Dental patients receiving warfarin therapy

Editor, – We refer to 'Dental notes: Managing dental patients receiving warfarin therapy' (Aust Prescr 2002;25:69). This commentary is unfortunate because it presents the historical approach to managing patients on warfarin therapy and does not reflect current best practice.

The key issue is the risk: benefit analysis of ceasing warfarin and risking thromboembolism, versus reducing it and risking local wound bleeding. Any logical analysis clearly comes down on the side that if warfarin is indicated and has been appropriately prescribed, then one should leave it alone. The real and potential risks such as stroke or myocardial infarction are clearly catastrophic events, whereas at worst local wound bleeding is messy and inconvenient.

There is an extensive body of research which shows that the appropriate management of patients on warfarin who require dentoalveolar surgery is as follows:

• preoperative - check INR the day before the procedure to ensure it is within the therapeutic range for the patient. If greater than 4.0, advise the patient's physician and delay surgery until the INR is within the therapeutic range.
• intraoperative - the use of a local anaesthetic combined with a vasoconstrictor, plus a controlled, minimally traumatic surgical technique and local haemostatic methods are recommended. This includes irrigating the operative field with a 4.8% tranexamic acid solution. The sockets and mucoperiosteal flaps should then be sutured and oxidised cellulose gauze placed in the sockets.
• postoperative - the patients should be given a 4.8% tranexamic acid mouthwash with instructions to rinse with 10 mL of the solution for two minutes four times a day for 2-5 days.

There are some issues of supply, although most major hospitals on appropriate request from the patient's pharmacy, are happy to supply tranexamic acid. The pharmacy of the Royal Adelaide Hospital is certainly willing and able to provide appropriate advice on this.

It is appropriate for the patient's dentist and the treating general medical practitioner to review the patient's anticoagulation therapy. In our studies, we found over one-third of patients on warfarin either no longer met the clinical indications for this therapy, or had an inappropriate dosage and thus either a sub-therapeutic INR or an INR above 4.

Alastair N. Goss
Professor
and
Glen Carter
Registrar
Oral & Maxillofacial Surgery Unit
The University of Adelaide

Further reading

Sindet-Pedersen S, Ramstrom G, Bernvil S, Blomback M. Hemostatic effect of tranexamic acid mouthwash in anticoagulant-treated patients undergoing oral surgery. N Engl J Med 1989;320:840-3.
Borea G, Montebugnoli L, Capuzzi P, Magelli C. Tranexamic acid as a mouthwash in anticoagulant-treated patients undergoing oral surgery. An alternative method to discontinuing anticoagulant therapy. Oral Surg Oral Med Oral Pathol 1993;75:29-31.
Devani P, Lavery KM, Howell CJT. Dental extractions in patients on warfarin: is alteration of anticoagulant regime necessary? Br J Oral Maxillofac Surg 1998;36:107-11.
Wahl MJ. Dental surgery in anticoagulated patients [review]. Arch Intern Med 1998;158:1610-6.
Souto JC, Oliver A, Zuazu-Jausoro I, Vives A, Fontcuberta J. Oral surgery in anticoagulated patients without reducing the dose of oral anticoagulant: a prospective randomized study. J Oral Maxillofac Surg 1996;54:27-32.
Webster K, Wilde J. Management of anticoagulation in patients with prosthetic heart valves undergoing oral and maxillofacial operations. Br J Oral Maxillofac Surg 2000;38:124-6.

Professor Woods and Professor Savage, authors of 'Managing dental patients receiving warfarin therapy', comment:

We thank Professor Goss and Dr Carter for drawing attention to the management of minor oral surgery performed for patients taking warfarin. Certainly the procedure we recommend is based on the –historical– approach, it is well tested, safe and effective. In this respect our recommendations are consistent with recommendations of Professor Goss and Dr Carter. Essentially, dental management of patients having warfarin therapy is a matter of co-operation between dentists and the physician managing the patient–s coagulation.

Notwithstanding this comment, the use of tranexamic acid as a mouthwash is a promising development. The technique has been tested with a number of favourable reports in the literature. The present position however, for most dentists treating patients taking warfarin, is that they have no ready access to a tranexamic acid mouthwash, there is no proprietary tranexamic mouthwash available.

For the present, the majority of dentists treating patients having warfarin therapy have no ready access to or assistance from a teaching hospital and will in practical terms, have to rely on the 'historic' advice in the Dental Notes.