyces viscosus
Streptococcus mutans
Porphyromonas gingivalis (Correct answer)

Correct answer: Porphyromonas gingivalis

Porphyromonas gingivalis is a keystone pathogen in chronic periodontitis, producing virulence factors including gingipains that disrupt the host immune response.

Question 61: Which type of ameloblastoma is most commonly found in the posterior mandible and is characterized by islands of odontogenic epithelium within a fibrous stroma?

Solid/multicystic ameloblastoma (Correct answer)
Peripheral ameloblastoma
Unicystic ameloblastoma
Desmoplastic ameloblastoma

Correct answer: Solid/multicystic ameloblastoma

The solid/multicystic (conventional) ameloblastoma is the most common type, arising predominantly in the posterior mandible with classic histological patterns including follicular and plexiform subtypes.

Question 62: Penicillin V potassium is classified as which type of antibiotic?

Aminoglycoside
Macrolide
Beta-lactam (Correct answer)
Cephalosporin

Correct answer: Beta-lactam

Penicillin V is a beta-lactam antibiotic that inhibits bacterial cell wall synthesis by binding to penicillin-binding proteins.

Question 63: The mucogingival junction (MGJ) is described as the boundary between:

Free and attached gingiva
Attached gingiva and alveolar mucosa (Correct answer)
Gingiva and palatal mucosa
Junctional epithelium and sulcular epithelium

Correct answer: Attached gingiva and alveolar mucosa

The mucogingival junction separates the firmly attached, keratinized attached gingiva from the loose, non-keratinized alveolar mucosa.

Question 64: Which systemic disease is associated with cyclosporine-induced gingival overgrowth?

Organ transplantation (Correct answer)
Leukemia
HIV/AIDS
Type 1 diabetes

Correct answer: Organ transplantation

Cyclosporine is an immunosuppressant used in organ transplant patients; it causes gingival overgrowth in about 25–30% of patients through altered fibroblast metabolism.

Question 65: Which medication used for oral sedation has the highest risk of paradoxical excitation in children?

Midazolam (Correct answer)
Diazepam
Hydroxyzine
Chloral hydrate

Correct answer: Midazolam

Midazolam can cause paradoxical reactions (agitation, combativeness, increased anxiety) in approximately 1–15% of pediatric patients.

Question 66: Which cells are primarily responsible for producing dentin?

Ameloblasts
Osteoblasts
Odontoblasts (Correct answer)
Cementoblasts

Correct answer: Odontoblasts

Odontoblasts are the cells that synthesize and secrete the organic matrix of dentin throughout life.

Question 67: Vertical root fracture is most commonly associated with:

Excessive lateral condensation during obturation (Correct answer)
Excessive irrigation pressure
Perforation with a post drill
Trauma from occlusion

Correct answer: Excessive lateral condensation during obturation

Excessive lateral condensation pressure during cold lateral compaction of gutta-percha is a major cause of vertical root fracture.

Question 68: Which drug interaction is most concerning when prescribing metronidazole?

Warfarin — increased anticoagulant effect (Correct answer)
Lidocaine — cardiac arrhythmia
Ibuprofen — nephrotoxicity
Amoxicillin — reduced efficacy

Correct answer: Warfarin — increased anticoagulant effect

Metronidazole inhibits CYP2C9, reducing warfarin metabolism and significantly increasing INR, raising the risk of bleeding.

Question 69: Naloxone is the reversal agent for which class of drugs?

Benzodiazepines
Barbiturates
Opioids (Correct answer)
Anticholinergics

Correct answer: Opioids

Naloxone is a competitive opioid receptor antagonist that rapidly reverses respiratory depression, sedation, and analgesia caused by opioid overdose.

Question 70: Methemoglobinemia is a rare but serious side effect associated with which local anesthetic?

Articaine
Bupivacaine
Lidocaine
Prilocaine (Correct answer)

Correct answer: Prilocaine

Prilocaine's metabolite o-toluidine oxidizes hemoglobin to methemoglobin; this is clinically significant at doses above 400 mg.

Question 71: Which of the following is the most effective way to improve a dental clinic's business?

Decrease rate of amortization
Increase rate of production (Correct answer)
Decrease staff benefits
Purchase life insurance

Correct answer: Increase rate of production

Question 72: Post-exposure blood testing routinely tests for

Inpatient or hospital based coverage
hepatitis B, hepatitis C and human immunodeficiency virus. (Correct answer)
should be treated in an airborne infection isolation room.
heat and moisture-sensitive medical and dental equipment.

Correct answer: hepatitis B, hepatitis C and human immunodeficiency virus.

Post-exposure blood testing routinely tests

Question 73: Which bacteria is most commonly found in failed root canal treatments?

Enterococcus faecalis (Correct answer)
Porphyromonas gingivalis
Streptococcus mutans
Fusobacterium nucleatum

Correct answer: Enterococcus faecalis

Enterococcus faecalis is the most frequently isolated organism in failed root canals due to its ability to survive in the alkaline environment created by calcium hydroxide.

Question 74: Erythema multiforme most commonly affects young adults and is characterized by which pathognomonic skin lesion?

Nikolsky's sign
Koebner phenomenon
Target (iris) lesion (Correct answer)
Wickham's striae

Correct answer: Target (iris) lesion

The target or iris lesion — concentric rings of erythema — is the hallmark cutaneous lesion of erythema multiforme.

Question 75: Which liner material provides therapeutic benefit by stimulating reparative dentin formation?

Glass ionomer cement
Calcium hydroxide (Ca(OH)2) (Correct answer)
Zinc oxide eugenol
Zinc phosphate cement

Correct answer: Calcium hydroxide (Ca(OH)2)

Calcium hydroxide (Ca(OH)2) has a high pH that is bactericidal and stimulates odontoblast differentiation to produce reparative (tertiary) dentin when placed near the pulp.

Question 76: Which property of dental composite resins is most responsible for post-operative sensitivity?

Thermal expansion coefficient mismatch
Hydrolytic degradation
Polymerization shrinkage creating gap formation (Correct answer)
Lack of fluoride release

Correct answer: Polymerization shrinkage creating gap formation

Polymerization shrinkage (1–5% volumetric) creates contraction stress at the bonded margins, leading to gap formation and post-operative sensitivity.

Question 77: Which analgesic is contraindicated in patients with aspirin-exacerbated respiratory disease (AERD)?

Ibuprofen (Correct answer)
Codeine
Acetaminophen
Tramadol

Correct answer: Ibuprofen

NSAIDs like ibuprofen inhibit COX-1, shunting arachidonic acid toward leukotriene production, which triggers bronchoconstriction in patients with AERD.

Question 78: Which type of porcelain failure most commonly occurs in porcelain-fused-to-metal restorations?

Adhesive failure at the metal-porcelain interface
Crazing of surface glaze
Cohesive failure within the porcelain (Correct answer)
Compressive failure at the occlusal surface

Correct answer: Cohesive failure within the porcelain

Cohesive failure (fracture within the porcelain itself) is the most common type of failure in PFM restorations, often related to inadequate support or occlusal overload.

Question 79: Which enzyme found in saliva initiates carbohydrate digestion?

Lysozyme
Kallikrein
Lingual lipase
Salivary amylase (ptyalin) (Correct answer)

Correct answer: Salivary amylase (ptyalin)

Salivary amylase (ptyalin) cleaves alpha-1,4 glycosidic bonds in starch, initiating carbohydrate digestion in the oral cavity.

Question 80: The working time of zinc phosphate cement can be extended by:

Adding more liquid to the mix
Increasing the powder-to-liquid ratio
Mixing rapidly in a circular motion
Spatulating on a cold, thick glass slab (Correct answer)

Correct answer: Spatulating on a cold, thick glass slab

Cooling the glass slab to 18°C slows the exothermic setting reaction, extending working time; large slab area also dissipates heat.

Question 81: Sodium hypochlorite (NaOCl) is used as an irrigant in root canal therapy primarily because it:

Stimulates periapical healing
Dissolves organic tissue and has broad antimicrobial activity (Correct answer)
Chelates smear layer
Prevents instrument fracture

Correct answer: Dissolves organic tissue and has broad antimicrobial activity

Sodium hypochlorite is the primary root canal irrigant due to its ability to dissolve pulp tissue and its potent antimicrobial activity against endodontic pathogens.

Question 82: Which periodontal classification was adopted by the AAP/EFP World Workshop in 2017?

Stage and Grade classification (Correct answer)
Page and Schroeder 1976 classification
Armitage 1999 classification
AAP 1989 classification

Correct answer: Stage and Grade classification

The 2017 AAP/EFP World Workshop introduced the Stage (I–IV) and Grade (A–C) classification system to replace the previous aggressive/chronic periodontitis terminology.

Question 83: The neonatal line in primary tooth enamel marks the boundary between:

Crown and root enamel
Enamel and dentin
Prenatal and postnatal enamel (Correct answer)
Outer and inner enamel

Correct answer: Prenatal and postnatal enamel

The neonatal line is a prominent stria of Retzius that marks the junction between prenatally and postnatally formed enamel in primary teeth.

Question 84: Which of the following organizations should be contacted about the safety of the dental laser?

American Dental Association (ADA)
Food and Drug Administration (FDA) (Correct answer)
Occupational Health and Safety Administration (OSHA)
Centers for Disease Control and Prevention (CDC)

Correct answer: Food and Drug Administration (FDA)

The FDA is responsible for regulating medical devices, including dental lasers, to ensure their safety and effectiveness.

Question 85: Nitrous oxide/oxygen sedation is contraindicated in which patient?

A patient with controlled hypertension
A 10-year-old child
A patient with chronic obstructive pulmonary disease (COPD) (Correct answer)
A patient with mild anxiety

Correct answer: A patient with chronic obstructive pulmonary disease (COPD)

Patients with COPD rely on hypoxic drive; supplemental oxygen via nitrous oxide sedation can suppress their respiratory drive and cause respiratory depression.

Question 86: Pemphigus vulgaris is caused by autoantibodies directed against which target?

Laminin-332
Type VII collagen
BP180 (BPAG2)
Desmoglein 3 (Correct answer)

Correct answer: Desmoglein 3

Pemphigus vulgaris results from IgG autoantibodies against desmoglein 3 (and desmoglein 1 in skin involvement), disrupting keratinocyte adhesion and causing intraepithelial blistering.

Question 87: Which zone of the dental pulp contains the highest concentration of collagen fibers?

Cell-rich zone
Odontoblastic zone
Cell-free zone of Weil
Pulp core (Correct answer)

Correct answer: Pulp core

The pulp core (central zone) contains the largest blood vessels and nerves and has the highest density of collagen fibers.

Question 88: The 'sunburst' or 'sunray' pattern on radiographs of the jaw in a teenager is most characteristic of which malignancy?

Metastatic carcinoma
Osteosarcoma (Correct answer)
Multiple myeloma
Ewing's sarcoma

Correct answer: Osteosarcoma

Osteosarcoma classically produces a 'sunburst' or 'sunray' radiographic pattern due to periosteal reaction perpendicular to the cortex, often seen in adolescents and young adults.

Question 89: The Ramfjord teeth used for periodontal epidemiological studies are:

First molars and central incisors
Teeth #3, #9, #12, #19, #25, #28 (Correct answer)
All posterior teeth
First molars only

Correct answer: Teeth #3, #9, #12, #19, #25, #28

The Ramfjord index teeth (#3, #9, #12, #19, #25, #28) represent all six tooth types and both arches, allowing efficient periodontal assessment in epidemiological surveys.

Question 90: Which antibiotic is the first-line prophylaxis for patients at high risk of infective endocarditis undergoing dental procedures?

Doxycycline
Amoxicillin (Correct answer)
Clindamycin
Metronidazole

Correct answer: Amoxicillin

Amoxicillin 2 g orally one hour before the procedure is the AHA-recommended first-line prophylaxis for high-risk cardiac patients undergoing dental procedures.

Question 91: Which of the following peptide hormones is released in response to the stimulation of pituitary gonadotropes?

prolactin
growth hormone
ACTH
follicle-stimulating hormone (Correct answer)

Correct answer: follicle-stimulating hormone

The pituitary gonadotrophs are cells that secrete the gonadotrophic peptide hormones, follicle-stimulating hormone (FSH), and leutinizing hormone (LH).

Question 92: Which cells produce the principal fibers of the periodontal ligament?

Undifferentiated mesenchymal cells
Cementoblasts
Osteoblasts
Fibroblasts (Correct answer)

Correct answer: Fibroblasts

Fibroblasts are the most numerous cells of the periodontal ligament and are responsible for synthesizing and maintaining the collagen fibers.

Question 93: Which of the following is not considered to be common risk factor for CVA / stroke?

Hypertension
Atherosclerosis
Orthostatic hypotension (Correct answer)
Diabetes

Correct answer: Orthostatic hypotension

Orthostatic hypertension is not a common risk factor for CVA/stroke. The common risk factors for CVA / stroke include diabetes, atherosclerosis, hypertension, and heart disease.

Question 94: What is the primary purpose of acid etching enamel before bonding?

Increase the surface energy of dentin
Activate the primer component
Create microporosities for micromechanical retention (Correct answer)
Remove the fluoride-rich surface layer

Correct answer: Create microporosities for micromechanical retention

Phosphoric acid (30–40%) selectively dissolves enamel hydroxyapatite, creating microporosities that allow resin tags to form and provide micromechanical retention.

Question 95: Pier abutments in fixed prosthodontics are a problem because they:

Increase the span length of the bridge excessively
Create a Class I lever when the terminal abutments flex differentially (Correct answer)
Are unable to support porcelain veneers
Have insufficient root surface area

Correct answer: Create a Class I lever when the terminal abutments flex differentially

A pier (middle) abutment creates a Class I lever arm; when one terminal abutment is depressed, the pier acts as a fulcrum, placing destructive tipping forces on the other terminal abutment.

Question 96: Which sign is pathognomonic for a draining sinus tract of endodontic origin?

Deepened probing depth at one surface
Radiolucency at the furcation
Parulis (stoma) with tracking to the apex of a non-vital tooth (Correct answer)
Gingival bleeding on probing

Correct answer: Parulis (stoma) with tracking to the apex of a non-vital tooth

A parulis (sinus tract opening/stoma) that tracks with a gutta-percha cone to the apex of a non-vital tooth on radiograph confirms endodontic origin.

Question 97: A patient taking a MAO inhibitor should NOT receive which drug?

Amoxicillin
Lidocaine
Meperidine (Demerol) (Correct answer)
Ibuprofen

Correct answer: Meperidine (Demerol)

Meperidine combined with MAO inhibitors can cause a serotonin syndrome, characterized by hyperthermia, seizures, and death.

Question 98: Scaling and root planing (SRP) is most accurately described as:

Surgical debridement of the periodontium
Removal of all cementum from root surfaces
Prophylactic polishing of root surfaces
Removal of calculus and contaminated cementum with root smoothing (Correct answer)

Correct answer: Removal of calculus and contaminated cementum with root smoothing

SRP involves removal of supragingival and subgingival calculus, contaminated cementum, and plaque from root surfaces to create a biologically acceptable root surface.

Question 99: Which type of dentin is formed in response to irritation or injury?

Primary dentin
Tertiary (reparative) dentin (Correct answer)
Interglobular dentin
Secondary dentin

Correct answer: Tertiary (reparative) dentin

Tertiary (reparative) dentin is produced by newly differentiated odontoblast-like cells as a protective response to local stimuli such as caries or trauma.

Question 100: A facebow transfer records the relationship of:

Vertical dimension of occlusion to rest position
Upper teeth to lower teeth in centric occlusion
Mandible to the Frankfurt horizontal plane
Maxillary arch to the transverse hinge axis of the condyles (Correct answer)

Correct answer: Maxillary arch to the transverse hinge axis of the condyles

A facebow records the spatial relationship of the maxillary arch to the opening axis of the condyles (transverse hinge axis), allowing accurate mounting on an articulator.

Question 101: Cementum is thickest at which region of the root?

Cervical third
Furcation area
Apical third (Correct answer)
Middle third

Correct answer: Apical third

Cementum is thickest at the apex (apical third) of the root, where it can be 200–600 μm thick, compensating for passive eruption and wear.

Question 102: In which of the following transport processes do solid materials enter the cell in membrane-bound vesicles?

Phagocytosis (Correct answer)
Osmosis
Pinocytosis
Passive transport

Correct answer: Phagocytosis

In active transport, materials enter the cell in membrane-bound vesicles that are formed by the membrane. This process is generally known as endocytosis and is of two types. Endocytosis of solid material and liquid materials is called phagocytosis and pinocytosis respectively.

Question 103: Which structure connects the enamel organ to the oral epithelium during tooth development?

Stellate reticulum
Dental lamina (Correct answer)
Stratum intermedium
Outer enamel epithelium

Correct answer: Dental lamina

The dental lamina is the band of epithelium that connects the developing enamel organ to the oral epithelium.

Question 104: The Knoop hardness test is most appropriate for measuring which dental material?

Dental ceramics and enamel (Correct answer)
Elastomeric impression materials
Impression materials
Alginate

Correct answer: Dental ceramics and enamel

The Knoop hardness test uses a rhombus-shaped diamond indenter and is ideal for hard, brittle materials like dental ceramics and enamel.

Question 105: Gutta-percha is primarily composed of which material?

Resin and glass ionomer
Trans-polyisoprene (rubber), zinc oxide, and barium sulfate (Correct answer)
Calcium hydroxide and silicone
Zinc oxide and eugenol

Correct answer: Trans-polyisoprene (rubber), zinc oxide, and barium sulfate

Gutta-percha points consist primarily of trans-polyisoprene (gutta-percha resin), zinc oxide (filler), barium sulfate (radiopacifier), and waxes/resins.

Question 106: Which type of lichen planus carries the highest risk of malignant transformation?

Reticular lichen planus
Plaque-type lichen planus
Erosive lichen planus (Correct answer)
Papular lichen planus

Correct answer: Erosive lichen planus

Erosive (atrophic/ulcerative) lichen planus has the greatest malignant potential among lichen planus variants, with an estimated 0.5–2% risk of transformation to squamous cell carcinoma.

Question 107: Mineral trioxide aggregate (MTA) is used in endodontics for all of the following EXCEPT:

Root-end filling
Pulp capping
Mechanical canal enlargement (Correct answer)
Perforation repair

Correct answer: Mechanical canal enlargement

MTA is a biocompatible hydraulic cement used for pulp capping, root-end filling, and perforation repair, but it is not used for mechanical canal shaping.

Question 108: Obturation of a root canal is considered acceptable when:

The canal is completely filled with sealer alone
Fill material extends 1 mm beyond the apex
Gutta-percha reaches the radiographic apex
Fill material ends 0–2 mm short of the radiographic apex with no voids (Correct answer)

Correct answer: Fill material ends 0–2 mm short of the radiographic apex with no voids

Ideal obturation terminates 0–2 mm short of the radiographic apex (at the apical constriction) with well-adapted gutta-percha and minimal sealer without voids.

Question 109: A patient presents with multiple basal cell carcinomas, calcified falx cerebri, and odontogenic keratocysts of the jaw. What syndrome is present?

Gardner syndrome
Cowden syndrome
Peutz-Jeghers syndrome
Gorlin-Goltz syndrome (Correct answer)

Correct answer: Gorlin-Goltz syndrome

Gorlin-Goltz (nevoid basal cell carcinoma) syndrome is characterized by multiple OKCs of the jaws, basal cell nevi/carcinomas, and calcification of the falx cerebri.

Question 110: A patient presents with a blue, dome-shaped, fluctuant lesion on the floor of the mouth that displaces the tongue. What is the most likely diagnosis?

Ranula (Correct answer)
Dermoid cyst
Mucocele
Lymphoepithelial cyst

Correct answer: Ranula

A ranula is a mucus-retention or extravasation phenomenon arising from the sublingual or submandibular salivary glands, presenting as a blue, fluctuant swelling on the floor of the mouth.

Question 111: Class II composite restorations are most challenging compared to Class I because of the need for:

Restoration of the proximal contact and marginal ridge (Correct answer)
Greater occlusal reduction
Extended curing times
Use of a rubber dam

Correct answer: Restoration of the proximal contact and marginal ridge

Restoring a proximal contact, marginal ridge, and gingival margin against an adjacent tooth in a confined space makes Class II composites technically demanding.

Question 112: Epinephrine is added to local anesthetic solutions primarily to:

Prolong the duration of anesthesia by causing vasoconstriction (Correct answer)
Prevent allergic reactions
Increase the rate of absorption
Decrease the pH of the solution

Correct answer: Prolong the duration of anesthesia by causing vasoconstriction

Epinephrine causes local vasoconstriction, reducing the rate of systemic absorption of the local anesthetic and thereby prolonging its duration and reducing toxicity.

Question 113: The designation for the glycosylated form of hemoglobin is called:

HbC
HbA1c (Correct answer)
HbG
HbA2

Correct answer: HbA1c

HbA1c is the designation for the glycosylated form of hemoglobin. Normal levels of glycosylated hemoglobin represent about 5% of the total.

Question 114: Which crown-to-root ratio is generally considered the minimum acceptable for a tooth to serve as an abutment?

1:1.5
2:3
1:2
1:1 (Correct answer)

Correct answer: 1:1

A crown-to-root ratio of 1:1 is generally considered the minimum acceptable for a tooth to be used as a fixed prosthetic abutment, with 2:3 being ideal.

Question 115: What is the working length in endodontics?

The distance from a reference point to the apical constriction where instrumentation ends (Correct answer)
The full length of the root canal from orifice to apex
The length of gutta-percha used for obturation
The length of the root as measured on the radiograph

Correct answer: The distance from a reference point to the apical constriction where instrumentation ends

Working length is the measured distance from an occlusal/incisal reference point to the apical stop (apical constriction), establishing the limit of instrumentation.

Question 116: A painless, slow-growing mass at the angle of the mandible in a 60-year-old is found to contain perineural invasion on biopsy. Which salivary gland tumor is most likely?

Adenoid cystic carcinoma (Correct answer)
Acinic cell carcinoma
Warthin's tumor
Pleomorphic adenoma

Correct answer: Adenoid cystic carcinoma

Adenoid cystic carcinoma is notorious for perineural invasion and spread, explaining pain or facial nerve symptoms despite its deceptively slow growth.

Question 117: Necrotizing sialometaplasia most commonly occurs on the hard palate and can mimic squamous cell carcinoma clinically and histologically. What is its most likely etiology?

Viral infection of salivary glands
Trauma-induced salivary gland neoplasm
Ischemic infarction of salivary gland tissue (Correct answer)
Autoimmune destruction of acini

Correct answer: Ischemic infarction of salivary gland tissue

Necrotizing sialometaplasia results from ischemic necrosis of minor salivary gland lobules, typically following trauma, surgery, or vascular compromise, with subsequent squamous metaplasia of ducts.

Question 118: The biologic width refers to the combined measurement of:

Free gingival groove to mucogingival junction
Sulcus depth and attached gingiva
Junctional epithelium and connective tissue attachment above the alveolar crest (Correct answer)
Gingival margin to alveolar crest

Correct answer: Junctional epithelium and connective tissue attachment above the alveolar crest

The biologic width (~2.04 mm) consists of the junctional epithelium (~0.97 mm) and supracrestal connective tissue attachment (~1.07 mm) above the alveolar bone crest.

Question 119: A painless, lobulated mass arising from the interdental papilla with a pedunculated base is found in a 28-year-old pregnant woman. What is the most likely diagnosis?

Giant cell granuloma
Pyogenic granuloma (Correct answer)
Fibroma
Peripheral ossifying fibroma

Correct answer: Pyogenic granuloma

Pyogenic granuloma (pregnancy tumor/epulis gravidarum) is a highly vascular reactive lesion that commonly arises from the gingival papilla and is exacerbated by hormonal changes during pregnancy.

Question 120: Secondary caries (recurrent caries) occurs most frequently at which location of an existing restoration?

Proximal gingival margin (Correct answer)
Occlusal surface
Pulpal wall
Axial wall

Correct answer: Proximal gingival margin

The proximal gingival margin is the most common site for recurrent caries due to difficulty in cleaning, plaque accumulation, and microleakage at the cervical margin.

Question 121: Which local anesthetic has the longest duration of action?

Mepivacaine
Lidocaine
Bupivacaine (Correct answer)
Prilocaine

Correct answer: Bupivacaine

Bupivacaine (Marcaine) has the longest duration of pulpal and soft tissue anesthesia among common dental local anesthetics due to its high protein-binding affinity.

Question 122: A patient with HIV presents with painless, bluish-purple nodules on the hard palate. What is the most likely diagnosis?

Hairy leukoplakia
Kaposi's sarcoma (Correct answer)
Bacillary angiomatosis
Necrotizing ulcerative periodontitis

Correct answer: Kaposi's sarcoma

Kaposi's sarcoma is an AIDS-defining malignancy commonly presenting as blue-purple vascular lesions on the palate in HIV-infected individuals.

Question 123: What is the particulate filtration rate of a level 1 mask at the standard of 0.1 microns?

95-97% (Correct answer)
85-89%
90-94%
98-99%

Correct answer: 95-97%

The particulate filtration rate of a level 1 mask at the standard of 0.1 microns

Question 124: What is the primary inorganic component of enamel?

Hydroxyapatite (Correct answer)
Tricalcium phosphate
Calcium fluoride
Calcium carbonate

Correct answer: Hydroxyapatite

Hydroxyapatite crystals [Ca10(PO4)6(OH)2] make up approximately 96% of the inorganic content of mature enamel.

Question 125: The apical constriction (minor diameter) of the canal is located approximately:

At the cemento-dentinal junction
At the mid-root level
At the radiographic apex
0.5–1.0 mm coronal to the anatomic apex (Correct answer)

Correct answer: 0.5–1.0 mm coronal to the anatomic apex

The apical constriction, where the canal is narrowest, is located approximately 0.5–1.0 mm coronal to the anatomic apex and is the ideal endpoint for canal instrumentation.

Question 126: A semi-adjustable articulator can replicate:

Exact patient-specific condylar paths using custom incisal guidance
Only centric occlusion
Average condylar settings with some adjustability for protrusive and lateral movements (Correct answer)
All mandibular movements with perfect accuracy

Correct answer: Average condylar settings with some adjustability for protrusive and lateral movements

Semi-adjustable articulators accept protrusive records and facebow transfers to approximate condylar guidance, balancing side angles, and incisal guidance for most clinical procedures.

Question 127: Which local anesthetic is safest for a patient with a true amide allergy?

Prilocaine
Lidocaine
Mepivacaine
Procaine (Novocain) (Correct answer)

Correct answer: Procaine (Novocain)

Procaine is an ester-type local anesthetic and can be used in patients with confirmed allergy to amide local anesthetics, as the two classes are chemically distinct.

Question 128: A maxillary first molar most commonly has how many canals?

4 (Correct answer)
5
3
2

Correct answer: 4

The maxillary first molar typically has 3 roots and most commonly 4 canals (2 in the mesiobuccal root — MB1 and MB2, 1 in the distobuccal, 1 in the palatal).

Question 129: Which of the following drugs is NOT a calcium channel blocker?

Metoprolol (Correct answer)
Verapamil
Nifedipine
Amplodipine

Correct answer: Metoprolol

Metoprolol is not a calcium channel blocker; it is a beta channel antagonist.

Question 130: Which bone disease presents radiographically as a 'ground glass' or 'orange peel' appearance and results from replacement of normal bone with fibrous connective tissue?

Langerhans cell histiocytosis
Cherubism
Fibrous dysplasia (Correct answer)
Paget's disease of bone

Correct answer: Fibrous dysplasia

Fibrous dysplasia replaces normal medullary bone with fibrous connective tissue containing woven bone trabeculae, producing the classic ground-glass radiographic pattern.

Question 131: Which of the following organizations in the United States is responsible for enforcing standard precautions for dental practices, providing guidelines for personal protective equipment, and exposure to bloodborne pathogens.

EPA
COBRA
FDA
OSHA (Correct answer)

Correct answer: OSHA

The organization responsible for enforcing standard precautions for dental practices, providing guidelines for personal protective equipment, and exposure to bloodborne pathogens

Question 132: An apicoectomy involves:

Complete extraction of a tooth with periapical pathology
Intentional replantation of a tooth
Internal bleaching of a discolored tooth
Surgical removal of the root apex and curettage of periapical tissue (Correct answer)

Correct answer: Surgical removal of the root apex and curettage of periapical tissue

An apicoectomy (root-end resection) involves surgical access, removal of the apical 3 mm of root, and curettage of periapical pathology, followed by root-end filling.

Question 133: A cusp that is fully included within the outer cusp ridges of the opposing arch during maximum intercuspation is classified as a:

Non-supporting cusp (non-centric cusp)
Shearing cusp
Supporting cusp (centric holding cusp) (Correct answer)
Stamp cusp

Correct answer: Supporting cusp (centric holding cusp)

Supporting (centric holding) cusps — maxillary palatal and mandibular buccal — contact the opposing tooth in centric occlusion, maintaining vertical dimension.

Question 134: Which impression material provides the highest dimensional accuracy and detail reproduction?

Polyvinyl siloxane (PVS/addition silicone) (Correct answer)
Polysulfide rubber
Zinc oxide eugenol paste
Alginate (irreversible hydrocolloid)

Correct answer: Polyvinyl siloxane (PVS/addition silicone)

Polyvinyl siloxane (addition silicone) provides the highest dimensional accuracy, excellent detail reproduction, and good dimensional stability over time.

Question 135: Dead tracts in dentin appear black in transmitted light because they contain:

Air (Correct answer)
Bacteria
Blood pigments
Secondary dentin

Correct answer: Air

Dead tracts are areas where odontoblastic processes have degenerated and the empty dentinal tubules become filled with air, causing them to appear dark in transmitted light.

Question 136: About 75% of the blood supply of the spinal cord is derived from the anterior spinal artery. This artery originates from which of the following?

Vertebral artery (Correct answer)
Basilar artery
Internal carotid artery
Posterior inferior cerebellar artery

Correct answer: Vertebral artery

The anterior spinal artery is a small branch, which arises near the termination of the vertebral, and, descending in front of the medulla oblongata, unites with its fellow of the opposite side at the level of the foramen magnum.

Question 137: Which drug used for seizure management commonly causes gingival enlargement?

Phenytoin (Dilantin) (Correct answer)
Valproic acid
Carbamazepine
Phenobarbital

Correct answer: Phenytoin (Dilantin)

Phenytoin-induced gingival overgrowth occurs in approximately 50% of patients and is related to altered gingival fibroblast metabolism and collagen turnover.

Question 138: The step-back technique in canal preparation refers to:

Using rotary instruments from coronal to apical
Alternating between two files of the same size
Progressively using larger files at shorter lengths to create a tapered canal (Correct answer)
Beginning instrumentation at the apex and moving coronally

Correct answer: Progressively using larger files at shorter lengths to create a tapered canal

In the step-back technique, after establishing the working length with the master apical file, larger files are used at progressively shorter lengths to create a funnel-shaped taper.

Question 139: Which of the following layers of the heart is primarily composed of cardiac muscle?

Pericardium
Myocardium (Correct answer)
Endocardium
Epicardium

Correct answer: Myocardium

Mycocardium or middle layer of the heart consists of cardiac muscle. The heart is a highly specialized pumping organ composed of the following layers Endocardium (lining coat; epithelium) Myocardium (middle coat; cardiac muscle), and Epicardium (external coat or visceral layer of pericardium; epithelium).

Question 140: Which type of bone defect has the best prognosis for regeneration?

One-wall (hemiseptal) defect
Crater defect
Three-wall (intrabony) defect (Correct answer)
Two-wall defect

Correct answer: Three-wall (intrabony) defect

Three-wall intrabony defects have the best regenerative prognosis because three bony walls provide maximum blood supply, stability, and a scaffold for regeneration.

Question 141: Residual ridge resorption after tooth extraction follows a pattern that is:

Greater in the maxilla vertically, greater in the mandible horizontally
Equal in maxilla and mandible
Greater in the mandible in all dimensions (Correct answer)
Ceases after 6 months post-extraction

Correct answer: Greater in the mandible in all dimensions

The mandibular ridge typically resorbs 4 times faster than the maxilla overall, and resorption is greater in all dimensions in the mandible, making mandibular dentures more challenging.

Question 142: The epithelial rests of Malassez are remnants of which structure?

Reduced enamel epithelium
Hertwig's epithelial root sheath (Correct answer)
Dental lamina
Nasmyth's membrane

Correct answer: Hertwig's epithelial root sheath

The epithelial rests of Malassez are remnants of Hertwig's epithelial root sheath that persist in the periodontal ligament throughout life.

Question 143: Obesity, genetic profile, and aging all contribute to the development of Type II diabetes. Of the following, which is the most important additive factor for these three conditions in the development of Type II diabetes?

elevated hepatic ketogenesis
elevated pancreatic glucagon secretion
muscle resistance to insulin (Correct answer)
impaired renal clearance of glucose

Correct answer: muscle resistance to insulin

Muscle resistance to insulin is the most important additive factor for these three conditions in the development of Type II diabetes. Progressive loss of skeletal muscle sensitivity to insulin leads to increased rates of visceral cell lipolysis and pancreatic betA-cell compensation.

Question 144: Which of the following is a true statement about the 'phoenix abscess'?

It is caused by periodontal pathogens
It always presents with a sinus tract
It is an acute exacerbation of a pre-existing chronic periapical lesion (Correct answer)
It occurs only in previously healthy teeth

Correct answer: It is an acute exacerbation of a pre-existing chronic periapical lesion

A phoenix abscess is an acute inflammatory exacerbation of a chronic periapical lesion, often occurring after endodontic instrumentation stirs up the existing pathology.

Question 145: A free gingival graft is used primarily to:

Regenerate lost bone
Cover exposed root surfaces aesthetically
Eliminate periodontal pockets
Increase the zone of attached (keratinized) gingiva (Correct answer)

Correct answer: Increase the zone of attached (keratinized) gingiva

A free gingival graft harvested from the palate is the gold standard for augmenting the width of attached keratinized gingiva.

Question 146: Retzius lines in enamel represent:

Areas of enamel hypocalcification
Boundaries between primary and secondary enamel
Directions of enamel rod orientation
Incremental lines of enamel matrix deposition (Correct answer)

Correct answer: Incremental lines of enamel matrix deposition

Striae of Retzius are incremental lines in enamel that represent successive layers of enamel matrix deposited during crown formation.

Question 147: Which composite placement technique best minimizes polymerization shrinkage stress?

Oblique incremental placement (Correct answer)
Horizontal incremental placement
Diagonal incremental placement
Bulk fill technique

Correct answer: Oblique incremental placement

Oblique (diagonal) incremental placement reduces the C-factor (ratio of bonded to unbonded surfaces) and allows shrinkage stress relief as each increment cures.

Question 148: Periodontal probing depth is measured from the:

Alveolar crest to the base of the pocket
Mucogingival junction to the gingival margin
Gingival margin to the base of the pocket (Correct answer)
Cemento-enamel junction to the alveolar crest

Correct answer: Gingival margin to the base of the pocket

Probing depth is the distance from the free gingival margin to the base of the periodontal pocket or sulcus.

Question 149: A radiopaque lesion surrounded by a radiolucent halo is found at the root apex of a non-vital tooth in a 30-year-old. What is the most likely diagnosis?

Cementoblastoma (Correct answer)
Condensing osteitis
Periapical ossifying fibroma
Periapical cemento-osseous dysplasia

Correct answer: Cementoblastoma

Cementoblastoma presents as a well-defined radiopaque mass fused to the root of a vital or non-vital tooth, surrounded by a thin radiolucent rim, and often causes expansion.

Question 150: Which odontogenic cyst has the highest recurrence rate due to an aggressive, thin-walled epithelial lining that produces keratin?

Odontogenic keratocyst (Correct answer)
Dentigerous cyst
Radicular cyst
Nasopalatine duct cyst

Correct answer: Odontogenic keratocyst

The odontogenic keratocyst (OKC) has a high recurrence rate (25–60%) because its thin, friable parakeratinized epithelial lining is prone to incomplete removal and satellite cyst formation.

Question 151: Which systemic condition is most strongly associated with an increased risk of periodontitis?

Hyperlipidemia
Hypothyroidism
Osteoporosis
Type 2 diabetes mellitus (Correct answer)

Correct answer: Type 2 diabetes mellitus

Type 2 diabetes mellitus significantly increases the risk and severity of periodontitis through impaired neutrophil function, advanced glycation end-products, and altered wound healing.

Integrated National Board Dental Examination (INBDE)

The INBDE is a two-day, 500-question dental licensure examination administered by the Joint Commission on National Dental Examinations (JCNDE/ADA), assessing candidates' ability to integrate biomedical, clinical, and behavioral sciences to make patient-centered clinical decisions required for safe, entry-level general dental practice.

500

Questions

750 min

Time Limit

75%

To Pass

Checking for saved progress...

Exam Rules

You can skip questions and return to them later
Flag questions for review before submitting
No feedback shown until you submit the entire exam
Unanswered questions count as wrong — answer everything
10 pretest questions are mixed in and don't affect your score
Timer auto-submits when time runs out
Your progress is auto-saved every 30 seconds