MJDF Dental Anatomy & Physiology 4

Question 1

What is the term for the junction between enamel and cementum on the tooth surface?

Accepted Answer

Cemento-enamel junction (CEJ)

Answer

The cemento-enamel junction (CEJ) marks the boundary between the enamel-covered crown and the cementum-covered root, serving as a critical clinical reference for attachment level measurements.

Question 2

What is the approximate percentage of inorganic content in mature enamel?

Accepted Answer

96%

Answer

Mature enamel is approximately 96% inorganic (hydroxyapatite crystals), making it the hardest and most mineralised tissue in the human body, with only about 1% organic matrix and 3% water.

Question 3

Which region of the pulp contains the highest density of nerve endings?

Accepted Answer

Sub-odontoblastic plexus of Raschkow

Answer

The plexus of Raschkow, located just below the odontoblast layer in the coronal pulp, contains a dense network of unmyelinated C-fibres and myelinated Aδ fibres responsible for pain perception.

Question 4

What is the biological mechanism by which dentine hypersensitivity is explained by the hydrodynamic theory?

Accepted Answer

Fluid movement in dentinal tubules triggers mechanoreceptors at the pulp-dentine boundary

Answer

Brannstrom's hydrodynamic theory proposes that stimuli (cold, touch, osmosis) cause rapid dentinal fluid movement, which activates Aδ fibres at the pulp-dentine boundary, producing a sharp pain response.

Question 5

How does secondary dentine differ from tertiary (reactionary) dentine?

Accepted Answer

Secondary forms throughout life at a slow rate; tertiary forms rapidly in response to injury

Answer

Secondary dentine deposits slowly throughout life, reducing pulp chamber volume; tertiary (reactionary or reparative) dentine forms rapidly in response to caries, attrition, or restorative procedures.

MJDF Part 1 Practice Test

MJDF Part 1 Practice Test

MJDF Dental Anatomy & Physiology 4