Oral Surgery · single question
External root resorption affecting the DISTAL SURFACE of a lower second molar is caused by:
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Correct answer: C. Pressure from an impacted horizontally positioned lower third molar pushing against it
- A. Chronic pulpitis causes internal resorption from within the pulp — not external pressure resorption.
- B. Orthodontic forces can cause external apical resorption but not the specific distal surface pattern from third molar impaction.
- C. Correct. A HORIZONTALLY IMPACTED LOWER THIRD MOLAR that is pressed against the distal root of the second molar causes EXTERNAL PRESSURE RESORPTION of the second molar's distal root. The continuous pressure from the impacted tooth activates osteoclasts/odontoclasts on the root surface. This is a significant complication of impacted third molars and one reason for early removal consideration.
- D. Trauma can cause external resorption but is not the mechanism in this impacted third molar scenario.