Asymptomatic apical radiolucency on a previously treated molar
Mr. R, 58, presents for a second-opinion consult on tooth #19. The tooth was root canal treated six years ago and carries a full-coverage crown; he reports no pain, no swelling, and no chewing discomfort. Probing depths are 3 mm or less on all surfaces with no bleeding on probing, and there is no sinus tract. A periapical radiograph shows a 6 x 8 mm well-defined radiolucency at the mesial root apex that is essentially unchanged when compared with a film taken four years ago. The crown margins are sealed and there is no caries. A limited CBCT shows intact buccal and lingual cortical plates, no root fracture, and no root resorption. Medical history is limited to well-controlled hypertension. He has read about implants online and asks whether the tooth should come out "before it causes trouble."
1. How do you decide whether this radiolucency represents a failing root canal treatment or a healed apical scar, and what findings would change your conclusion?
Read the worked answer
The radiograph is not the diagnosis; the trend and the clinical picture are.
Points toward a scar (no treatment indicated)
- Stable size and shape across four years - a failing endodontic case usually enlarges or at least changes.
- Well-defined, corticated border rather than a diffuse or expanding lesion.
- No symptoms, no sinus tract, no tenderness to percussion or palpation.
- No probing defect and no sulcular communication (a narrow deep pocket would suggest a draining sinus or root fracture).
- Intact cortical plates on CBCT; no fracture, no resorption.
Findings that would flip the decision
- New or enlarging radiolucency, loss of cortication, or cortical perforation.
- Development of a sinus tract, percussion sensitivity, or a deep isolated probing depth.
- A J-shaped lesion or a visible fracture line on CBCT.
- Symptoms on chewing that localize to that tooth after other teeth are ruled out.
Radiographic review over time is the highest-value test here; ordering more imaging now adds little. The key judgment is resisting the urge to treat a number that is not changing.
2. The patient's stated preference is extraction and an implant. Lay out the options and give your recommendation, including how you would frame the uncertainty to him.
Read the worked answer
Three options, each with its own failure mode:
- Retain and monitor. No intervention on a stable, asymptomatic, clinically sound tooth. Risk: something is smoldering and you lose a year of surveillance. Mitigation: 12-month periapical radiograph and clinical exam, with a defined trigger for retreatment (growth, symptoms, sinus tract).
- Nonsurgical retreatment. Addresses a possible missed canal or coronal leak, but carries real costs: crown removal and replacement, possible perforation, possible loss of the tooth anyway, and it treats a lesion that may not be disease.
- Extraction and implant. Replaces a functioning tooth with a surgical site, a healing period, a prosthesis, and its own complications (peri-implant disease, esthetic risk, cost). Implant survival in a molar site is good but not guaranteed, and revision is more costly than monitoring.
Recommendation: retain and monitor. Nothing in the record shows active disease, and the burden of proof sits with the intervention.
Framing: do not answer "should it come out" with a yes or no. Say plainly: "The shadow has not changed in four years, your tooth is comfortable and the gums are healthy, so I do not think the shadow is infection right now. Removing a tooth that is working is a bigger, permanent step than watching a spot that is stable. Here is what we will watch for, and here is what I would do if it changes." This respects autonomy without converting a patient's internet reading into an indication for surgery.