Failed Premolar With a Cast Post, a Buccal Perforation and an INR of 3.1

What the imaging tells us. Three findings shape the decision: a cast post occupying two-thirds of the root, a canal filling 3 mm short, and a lesion with cortical perforation extending to within 2 mm of the mental foramen. The short filling means the apical canal was never cleaned, so there is almost certainly an intraradicular cause of failure; the cortical perforation also suggests an extraradicular component or a cyst that will not resolve whatever is done inside the canal.

Nonsurgical retreatment. This addresses the actual cause and, if successful, is the more conservative option. However, removing a cast post from a premolar carries a real risk of vertical root fracture (reported in the low single digits but catastrophic when it occurs), risks damaging the 1.2-mm buccal wall, and may destroy the crown; if the post cannot be removed, the canal cannot be re-entered. Even after removal, negotiating the apical 3 mm of a prepared and possibly calcified canal with a lesion is not guaranteed. Success for retreatment of apical periodontitis is around 80–85% in favourable anatomy; here the anatomy is unfavourable.

Apical microsurgery. The CBCT already demonstrates a buccal cortical defect, which makes osteotomy straightforward and reduces the need for bone removal; the lesion can be enucleated, sent for histopathology, the root resected 3 mm with minimal or no bevel, a 3-mm retrograde preparation made with ultrasonic tips, and a bioceramic root-end filling placed. Success rates for contemporary microsurgery are comparable to retreatment and the procedure deals directly with the extraradicular component. The main risk is injury to the mental nerve, which lies 2 mm away; the mental foramen must be identified clinically and radiographically, and osteotomy confined accordingly.

Recommendation. Microsurgery is the better first choice here: it avoids the fracture risk of post removal, addresses a lesion that probably has an extraradicular component, and the existing cortical perforation makes access favourable. If the post were retrievable and the patient preferred to preserve the crown, an attempt at retreatment with ultrasonic post removal under the microscope would be defensible, with surgery as the fallback. His warfarin status does not preclude either option.

Anticoagulation. Warfarin must not be stopped for a routine endodontic microsurgical procedure. A mechanical mitral valve carries a high risk of thrombosis, and the morbidity of a stroke vastly exceeds that of bleeding from a small osteotomy. Current evidence supports performing minor oral surgery with an INR within the therapeutic range, commonly up to about 3.5, provided local haemostatic measures are used. I would check the INR within 24 hours of surgery, liaise with his cardiologist or anticoagulation clinic in writing, and proceed if the value is stable and acceptable; if the INR is above the agreed threshold, the procedure is deferred and the physician contacted rather than adjusting the drug myself.

Haemostasis. A 4.8% tranexamic acid mouthwash, 10 mL rinsed for 2 minutes before surgery and repeated after, then four times daily for 2–5 days, is the main adjunct. Add atraumatic full-thickness flap design with a papilla-preserving incision, a small osteotomy, a gelatin sponge or oxidised cellulose in the crypt if needed, and primary closure with 5-0 sutures plus gauze pressure for 10–15 minutes. Postoperative instructions include no rinsing or smoking for 24 hours and immediate contact if bleeding persists.

Anaesthesia and analgesia. Buccal infiltration plus inferior alveolar nerve block with 2% lidocaine 1:100,000, limited to about two cartridges; vasoconstrictor is not contraindicated with warfarin and improves surgical field control. For analgesia, paracetamol 500–1000 mg every 6 hours, maximum 4 g per day, is the drug of choice; NSAIDs such as ibuprofen or diclofenac are avoided because of the antiplatelet effect and gastrointestinal risk on anticoagulation. If an antibiotic is needed, amoxicillin is acceptable, but macrolides and metronidazole potentiate warfarin and should be avoided; any antibiotic prescription warrants an INR check.

Consent content. The consent discussion should cover: the diagnosis (persistent apical periodontitis with a short filling, a cast post and a buccal cortical perforation) and why the tooth has failed; the alternative options - nonsurgical retreatment with post removal, microsurgery, no treatment with monitoring, or extraction with later replacement; the specific risks of surgery, including temporary or permanent numbness, altered sensation or dysaesthesia of the lower lip and chin from mental nerve injury (more relevant here because the lesion lies 2 mm from the foramen), bleeding and haematoma, bruising, swelling, infection, sinus involvement, damage to the adjacent tooth, crown or restoration, wound dehiscence, and the possibility that the tooth is found to be fractured at surgery and is extracted; and the risk of post-removal fracture if retreatment is chosen.

He must also be told that the procedure will not restore lost tooth structure, that a new restoration or crown may be required, and that a treated tooth remains more brittle than a vital one. The financial cost of each option and the possibility that a second procedure might be needed should be stated. A signed, dated record with the alternatives discussed satisfies both clinical governance and the ethical duty of candour.

Prognosis. For contemporary microsurgery on a tooth with a favourable root-end seal, healing is roughly 85–90% at one year, but this estimate drops with a large lesion, an extraradicular component and previous post preparation. I would tell him that success is likely but not guaranteed, that healing will be judged radiographically at 6 and 12 months, and that if the tooth fails, extraction and a single implant after healing is a predictable option. His "quickest fix" framing should be answered directly: extraction is faster, but it costs him a tooth and commits him to replacement, whereas surgery gives a good chance of keeping the tooth with one procedure.