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NEET MDS Quiz - Practice Test
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Practice Test

oral surgery - 3 Questions

1
Oral Surgery
In which type of nerve fibres is sensitivity to local anaesthetics greater?
1) Type B fibres
2) Type C fibres
3) Type A‑delta fibres
4) Fibres supplying the muscle spindles

📝 Explanation:

Local anaesthetics act by blocking voltage‑gated sodium channels, preventing depolarization and conduction of nerve impulses. The sensitivity of different nerve fibres depends on their diameter, myelination, and conduction velocity.

  • Type B fibres

    • Small, myelinated preganglionic autonomic fibres.

    • Moderately sensitive to local anaesthetics.

  • Type C fibres

    • Smallest, unmyelinated fibres.

    • Carry dull, aching pain and temperature sensations.

    • Most sensitive to local anaesthetics because of their small diameter and lack of myelin.

  • Type A‑delta fibres

    • Small, thinly myelinated fibres.

    • Carry sharp, pricking pain.

    • Less sensitive than Type C fibres but more sensitive than larger A‑alpha fibres.

  • Fibres supplying muscle spindles (Type A‑alpha fibres)

    • Large, heavily myelinated fibres.

    • Conduct proprioception and motor signals.

    • Least sensitive to local anaesthetics due to their large diameter and thick myelin sheath.

 Local anaesthetics preferentially block small, unmyelinated fibres first (Type C), followed by small myelinated fibres (Type B, A‑delta). Large myelinated fibres (A‑alpha) are blocked last. This explains why pain sensation is lost before motor function during local anaesthesia.

2
Oral Surgery
The primary objective of removing bone when extracting a badly impacted mandibular third molar is to
1. expose the root bifurcation
2. expose the cervical line
3. allow proper closure of the wound
4. expose the height of contour of the tooth

📝 Explanation:

When extracting a badly impacted mandibular third molar, bone removal is often required to gain access to the tooth. The primary objective of bone removal is to expose the cervical line (cementoenamel junction) of the tooth.
Once the cervical line is exposed, elevators and forceps can be applied effectively to luxate and remove the tooth.
Exposing the root bifurcation or height of contour is not necessary for extraction.
Proper closure of the wound is a postoperative consideration, not the main purpose of bone removal.

3
Oral Surgery
Commonest complication after removal of mandibular 3rd molar
1) Lingual nerve damage
2) Dry socket
3) # mandible
4) Bleeding

📝 Explanation:

The most common complication following the removal of a mandibular third molar (wisdom tooth) is alveolar osteitis, commonly known as a "dry socket".

This condition occurs when the blood clot at the extraction site is lost prematurely, exposing the underlying bone.

It leads to significant pain and a foul odor, typically developing a few days after surgery.

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