Endodontics · patient case question
What is the source of the infection?
Patient case: Swelling and pain on a lower first molar
Patient: 32-year-old patient, emergency visit.
Chief complaint: Throbbing pain and a swelling on the lower right.
History: Two days of increasing pain, now spontaneous and keeping him awake. No systemic upset.
Findings: Gross carious lesion on tooth 30 with a periapical radiolucency. The tooth is tender to percussion and does not respond to cold testing. Localized vestibular swelling. The tooth is restorable with adequate remaining structure and normal periodontal support.
Show answer and explanation
Correct answer: A. The carious lesion
- A. CORRECT. The pathway is CARIES to pulpitis to pulpal necrosis to periapical abscess. Extensive caries let bacteria reach the pulp; the infection then exited through the apical foramen.
- B. A salivary stone affects the gland and duct, not the pulp.
- C. A periodontal pocket would produce a PERIODONTAL abscess lateral to the root, with a vital pulp and a different radiographic pattern.
- D. Occlusal trauma can cause widened PDL space and tenderness but does not seed a bacterial infection.