Irreversible pulpitis in a pregnant patient: urgency, anaesthesia, and materials
A 34-year-old woman at 26 weeks' gestation presents with a 3-day history of spontaneous, throbbing pain in the mandibular right first molar that wakes her at night. The tooth has a large composite restoration; cold testing produces pain lasting 40 seconds, percussion is mildly tender, probing depths are 3 mm except 4 mm distally, and the tooth is not mobile. A periapical radiograph shows a 3-mm radiolucency at the mesial apex and a 2-mm coronal restoration–pulp distance. Maximum opening is 38 mm. She takes no regular medication and has no drug allergies. The dentist plans single-visit rotary root canal treatment under rubber dam but is unsure about anaesthesia, analgesia, and interim restoration because of the pregnancy. The patient is anxious and asks whether treatment can wait until after delivery.
1. What is the pulpal and periapical diagnosis, and should root canal treatment be deferred until after delivery? Explain your reasoning.
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The diagnosis is symptomatic irreversible pulpitis with symptomatic apical periodontitis in the mandibular right first molar. The spontaneous night pain and lingering cold response (>30 seconds) indicate irreversible pulpal inflammation; mild percussion tenderness and the 3-mm apical radiolucency indicate apical periodontitis. Deferral is not appropriate: untreated irreversible pulpitis will not resolve, and the patient is losing sleep and at risk of acute exacerbation. The second trimester is generally the safest period for necessary dental treatment; the risk of untreated infection and pain outweighs the risk of a carefully performed procedure. Treatment should be urgent but not emergent; arrange a morning appointment, use left lateral uterine displacement after 20 weeks, and keep appointments short. If she were in the first or third trimester, urgent pulp extirpation and analgesia would still be indicated, with definitive treatment timed appropriately.
2. Outline the local anaesthetic and analgesic plan, naming agents and doses to use or avoid.
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Use 2% lidocaine with 1:100,000 epinephrine for an inferior alveolar nerve block, with aspiration before injection. The maximum safe dose is about 4.4 mg/kg, not exceeding 300 mg; for a 65-kg patient this is roughly 286 mg, or about 14 mL of 2% solution, but the smallest effective volume should be used. Epinephrine is not contraindicated and improves haemostasis and anaesthesia. Avoid prilocaine in high doses because of methaemoglobinaemia risk, and avoid bupivacaine for routine use. For analgesia, acetaminophen 500–1,000 mg every 6 hours (maximum 3 g/day) is preferred. Avoid NSAIDs, especially in the third trimester, because of ductus arteriosus constriction, fetal renal effects, and oligohydramnios; avoid aspirin. Do not prescribe antibiotics unless there is systemic involvement or spreading infection; if needed, amoxicillin or cephalexin is appropriate, and metronidazole can be used after the first trimester if anaerobic coverage is required. Nitrous oxide may be used with appropriate precautions, but is not required.
3. How would you complete the visit and select the interim restoration, and what follow-up would you arrange?
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Complete root canal treatment in one visit if the canals are accessible and the patient is comfortable; single-visit treatment reduces the number of appointments and avoids repeated anaesthesia. Use a rubber dam, maintain left lateral displacement, and monitor for dizziness or supine hypotension. Irrigate with sodium hypochlorite carefully, avoiding extrusion; the pregnancy does not change the choice of irrigant. Obturate with a bioceramic sealer or conventional gutta-percha and sealer; there is no evidence that these materials are hazardous in pregnancy. Place a glass ionomer or resin-modified glass ionomer interim restoration rather than leaving a cotton pellet and temporary zinc oxide eugenol, because a durable seal prevents coronal leakage. Avoid elective full-coverage restoration until after delivery, but if the tooth is heavily broken down, a well-sealed interim build-up is acceptable. Arrange review at 1–2 weeks for symptoms and again after delivery for the definitive restoration; advise her to return if pain, swelling, or fever develops.