A root-filled molar with a narrow deep pocket and a J-shaped lesion
A 52-year-old man attends for a check-up. Tooth 36 was root canal treated 12 years ago and restored with a large mesio-occlusal composite; it has no symptoms and he is unaware of any problem. On examination there is a 9 mm isolated probing depth at the mid-buccal aspect with a narrow defect, no mobility, and the restoration margins are intact. The periapical radiograph shows a post-retained root filling in the mesial root with a 5 mm periapical radiolucency that extends coronally along the buccal aspect to the furcation, giving a J-shaped appearance. The remaining dentition is sound and periodontally healthy, with probing depths of 2-3 mm elsewhere. He is medically well, does not smoke, and asks whether he can 'just leave it, since it doesn't hurt'.
1. What is your differential diagnosis, and how would you narrow it before deciding on treatment?
Read the worked answer
The combination of an isolated narrow 9 mm pocket on a root-filled tooth with a J-shaped radiolucency is the classic presentation of a vertical root fracture, but it is a differential, not a diagnosis.
Differential:
- Vertical root fracture - most likely. The narrow, isolated, deep pocket on one aspect of a root-filled tooth is the discriminating sign; a periodontal lesion from plaque would not be that isolated in a periodontally healthy mouth.
- Endodontic failure with a draining sinus or an endo-perio lesion - possible; the post complicates retreatment but the coronal extension could reflect a lateral canal or an unfilled space.
- Perforation at the furcation, from post space preparation; a furcal radiolucency with a narrow pocket can mimic fracture.
- Periodontal abscess of a single site - unlikely without generalised disease or a local factor such as an overhang.
How to narrow it:
- CBCT is the key investigation: it is far more sensitive than periapical radiography for fracture lines, perforations and the true extent of bone loss, and it changes management when a fracture is confirmed.
- Probe the defect: a narrow, deep, localised pocket that is reproducible and does not respond to scaling supports fracture. Examine whether the two ends of the probe meet on the opposite side.
- Test vitality of adjacent teeth and check for a sinus tract, which would favour an endodontic cause.
- Take a careful history of the original restoration and any post placement.
Do not begin retreatment or surgery before this is resolved - a post-retained fracture is not treatable by any of those means.
2. If a fracture is confirmed, how do you present the options and justify your recommendation?
Read the worked answer
Recommendation: extraction with planned replacement, explained as a prognosis-led decision.
Reasoning to convey:
- A confirmed vertical root fracture has no predictable treatment. Neither retreatment nor apical surgery nor resective surgery addresses a fracture through the root; retaining it risks progressive bone loss at the site, which compromises any later implant.
- Its asymptomatic state is irrelevant to prognosis. Chronic infection with a deep defect can cause silent, continuing bone loss, and can flare with acute abscess at any time. This directly answers his 'leave it' question: symptoms are not the measure of disease.
Options to present neutrally, with costs and timeframes:
- Extraction plus implant - 3-4 months healing, adequate bone, good long-term outcome in a healthy non-smoker; requires adequate attached tissue and no residual infection.
- Extraction plus resin-bonded or conventional bridge using 35 and 37 - less surgery, but involves preparing or bonding to sound teeth.
- Extraction and accept a shortened arch - he has a healthy, sound remaining dentition and no reported masticatory problems; this is a legitimate option and often under-offered.
- Retain and monitor - only if he explicitly accepts the risks after being told that bone loss may make future replacement harder; document this.
Discuss timing: extraction when convenient, not as an emergency, since it is asymptomatic; but do not defer indefinitely. Also consider that if he waits and an acute abscess develops, he will need urgent care at a less convenient time.
3. He chooses extraction and asks whether the tooth could have been saved if he had attended earlier. How do you answer, and what are the consent implications?
Read the worked answer
Answer honestly and without assigning blame, while being clear about what is and is not known.
- A vertical root fracture is usually a late complication of loss of dentine support - often following post space preparation, heavy occlusal loading on a large restoration, or a history of root canal treatment in a tooth that then flexes. It is typically not detectable before it propagates.
- Whether earlier attendance would have changed the outcome is unknowable. Earlier review may have identified the deep pocket before extensive bone loss, but the fracture itself is not preventable once the tooth is in that configuration. Saying 'yes, if you had come earlier' overstates certainty.
- What is defensible is to say that regular review allows problems to be found while more options exist, which is true and useful.
Consent implications:
- Record the CBCT report or the clinical basis for the diagnosis of fracture - this is the pivotal evidence if the diagnosis is later questioned.
- Record that all options, including no treatment, were discussed with their risks and costs, and that the risk of continued bone loss with retention was explained.
- Record the discussion about replacement timing and the effect of extraction on the ridge.
- Avoid language in the notes that implies an earlier failure by another clinician unless there is evidence; describe findings, not blame.