Deep Caries, a Fractured Marginal Ridge, and a Teenager Who Wants a Tooth-Coloured Restoration
A 17-year-old student attends with a fractured MOD amalgam in tooth 36 (FDI). She has had no spontaneous pain, but the tooth is sensitive to cold drinks for a few seconds and to biting. The radiograph shows recurrent caries extending to within 0.5 mm of the mesial pulp horn, with a normal periodontal ligament and intact lamina dura. Cold testing with refrigerant produces a sharp response that resolves within 3 seconds; percussion and palpation are not tender. The marginal ridge and distobuccal cusp are unsupported, and the adjacent 37 has a small occlusal composite. She drinks two energy drinks daily, and her mother reports night-time grinding. She wants "the white filling" because she is self-conscious about the amalgam. She is medically fit, takes no medication, has no allergies, and asks whether it can all be done in one visit.
1. Give the pulp diagnosis and justify your choice between selective caries removal with indirect pulp capping, a partial pulpotomy, and root canal treatment.
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Pulp diagnosis: reversible pulpitis. The evidence is a sharp cold response that resolves within 3 seconds, no spontaneous or night pain, no pain on percussion, no periapical change, and caries that is close to but not visibly communicating with the pulp. A lingering response (roughly beyond 5–10 seconds) or spontaneous pain would move the diagnosis toward irreversible pulpitis.
First choice: selective caries removal with a bioactive cap. Remove peripheral caries completely to sound, hard dentine, but over the deepest pulpal point leave soft, leathery, affected dentine and do not expose the pulp. Place a calcium silicate cement (MTA or a tricalcium silicate material) or a resin-modified glass ionomer over that dentine, then restore. This preserves pulp vitality and avoids the small but real risk of a pulpotomy in a 17-year-old whose tooth must survive decades.
Partial pulpotomy is the fallback: if a pulp exposure occurs, or bleeding cannot be controlled, amputate 1–2 mm with a sterile bur under rubber dam, achieve haemostasis with sodium hypochlorite, and place a calcium silicate. Success depends on haemostasis within a few minutes. Full pulpectomy is not indicated - there is no irreversible pulpitis, and it would sacrifice a healthy, fully formed pulp.
Modifying factors: her age means a large pulp with high reparative capacity and a better prognosis for vital pulp therapy; her grinding habit and the unsupported cusp mean the final restoration must protect the remaining tooth structure regardless of the pulp decision.
2. Explain the restorative design and material choice for this tooth, including how you would manage the unsupported cusp and the sensitivity risk.
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Design. The unsupported marginal ridge and distobuccal cusp mean a simple occlusal composite is likely to fail and may allow cuspal flexure and microleakage. Options in order of preference:
- Indirect cuspal-coverage onlay - the most conservative way to protect the weakened cusps while preserving enamel margins. Requires a provisional and a second visit, which conflicts with her single-visit request and must be negotiated.
- Direct composite with cuspal replacement and a bonded base - acceptable if the remaining walls give the composite enough support and the cusps can be built with a proper anatomical form and occlusal contacts centred on the restorative material rather than on unsupported enamel.
Base and material. A calcium silicate or RMGI base is placed first, then a bulk-fill composite in increments following the manufacturer's depth limits, with careful enamel etching (phosphoric acid) and a separate dentine bonding protocol, all under rubber dam - isolation is the single biggest determinant of longevity here. Avoid layering a large RMGI base that will dissolve or be left exposed at the margin.
Sensitivity risk. Post-operative sensitivity is driven by poor isolation, inadequate bonding, and pulpal inflammation rather than by the composite itself. Use a desensitizing/bonding strategy, avoid air-drying dentine aggressively, and check the occlusion so her grinding habit does not load a premature contact.
Adjuncts. Provide an occlusal splint for the reported bruxism, discuss the two energy drinks per day (erosion and sugar exposure), and give dietary and fluoride advice. If an indirect onlay is chosen, choose a material with a documented track record in molars and confirm adequate occlusal space.
3. State your follow-up plan and the clinical findings that would make you convert to a pulpectomy.
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Follow-up at 6–8 weeks, then 6 and 12 months. At each visit: spontaneous or night pain history, response to cold (and to percussion), tenderness to palpation, probing depths, restoration integrity and margins, and a periapical radiograph at 6 and 12 months to look for dentine bridge formation and periapical change.
Reassuring course: mild cold sensitivity that fades over 2–4 weeks, no spontaneous pain, a positive and non-lingering cold response, no percussion tenderness, and a normal periapical appearance.
Convert to pulpectomy if: spontaneous or night pain develops; the cold response becomes lingering; percussion tenderness or a sinus tract appears; a new periapical radiolucency or widening of the periodontal ligament develops; or the tooth becomes non-responsive and symptomatic. Also act if the patient reports pain that is not controlled by simple analgesia or if the provisional/base seal is lost and the pulp becomes re-infected.
Alternative escalation: if the pulp becomes exposed at review with uncontrollable haemorrhage, a partial pulpotomy rather than immediate full pulpectomy may still be considered in a young molar - but only with a stable haemorrhage and a good coronal seal.
Document the discussion: the patient should know that a small proportion of deeply carious teeth progress to irreversible pulpitis, and that attending review is what allows early, less invasive rescue.