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Periodontics · patient case question

What is the MOST likely sequence of events producing this lesion?

Patient case: Abandoned periodontal therapy with pain at tooth #29

Patient: Female, 55 years old

Chief Complaint: Pain in the lower right premolar region.

Background: Began scaling and root planing two years ago but never completed the course and did not return for review.

Current Findings: Generalised heavy subgingival calculus with profuse bleeding on probing. Deep pockets and generalised horizontal bone loss. A panoramic shows a periapical radiolucency associated with tooth #29 continuous with the marginal bone loss. Tooth #29 has no caries and no restoration.

  1. An independent endodontic lesion unrelated to the periodontal disease
  2. A primary endodontic lesion with secondary periodontal involvement
  3. A vertical root fracture
  4. A primary periodontal lesion with secondary endodontic involvement
Show answer and explanation

Correct answer: D. A primary periodontal lesion with secondary endodontic involvement

  • A. Coincidental independent lesions do occur, but here the periapical lucency is continuous with the marginal bone loss and the tooth has no independent cause of pulpal death.
  • B. A primary endodontic lesion begins in a necrotic pulp and drains coronally through the periodontal ligament, producing a NARROW, isolated probing defect at one point on a tooth that is otherwise periodontally sound. Neither the tooth nor the mouth fits that description.
  • C. A vertical root fracture produces a narrow J-shaped or halo radiolucency along the root with an isolated deep probing defect, usually in a root-filled or heavily restored tooth. This tooth is unrestored.
  • D. CORRECT. The tooth has no caries and no restoration, so there is no coronal route by which bacteria could have reached the pulp. What there IS is long-standing untreated periodontitis. Deep pocketing and progressive attachment loss expose lateral and accessory canals, and eventually the apical foramen, allowing bacteria and their products to reach the pulp from the periodontium. That is a primary periodontal lesion with secondary endodontic involvement.

Note: Sequence the treatment accordingly: address the ENDODONTIC component first (it heals predictably and quickly), then re-evaluate the periodontal response after non-surgical therapy before committing to periodontal surgery. Prognosis in a true combined lesion is governed by the PERIODONTAL component.

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