All Free Oral Histology MCQs with Answers

• A. Dentin of all teeth, as if is formed first
• B. Enamel of permanent incisors
• C. Enamel of premolars
• D. Enamel of deciduous incisiors

Explanation: The neonatal line marks the abrupt change in mineralization associated with birth and is prominent in the enamel of primary teeth.

• A. Cusp tips of tooth
• B. Cervical region of tooth
• C. Proximal surface of tooth
• D. All of the above

Explanation: Gnarled or twisted enamel occurs where enamel rods change direction markedly, especially at cusp tips and incisal edges.

• A. 50 μ m
• B. 25 μ m
• C. 75 μ m
• D. 100 μ m

Explanation: The prismless enamel layer in primary teeth is a thin superficial layer of approximately 25 micrometres.

• A. Straight
• B. Shallow
• C. Bent
• D. Curved

Explanation: In permanent teeth, enamel rods are bent in the cervical region and near occlusal or incisal edges rather than following a uniformly…

• A. As lines in the enamel running at right angles to the enamel surface
• B. As lines in the dentin running at right angles to the dentino-enamel junction
• C. In dentin and follow the appositional pattern
• D. In enamel and follow the apposition pattern

Explanation: Lines of Retzius are incremental growth lines in enamel that record the appositional rhythm of ameloblast activity.

• A. Odontoblasts
• B. Ameloblasts
• C. Cracks
• D. Hypocalcified rods

Explanation: Enamel spindles are extensions of odontoblast processes that become trapped across the dentino-enamel junction during enamel formation.

• A. Hyperplasia
• B. Normal development
• C. Hypoplacification
• D. Interstitial development

Explanation: Perikymata are shallow grooves or ridges on the enamel surface that represent the external endings of the incremental lines of Retzius.

• A. A tumour of the jaw
• B. A tissue from which tooth erupts
• C. A cell from which tooth enamel is formed:
• D. Pertaining to dentin

Explanation: Ameloblasts are specialized epithelial cells that secrete and form the enamel matrix during amelogenesis.

• A. None of the above
• B. Square
• C. Round
• D. Key hole or paddle shaped

Explanation: In cross-section, most enamel rods have a keyhole or paddle-shaped outline, with a rounded head and a narrower tail.

• A. Enamel lamella
• B. Enamel spindles
• C. Enamel tufts
• D. Perikymata

Explanation: Enamel lamellae are thin, leaf-like hypomineralized structures that extend from the enamel surface toward, and sometimes reach, the…

• A. Less than the thickness of enamel
• B. Greater than the thickness of enamel
• C. Equal to the thickness of enimal
• D. None of the above

Explanation: Enamel rods are longer than the apparent enamel thickness because they run in a curved or oblique course from the dentinoenamel junction…

• A. 2.8
• B. 3.8
• C. 4.8
• D. 2.3

Explanation: Mature enamel has a specific gravity of approximately 2.8, reflecting its very high mineral content.

• A. Keratin like fibre
• B. Tono filament
• C. Collagen fibre
• D. Vimentin filament

Explanation: The organic component of enamel includes keratin-like fibrous proteins, although enamel is predominantly mineral.

• A. Dentin
• B. Enamel
• C. Cementum
• D. Periodontal ligament

Explanation: Mature enamel has no reparative capacity because ameloblasts are lost after enamel formation and enamel contains no living cells.

• A. Hunter schreger bands
• B. Enamel tufts
• C. Enamel spindles
• D. Enamel lamellae

Explanation: Enamel spindles are extensions of odontoblast processes that cross the dentinoenamel junction, so they are mesodermal in origin rather…

• A. 5 million
• B. 7 million
• C. 9 million
• D. 12 million

Explanation: A maxillary molar contains approximately 12 million enamel rods, reflecting its large crown surface and volume.

• A. Produced by ameloblasts
• B. Found in the region of cusps
• C. Surrounded by inter prismatic enamel
• D. Terminate as rounded process

Explanation: Enamel spindles are trapped odontoblast processes, not structures produced by ameloblasts.

• A. Enamel spindles
• B. Gnarled enamel
• C. Incremental lies of woven
• D. Incremental lines of retzius

Explanation: Gnarled enamel is formed by the intertwining and irregular course of enamel rods near cusp tips and incisal edges, where enamel must…

• A. Thin tuft like structure extending from enamel surface of dentin enamel junction
• B. None of the above
• C. Odontoblastic processes extending into enamel
• D. Tuft like structure arising from dentin-enamel junction towards enamel surface

Explanation: Enamel tufts arise from the dentinoenamel junction and extend a short distance into the enamel as hypomineralized tuft-like structures.

• A. Occlusal surface
• B. Middle third of buccal surface
• C. Middle third of lingual surface
• D. Cervical third of buccal surface

Explanation: Enamel is thickest over the occlusal surface, particularly around cusp regions, because these areas bear the greatest masticatory forces.