Persistent Pain in a Cracked Mandibular Molar
A 39-year-old woman attends with a 3-month history of sharp pain in the lower left first molar (tooth 36) when chewing. The pain lasts 10–15 seconds after cold drinks and is never spontaneous. She has a large MOD amalgam, a visible crack in the distal marginal ridge, and a 4-mm distal pocket with bleeding. The bite-stick test reproduces pain on the buccal cusp; percussion is not tender. Cold testing produces a sharp response that resolves within 10 seconds. Radiographs show no periapical radiolucency, and the crestal bone is 2 mm below the cementoenamel junction. The tooth is not mobile; probing depths elsewhere are 2–3 mm. She has no known drug allergies and no bleeding disorder. She insists on keeping the tooth and asks whether a crown alone will solve the problem.
1. State the most likely pulpal and periapical diagnosis and explain how the history and tests support it.
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The most likely diagnosis is cracked tooth syndrome with reversible pulpitis and no apical periodontitis. The pain is provoked by chewing and cold, lasts only seconds, and is not spontaneous; the bite-stick test is positive on the buccal cusp, and a crack is visible in the distal marginal ridge. A normal percussion response and absence of periapical radiolucency argue against symptomatic apical periodontitis. The 4-mm distal pocket is a warning sign: an isolated deep pocket on a cracked tooth may mean the fracture extends subgingivally or toward the root. A cold response that resolves within 10 seconds fits reversible pulpitis; a lingering response or spontaneous pain would shift the diagnosis toward irreversible pulpitis. Because the pulp status can change and crack depth is uncertain, the diagnosis is provisional until the restoration is removed and the crack is inspected under magnification and transillumination.
2. The patient asks whether a crown alone will solve the problem. Explain your treatment plan and the prognostic factors that determine whether the tooth can be saved.
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A crown alone is not reliable if the crack already involves the pulp or extends subgingivally. The first step is to remove the amalgam and inspect the crack with magnification and transillumination. If the crack is confined to enamel and dentin and does not reach the pulp, a bonded core and immediate cuspal coverage-usually a provisional crown or an onlay-can splint the tooth and reduce flexure. If pulp exposure occurs, root canal treatment is needed before final restoration. If the crack extends more than about 2 mm below the gingival margin, involves the root, or produces a persistent narrow pocket, the tooth has a poor prognosis and extraction is usually more predictable. Other prognostic factors include whether the crack reaches the pulp or root, the presence of mobility, and the restorability of the tooth. I would not place a final crown until pulp status and crack depth are known.
3. How would the 4-mm distal pocket alter your decision if it persists after a provisional restoration?
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A persistent 4-mm distal pocket with bleeding after a well-adapted provisional restoration raises concern that the crack extends into the root or that the periodontal defect is independent. I would re-probe, take a periapical radiograph, and consider a CBCT to assess bone loss and crack extension. If the pocket is narrow and isolated, exploratory surgery may show a vertical root fracture; if fracture is confirmed, extraction is indicated. If the pocket is due to plaque and the crack is stable, periodontal therapy and re-evaluation may allow retention. The key is not to proceed to a final crown while an unexplained pocket persists, because cementation may mask a progressing fracture and lead to failure.