Free NBDE Sample Questions


401.                     What are the two primary cusps of the maxillary primary first molar?

a.       Mesial and distal

b.      Mesiobuccal and mesiolingual

c.       Distobuccal and distolingual

d.      Lingual and mesiobuccal

ANSWER: B. The distobuccal and distolingual cusps are small or absent.


402.                     Where might you find a parastyle on the maxillary primary first molar?

a.       On the mesiobuccal cusp

b.      Between the mesiobuccal and distobuccal cusps

c.       In the oblique ridge

d.      Between the facial roots

ANSWER: A. A parastyle is a nodule resembling a tiny cusp.


403.                     What are the cusps of the mandibular primary first molar?

a.       Mesiobuccal, distobuccal, mesiolingual, and distolingual.

b.      Mesiobuccal and distobuccal.

c.       Lingual, mesiobuccal, and distobuccal.

d.      Mesiobuccal, distobuccal, and mesiolingual.

ANSWER: A. There are four cusps on this tooth.


404.                     What does the labioincisal angle of the mandibular central incisor oppose?

a.       The lingua fossa of its counterpart

b.      The holding cusp of its maxillary counterpart

c.       The incisal edge of its counterpart

d.      The incisal edge of its counterpart and the maxillary lateral incisor

ANSWER: A. It also opposes the marginal ridge of its counterpart.


405.                     What does the mandibular lateral incisor oppose?

a.       It opposes the lingual fossae of its counterpart and of the maxillary central incisor.

b.      It opposes the mesial marginal ridge of the maxillary canine and the distal marginal ridge of the maxillary lateral incisor.

c.       It opposes the distal marginal ridge of the maxillary central incisor and the mesial marginal ridge of the maxillary lateral incisor.

d.      It opposes the mesial marginal ridge of its counterpart and the lingual fossa of the maxillary central incisor.

ANSWER: C. It also opposes the lingual fossa of its counterpart.


406.                     The maxillary lateral incisor overjets what tooth or teeth?

a.       The mandibular central incisor

b.      The mandibular canine

c.       The mandibular lateral incisor

d.      The mandibular central and lateral incisors

ANSWER: D. It overlaps and overjets both.


407.                     Which of the following does not describe one of Angle’s three arch classifications?

a.       Normal occlusion

b.      Neutrocclusion

c.       Distocclusion

d.      Mesiocclusion

ANSWER: A. Class I neutrocclusion is actually slightly different from normal occlusion.


408.                     Which of the following is part of the gingival unit?

a.       Alveolar bone

b.      Cementum

c.       Alveolar mucosa

d.      Collagen fiber attachment

ANSWER: C. The rest are part of the attachment apparatus.


409.                     What is the name for compact bone with collagen fibers from the cementum incorporated into it?

a.       Spongy bone

b.      Mucosa

c.       Circular fibers

d.      Bundle bone



410.                     Where can you find compact bone?

a.       Above the mucogingival junction

b.      In the free gingival groove

c.       Lining the alveolar socket

d.      Surrounding the condyles

ANSWER: C. This is also called the cribiform plate.


411.                     How is the cementum like the compact bone?

a.       They both act as the origin for collagen fibers of the principal groups.

b.      The have similar densities.

c.       They both form parts of the cribiform plate.

d.      They both invest the root structure of the tooth.

ANSWER: B. Compact bone is the attachment for collagen fibers, not the origin.


412.                     Where wouldn’t you find masticatory mucosa?

a.       Attached gingiva

b.      Free gingiva

c.       Vestibule

d.      Hard palate

ANSWER: C. It’s also found in the dorsum of the tongue.


413.                     You are looking at the lining epithelium of the free gingiva. What wouldn’t you expect to see?

a.       Keratinized epithelium

b.      Elastic fibers

c.       Dense collagenous connective tissue corium

d.      Thick epithelium

ANSWER: B. These are only present in the lining mucosa.


414.                     How wide is the attached gingiva?

a.       2-3mm

b.      1-2mm

c.       3.5-4mm

d.      It varies.

ANSWER: D. The width of the attached gingiva varies throughout the mouth.


415.                     Which of the following is above the base of the gingival sulcus?

a.       The crown of the tooth

b.      The muco-gingival junction

c.       The attached gingiva

d.      The vestibule

ANSWER: A. The free gingiva is also above this level.


416.                     What is the typical maximum height of the free gingiva?

a.       1mm

b.      2mm

c.       3mm

d.      4mm



417.                     Which of the following separates the free gingiva from the attached gingiva?

a.       Muco-gingival junction

b.      Gingival crest

c.       Free gingival groove

d.      Alveolar mucosa

ANSWER: C. It’s marked on the other side by the base of sulcus.


418.                     What is the name of the interproximal free gingiva?

a.       Papilla

b.      Sulcus

c.       Gingival crest

d.      Masticatory mucosa



419.                     The attachment apparatus consists of the collagen fiber attachment, cementum of the tooth, and what else?

a.       Dento-gingival group

b.      Periodontal fiber group

c.       Root

d.      Alveolar bone

ANSWER: D. “A” and “B” are part of the collagen fiber attachment.


420.                     Which of the following measures about 1mm?

a.       The distance between the crest of the alveolar bone and cervical line.

b.      The height of the free gingiva.

c.       The width of the cementum

d.      The distance between the disto-gingival and oblique fibers.

ANSWER: A. The crest is 1mm below the cervical line.


421.                     Which of the following fiber groups never run apically?

a.       Dento-periosteal

b.      Oblique

c.       Periodontal fiber group

d.      Transseptal group

ANSWER: D. The oblique fibers are part of the periodontal group.


422.                     Which of the following fiber groups is attached in the cementum?

a.       Circular fibers

b.      Dento-periosteal group

c.       Horizontal fibers

d.      Alveolar crestal fibers

ANSWER: B. “A” is also in the principal fiber group, but its fibers are unattached.


423.                     Which of the following fiber groups does not connect to the free or attached gingiva?

a.       Dento-gingival

b.      Circular fibers

c.       Dento-periosteal group

d.      Oblique

ANSWER: D. They run directly from the cementum to the bone.


424.                     What is the biggest difference between the principal fiber group and the alveolar-dental group?

a.       The latter attaches to the alveolar bone.

b.      The former can run over the alveolar crest.

c.       The latter is not attached to the cementum.

d.      The former is made up of fibers deeper on the tooth’s root.

ANSWER: A. Both attach to the cementum, but this differentiates them.


425.                     How do the fibers of the transseptal group get from the cementum of one tooth to the cementum of the other?

a.       They tunnel under the vestibule.

b.      Through the free gingiva

c.       They run over the alveolar crest bone.

d.       They move around the cementum apically.

ANSWER: C. The dento-periosteal nerves do the same.


426.                     What fibers connect to the alveolar crest?

a.       Alveolar crestal fibers

b.      Oblique fibers

c.       Transseptal fibers

d.      Dento-periosteal fibers

ANSWER: A. They move from the supra-alveolar cementum down.


427.                     Which of the following is a part of the alveolar-dental fiber group that runs straight across from the cementum to the alveolar bone?

a.       Horizontal

b.      Dento-gingival

c.       Dento-periosteal

d.      Circular

ANSWER: A. The other three options aren’t actually alveolar-dental.


428.                     The act of swallowing is generally broken down into three parts. Which isn’t one of them?

a.       Pharyngeal

b.      Oral

c.       Esophageal

d.      Lingual

ANSWER: D. Oral is also called voluntary.


429.                     In which of the following sections is the PDL thinnest?

a.       Apical 1/3

b.      Cervical 1/3

c.       Middle 1/3

d.      Cervical and apical 1/3

ANSWER: C. It is wider on the other two thirds.