Integrated National Board Dental
Examination (INBDE) Practice
Examination Questions And Correct
Answers (Verified Answers) Plus
Rationales 2026 Q&A | Instant
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1. A 55-year-old patient with mitral valve prolapse and mild regurgitation but
no history of infective endocarditis requires routine extraction of a
mandibular molar. According to the current American Heart Association
guidelines, which prophylactic regimen is indicated?
A. Amoxicillin 2 g orally 30 minutes before the procedure
B. Amoxicillin 2 g orally 1 hour before the procedure
C. Clindamycin 600 mg orally 1 hour before the procedure
D. No antibiotic prophylaxis is needed
Answer: D
Rationale: The 2007 AHA guidelines and subsequent reaffirmations reserve
antibiotic prophylaxis for patients with the highest risk of adverse outcomes
from infective endocarditis, such as those with prosthetic heart valves, previous
IE, unrepaired cyanotic congenital heart disease, or cardiac transplant recipients
with valvulopathy. Isolated mitral valve prolapse, even with regurgitation, is no
longer considered an indication. Thus, no prophylaxis is warranted.
2. Which permanent tooth consistently exhibits the greatest mesiodistal
dimension of its clinical crown in the maxillary arch?
A. Maxillary canine
B. Maxillary central incisor
, C. Maxillary first molar
D. Maxillary second premolar
Answer: B
Rationale: The maxillary central incisor has the widest mesiodistal crown
measurement of any maxillary tooth (averaging 8.5 mm), exceeding that of the
canine, premolars, and molars. This anatomical feature is critical for anterior
esthetics and proportional smile design.
3. A patient develops wheezing, urticaria, and hypotension within minutes of
receiving an oral dose of amoxicillin. This reaction is best classified as which
type of hypersensitivity?
A. Type II (antibody-mediated)
B. Type III (immune complex)
C. Type I (immediate) hypersensitivity
D. Type IV (delayed-type)
Answer: C
Rationale: Acute onset of urticaria, bronchospasm, and hypotension following
drug exposure is a classic manifestation of IgE-mediated type I hypersensitivity.
Mast cell degranulation releases histamine and other mediators, leading to
vasodilation, bronchoconstriction, and increased vascular permeability.
4. During root planing, a cementum-like tissue containing entrapped viable
cells within lacunae is encountered in the apical third of the root. This tissue
is best described as:
A. Acellular cementum
B. Intermediate cementum
C. Cellular cementum
D. Primary acellular fiber cementum
Answer: C
Rationale: Cellular cementum is characterized by cementocytes embedded in
lacunae within the mineralized matrix. It is typically found in the apical third and
interradicular areas of roots and functions in adaptive and reparative processes.
,Acellular cementum, in contrast, lacks cells and covers the cervical to mid-root
portion.
5. Which receptor-ligand interaction is primarily responsible for stimulating
osteoclast differentiation and activation?
A. OPG binding to RANK
B. M-CSF binding to c-Fms
C. RANKL binding to RANK
D. PTH binding to osteoblast receptor
Answer: C
Rationale: Osteoclastogenesis is driven by the binding of receptor activator of
nuclear factor-κB ligand (RANKL), expressed on osteoblastic stromal cells, to the
RANK receptor on osteoclast precursors. Osteoprotegerin (OPG) acts as a decoy
receptor that inhibits this interaction.
6. A healthy 70-kg adult requires mandibular quadrant dentistry using 2%
lidocaine with 1:100,000 epinephrine. The maximum recommended dose of
lidocaine is 7 mg/kg. How many 1.8-mL cartridges can be safely
administered?
A. 7
B. 11
C. 13
D. 15
Answer: C
Rationale: Each 1.8-mL cartridge of 2% lidocaine contains 36 mg of anesthetic
(20 mg/mL × 1.8 mL). The maximum dose for a 70-kg patient is 490 mg (7 mg/kg
× 70 kg). 490 mg divided by 36 mg/cartridge yields 13.6, so 13 full cartridges
may be delivered without exceeding the maximum.
7. A 9-year-old child presents with a large, unilocular radiolucency surrounding
the crown of an unerupted mandibular second premolar. The lesion is well-
corticated and the tooth is displaced. Histopathology reveals a thin,
nonkeratinized stratified squamous epithelium lining a fibrous capsule. The
, most likely diagnosis is:
A. Ameloblastoma
B. Odontogenic keratocyst
C. Adenomatoid odontogenic tumor
D. Dentigerous cyst
Answer: D
Rationale: A dentigerous cyst is an epithelium-lined developmental odontogenic
cyst that encloses the crown of an unerupted tooth and attaches at the
cementoenamel junction. Its radiographic appearance is a well-defined
unilocular radiolucency. The lining is nonkeratinized, distinguishing it from the
parakeratinized epithelium of an odontogenic keratocyst.
8. The principal immunoglobulin responsible for mucosal immunity in the oral
cavity is:
A. IgG
B. Secretory IgA
C. IgM
D. IgE
Answer: B
Rationale: Secretory IgA (sIgA) is produced by plasma cells in salivary glands and
transported through the epithelium as a dimer stabilized by the J chain and
secretory component. It neutralizes pathogens and prevents microbial adhesion
to oral mucosal surfaces.
9. In chronic periodontitis, the “red complex” consortium includes which of
the following bacteria?
A. Streptococcus mutans
B. Actinomyces naeslundii
C. Fusobacterium nucleatum
D. Porphyromonas gingivalis
Answer: D
Rationale: The red complex consists of Porphyromonas gingivalis, Tannerella
Examination (INBDE) Practice
Examination Questions And Correct
Answers (Verified Answers) Plus
Rationales 2026 Q&A | Instant
Download Pdf
1. A 55-year-old patient with mitral valve prolapse and mild regurgitation but
no history of infective endocarditis requires routine extraction of a
mandibular molar. According to the current American Heart Association
guidelines, which prophylactic regimen is indicated?
A. Amoxicillin 2 g orally 30 minutes before the procedure
B. Amoxicillin 2 g orally 1 hour before the procedure
C. Clindamycin 600 mg orally 1 hour before the procedure
D. No antibiotic prophylaxis is needed
Answer: D
Rationale: The 2007 AHA guidelines and subsequent reaffirmations reserve
antibiotic prophylaxis for patients with the highest risk of adverse outcomes
from infective endocarditis, such as those with prosthetic heart valves, previous
IE, unrepaired cyanotic congenital heart disease, or cardiac transplant recipients
with valvulopathy. Isolated mitral valve prolapse, even with regurgitation, is no
longer considered an indication. Thus, no prophylaxis is warranted.
2. Which permanent tooth consistently exhibits the greatest mesiodistal
dimension of its clinical crown in the maxillary arch?
A. Maxillary canine
B. Maxillary central incisor
, C. Maxillary first molar
D. Maxillary second premolar
Answer: B
Rationale: The maxillary central incisor has the widest mesiodistal crown
measurement of any maxillary tooth (averaging 8.5 mm), exceeding that of the
canine, premolars, and molars. This anatomical feature is critical for anterior
esthetics and proportional smile design.
3. A patient develops wheezing, urticaria, and hypotension within minutes of
receiving an oral dose of amoxicillin. This reaction is best classified as which
type of hypersensitivity?
A. Type II (antibody-mediated)
B. Type III (immune complex)
C. Type I (immediate) hypersensitivity
D. Type IV (delayed-type)
Answer: C
Rationale: Acute onset of urticaria, bronchospasm, and hypotension following
drug exposure is a classic manifestation of IgE-mediated type I hypersensitivity.
Mast cell degranulation releases histamine and other mediators, leading to
vasodilation, bronchoconstriction, and increased vascular permeability.
4. During root planing, a cementum-like tissue containing entrapped viable
cells within lacunae is encountered in the apical third of the root. This tissue
is best described as:
A. Acellular cementum
B. Intermediate cementum
C. Cellular cementum
D. Primary acellular fiber cementum
Answer: C
Rationale: Cellular cementum is characterized by cementocytes embedded in
lacunae within the mineralized matrix. It is typically found in the apical third and
interradicular areas of roots and functions in adaptive and reparative processes.
,Acellular cementum, in contrast, lacks cells and covers the cervical to mid-root
portion.
5. Which receptor-ligand interaction is primarily responsible for stimulating
osteoclast differentiation and activation?
A. OPG binding to RANK
B. M-CSF binding to c-Fms
C. RANKL binding to RANK
D. PTH binding to osteoblast receptor
Answer: C
Rationale: Osteoclastogenesis is driven by the binding of receptor activator of
nuclear factor-κB ligand (RANKL), expressed on osteoblastic stromal cells, to the
RANK receptor on osteoclast precursors. Osteoprotegerin (OPG) acts as a decoy
receptor that inhibits this interaction.
6. A healthy 70-kg adult requires mandibular quadrant dentistry using 2%
lidocaine with 1:100,000 epinephrine. The maximum recommended dose of
lidocaine is 7 mg/kg. How many 1.8-mL cartridges can be safely
administered?
A. 7
B. 11
C. 13
D. 15
Answer: C
Rationale: Each 1.8-mL cartridge of 2% lidocaine contains 36 mg of anesthetic
(20 mg/mL × 1.8 mL). The maximum dose for a 70-kg patient is 490 mg (7 mg/kg
× 70 kg). 490 mg divided by 36 mg/cartridge yields 13.6, so 13 full cartridges
may be delivered without exceeding the maximum.
7. A 9-year-old child presents with a large, unilocular radiolucency surrounding
the crown of an unerupted mandibular second premolar. The lesion is well-
corticated and the tooth is displaced. Histopathology reveals a thin,
nonkeratinized stratified squamous epithelium lining a fibrous capsule. The
, most likely diagnosis is:
A. Ameloblastoma
B. Odontogenic keratocyst
C. Adenomatoid odontogenic tumor
D. Dentigerous cyst
Answer: D
Rationale: A dentigerous cyst is an epithelium-lined developmental odontogenic
cyst that encloses the crown of an unerupted tooth and attaches at the
cementoenamel junction. Its radiographic appearance is a well-defined
unilocular radiolucency. The lining is nonkeratinized, distinguishing it from the
parakeratinized epithelium of an odontogenic keratocyst.
8. The principal immunoglobulin responsible for mucosal immunity in the oral
cavity is:
A. IgG
B. Secretory IgA
C. IgM
D. IgE
Answer: B
Rationale: Secretory IgA (sIgA) is produced by plasma cells in salivary glands and
transported through the epithelium as a dimer stabilized by the J chain and
secretory component. It neutralizes pathogens and prevents microbial adhesion
to oral mucosal surfaces.
9. In chronic periodontitis, the “red complex” consortium includes which of
the following bacteria?
A. Streptococcus mutans
B. Actinomyces naeslundii
C. Fusobacterium nucleatum
D. Porphyromonas gingivalis
Answer: D
Rationale: The red complex consists of Porphyromonas gingivalis, Tannerella
