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Dentistry · Oral histology and anatomy: acellular extrinsic fibre cementum
Sample itemWhich type of cementum covers the cervical two-thirds of the root, contains no cells and carries the main Sharpey's fibres that anchor the tooth?
Original practice item, not a recalled exam question. Nothing here is recorded.
The answer and the reasoning
B. Acellular extrinsic fibre cementum
Acellular extrinsic fibre cementum is formed slowly with the eruption of the tooth and is the main attachment tissue, with Sharpey's fibres embedded in it. Cellular intrinsic fibre cementum forms in repair of resorption, and the mixed stratified type lies in the apical region and furcations.
Option by option
A. Acellular afibrillar cementum
Acellular afibrillar cementum forms small patches on enamel near the cementoenamel junction.
B. Acellular extrinsic fibre cementum (correct)
Correct. This cementum anchors the tooth through embedded extrinsic fibres.
C. Cellular intrinsic fibre cementum
Cellular intrinsic fibre cementum fills in resorption defects and is not the main anchor.
D. Cellular mixed stratified cementum
Cellular mixed stratified cementum lies in the apical third and furcations.
Source note: Original NextPrep sample item — pending expert review. This item is original practice material awaiting independent expert review, so confirm important facts in a standard textbook.
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