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

Question 1: The epithelial rests of Malassez are remnants of which structure?

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

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 2: Glass ionomer cement bonds to tooth structure primarily through:

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

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 3: 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?

Fibrous dysplasia
Giant cell granuloma
Osteosarcoma
Cherubism (Correct answer)

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

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

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

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

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

Opioids
Antihistamines
Barbiturates
Benzodiazepines (Correct answer)

Correct answer: Benzodiazepines

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

Question 7: Necrotizing ulcerative gingivitis (NUG) is characterized by:

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

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 8: Obturation of a root canal is considered acceptable when:

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

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 9: 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 10: Which local anesthetic has the longest duration of action?

Prilocaine
Mepivacaine
Lidocaine
Bupivacaine (Correct answer)

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 11: Vertical root fracture is most commonly associated with:

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

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 12: 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?

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

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

Lorazepam
Midazolam (Correct answer)
Triazolam
Diazepam

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

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

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

Engineering control (Correct answer)
Administrative control
Work practice control
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.<br> 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 16: 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?

Peripheral ossifying fibroma
Pyogenic granuloma (Correct answer)
Giant cell granuloma
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 17: Which analgesic is contraindicated in patients with aspirin-exacerbated respiratory disease (AERD)?

Acetaminophen
Tramadol
Ibuprofen (Correct answer)
Codeine

Correct answer: Ibuprofen

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

Question 18: The neonatal line in primary tooth enamel marks the boundary between:

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

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

Beta-lactam (Correct answer)
Macrolide
Aminoglycoside
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 20: Erythema multiforme most commonly affects young adults and is characterized by which pathognomonic skin lesion?

Nikolsky's sign
Target (iris) lesion (Correct answer)
Koebner phenomenon
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 21: Which drug used for seizure management commonly causes gingival enlargement?

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

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 22: Which cells are primarily responsible for producing dentin?

Cementoblasts
Ameloblasts
Odontoblasts (Correct answer)
Osteoblasts

Correct answer: Odontoblasts

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

Question 23: Which type of lichen planus carries the highest risk of malignant transformation?

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

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 24: Centric relation (CR) is best defined as:

The habitual closure position of the mandible
The most retruded position of the mandible
The most superior, anterior position of the condyles in the glenoid fossae (Correct answer)
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 25: Pemphigus vulgaris is caused by autoantibodies directed against which target?

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

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 26: What is the working length in endodontics?

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

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 27: About 75% of the blood supply of the spinal cord is derived from the anterior spinal artery. <br>This artery originates from which of the following?

Posterior inferior cerebellar artery
Vertebral artery (Correct answer)
Internal carotid artery
Basilar 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 28: Class II composite restorations are most challenging compared to Class I because of the need for:

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

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 29: Medicare Part: B<br> 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 30: The closest speaking space refers to:

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

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'.

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.

Questions

35 min

Time Limit

75%

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