All Free Oral Histology MCQs with Answers

• A. They elicit pain to hot and cold
• B. They elicit pain to touch and pressure
• C. They elicit pain to chemicals
• D. Elicit only pain as a response

Explanation: Dentin sensitivity is unusual because different stimuli applied to dentin are perceived mainly as pain rather than as distinct sensations…

• A. Cavity preparation
• B. Dehydration
• C. Water irrigation
• D. None of the above

Explanation: During cavity preparation, pressure changes and drying can cause odontoblasts or their processes to be displaced into dentinal tubules, a…

• A. Circumpulpal dentin
• B. Mantle dentin
• C. Predentin
• D. Secondary dentin

Explanation: Mantle dentin is the outermost dentin layer immediately beneath the dentinoenamel junction.

• A. Dentinal tubules
• B. Inter tubular dentin
• C. Peritubular dentin
• D. Circum pulpal dentin

Explanation: Peritubular dentin is more highly mineralized than intertubular dentin because it forms a mineral-rich sheath around each dentinal tubule.

• A. Black in transmitted light and white in reflected light
• B. Coarse fibril bundles arranged at right angle to the dentinal surface
• C. Dentinal tubules
• D. White in transmitted light and dark in reflected light

Explanation: Dead tracts are tubules containing air after the odontoblast processes have degenerated, so they appear black in transmitted light and…

• A. Concave
• B. S0shaped
• C. Straight
• D. None of the above

Explanation: Dentinal tubules follow an S-shaped course, especially in the crown, although they are relatively straighter near the root and cervical…

• A. Enamel
• B. Dentin
• C. Pulp
• D. Cementum

Explanation: Pulp is soft, vascular connective tissue and does not normally undergo calcification, whereas enamel, dentin, and cementum are mineralized…

• A. Incremental lines of retzius
• B. Incremental lines of von Ebner
• C. None of the above
• D. Contour lines lines of owen

Explanation: Contour lines of Owen are accentuated incremental lines in dentin that reflect disturbances or changes during dentin formation.

• A. Odontoclasts
• B. Osteoblasts
• C. Osteoclasts
• D. Odontoblasts

Explanation: Odontoclasts are the tooth-resorbing cells, functionally comparable to osteoclasts but specialized for dental hard tissues.

• 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.