Free Enamel MCQs with Answers

• A. Enamel is harder than dentine
• B. Ameloblast secrete enamel and dentine
• C. Enamel has no cells
• D. Odontoblast produce dentin

Explanation: Ameloblasts form enamel only; odontoblasts form dentin, so the statement that ameloblasts secrete both is wrong.

• A. Ca3 (Po4)2 CaCo3
• B. 3Ca (Po4)2 Ca(OH)2
• C. CaPo4 Ca(OH)2
• D. None of the above

Explanation: Hydroxyapatite is written as Ca10(PO4)6(OH)2, or equivalently 3Ca3(PO4)2·Ca(OH)2.

• A. Furcation areas of permanent molars
• B. Occlusal surface of premolars
• C. On the incisal edges of incisors
• D. None of the above

Explanation: Enamel pearls are localized enamel deposits found most often in the cervical or furcation regions of permanent molars, where they may…

• A. Semipermeable membrane
• B. Impermeable membrane
• C. Permeable membrane
• D. Infrapermeable membrane

Explanation: Enamel is not completely impermeable; water and small ions can diffuse through its interprismatic spaces and pores.

• A. Neonantal bands
• B. Cross striations
• C. Striae of Retzius
• D. Hunter-Schregar bands

Explanation: Cross striations are transverse markings across enamel rods, usually appearing at about 4 μm intervals and representing the daily rhythm…

• A. Cracks
• B. Pellicle
• C. perikymata
• D. Enamel lamellae

Explanation: Perikymata are shallow horizontal grooves or ridges on the enamel surface formed where the striae of Retzius reach the surface.

• A. Aprismatic enamel
• B. Intratubular dentin
• C. Intertubular dentin
• D. Prismatic enamel

Explanation: In cross-section, each enamel rod with its surrounding interprismatic enamel produces the characteristic keyhole or arcade pattern of…

• A. Amelogenin
• B. Enamelin
• C. Tuftelin
• D. Ameloplakin

Explanation: Amelogenin is the predominant low-molecular-weight enamel matrix protein during enamel formation and helps regulate crystal growth.

• A. Organising
• B. Protective
• C. Formative/ Secretory
• D. Desmolytic

Explanation: Matrix metalloproteinase-20 is active mainly during the formative or secretory stage, where it processes newly secreted enamel matrix…

• A. Enamel lamella
• B. Enamel tuft
• C. Enamel spindle
• D. Enamel rod

Explanation: The enamel rod is the most highly mineralized of these structures and consists predominantly of tightly packed hydroxyapatite crystals.

• A. Ameloblast
• B. Outer enamel epithelium
• C. Stratum intermedium
• D. Stratum granulosum

Explanation: Ameloblasts are specialized secretory cells that synthesize and secrete enamel matrix proteins, including amelogenin.

• A. Mainly by odontoblasts
• B. Only by ameloblasts
• C. Only on odontoblasts
• D. Mainly by ameloblasts

Explanation: Enamel matrix is produced and laid down exclusively by ameloblasts, whereas odontoblasts form dentin.

• A. Presence of high percentage of organic matrix
• B. Presence of incremental lines
• C. Most of organic component is lost during mineralization
• D. Enamel has high reparative capacity

Explanation: Enamel is distinctive because most of its organic matrix is removed during mineralization, leaving it highly mineralized.

• A. Hypoplasia of local origin
• B. None of the above
• C. Hypoplasia of hereditary origin
• D. Hypoplasia of systemic origin

Explanation: Chronological hypoplasia results from a systemic disturbance affecting ameloblasts during a particular period, so the defect follows a…

• A. Scalloped and the convexities are directed towards dentin
• B. Straight
• C. Non-scalloped
• D. Scalloped and the convexities are directed towards enamel

Explanation: The dentinoenamel junction is scalloped, with its convexities directed toward dentin, allowing enamel and dentin to interlock…

• A. All of the above
• B. They are almost vertical near the incisal edge (or) cusp tip areas
• C. In the cervical third of deciduous crowns they are almost horizontal in direction
• D. In cervical region of permanent teeth, they deviate in apical direction
• E. They originate at right angle to dentin surface

Explanation: Enamel rods generally begin approximately perpendicular to the dentin surface, become nearly vertical near cusps and incisal edges, and…

• A. 2 μ m
• B. 9 μ m
• C. 7 μ m
• D. 4 μ m

Explanation: An enamel rod is typically about 4 to 8 μm in diameter, with approximately 4 μm being the standard figure used in basic histology…

• A. 35%
• B. 50%
• C. 4%
• D. 96%

Explanation: Mature enamel contains approximately 96% inorganic mineral by weight, mainly hydroxyapatite, with only small organic and water fractions.

• A. Enamel matrix
• B. DEJ
• C. CEJ
• D. Root

Explanation: Enamel calcification begins at the dentinoenamel junction and progresses outward toward the surface.

• A. It has only a small percent of organic content
• B. Its formative cells are lost once it is completely formed
• C. It is essentially a keratin tissue and has no blood vessels
• D. It has no direct connection with the active cells of the dental pulp

Explanation: Ameloblasts form enamel but are lost after enamel formation is complete, so mature enamel cannot regenerate itself.