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Oral Surgery · single question

Which flap characteristic is required for surgical extraction of an impacted third molar?

  1. Full-thickness (mucoperiosteal) flap with the base resting on sound bone
  2. Split-thickness flap with a narrow base
  3. A flap whose base is narrower than its free margin
  4. An envelope flap with no periosteal reflection
Show answer and explanation

Correct answer: A. Full-thickness (mucoperiosteal) flap with the base resting on sound bone

  • A. Correct. Third molar surgery requires a FULL-THICKNESS mucoperiosteal flap — mucosa, submucosa and periosteum reflected together as one layer — with a BROAD BASE that rests on SOLID, uncut bone. Margins must lie over intact bone so the flap is supported on closure, and the broad base preserves the blood supply.
  • B. Split-thickness flaps leave periosteum on the bone and are used in periodontal mucogingival surgery, not for bone removal in third molar surgery.
  • C. This is the classic flap design ERROR. The base must always be WIDER than the free margin to preserve perfusion; a narrow base risks flap necrosis.
  • D. Periosteal reflection is essential for access to the bone and for tooth sectioning.

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