A 'Recurrent Periodontal Abscess' That Was Never Periodontal
47-year-old woman, non-smoker, medically healthy, referred for a 'recurrent periodontal abscess' of the maxillary right lateral incisor (#7). The same mid-facial swelling has drained through the sulcus three times in 18 months; each episode settled after scaling and chlorhexidine and was labelled periodontal. She recalls a bicycle fall at age 12, and the tooth has been slightly grey since. Today there is no caries, no restoration, and no mobility. Cold: no response on #7; #6 and #8 respond briskly without lingering. Electric pulp test: #7 silent at 80/80. Percussion is mildly tender. Probing is 2-3 mm at all sites except a narrow 9 mm defect mid-facial that bleeds on probing; adjacent teeth probe at 3 mm. Periapical radiograph shows an intact lamina dura at the lateral incisor apex but a lateral radiolucency along the mid-root. CBCT shows a 4 mm cortical window mid-facial and a lateral canal, with no root fracture.
1. State the pulpal and periapical diagnosis and explain why the periodontal label is wrong. Which findings carry the most diagnostic weight, and what single additional test would you add?
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Diagnosis
- Pulpal: necrotic. Cold and EPT are both negative at maximum output, while both adjacent teeth respond normally, so the negative result is validated by controls.
- Apical: chronic apical abscess. A draining sinus tract is present even though it exits through the sulcus rather than attached gingiva.
Why this is not periodontal
- Probing is 2-3 mm everywhere except one narrow, isolated, bleeding 9 mm site. Generalized periodontal health around a single deep isolated defect is not periodontitis.
- The lateral radiolucency and the cortical window sit at mid-root level, exactly where the CBCT shows a lateral canal. That anatomy explains drainage at that level rather than at the apex, and it explains why scaling never cured it.
- Trauma at 12, grey discoloration, no caries or restoration, and no fracture on CBCT all point to a pulpal origin.
Diagnostic weight
- The greatest weight goes to the reproducible non-response to cold plus EPT with positive controls, followed by the CBCT demonstration of the lateral canal and cortical defect. A single negative vitality test without controls is weak evidence.
Test to add
- Trace the sinus tract with gutta-percha and radiograph it. If the cone stops at the lateral canal, the diagnosis is confirmed and you know where to look during treatment. Also check fremitus and occlusal contacts, since secondary occlusal trauma could slow healing of the mid-root defect.
2. Outline the treatment sequence. How would you manage the 9 mm defect, and what prognosis would you give for pocket resolution?
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Sequence
- Endodontics first. Periodontal surgery before the pulp is treated is the classic avoidable error in this presentation.
- Access and locate the lateral canal at the level predicted by the traced tract. Mid-root dentin is thin, so shape gently; over-enlargement here risks a strip perforation that turns a treatable case into an extraction.
- Irrigate with NaOCl and finish with EDTA; place calcium hydroxide if there is exudate.
- Obturate with warm vertical compaction and sealer. The lateral canal must be filled or the lesion will persist.
- Seal coronally with composite immediately, with no marginal gap.
Managing the defect
- Do not degranulate or aggressively scale the root surface now. The pocket is a drainage pathway through the attachment, and it will collapse once drainage stops.
- Postpone probing until 6 months; probing at 3 months can reopen a healing tract.
Prognosis
- A narrow, isolated defect with an identifiable endodontic cause generally heals well; I would expect the pocket to reduce to 3-4 mm in most cases.
- A residual pocket is possible because a true mid-root communication rarely regenerates attachment. That is a maintenance issue rather than a failure, and it should be explained in advance.
- Be candid that the tooth has thin mid-root walls and a trauma history: survival is good but not guaranteed, and a nightguard is sensible if there is parafunction.
3. At the 6-month review the tooth is asymptomatic and the periapical radiolucency has resolved, but the mid-facial pocket still measures 8 mm. What are your options and how do you decide?
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First, re-establish what the problem is now
- Re-probe and record bleeding and suppuration; take a periapical radiograph and a limited CBCT for unfilled lateral anatomy, fracture, or a separated instrument.
- If the endodontic lesion has healed and the residual pocket is not inflamed, this has become a periodontal problem.
Options if it is now periodontal
- Periodontal maintenance with careful root debridement: reasonable for a stable, non-bleeding, asymptomatic 8 mm site in a patient with excellent hygiene.
- Periodontal surgery: a narrow angular mid-root defect is a candidate for guided tissue regeneration or enamel matrix derivative, and this offers the best chance of reducing the pocket.
- Extraction is premature for an asymptomatic tooth with a healed apex.
Options if the CBCT shows a still-unfilled lateral canal or a persistent lesion at the same level
- Nonsurgical retreatment is difficult because the exit is mid-root; a root-end resection removes the apex but not the lateral exit.
- Intentional replantation becomes a consideration, but with a high risk of resorption and a narrow extraoral window.
Decision rule
- Base it on symptoms, inflammation on probing, and whether the defect is stable over 6-12 months. A stable, non-bleeding 8 mm site can be monitored; a bleeding, suppurating, progressing pocket needs surgery.
- Document the discussion, including that the earlier periodontal label may have cost 18 months of attachment.