Endodontics · patient case question
What is the source of the infection?
Patient case: Periapical abscess on the lower right first molar
Scenario: A PERIAPICAL ABSCESS on the lower right mandibular first molar.
Show answer and explanation
Correct answer: D. Necrotic pulp
- A. Hematogenous seeding of the periapex is exceedingly rare (anachoresis) and is not the standard mechanism.
- B. Salivary gland infection produces sialadenitis, an entirely separate condition.
- C. A periodontal abscess arises from an existing PERIODONTAL POCKET in a tooth with a VITAL pulp — a different entity, and pulp testing is what distinguishes the two.
- D. Correct. A periapical abscess arises from a NECROTIC PULP. Bacteria and their toxins exit through the apical foramen and provoke acute inflammation in the periapical tissues. The pathway is usually caries, then pulpitis, then necrosis, then periapical involvement.
Note: When facing an endodontic-versus-periodontal abscess question, PULP VITALITY is the deciding test: non-vital points to endodontic origin, vital points to periodontal origin. Combined endo-perio lesions exist and require both therapies.