To bleed or not to bleed: What every dental hygienist needs to know about antithrombotic agents

For many years, dentists and dental hygienists have been on the front lines of the debate over discontinuation of antiplatelet and anticoagulant agents prior to and after dental and dental hygiene procedures. While this debate has been ongoing with strong arguments on both sides of the issue, the addition of several new anticoagulants in recent years has only added to the confusion.¹

A look at both sides

Proponents of continuing the use of antiplatelet and anticoagulant agents in patients undergoing dental and dental hygiene procedures contend that by discontinuing the agent, the risk of formation of an embolism and, therefore, inducing a potentially life-threatening stroke, myocardial infarction, pulmonary embolism, or deep vein thrombosis far outweighs the benefit of reducing the risk of possible significant bleeding during or after the procedure. This may be especially true since dental and dental hygiene treatments rarely involve trauma to major blood vessels and thus may not result in serious hemorrhagic complications. Dental practitioners often have agents available in the office that can effectively promote rapid local hemostasis if necessary.²

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Proponents of discontinuation contend that in certain procedures, even moderate bleeding would be disadvantageous in achieving optimum outcomes. It is nearly impossible to anticipate if a procedure would or would not induce a potentially significant bleeding event, which many practitioners would be ill-equipped to manage in a dental office. Moreover, the potential for a significant bleeding event is highly variable from patient to patient since they may also be taking other medications, dietary supplements, etc., which may enhance the effect of antiplatelets and anticoagulants in unpredictable ways, further increasing the risk of significant peri- and postoperative bleeding.²

How antiplatelets work, and why they are prescribed

Antiplatelet agents work by inhibiting platelet function and aggregation and are distinct from anticoagulant agents, which work by inhibiting the production of clotting factors. The choice of antiplatelet or anticoagulant agent and duration of treatment depend on the individual’s specific medical condition and associated risk factors.

Antiplatelet agents are medications that help prevent the formation of blood clots by inhibiting platelet function and aggregation. The primary reason for prescribing these agents is for the prevention of cardiovascular events, such as myocardial infarctions and ischemic strokes, especially in patients predisposed to such events. However, antiplatelet agents may also be prescribed for patients who have already experienced these and other thrombotic events to reduce the risk of recurrence.³

In addition, antiplatelet agents (or anticoagulants) may be prescribed to patients with atrial fibrillation to reduce the risk of blood clots forming in the atria and to patients with peripheral arterial disease to improve blood flow and prevent clots from forming in the arteries of the limbs.

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Finally, antiplatelet agents may also be prescribed after certain procedures, such as coronary artery stent placement, to prevent stent thrombosis and maintain vessel patency, as well as after hospitalizations or other situations in which a patient has been immobilized for some time, to prevent deep vein thrombosis (DVT) and pulmonary embolism (PE).³

The pharmacology of antiplatelets

Common antiplatelet agents include aspirin, clopidogrel (Plavix), prasugrel (Effient), and ticagrelor (Brilinta). Aspirin works by irreversibly inhibiting the cyclooxygenase-1 enzyme, which is involved in the production of thromboxane A2, a potent platelet aggregator. Adverse effects of aspirin include gastrointestinal irritation and bleeding and, thus, aspirin is contraindicated in patients with a history of active peptic ulcers, bleeding disorders, gastrointestinal bleeding as well as a history of aspirin allergy.

Clopidogrel is a P2Y12 receptor antagonist that prevents ADP-induced platelet activation and aggregation. Adverse effects of clopidogrel include gastrointestinal upset, bleeding, and, rarely, a severe and life-threatening condition called thrombotic thrombocytopenic purpura (TTP). As such, clopidogrel is contraindicated in patients with active bleeding, a history of TTP, and hypersensitivity to the drug.

Prasugrel (Effient) and Ticagrelor (Brilinta) are also P2Y12 receptor antagonists that may incur a higher risk of bleeding compared to clopidogrel.⁴

How anticoagulants work

Anticoagulants are used to prevent the formation of blood clots or inhibit the growth of existing clots by inhibiting the production of certain clotting factors. They are commonly prescribed to reduce the risk of thromboembolic events such as deep vein thrombosis (DVT), pulmonary embolism (PE), and stroke. Many medications belong to this category, but their mechanisms of action, indications for use, and adverse effects vary.

Common anticoagulant agents include warfarin (Coumadin), direct oral anticoagulants (DOACs), heparin, and low molecular weight heparins (LMWHs).⁵ Warfarin (Coumadin) is a vitamin K antagonist that interferes with the clotting process by inhibiting the production of clotting factors II, VII, IX, and X.

Adverse effects and contraindications

Adverse effects of warfarin include bleeding and increased risk of hemorrhage. Routine INR (international normalized ratio) monitoring has been used successfully in determining the relative risk of hemorrhage for certain procedures in patients taking warfarin. Contraindications include active bleeding, a history of heparin-induced thrombocytopenia, severe liver disease, and pregnancy. Vitamin K₁ antagonizes the effect of warfarin, which is why patients taking warfarin are instructed to avoid dietary sources of vitamin K. Ultimately, warfarin is considered a narrow therapeutic index drug, which means that maintaining the right dosage is essential to prevent both bleeding and thrombosis. INR levels should be checked before performing any dental hygiene procedures.⁶

Direct oral anticoagulants (DOACs), also known as novel oral anticoagulants (NOACs), include dabigatran (Pradaxa), rivaroxaban (Xarelto), apixaban (Eliquis), and edoxaban (Savaysa). These agents directly target specific clotting factors (such as thrombin or factor Xa) to inhibit the coagulation cascade. Adverse effects may include bleeding, and, like warfarin, there may also be an increased risk of hemorrhage. However, unlike warfarin, DOACs do not require INR monitoring.

While many patients see this as advantageous, it’s more difficult to assess the risk of serious bleeding events. In addition, Vitamin K₁ does not antagonize the effect of these agents. Again, while the lack of dietary restrictions is seen as advantageous by many patients, these agents require specific antidotes, which can be quite costly. Contraindications are similar to warfarin and include active bleeding and severe renal or hepatic impairment. Ultimately, DOACs are thought to have a more predictable and consistent anticoagulant effect compared to warfarin.⁶

Heparin and LMWHs, such as enoxaparin (Lovenox), inhibit clot formation by enhancing the activity of antithrombin, a natural anticoagulant. While the primary adverse effect is bleeding, heparin-induced thrombocytopenia is also a rare but serious complication. Contraindications include active bleeding, a history of heparin-induced thrombocytopenia, and other conditions associated with an increased risk of active bleeding. Ultimately, heparin and LMWHs are not commonly used in dental care.⁶

Implications for dentistry

While some believe that oral anticoagulant therapy must be discontinued before dental treatment to prevent serious hemorrhagic complications, the potential for excessive bleeding with therapy must always be weighed against the potential for serious adverse effects resulting from discontinuation of such therapy. For patients undergoing dental procedures, routine discontinuation of oral anticoagulant therapy, especially DOACs, may put the patient at unnecessary risk for severe morbidity and mortality.⁷

We should be cautious about the risk of bleeding with antiplatelets and anticoagulants. Obtain a thorough medical history and medication list from patients to ensure safe hygiene therapy. Depending on the specific agent and the planned procedure, coordination with the dentist and patient’s health-care providers as well as possible regimen adjustments may be necessary to effectively manage the risk of bleeding.

Editor's note: This article appeared in the January/February 2024 print edition of RDH magazine. Dental hygienists in North America are eligible for a complimentary print subscription. Sign up here.

References

1. Shah AH, Almoallim HSK, Khan SQ, et al. Knowledge of medical and dental practitioners towards dental management of patients on anticoagulant and/or anti-platelet therapy. Saudi J Dent Res. 2015;6(2):91-97. doi:10.1016/j.sjdr.2014.10.002
2. Kumar AJ, Kumari MM, Arora N, Haritha A. Is anti-platelet therapy interruption a real clinical issue? Its implications in dentistry and particularly in periodontics. J Indian Soc Periodontol. 2009;13(3):121-125. doi:10.4103/0972-124X.60223
3. McNicol A, Israels SJ. Platelets and anti-platelet therapy. J Pharmacol Sci. 2003;93(4):381-396. doi:10.1254/jphs.93.381
4. Binazon O, Dubois-Gauche A, Nanau RM, Neuman MG. Efficacy and safety of platelet inhibitors. J Pharm Pharm Sci. 2013;16(1):1-39. doi:10.18433/j3mp4z
5. Reardon DP, Zemaitis C. Review of anticoagulants. In: Szumita RP, Szumita PM, eds. Hemostasis in Dentistry. Springer; 2018:99-108.
6. Wynn RL. New antiplatelet and anticoagulant drugs. Gen Dent. 2012;60(1):8-11.
7. Wahl MJ. The mythology of anticoagulation therapy interruption for dental surgery. J Am Dent Assoc. 2018;149(1):e1-e10. doi:10.1016/j.adaj.2017.09.05

With more than 30 years’ experience as a board-certified pharmacist, clinical educator, professional speaker, and published author, Tom Viola, RPh, CCP, has earned his reputation as the go-to specialist for making pharmacology practical and useful for dental teams. He is the founder of Pharmacology Declassified and is a member of the faculty of more than 10 dental professional degree programs. Viola has contributed to several professional journals and pharmacology textbooks, and currently serves as a consultant to the American Dental Association’s Council on Scientific Affairs.